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Adding zlib example files

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Avi Halachmi (:avih) 2014-04-27 01:33:37 +03:00
parent a86f2615be
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This directory contains examples of the use of zlib and other relevant
programs and documentation.
enough.c
calculation and justification of ENOUGH parameter in inftrees.h
- calculates the maximum table space used in inflate tree
construction over all possible Huffman codes
fitblk.c
compress just enough input to nearly fill a requested output size
- zlib isn't designed to do this, but fitblk does it anyway
gun.c
uncompress a gzip file
- illustrates the use of inflateBack() for high speed file-to-file
decompression using call-back functions
- is approximately twice as fast as gzip -d
- also provides Unix uncompress functionality, again twice as fast
gzappend.c
append to a gzip file
- illustrates the use of the Z_BLOCK flush parameter for inflate()
- illustrates the use of deflatePrime() to start at any bit
gzjoin.c
join gzip files without recalculating the crc or recompressing
- illustrates the use of the Z_BLOCK flush parameter for inflate()
- illustrates the use of crc32_combine()
gzlog.c
gzlog.h
efficiently and robustly maintain a message log file in gzip format
- illustrates use of raw deflate, Z_PARTIAL_FLUSH, deflatePrime(),
and deflateSetDictionary()
- illustrates use of a gzip header extra field
zlib_how.html
painfully comprehensive description of zpipe.c (see below)
- describes in excruciating detail the use of deflate() and inflate()
zpipe.c
reads and writes zlib streams from stdin to stdout
- illustrates the proper use of deflate() and inflate()
- deeply commented in zlib_how.html (see above)
zran.c
index a zlib or gzip stream and randomly access it
- illustrates the use of Z_BLOCK, inflatePrime(), and
inflateSetDictionary() to provide random access

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/* enough.c -- determine the maximum size of inflate's Huffman code tables over
* all possible valid and complete Huffman codes, subject to a length limit.
* Copyright (C) 2007, 2008, 2012 Mark Adler
* Version 1.4 18 August 2012 Mark Adler
*/
/* Version history:
1.0 3 Jan 2007 First version (derived from codecount.c version 1.4)
1.1 4 Jan 2007 Use faster incremental table usage computation
Prune examine() search on previously visited states
1.2 5 Jan 2007 Comments clean up
As inflate does, decrease root for short codes
Refuse cases where inflate would increase root
1.3 17 Feb 2008 Add argument for initial root table size
Fix bug for initial root table size == max - 1
Use a macro to compute the history index
1.4 18 Aug 2012 Avoid shifts more than bits in type (caused endless loop!)
Clean up comparisons of different types
Clean up code indentation
*/
/*
Examine all possible Huffman codes for a given number of symbols and a
maximum code length in bits to determine the maximum table size for zilb's
inflate. Only complete Huffman codes are counted.
Two codes are considered distinct if the vectors of the number of codes per
length are not identical. So permutations of the symbol assignments result
in the same code for the counting, as do permutations of the assignments of
the bit values to the codes (i.e. only canonical codes are counted).
We build a code from shorter to longer lengths, determining how many symbols
are coded at each length. At each step, we have how many symbols remain to
be coded, what the last code length used was, and how many bit patterns of
that length remain unused. Then we add one to the code length and double the
number of unused patterns to graduate to the next code length. We then
assign all portions of the remaining symbols to that code length that
preserve the properties of a correct and eventually complete code. Those
properties are: we cannot use more bit patterns than are available; and when
all the symbols are used, there are exactly zero possible bit patterns
remaining.
The inflate Huffman decoding algorithm uses two-level lookup tables for
speed. There is a single first-level table to decode codes up to root bits
in length (root == 9 in the current inflate implementation). The table
has 1 << root entries and is indexed by the next root bits of input. Codes
shorter than root bits have replicated table entries, so that the correct
entry is pointed to regardless of the bits that follow the short code. If
the code is longer than root bits, then the table entry points to a second-
level table. The size of that table is determined by the longest code with
that root-bit prefix. If that longest code has length len, then the table
has size 1 << (len - root), to index the remaining bits in that set of
codes. Each subsequent root-bit prefix then has its own sub-table. The
total number of table entries required by the code is calculated
incrementally as the number of codes at each bit length is populated. When
all of the codes are shorter than root bits, then root is reduced to the
longest code length, resulting in a single, smaller, one-level table.
The inflate algorithm also provides for small values of root (relative to
the log2 of the number of symbols), where the shortest code has more bits
than root. In that case, root is increased to the length of the shortest
code. This program, by design, does not handle that case, so it is verified
that the number of symbols is less than 2^(root + 1).
In order to speed up the examination (by about ten orders of magnitude for
the default arguments), the intermediate states in the build-up of a code
are remembered and previously visited branches are pruned. The memory
required for this will increase rapidly with the total number of symbols and
the maximum code length in bits. However this is a very small price to pay
for the vast speedup.
First, all of the possible Huffman codes are counted, and reachable
intermediate states are noted by a non-zero count in a saved-results array.
Second, the intermediate states that lead to (root + 1) bit or longer codes
are used to look at all sub-codes from those junctures for their inflate
memory usage. (The amount of memory used is not affected by the number of
codes of root bits or less in length.) Third, the visited states in the
construction of those sub-codes and the associated calculation of the table
size is recalled in order to avoid recalculating from the same juncture.
Beginning the code examination at (root + 1) bit codes, which is enabled by
identifying the reachable nodes, accounts for about six of the orders of
magnitude of improvement for the default arguments. About another four
orders of magnitude come from not revisiting previous states. Out of
approximately 2x10^16 possible Huffman codes, only about 2x10^6 sub-codes
need to be examined to cover all of the possible table memory usage cases
for the default arguments of 286 symbols limited to 15-bit codes.
Note that an unsigned long long type is used for counting. It is quite easy
to exceed the capacity of an eight-byte integer with a large number of
symbols and a large maximum code length, so multiple-precision arithmetic
would need to replace the unsigned long long arithmetic in that case. This
program will abort if an overflow occurs. The big_t type identifies where
the counting takes place.
An unsigned long long type is also used for calculating the number of
possible codes remaining at the maximum length. This limits the maximum
code length to the number of bits in a long long minus the number of bits
needed to represent the symbols in a flat code. The code_t type identifies
where the bit pattern counting takes place.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#define local static
/* special data types */
typedef unsigned long long big_t; /* type for code counting */
typedef unsigned long long code_t; /* type for bit pattern counting */
struct tab { /* type for been here check */
size_t len; /* length of bit vector in char's */
char *vec; /* allocated bit vector */
};
/* The array for saving results, num[], is indexed with this triplet:
syms: number of symbols remaining to code
left: number of available bit patterns at length len
len: number of bits in the codes currently being assigned
Those indices are constrained thusly when saving results:
syms: 3..totsym (totsym == total symbols to code)
left: 2..syms - 1, but only the evens (so syms == 8 -> 2, 4, 6)
len: 1..max - 1 (max == maximum code length in bits)
syms == 2 is not saved since that immediately leads to a single code. left
must be even, since it represents the number of available bit patterns at
the current length, which is double the number at the previous length.
left ends at syms-1 since left == syms immediately results in a single code.
(left > sym is not allowed since that would result in an incomplete code.)
len is less than max, since the code completes immediately when len == max.
The offset into the array is calculated for the three indices with the
first one (syms) being outermost, and the last one (len) being innermost.
We build the array with length max-1 lists for the len index, with syms-3
of those for each symbol. There are totsym-2 of those, with each one
varying in length as a function of sym. See the calculation of index in
count() for the index, and the calculation of size in main() for the size
of the array.
For the deflate example of 286 symbols limited to 15-bit codes, the array
has 284,284 entries, taking up 2.17 MB for an 8-byte big_t. More than
half of the space allocated for saved results is actually used -- not all
possible triplets are reached in the generation of valid Huffman codes.
*/
/* The array for tracking visited states, done[], is itself indexed identically
to the num[] array as described above for the (syms, left, len) triplet.
Each element in the array is further indexed by the (mem, rem) doublet,
where mem is the amount of inflate table space used so far, and rem is the
remaining unused entries in the current inflate sub-table. Each indexed
element is simply one bit indicating whether the state has been visited or
not. Since the ranges for mem and rem are not known a priori, each bit
vector is of a variable size, and grows as needed to accommodate the visited
states. mem and rem are used to calculate a single index in a triangular
array. Since the range of mem is expected in the default case to be about
ten times larger than the range of rem, the array is skewed to reduce the
memory usage, with eight times the range for mem than for rem. See the
calculations for offset and bit in beenhere() for the details.
For the deflate example of 286 symbols limited to 15-bit codes, the bit
vectors grow to total approximately 21 MB, in addition to the 4.3 MB done[]
array itself.
*/
/* Globals to avoid propagating constants or constant pointers recursively */
local int max; /* maximum allowed bit length for the codes */
local int root; /* size of base code table in bits */
local int large; /* largest code table so far */
local size_t size; /* number of elements in num and done */
local int *code; /* number of symbols assigned to each bit length */
local big_t *num; /* saved results array for code counting */
local struct tab *done; /* states already evaluated array */
/* Index function for num[] and done[] */
#define INDEX(i,j,k) (((size_t)((i-1)>>1)*((i-2)>>1)+(j>>1)-1)*(max-1)+k-1)
/* Free allocated space. Uses globals code, num, and done. */
local void cleanup(void)
{
size_t n;
if (done != NULL) {
for (n = 0; n < size; n++)
if (done[n].len)
free(done[n].vec);
free(done);
}
if (num != NULL)
free(num);
if (code != NULL)
free(code);
}
/* Return the number of possible Huffman codes using bit patterns of lengths
len through max inclusive, coding syms symbols, with left bit patterns of
length len unused -- return -1 if there is an overflow in the counting.
Keep a record of previous results in num to prevent repeating the same
calculation. Uses the globals max and num. */
local big_t count(int syms, int len, int left)
{
big_t sum; /* number of possible codes from this juncture */
big_t got; /* value returned from count() */
int least; /* least number of syms to use at this juncture */
int most; /* most number of syms to use at this juncture */
int use; /* number of bit patterns to use in next call */
size_t index; /* index of this case in *num */
/* see if only one possible code */
if (syms == left)
return 1;
/* note and verify the expected state */
assert(syms > left && left > 0 && len < max);
/* see if we've done this one already */
index = INDEX(syms, left, len);
got = num[index];
if (got)
return got; /* we have -- return the saved result */
/* we need to use at least this many bit patterns so that the code won't be
incomplete at the next length (more bit patterns than symbols) */
least = (left << 1) - syms;
if (least < 0)
least = 0;
/* we can use at most this many bit patterns, lest there not be enough
available for the remaining symbols at the maximum length (if there were
no limit to the code length, this would become: most = left - 1) */
most = (((code_t)left << (max - len)) - syms) /
(((code_t)1 << (max - len)) - 1);
/* count all possible codes from this juncture and add them up */
sum = 0;
for (use = least; use <= most; use++) {
got = count(syms - use, len + 1, (left - use) << 1);
sum += got;
if (got == (big_t)0 - 1 || sum < got) /* overflow */
return (big_t)0 - 1;
}
/* verify that all recursive calls are productive */
assert(sum != 0);
/* save the result and return it */
num[index] = sum;
return sum;
}
/* Return true if we've been here before, set to true if not. Set a bit in a
bit vector to indicate visiting this state. Each (syms,len,left) state
has a variable size bit vector indexed by (mem,rem). The bit vector is
lengthened if needed to allow setting the (mem,rem) bit. */
local int beenhere(int syms, int len, int left, int mem, int rem)
{
size_t index; /* index for this state's bit vector */
size_t offset; /* offset in this state's bit vector */
int bit; /* mask for this state's bit */
size_t length; /* length of the bit vector in bytes */
char *vector; /* new or enlarged bit vector */
/* point to vector for (syms,left,len), bit in vector for (mem,rem) */
index = INDEX(syms, left, len);
mem -= 1 << root;
offset = (mem >> 3) + rem;
offset = ((offset * (offset + 1)) >> 1) + rem;
bit = 1 << (mem & 7);
/* see if we've been here */
length = done[index].len;
if (offset < length && (done[index].vec[offset] & bit) != 0)
return 1; /* done this! */
/* we haven't been here before -- set the bit to show we have now */
/* see if we need to lengthen the vector in order to set the bit */
if (length <= offset) {
/* if we have one already, enlarge it, zero out the appended space */
if (length) {
do {
length <<= 1;
} while (length <= offset);
vector = realloc(done[index].vec, length);
if (vector != NULL)
memset(vector + done[index].len, 0, length - done[index].len);
}
/* otherwise we need to make a new vector and zero it out */
else {
length = 1 << (len - root);
while (length <= offset)
length <<= 1;
vector = calloc(length, sizeof(char));
}
/* in either case, bail if we can't get the memory */
if (vector == NULL) {
fputs("abort: unable to allocate enough memory\n", stderr);
cleanup();
exit(1);
}
/* install the new vector */
done[index].len = length;
done[index].vec = vector;
}
/* set the bit */
done[index].vec[offset] |= bit;
return 0;
}
/* Examine all possible codes from the given node (syms, len, left). Compute
the amount of memory required to build inflate's decoding tables, where the
number of code structures used so far is mem, and the number remaining in
the current sub-table is rem. Uses the globals max, code, root, large, and
done. */
local void examine(int syms, int len, int left, int mem, int rem)
{
int least; /* least number of syms to use at this juncture */
int most; /* most number of syms to use at this juncture */
int use; /* number of bit patterns to use in next call */
/* see if we have a complete code */
if (syms == left) {
/* set the last code entry */
code[len] = left;
/* complete computation of memory used by this code */
while (rem < left) {
left -= rem;
rem = 1 << (len - root);
mem += rem;
}
assert(rem == left);
/* if this is a new maximum, show the entries used and the sub-code */
if (mem > large) {
large = mem;
printf("max %d: ", mem);
for (use = root + 1; use <= max; use++)
if (code[use])
printf("%d[%d] ", code[use], use);
putchar('\n');
fflush(stdout);
}
/* remove entries as we drop back down in the recursion */
code[len] = 0;
return;
}
/* prune the tree if we can */
if (beenhere(syms, len, left, mem, rem))
return;
/* we need to use at least this many bit patterns so that the code won't be
incomplete at the next length (more bit patterns than symbols) */
least = (left << 1) - syms;
if (least < 0)
least = 0;
/* we can use at most this many bit patterns, lest there not be enough
available for the remaining symbols at the maximum length (if there were
no limit to the code length, this would become: most = left - 1) */
most = (((code_t)left << (max - len)) - syms) /
(((code_t)1 << (max - len)) - 1);
/* occupy least table spaces, creating new sub-tables as needed */
use = least;
while (rem < use) {
use -= rem;
rem = 1 << (len - root);
mem += rem;
}
rem -= use;
/* examine codes from here, updating table space as we go */
for (use = least; use <= most; use++) {
code[len] = use;
examine(syms - use, len + 1, (left - use) << 1,
mem + (rem ? 1 << (len - root) : 0), rem << 1);
if (rem == 0) {
rem = 1 << (len - root);
mem += rem;
}
rem--;
}
/* remove entries as we drop back down in the recursion */
code[len] = 0;
}
/* Look at all sub-codes starting with root + 1 bits. Look at only the valid
intermediate code states (syms, left, len). For each completed code,
calculate the amount of memory required by inflate to build the decoding
tables. Find the maximum amount of memory required and show the code that
requires that maximum. Uses the globals max, root, and num. */
local void enough(int syms)
{
int n; /* number of remaing symbols for this node */
int left; /* number of unused bit patterns at this length */
size_t index; /* index of this case in *num */
/* clear code */
for (n = 0; n <= max; n++)
code[n] = 0;
/* look at all (root + 1) bit and longer codes */
large = 1 << root; /* base table */
if (root < max) /* otherwise, there's only a base table */
for (n = 3; n <= syms; n++)
for (left = 2; left < n; left += 2)
{
/* look at all reachable (root + 1) bit nodes, and the
resulting codes (complete at root + 2 or more) */
index = INDEX(n, left, root + 1);
if (root + 1 < max && num[index]) /* reachable node */
examine(n, root + 1, left, 1 << root, 0);
/* also look at root bit codes with completions at root + 1
bits (not saved in num, since complete), just in case */
if (num[index - 1] && n <= left << 1)
examine((n - left) << 1, root + 1, (n - left) << 1,
1 << root, 0);
}
/* done */
printf("done: maximum of %d table entries\n", large);
}
/*
Examine and show the total number of possible Huffman codes for a given
maximum number of symbols, initial root table size, and maximum code length
in bits -- those are the command arguments in that order. The default
values are 286, 9, and 15 respectively, for the deflate literal/length code.
The possible codes are counted for each number of coded symbols from two to
the maximum. The counts for each of those and the total number of codes are
shown. The maximum number of inflate table entires is then calculated
across all possible codes. Each new maximum number of table entries and the
associated sub-code (starting at root + 1 == 10 bits) is shown.
To count and examine Huffman codes that are not length-limited, provide a
maximum length equal to the number of symbols minus one.
For the deflate literal/length code, use "enough". For the deflate distance
code, use "enough 30 6".
This uses the %llu printf format to print big_t numbers, which assumes that
big_t is an unsigned long long. If the big_t type is changed (for example
to a multiple precision type), the method of printing will also need to be
updated.
*/
int main(int argc, char **argv)
{
int syms; /* total number of symbols to code */
int n; /* number of symbols to code for this run */
big_t got; /* return value of count() */
big_t sum; /* accumulated number of codes over n */
code_t word; /* for counting bits in code_t */
/* set up globals for cleanup() */
code = NULL;
num = NULL;
done = NULL;
/* get arguments -- default to the deflate literal/length code */
syms = 286;
root = 9;
max = 15;
if (argc > 1) {
syms = atoi(argv[1]);
if (argc > 2) {
root = atoi(argv[2]);
if (argc > 3)
max = atoi(argv[3]);
}
}
if (argc > 4 || syms < 2 || root < 1 || max < 1) {
fputs("invalid arguments, need: [sym >= 2 [root >= 1 [max >= 1]]]\n",
stderr);
return 1;
}
/* if not restricting the code length, the longest is syms - 1 */
if (max > syms - 1)
max = syms - 1;
/* determine the number of bits in a code_t */
for (n = 0, word = 1; word; n++, word <<= 1)
;
/* make sure that the calculation of most will not overflow */
if (max > n || (code_t)(syms - 2) >= (((code_t)0 - 1) >> (max - 1))) {
fputs("abort: code length too long for internal types\n", stderr);
return 1;
}
/* reject impossible code requests */
if ((code_t)(syms - 1) > ((code_t)1 << max) - 1) {
fprintf(stderr, "%d symbols cannot be coded in %d bits\n",
syms, max);
return 1;
}
/* allocate code vector */
code = calloc(max + 1, sizeof(int));
if (code == NULL) {
fputs("abort: unable to allocate enough memory\n", stderr);
return 1;
}
/* determine size of saved results array, checking for overflows,
allocate and clear the array (set all to zero with calloc()) */
if (syms == 2) /* iff max == 1 */
num = NULL; /* won't be saving any results */
else {
size = syms >> 1;
if (size > ((size_t)0 - 1) / (n = (syms - 1) >> 1) ||
(size *= n, size > ((size_t)0 - 1) / (n = max - 1)) ||
(size *= n, size > ((size_t)0 - 1) / sizeof(big_t)) ||
(num = calloc(size, sizeof(big_t))) == NULL) {
fputs("abort: unable to allocate enough memory\n", stderr);
cleanup();
return 1;
}
}
/* count possible codes for all numbers of symbols, add up counts */
sum = 0;
for (n = 2; n <= syms; n++) {
got = count(n, 1, 2);
sum += got;
if (got == (big_t)0 - 1 || sum < got) { /* overflow */
fputs("abort: can't count that high!\n", stderr);
cleanup();
return 1;
}
printf("%llu %d-codes\n", got, n);
}
printf("%llu total codes for 2 to %d symbols", sum, syms);
if (max < syms - 1)
printf(" (%d-bit length limit)\n", max);
else
puts(" (no length limit)");
/* allocate and clear done array for beenhere() */
if (syms == 2)
done = NULL;
else if (size > ((size_t)0 - 1) / sizeof(struct tab) ||
(done = calloc(size, sizeof(struct tab))) == NULL) {
fputs("abort: unable to allocate enough memory\n", stderr);
cleanup();
return 1;
}
/* find and show maximum inflate table usage */
if (root > max) /* reduce root to max length */
root = max;
if ((code_t)syms < ((code_t)1 << (root + 1)))
enough(syms);
else
puts("cannot handle minimum code lengths > root");
/* done */
cleanup();
return 0;
}

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/* fitblk.c: example of fitting compressed output to a specified size
Not copyrighted -- provided to the public domain
Version 1.1 25 November 2004 Mark Adler */
/* Version history:
1.0 24 Nov 2004 First version
1.1 25 Nov 2004 Change deflateInit2() to deflateInit()
Use fixed-size, stack-allocated raw buffers
Simplify code moving compression to subroutines
Use assert() for internal errors
Add detailed description of approach
*/
/* Approach to just fitting a requested compressed size:
fitblk performs three compression passes on a portion of the input
data in order to determine how much of that input will compress to
nearly the requested output block size. The first pass generates
enough deflate blocks to produce output to fill the requested
output size plus a specfied excess amount (see the EXCESS define
below). The last deflate block may go quite a bit past that, but
is discarded. The second pass decompresses and recompresses just
the compressed data that fit in the requested plus excess sized
buffer. The deflate process is terminated after that amount of
input, which is less than the amount consumed on the first pass.
The last deflate block of the result will be of a comparable size
to the final product, so that the header for that deflate block and
the compression ratio for that block will be about the same as in
the final product. The third compression pass decompresses the
result of the second step, but only the compressed data up to the
requested size minus an amount to allow the compressed stream to
complete (see the MARGIN define below). That will result in a
final compressed stream whose length is less than or equal to the
requested size. Assuming sufficient input and a requested size
greater than a few hundred bytes, the shortfall will typically be
less than ten bytes.
If the input is short enough that the first compression completes
before filling the requested output size, then that compressed
stream is return with no recompression.
EXCESS is chosen to be just greater than the shortfall seen in a
two pass approach similar to the above. That shortfall is due to
the last deflate block compressing more efficiently with a smaller
header on the second pass. EXCESS is set to be large enough so
that there is enough uncompressed data for the second pass to fill
out the requested size, and small enough so that the final deflate
block of the second pass will be close in size to the final deflate
block of the third and final pass. MARGIN is chosen to be just
large enough to assure that the final compression has enough room
to complete in all cases.
*/
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include "zlib.h"
#define local static
/* print nastygram and leave */
local void quit(char *why)
{
fprintf(stderr, "fitblk abort: %s\n", why);
exit(1);
}
#define RAWLEN 4096 /* intermediate uncompressed buffer size */
/* compress from file to def until provided buffer is full or end of
input reached; return last deflate() return value, or Z_ERRNO if
there was read error on the file */
local int partcompress(FILE *in, z_streamp def)
{
int ret, flush;
unsigned char raw[RAWLEN];
flush = Z_NO_FLUSH;
do {
def->avail_in = fread(raw, 1, RAWLEN, in);
if (ferror(in))
return Z_ERRNO;
def->next_in = raw;
if (feof(in))
flush = Z_FINISH;
ret = deflate(def, flush);
assert(ret != Z_STREAM_ERROR);
} while (def->avail_out != 0 && flush == Z_NO_FLUSH);
return ret;
}
/* recompress from inf's input to def's output; the input for inf and
the output for def are set in those structures before calling;
return last deflate() return value, or Z_MEM_ERROR if inflate()
was not able to allocate enough memory when it needed to */
local int recompress(z_streamp inf, z_streamp def)
{
int ret, flush;
unsigned char raw[RAWLEN];
flush = Z_NO_FLUSH;
do {
/* decompress */
inf->avail_out = RAWLEN;
inf->next_out = raw;
ret = inflate(inf, Z_NO_FLUSH);
assert(ret != Z_STREAM_ERROR && ret != Z_DATA_ERROR &&
ret != Z_NEED_DICT);
if (ret == Z_MEM_ERROR)
return ret;
/* compress what was decompresed until done or no room */
def->avail_in = RAWLEN - inf->avail_out;
def->next_in = raw;
if (inf->avail_out != 0)
flush = Z_FINISH;
ret = deflate(def, flush);
assert(ret != Z_STREAM_ERROR);
} while (ret != Z_STREAM_END && def->avail_out != 0);
return ret;
}
#define EXCESS 256 /* empirically determined stream overage */
#define MARGIN 8 /* amount to back off for completion */
/* compress from stdin to fixed-size block on stdout */
int main(int argc, char **argv)
{
int ret; /* return code */
unsigned size; /* requested fixed output block size */
unsigned have; /* bytes written by deflate() call */
unsigned char *blk; /* intermediate and final stream */
unsigned char *tmp; /* close to desired size stream */
z_stream def, inf; /* zlib deflate and inflate states */
/* get requested output size */
if (argc != 2)
quit("need one argument: size of output block");
ret = strtol(argv[1], argv + 1, 10);
if (argv[1][0] != 0)
quit("argument must be a number");
if (ret < 8) /* 8 is minimum zlib stream size */
quit("need positive size of 8 or greater");
size = (unsigned)ret;
/* allocate memory for buffers and compression engine */
blk = malloc(size + EXCESS);
def.zalloc = Z_NULL;
def.zfree = Z_NULL;
def.opaque = Z_NULL;
ret = deflateInit(&def, Z_DEFAULT_COMPRESSION);
if (ret != Z_OK || blk == NULL)
quit("out of memory");
/* compress from stdin until output full, or no more input */
def.avail_out = size + EXCESS;
def.next_out = blk;
ret = partcompress(stdin, &def);
if (ret == Z_ERRNO)
quit("error reading input");
/* if it all fit, then size was undersubscribed -- done! */
if (ret == Z_STREAM_END && def.avail_out >= EXCESS) {
/* write block to stdout */
have = size + EXCESS - def.avail_out;
if (fwrite(blk, 1, have, stdout) != have || ferror(stdout))
quit("error writing output");
/* clean up and print results to stderr */
ret = deflateEnd(&def);
assert(ret != Z_STREAM_ERROR);
free(blk);
fprintf(stderr,
"%u bytes unused out of %u requested (all input)\n",
size - have, size);
return 0;
}
/* it didn't all fit -- set up for recompression */
inf.zalloc = Z_NULL;
inf.zfree = Z_NULL;
inf.opaque = Z_NULL;
inf.avail_in = 0;
inf.next_in = Z_NULL;
ret = inflateInit(&inf);
tmp = malloc(size + EXCESS);
if (ret != Z_OK || tmp == NULL)
quit("out of memory");
ret = deflateReset(&def);
assert(ret != Z_STREAM_ERROR);
/* do first recompression close to the right amount */
inf.avail_in = size + EXCESS;
inf.next_in = blk;
def.avail_out = size + EXCESS;
def.next_out = tmp;
ret = recompress(&inf, &def);
if (ret == Z_MEM_ERROR)
quit("out of memory");
/* set up for next reocmpression */
ret = inflateReset(&inf);
assert(ret != Z_STREAM_ERROR);
ret = deflateReset(&def);
assert(ret != Z_STREAM_ERROR);
/* do second and final recompression (third compression) */
inf.avail_in = size - MARGIN; /* assure stream will complete */
inf.next_in = tmp;
def.avail_out = size;
def.next_out = blk;
ret = recompress(&inf, &def);
if (ret == Z_MEM_ERROR)
quit("out of memory");
assert(ret == Z_STREAM_END); /* otherwise MARGIN too small */
/* done -- write block to stdout */
have = size - def.avail_out;
if (fwrite(blk, 1, have, stdout) != have || ferror(stdout))
quit("error writing output");
/* clean up and print results to stderr */
free(tmp);
ret = inflateEnd(&inf);
assert(ret != Z_STREAM_ERROR);
ret = deflateEnd(&def);
assert(ret != Z_STREAM_ERROR);
free(blk);
fprintf(stderr,
"%u bytes unused out of %u requested (%lu input)\n",
size - have, size, def.total_in);
return 0;
}

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@ -0,0 +1,702 @@
/* gun.c -- simple gunzip to give an example of the use of inflateBack()
* Copyright (C) 2003, 2005, 2008, 2010, 2012 Mark Adler
* For conditions of distribution and use, see copyright notice in zlib.h
Version 1.7 12 August 2012 Mark Adler */
/* Version history:
1.0 16 Feb 2003 First version for testing of inflateBack()
1.1 21 Feb 2005 Decompress concatenated gzip streams
Remove use of "this" variable (C++ keyword)
Fix return value for in()
Improve allocation failure checking
Add typecasting for void * structures
Add -h option for command version and usage
Add a bunch of comments
1.2 20 Mar 2005 Add Unix compress (LZW) decompression
Copy file attributes from input file to output file
1.3 12 Jun 2005 Add casts for error messages [Oberhumer]
1.4 8 Dec 2006 LZW decompression speed improvements
1.5 9 Feb 2008 Avoid warning in latest version of gcc
1.6 17 Jan 2010 Avoid signed/unsigned comparison warnings
1.7 12 Aug 2012 Update for z_const usage in zlib 1.2.8
*/
/*
gun [ -t ] [ name ... ]
decompresses the data in the named gzip files. If no arguments are given,
gun will decompress from stdin to stdout. The names must end in .gz, -gz,
.z, -z, _z, or .Z. The uncompressed data will be written to a file name
with the suffix stripped. On success, the original file is deleted. On
failure, the output file is deleted. For most failures, the command will
continue to process the remaining names on the command line. A memory
allocation failure will abort the command. If -t is specified, then the
listed files or stdin will be tested as gzip files for integrity (without
checking for a proper suffix), no output will be written, and no files
will be deleted.
Like gzip, gun allows concatenated gzip streams and will decompress them,
writing all of the uncompressed data to the output. Unlike gzip, gun allows
an empty file on input, and will produce no error writing an empty output
file.
gun will also decompress files made by Unix compress, which uses LZW
compression. These files are automatically detected by virtue of their
magic header bytes. Since the end of Unix compress stream is marked by the
end-of-file, they cannot be concantenated. If a Unix compress stream is
encountered in an input file, it is the last stream in that file.
Like gunzip and uncompress, the file attributes of the orignal compressed
file are maintained in the final uncompressed file, to the extent that the
user permissions allow it.
On my Mac OS X PowerPC G4, gun is almost twice as fast as gunzip (version
1.2.4) is on the same file, when gun is linked with zlib 1.2.2. Also the
LZW decompression provided by gun is about twice as fast as the standard
Unix uncompress command.
*/
/* external functions and related types and constants */
#include <stdio.h> /* fprintf() */
#include <stdlib.h> /* malloc(), free() */
#include <string.h> /* strerror(), strcmp(), strlen(), memcpy() */
#include <errno.h> /* errno */
#include <fcntl.h> /* open() */
#include <unistd.h> /* read(), write(), close(), chown(), unlink() */
#include <sys/types.h>
#include <sys/stat.h> /* stat(), chmod() */
#include <utime.h> /* utime() */
#include "zlib.h" /* inflateBackInit(), inflateBack(), */
/* inflateBackEnd(), crc32() */
/* function declaration */
#define local static
/* buffer constants */
#define SIZE 32768U /* input and output buffer sizes */
#define PIECE 16384 /* limits i/o chunks for 16-bit int case */
/* structure for infback() to pass to input function in() -- it maintains the
input file and a buffer of size SIZE */
struct ind {
int infile;
unsigned char *inbuf;
};
/* Load input buffer, assumed to be empty, and return bytes loaded and a
pointer to them. read() is called until the buffer is full, or until it
returns end-of-file or error. Return 0 on error. */
local unsigned in(void *in_desc, z_const unsigned char **buf)
{
int ret;
unsigned len;
unsigned char *next;
struct ind *me = (struct ind *)in_desc;
next = me->inbuf;
*buf = next;
len = 0;
do {
ret = PIECE;
if ((unsigned)ret > SIZE - len)
ret = (int)(SIZE - len);
ret = (int)read(me->infile, next, ret);
if (ret == -1) {
len = 0;
break;
}
next += ret;
len += ret;
} while (ret != 0 && len < SIZE);
return len;
}
/* structure for infback() to pass to output function out() -- it maintains the
output file, a running CRC-32 check on the output and the total number of
bytes output, both for checking against the gzip trailer. (The length in
the gzip trailer is stored modulo 2^32, so it's ok if a long is 32 bits and
the output is greater than 4 GB.) */
struct outd {
int outfile;
int check; /* true if checking crc and total */
unsigned long crc;
unsigned long total;
};
/* Write output buffer and update the CRC-32 and total bytes written. write()
is called until all of the output is written or an error is encountered.
On success out() returns 0. For a write failure, out() returns 1. If the
output file descriptor is -1, then nothing is written.
*/
local int out(void *out_desc, unsigned char *buf, unsigned len)
{
int ret;
struct outd *me = (struct outd *)out_desc;
if (me->check) {
me->crc = crc32(me->crc, buf, len);
me->total += len;
}
if (me->outfile != -1)
do {
ret = PIECE;
if ((unsigned)ret > len)
ret = (int)len;
ret = (int)write(me->outfile, buf, ret);
if (ret == -1)
return 1;
buf += ret;
len -= ret;
} while (len != 0);
return 0;
}
/* next input byte macro for use inside lunpipe() and gunpipe() */
#define NEXT() (have ? 0 : (have = in(indp, &next)), \
last = have ? (have--, (int)(*next++)) : -1)
/* memory for gunpipe() and lunpipe() --
the first 256 entries of prefix[] and suffix[] are never used, could
have offset the index, but it's faster to waste the memory */
unsigned char inbuf[SIZE]; /* input buffer */
unsigned char outbuf[SIZE]; /* output buffer */
unsigned short prefix[65536]; /* index to LZW prefix string */
unsigned char suffix[65536]; /* one-character LZW suffix */
unsigned char match[65280 + 2]; /* buffer for reversed match or gzip
32K sliding window */
/* throw out what's left in the current bits byte buffer (this is a vestigial
aspect of the compressed data format derived from an implementation that
made use of a special VAX machine instruction!) */
#define FLUSHCODE() \
do { \
left = 0; \
rem = 0; \
if (chunk > have) { \
chunk -= have; \
have = 0; \
if (NEXT() == -1) \
break; \
chunk--; \
if (chunk > have) { \
chunk = have = 0; \
break; \
} \
} \
have -= chunk; \
next += chunk; \
chunk = 0; \
} while (0)
/* Decompress a compress (LZW) file from indp to outfile. The compress magic
header (two bytes) has already been read and verified. There are have bytes
of buffered input at next. strm is used for passing error information back
to gunpipe().
lunpipe() will return Z_OK on success, Z_BUF_ERROR for an unexpected end of
file, read error, or write error (a write error indicated by strm->next_in
not equal to Z_NULL), or Z_DATA_ERROR for invalid input.
*/
local int lunpipe(unsigned have, z_const unsigned char *next, struct ind *indp,
int outfile, z_stream *strm)
{
int last; /* last byte read by NEXT(), or -1 if EOF */
unsigned chunk; /* bytes left in current chunk */
int left; /* bits left in rem */
unsigned rem; /* unused bits from input */
int bits; /* current bits per code */
unsigned code; /* code, table traversal index */
unsigned mask; /* mask for current bits codes */
int max; /* maximum bits per code for this stream */
unsigned flags; /* compress flags, then block compress flag */
unsigned end; /* last valid entry in prefix/suffix tables */
unsigned temp; /* current code */
unsigned prev; /* previous code */
unsigned final; /* last character written for previous code */
unsigned stack; /* next position for reversed string */
unsigned outcnt; /* bytes in output buffer */
struct outd outd; /* output structure */
unsigned char *p;
/* set up output */
outd.outfile = outfile;
outd.check = 0;
/* process remainder of compress header -- a flags byte */
flags = NEXT();
if (last == -1)
return Z_BUF_ERROR;
if (flags & 0x60) {
strm->msg = (char *)"unknown lzw flags set";
return Z_DATA_ERROR;
}
max = flags & 0x1f;
if (max < 9 || max > 16) {
strm->msg = (char *)"lzw bits out of range";
return Z_DATA_ERROR;
}
if (max == 9) /* 9 doesn't really mean 9 */
max = 10;
flags &= 0x80; /* true if block compress */
/* clear table */
bits = 9;
mask = 0x1ff;
end = flags ? 256 : 255;
/* set up: get first 9-bit code, which is the first decompressed byte, but
don't create a table entry until the next code */
if (NEXT() == -1) /* no compressed data is ok */
return Z_OK;
final = prev = (unsigned)last; /* low 8 bits of code */
if (NEXT() == -1) /* missing a bit */
return Z_BUF_ERROR;
if (last & 1) { /* code must be < 256 */
strm->msg = (char *)"invalid lzw code";
return Z_DATA_ERROR;
}
rem = (unsigned)last >> 1; /* remaining 7 bits */
left = 7;
chunk = bits - 2; /* 7 bytes left in this chunk */
outbuf[0] = (unsigned char)final; /* write first decompressed byte */
outcnt = 1;
/* decode codes */
stack = 0;
for (;;) {
/* if the table will be full after this, increment the code size */
if (end >= mask && bits < max) {
FLUSHCODE();
bits++;
mask <<= 1;
mask++;
}
/* get a code of length bits */
if (chunk == 0) /* decrement chunk modulo bits */
chunk = bits;
code = rem; /* low bits of code */
if (NEXT() == -1) { /* EOF is end of compressed data */
/* write remaining buffered output */
if (outcnt && out(&outd, outbuf, outcnt)) {
strm->next_in = outbuf; /* signal write error */
return Z_BUF_ERROR;
}
return Z_OK;
}
code += (unsigned)last << left; /* middle (or high) bits of code */
left += 8;
chunk--;
if (bits > left) { /* need more bits */
if (NEXT() == -1) /* can't end in middle of code */
return Z_BUF_ERROR;
code += (unsigned)last << left; /* high bits of code */
left += 8;
chunk--;
}
code &= mask; /* mask to current code length */
left -= bits; /* number of unused bits */
rem = (unsigned)last >> (8 - left); /* unused bits from last byte */
/* process clear code (256) */
if (code == 256 && flags) {
FLUSHCODE();
bits = 9; /* initialize bits and mask */
mask = 0x1ff;
end = 255; /* empty table */
continue; /* get next code */
}
/* special code to reuse last match */
temp = code; /* save the current code */
if (code > end) {
/* Be picky on the allowed code here, and make sure that the code
we drop through (prev) will be a valid index so that random
input does not cause an exception. The code != end + 1 check is
empirically derived, and not checked in the original uncompress
code. If this ever causes a problem, that check could be safely
removed. Leaving this check in greatly improves gun's ability
to detect random or corrupted input after a compress header.
In any case, the prev > end check must be retained. */
if (code != end + 1 || prev > end) {
strm->msg = (char *)"invalid lzw code";
return Z_DATA_ERROR;
}
match[stack++] = (unsigned char)final;
code = prev;
}
/* walk through linked list to generate output in reverse order */
p = match + stack;
while (code >= 256) {
*p++ = suffix[code];
code = prefix[code];
}
stack = p - match;
match[stack++] = (unsigned char)code;
final = code;
/* link new table entry */
if (end < mask) {
end++;
prefix[end] = (unsigned short)prev;
suffix[end] = (unsigned char)final;
}
/* set previous code for next iteration */
prev = temp;
/* write output in forward order */
while (stack > SIZE - outcnt) {
while (outcnt < SIZE)
outbuf[outcnt++] = match[--stack];
if (out(&outd, outbuf, outcnt)) {
strm->next_in = outbuf; /* signal write error */
return Z_BUF_ERROR;
}
outcnt = 0;
}
p = match + stack;
do {
outbuf[outcnt++] = *--p;
} while (p > match);
stack = 0;
/* loop for next code with final and prev as the last match, rem and
left provide the first 0..7 bits of the next code, end is the last
valid table entry */
}
}
/* Decompress a gzip file from infile to outfile. strm is assumed to have been
successfully initialized with inflateBackInit(). The input file may consist
of a series of gzip streams, in which case all of them will be decompressed
to the output file. If outfile is -1, then the gzip stream(s) integrity is
checked and nothing is written.
The return value is a zlib error code: Z_MEM_ERROR if out of memory,
Z_DATA_ERROR if the header or the compressed data is invalid, or if the
trailer CRC-32 check or length doesn't match, Z_BUF_ERROR if the input ends
prematurely or a write error occurs, or Z_ERRNO if junk (not a another gzip
stream) follows a valid gzip stream.
*/
local int gunpipe(z_stream *strm, int infile, int outfile)
{
int ret, first, last;
unsigned have, flags, len;
z_const unsigned char *next = NULL;
struct ind ind, *indp;
struct outd outd;
/* setup input buffer */
ind.infile = infile;
ind.inbuf = inbuf;
indp = &ind;
/* decompress concatenated gzip streams */
have = 0; /* no input data read in yet */
first = 1; /* looking for first gzip header */
strm->next_in = Z_NULL; /* so Z_BUF_ERROR means EOF */
for (;;) {
/* look for the two magic header bytes for a gzip stream */
if (NEXT() == -1) {
ret = Z_OK;
break; /* empty gzip stream is ok */
}
if (last != 31 || (NEXT() != 139 && last != 157)) {
strm->msg = (char *)"incorrect header check";
ret = first ? Z_DATA_ERROR : Z_ERRNO;
break; /* not a gzip or compress header */
}
first = 0; /* next non-header is junk */
/* process a compress (LZW) file -- can't be concatenated after this */
if (last == 157) {
ret = lunpipe(have, next, indp, outfile, strm);
break;
}
/* process remainder of gzip header */
ret = Z_BUF_ERROR;
if (NEXT() != 8) { /* only deflate method allowed */
if (last == -1) break;
strm->msg = (char *)"unknown compression method";
ret = Z_DATA_ERROR;
break;
}
flags = NEXT(); /* header flags */
NEXT(); /* discard mod time, xflgs, os */
NEXT();
NEXT();
NEXT();
NEXT();
NEXT();
if (last == -1) break;
if (flags & 0xe0) {
strm->msg = (char *)"unknown header flags set";
ret = Z_DATA_ERROR;
break;
}
if (flags & 4) { /* extra field */
len = NEXT();
len += (unsigned)(NEXT()) << 8;
if (last == -1) break;
while (len > have) {
len -= have;
have = 0;
if (NEXT() == -1) break;
len--;
}
if (last == -1) break;
have -= len;
next += len;
}
if (flags & 8) /* file name */
while (NEXT() != 0 && last != -1)
;
if (flags & 16) /* comment */
while (NEXT() != 0 && last != -1)
;
if (flags & 2) { /* header crc */
NEXT();
NEXT();
}
if (last == -1) break;
/* set up output */
outd.outfile = outfile;
outd.check = 1;
outd.crc = crc32(0L, Z_NULL, 0);
outd.total = 0;
/* decompress data to output */
strm->next_in = next;
strm->avail_in = have;
ret = inflateBack(strm, in, indp, out, &outd);
if (ret != Z_STREAM_END) break;
next = strm->next_in;
have = strm->avail_in;
strm->next_in = Z_NULL; /* so Z_BUF_ERROR means EOF */
/* check trailer */
ret = Z_BUF_ERROR;
if (NEXT() != (int)(outd.crc & 0xff) ||
NEXT() != (int)((outd.crc >> 8) & 0xff) ||
NEXT() != (int)((outd.crc >> 16) & 0xff) ||
NEXT() != (int)((outd.crc >> 24) & 0xff)) {
/* crc error */
if (last != -1) {
strm->msg = (char *)"incorrect data check";
ret = Z_DATA_ERROR;
}
break;
}
if (NEXT() != (int)(outd.total & 0xff) ||
NEXT() != (int)((outd.total >> 8) & 0xff) ||
NEXT() != (int)((outd.total >> 16) & 0xff) ||
NEXT() != (int)((outd.total >> 24) & 0xff)) {
/* length error */
if (last != -1) {
strm->msg = (char *)"incorrect length check";
ret = Z_DATA_ERROR;
}
break;
}
/* go back and look for another gzip stream */
}
/* clean up and return */
return ret;
}
/* Copy file attributes, from -> to, as best we can. This is best effort, so
no errors are reported. The mode bits, including suid, sgid, and the sticky
bit are copied (if allowed), the owner's user id and group id are copied
(again if allowed), and the access and modify times are copied. */
local void copymeta(char *from, char *to)
{
struct stat was;
struct utimbuf when;
/* get all of from's Unix meta data, return if not a regular file */
if (stat(from, &was) != 0 || (was.st_mode & S_IFMT) != S_IFREG)
return;
/* set to's mode bits, ignore errors */
(void)chmod(to, was.st_mode & 07777);
/* copy owner's user and group, ignore errors */
(void)chown(to, was.st_uid, was.st_gid);
/* copy access and modify times, ignore errors */
when.actime = was.st_atime;
when.modtime = was.st_mtime;
(void)utime(to, &when);
}
/* Decompress the file inname to the file outnname, of if test is true, just
decompress without writing and check the gzip trailer for integrity. If
inname is NULL or an empty string, read from stdin. If outname is NULL or
an empty string, write to stdout. strm is a pre-initialized inflateBack
structure. When appropriate, copy the file attributes from inname to
outname.
gunzip() returns 1 if there is an out-of-memory error or an unexpected
return code from gunpipe(). Otherwise it returns 0.
*/
local int gunzip(z_stream *strm, char *inname, char *outname, int test)
{
int ret;
int infile, outfile;
/* open files */
if (inname == NULL || *inname == 0) {
inname = "-";
infile = 0; /* stdin */
}
else {
infile = open(inname, O_RDONLY, 0);
if (infile == -1) {
fprintf(stderr, "gun cannot open %s\n", inname);
return 0;
}
}
if (test)
outfile = -1;
else if (outname == NULL || *outname == 0) {
outname = "-";
outfile = 1; /* stdout */
}
else {
outfile = open(outname, O_CREAT | O_TRUNC | O_WRONLY, 0666);
if (outfile == -1) {
close(infile);
fprintf(stderr, "gun cannot create %s\n", outname);
return 0;
}
}
errno = 0;
/* decompress */
ret = gunpipe(strm, infile, outfile);
if (outfile > 2) close(outfile);
if (infile > 2) close(infile);
/* interpret result */
switch (ret) {
case Z_OK:
case Z_ERRNO:
if (infile > 2 && outfile > 2) {
copymeta(inname, outname); /* copy attributes */
unlink(inname);
}
if (ret == Z_ERRNO)
fprintf(stderr, "gun warning: trailing garbage ignored in %s\n",
inname);
break;
case Z_DATA_ERROR:
if (outfile > 2) unlink(outname);
fprintf(stderr, "gun data error on %s: %s\n", inname, strm->msg);
break;
case Z_MEM_ERROR:
if (outfile > 2) unlink(outname);
fprintf(stderr, "gun out of memory error--aborting\n");
return 1;
case Z_BUF_ERROR:
if (outfile > 2) unlink(outname);
if (strm->next_in != Z_NULL) {
fprintf(stderr, "gun write error on %s: %s\n",
outname, strerror(errno));
}
else if (errno) {
fprintf(stderr, "gun read error on %s: %s\n",
inname, strerror(errno));
}
else {
fprintf(stderr, "gun unexpected end of file on %s\n",
inname);
}
break;
default:
if (outfile > 2) unlink(outname);
fprintf(stderr, "gun internal error--aborting\n");
return 1;
}
return 0;
}
/* Process the gun command line arguments. See the command syntax near the
beginning of this source file. */
int main(int argc, char **argv)
{
int ret, len, test;
char *outname;
unsigned char *window;
z_stream strm;
/* initialize inflateBack state for repeated use */
window = match; /* reuse LZW match buffer */
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
ret = inflateBackInit(&strm, 15, window);
if (ret != Z_OK) {
fprintf(stderr, "gun out of memory error--aborting\n");
return 1;
}
/* decompress each file to the same name with the suffix removed */
argc--;
argv++;
test = 0;
if (argc && strcmp(*argv, "-h") == 0) {
fprintf(stderr, "gun 1.6 (17 Jan 2010)\n");
fprintf(stderr, "Copyright (C) 2003-2010 Mark Adler\n");
fprintf(stderr, "usage: gun [-t] [file1.gz [file2.Z ...]]\n");
return 0;
}
if (argc && strcmp(*argv, "-t") == 0) {
test = 1;
argc--;
argv++;
}
if (argc)
do {
if (test)
outname = NULL;
else {
len = (int)strlen(*argv);
if (strcmp(*argv + len - 3, ".gz") == 0 ||
strcmp(*argv + len - 3, "-gz") == 0)
len -= 3;
else if (strcmp(*argv + len - 2, ".z") == 0 ||
strcmp(*argv + len - 2, "-z") == 0 ||
strcmp(*argv + len - 2, "_z") == 0 ||
strcmp(*argv + len - 2, ".Z") == 0)
len -= 2;
else {
fprintf(stderr, "gun error: no gz type on %s--skipping\n",
*argv);
continue;
}
outname = malloc(len + 1);
if (outname == NULL) {
fprintf(stderr, "gun out of memory error--aborting\n");
ret = 1;
break;
}
memcpy(outname, *argv, len);
outname[len] = 0;
}
ret = gunzip(&strm, *argv, outname, test);
if (outname != NULL) free(outname);
if (ret) break;
} while (argv++, --argc);
else
ret = gunzip(&strm, NULL, NULL, test);
/* clean up */
inflateBackEnd(&strm);
return ret;
}

504
3rdparty/zlib/examples/gzappend.c vendored Normal file
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@ -0,0 +1,504 @@
/* gzappend -- command to append to a gzip file
Copyright (C) 2003, 2012 Mark Adler, all rights reserved
version 1.2, 11 Oct 2012
This software is provided 'as-is', without any express or implied
warranty. In no event will the author be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
Mark Adler madler@alumni.caltech.edu
*/
/*
* Change history:
*
* 1.0 19 Oct 2003 - First version
* 1.1 4 Nov 2003 - Expand and clarify some comments and notes
* - Add version and copyright to help
* - Send help to stdout instead of stderr
* - Add some preemptive typecasts
* - Add L to constants in lseek() calls
* - Remove some debugging information in error messages
* - Use new data_type definition for zlib 1.2.1
* - Simplfy and unify file operations
* - Finish off gzip file in gztack()
* - Use deflatePrime() instead of adding empty blocks
* - Keep gzip file clean on appended file read errors
* - Use in-place rotate instead of auxiliary buffer
* (Why you ask? Because it was fun to write!)
* 1.2 11 Oct 2012 - Fix for proper z_const usage
* - Check for input buffer malloc failure
*/
/*
gzappend takes a gzip file and appends to it, compressing files from the
command line or data from stdin. The gzip file is written to directly, to
avoid copying that file, in case it's large. Note that this results in the
unfriendly behavior that if gzappend fails, the gzip file is corrupted.
This program was written to illustrate the use of the new Z_BLOCK option of
zlib 1.2.x's inflate() function. This option returns from inflate() at each
block boundary to facilitate locating and modifying the last block bit at
the start of the final deflate block. Also whether using Z_BLOCK or not,
another required feature of zlib 1.2.x is that inflate() now provides the
number of unusued bits in the last input byte used. gzappend will not work
with versions of zlib earlier than 1.2.1.
gzappend first decompresses the gzip file internally, discarding all but
the last 32K of uncompressed data, and noting the location of the last block
bit and the number of unused bits in the last byte of the compressed data.
The gzip trailer containing the CRC-32 and length of the uncompressed data
is verified. This trailer will be later overwritten.
Then the last block bit is cleared by seeking back in the file and rewriting
the byte that contains it. Seeking forward, the last byte of the compressed
data is saved along with the number of unused bits to initialize deflate.
A deflate process is initialized, using the last 32K of the uncompressed
data from the gzip file to initialize the dictionary. If the total
uncompressed data was less than 32K, then all of it is used to initialize
the dictionary. The deflate output bit buffer is also initialized with the
last bits from the original deflate stream. From here on, the data to
append is simply compressed using deflate, and written to the gzip file.
When that is complete, the new CRC-32 and uncompressed length are written
as the trailer of the gzip file.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include "zlib.h"
#define local static
#define LGCHUNK 14
#define CHUNK (1U << LGCHUNK)
#define DSIZE 32768U
/* print an error message and terminate with extreme prejudice */
local void bye(char *msg1, char *msg2)
{
fprintf(stderr, "gzappend error: %s%s\n", msg1, msg2);
exit(1);
}
/* return the greatest common divisor of a and b using Euclid's algorithm,
modified to be fast when one argument much greater than the other, and
coded to avoid unnecessary swapping */
local unsigned gcd(unsigned a, unsigned b)
{
unsigned c;
while (a && b)
if (a > b) {
c = b;
while (a - c >= c)
c <<= 1;
a -= c;
}
else {
c = a;
while (b - c >= c)
c <<= 1;
b -= c;
}
return a + b;
}
/* rotate list[0..len-1] left by rot positions, in place */
local void rotate(unsigned char *list, unsigned len, unsigned rot)
{
unsigned char tmp;
unsigned cycles;
unsigned char *start, *last, *to, *from;
/* normalize rot and handle degenerate cases */
if (len < 2) return;
if (rot >= len) rot %= len;
if (rot == 0) return;
/* pointer to last entry in list */
last = list + (len - 1);
/* do simple left shift by one */
if (rot == 1) {
tmp = *list;
memcpy(list, list + 1, len - 1);
*last = tmp;
return;
}
/* do simple right shift by one */
if (rot == len - 1) {
tmp = *last;
memmove(list + 1, list, len - 1);
*list = tmp;
return;
}
/* otherwise do rotate as a set of cycles in place */
cycles = gcd(len, rot); /* number of cycles */
do {
start = from = list + cycles; /* start index is arbitrary */
tmp = *from; /* save entry to be overwritten */
for (;;) {
to = from; /* next step in cycle */
from += rot; /* go right rot positions */
if (from > last) from -= len; /* (pointer better not wrap) */
if (from == start) break; /* all but one shifted */
*to = *from; /* shift left */
}
*to = tmp; /* complete the circle */
} while (--cycles);
}
/* structure for gzip file read operations */
typedef struct {
int fd; /* file descriptor */
int size; /* 1 << size is bytes in buf */
unsigned left; /* bytes available at next */
unsigned char *buf; /* buffer */
z_const unsigned char *next; /* next byte in buffer */
char *name; /* file name for error messages */
} file;
/* reload buffer */
local int readin(file *in)
{
int len;
len = read(in->fd, in->buf, 1 << in->size);
if (len == -1) bye("error reading ", in->name);
in->left = (unsigned)len;
in->next = in->buf;
return len;
}
/* read from file in, exit if end-of-file */
local int readmore(file *in)
{
if (readin(in) == 0) bye("unexpected end of ", in->name);
return 0;
}
#define read1(in) (in->left == 0 ? readmore(in) : 0, \
in->left--, *(in->next)++)
/* skip over n bytes of in */
local void skip(file *in, unsigned n)
{
unsigned bypass;
if (n > in->left) {
n -= in->left;
bypass = n & ~((1U << in->size) - 1);
if (bypass) {
if (lseek(in->fd, (off_t)bypass, SEEK_CUR) == -1)
bye("seeking ", in->name);
n -= bypass;
}
readmore(in);
if (n > in->left)
bye("unexpected end of ", in->name);
}
in->left -= n;
in->next += n;
}
/* read a four-byte unsigned integer, little-endian, from in */
unsigned long read4(file *in)
{
unsigned long val;
val = read1(in);
val += (unsigned)read1(in) << 8;
val += (unsigned long)read1(in) << 16;
val += (unsigned long)read1(in) << 24;
return val;
}
/* skip over gzip header */
local void gzheader(file *in)
{
int flags;
unsigned n;
if (read1(in) != 31 || read1(in) != 139) bye(in->name, " not a gzip file");
if (read1(in) != 8) bye("unknown compression method in", in->name);
flags = read1(in);
if (flags & 0xe0) bye("unknown header flags set in", in->name);
skip(in, 6);
if (flags & 4) {
n = read1(in);
n += (unsigned)(read1(in)) << 8;
skip(in, n);
}
if (flags & 8) while (read1(in) != 0) ;
if (flags & 16) while (read1(in) != 0) ;
if (flags & 2) skip(in, 2);
}
/* decompress gzip file "name", return strm with a deflate stream ready to
continue compression of the data in the gzip file, and return a file
descriptor pointing to where to write the compressed data -- the deflate
stream is initialized to compress using level "level" */
local int gzscan(char *name, z_stream *strm, int level)
{
int ret, lastbit, left, full;
unsigned have;
unsigned long crc, tot;
unsigned char *window;
off_t lastoff, end;
file gz;
/* open gzip file */
gz.name = name;
gz.fd = open(name, O_RDWR, 0);
if (gz.fd == -1) bye("cannot open ", name);
gz.buf = malloc(CHUNK);
if (gz.buf == NULL) bye("out of memory", "");
gz.size = LGCHUNK;
gz.left = 0;
/* skip gzip header */
gzheader(&gz);
/* prepare to decompress */
window = malloc(DSIZE);
if (window == NULL) bye("out of memory", "");
strm->zalloc = Z_NULL;
strm->zfree = Z_NULL;
strm->opaque = Z_NULL;
ret = inflateInit2(strm, -15);
if (ret != Z_OK) bye("out of memory", " or library mismatch");
/* decompress the deflate stream, saving append information */
lastbit = 0;
lastoff = lseek(gz.fd, 0L, SEEK_CUR) - gz.left;
left = 0;
strm->avail_in = gz.left;
strm->next_in = gz.next;
crc = crc32(0L, Z_NULL, 0);
have = full = 0;
do {
/* if needed, get more input */
if (strm->avail_in == 0) {
readmore(&gz);
strm->avail_in = gz.left;
strm->next_in = gz.next;
}
/* set up output to next available section of sliding window */
strm->avail_out = DSIZE - have;
strm->next_out = window + have;
/* inflate and check for errors */
ret = inflate(strm, Z_BLOCK);
if (ret == Z_STREAM_ERROR) bye("internal stream error!", "");
if (ret == Z_MEM_ERROR) bye("out of memory", "");
if (ret == Z_DATA_ERROR)
bye("invalid compressed data--format violated in", name);
/* update crc and sliding window pointer */
crc = crc32(crc, window + have, DSIZE - have - strm->avail_out);
if (strm->avail_out)
have = DSIZE - strm->avail_out;
else {
have = 0;
full = 1;
}
/* process end of block */
if (strm->data_type & 128) {
if (strm->data_type & 64)
left = strm->data_type & 0x1f;
else {
lastbit = strm->data_type & 0x1f;
lastoff = lseek(gz.fd, 0L, SEEK_CUR) - strm->avail_in;
}
}
} while (ret != Z_STREAM_END);
inflateEnd(strm);
gz.left = strm->avail_in;
gz.next = strm->next_in;
/* save the location of the end of the compressed data */
end = lseek(gz.fd, 0L, SEEK_CUR) - gz.left;
/* check gzip trailer and save total for deflate */
if (crc != read4(&gz))
bye("invalid compressed data--crc mismatch in ", name);
tot = strm->total_out;
if ((tot & 0xffffffffUL) != read4(&gz))
bye("invalid compressed data--length mismatch in", name);
/* if not at end of file, warn */
if (gz.left || readin(&gz))
fprintf(stderr,
"gzappend warning: junk at end of gzip file overwritten\n");
/* clear last block bit */
lseek(gz.fd, lastoff - (lastbit != 0), SEEK_SET);
if (read(gz.fd, gz.buf, 1) != 1) bye("reading after seek on ", name);
*gz.buf = (unsigned char)(*gz.buf ^ (1 << ((8 - lastbit) & 7)));
lseek(gz.fd, -1L, SEEK_CUR);
if (write(gz.fd, gz.buf, 1) != 1) bye("writing after seek to ", name);
/* if window wrapped, build dictionary from window by rotating */
if (full) {
rotate(window, DSIZE, have);
have = DSIZE;
}
/* set up deflate stream with window, crc, total_in, and leftover bits */
ret = deflateInit2(strm, level, Z_DEFLATED, -15, 8, Z_DEFAULT_STRATEGY);
if (ret != Z_OK) bye("out of memory", "");
deflateSetDictionary(strm, window, have);
strm->adler = crc;
strm->total_in = tot;
if (left) {
lseek(gz.fd, --end, SEEK_SET);
if (read(gz.fd, gz.buf, 1) != 1) bye("reading after seek on ", name);
deflatePrime(strm, 8 - left, *gz.buf);
}
lseek(gz.fd, end, SEEK_SET);
/* clean up and return */
free(window);
free(gz.buf);
return gz.fd;
}
/* append file "name" to gzip file gd using deflate stream strm -- if last
is true, then finish off the deflate stream at the end */
local void gztack(char *name, int gd, z_stream *strm, int last)
{
int fd, len, ret;
unsigned left;
unsigned char *in, *out;
/* open file to compress and append */
fd = 0;
if (name != NULL) {
fd = open(name, O_RDONLY, 0);
if (fd == -1)
fprintf(stderr, "gzappend warning: %s not found, skipping ...\n",
name);
}
/* allocate buffers */
in = malloc(CHUNK);
out = malloc(CHUNK);
if (in == NULL || out == NULL) bye("out of memory", "");
/* compress input file and append to gzip file */
do {
/* get more input */
len = read(fd, in, CHUNK);
if (len == -1) {
fprintf(stderr,
"gzappend warning: error reading %s, skipping rest ...\n",
name);
len = 0;
}
strm->avail_in = (unsigned)len;
strm->next_in = in;
if (len) strm->adler = crc32(strm->adler, in, (unsigned)len);
/* compress and write all available output */
do {
strm->avail_out = CHUNK;
strm->next_out = out;
ret = deflate(strm, last && len == 0 ? Z_FINISH : Z_NO_FLUSH);
left = CHUNK - strm->avail_out;
while (left) {
len = write(gd, out + CHUNK - strm->avail_out - left, left);
if (len == -1) bye("writing gzip file", "");
left -= (unsigned)len;
}
} while (strm->avail_out == 0 && ret != Z_STREAM_END);
} while (len != 0);
/* write trailer after last entry */
if (last) {
deflateEnd(strm);
out[0] = (unsigned char)(strm->adler);
out[1] = (unsigned char)(strm->adler >> 8);
out[2] = (unsigned char)(strm->adler >> 16);
out[3] = (unsigned char)(strm->adler >> 24);
out[4] = (unsigned char)(strm->total_in);
out[5] = (unsigned char)(strm->total_in >> 8);
out[6] = (unsigned char)(strm->total_in >> 16);
out[7] = (unsigned char)(strm->total_in >> 24);
len = 8;
do {
ret = write(gd, out + 8 - len, len);
if (ret == -1) bye("writing gzip file", "");
len -= ret;
} while (len);
close(gd);
}
/* clean up and return */
free(out);
free(in);
if (fd > 0) close(fd);
}
/* process the compression level option if present, scan the gzip file, and
append the specified files, or append the data from stdin if no other file
names are provided on the command line -- the gzip file must be writable
and seekable */
int main(int argc, char **argv)
{
int gd, level;
z_stream strm;
/* ignore command name */
argc--; argv++;
/* provide usage if no arguments */
if (*argv == NULL) {
printf(
"gzappend 1.2 (11 Oct 2012) Copyright (C) 2003, 2012 Mark Adler\n"
);
printf(
"usage: gzappend [-level] file.gz [ addthis [ andthis ... ]]\n");
return 0;
}
/* set compression level */
level = Z_DEFAULT_COMPRESSION;
if (argv[0][0] == '-') {
if (argv[0][1] < '0' || argv[0][1] > '9' || argv[0][2] != 0)
bye("invalid compression level", "");
level = argv[0][1] - '0';
if (*++argv == NULL) bye("no gzip file name after options", "");
}
/* prepare to append to gzip file */
gd = gzscan(*argv++, &strm, level);
/* append files on command line, or from stdin if none */
if (*argv == NULL)
gztack(NULL, gd, &strm, 1);
else
do {
gztack(*argv, gd, &strm, argv[1] == NULL);
} while (*++argv != NULL);
return 0;
}

449
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/* gzjoin -- command to join gzip files into one gzip file
Copyright (C) 2004, 2005, 2012 Mark Adler, all rights reserved
version 1.2, 14 Aug 2012
This software is provided 'as-is', without any express or implied
warranty. In no event will the author be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
Mark Adler madler@alumni.caltech.edu
*/
/*
* Change history:
*
* 1.0 11 Dec 2004 - First version
* 1.1 12 Jun 2005 - Changed ssize_t to long for portability
* 1.2 14 Aug 2012 - Clean up for z_const usage
*/
/*
gzjoin takes one or more gzip files on the command line and writes out a
single gzip file that will uncompress to the concatenation of the
uncompressed data from the individual gzip files. gzjoin does this without
having to recompress any of the data and without having to calculate a new
crc32 for the concatenated uncompressed data. gzjoin does however have to
decompress all of the input data in order to find the bits in the compressed
data that need to be modified to concatenate the streams.
gzjoin does not do an integrity check on the input gzip files other than
checking the gzip header and decompressing the compressed data. They are
otherwise assumed to be complete and correct.
Each joint between gzip files removes at least 18 bytes of previous trailer
and subsequent header, and inserts an average of about three bytes to the
compressed data in order to connect the streams. The output gzip file
has a minimal ten-byte gzip header with no file name or modification time.
This program was written to illustrate the use of the Z_BLOCK option of
inflate() and the crc32_combine() function. gzjoin will not compile with
versions of zlib earlier than 1.2.3.
*/
#include <stdio.h> /* fputs(), fprintf(), fwrite(), putc() */
#include <stdlib.h> /* exit(), malloc(), free() */
#include <fcntl.h> /* open() */
#include <unistd.h> /* close(), read(), lseek() */
#include "zlib.h"
/* crc32(), crc32_combine(), inflateInit2(), inflate(), inflateEnd() */
#define local static
/* exit with an error (return a value to allow use in an expression) */
local int bail(char *why1, char *why2)
{
fprintf(stderr, "gzjoin error: %s%s, output incomplete\n", why1, why2);
exit(1);
return 0;
}
/* -- simple buffered file input with access to the buffer -- */
#define CHUNK 32768 /* must be a power of two and fit in unsigned */
/* bin buffered input file type */
typedef struct {
char *name; /* name of file for error messages */
int fd; /* file descriptor */
unsigned left; /* bytes remaining at next */
unsigned char *next; /* next byte to read */
unsigned char *buf; /* allocated buffer of length CHUNK */
} bin;
/* close a buffered file and free allocated memory */
local void bclose(bin *in)
{
if (in != NULL) {
if (in->fd != -1)
close(in->fd);
if (in->buf != NULL)
free(in->buf);
free(in);
}
}
/* open a buffered file for input, return a pointer to type bin, or NULL on
failure */
local bin *bopen(char *name)
{
bin *in;
in = malloc(sizeof(bin));
if (in == NULL)
return NULL;
in->buf = malloc(CHUNK);
in->fd = open(name, O_RDONLY, 0);
if (in->buf == NULL || in->fd == -1) {
bclose(in);
return NULL;
}
in->left = 0;
in->next = in->buf;
in->name = name;
return in;
}
/* load buffer from file, return -1 on read error, 0 or 1 on success, with
1 indicating that end-of-file was reached */
local int bload(bin *in)
{
long len;
if (in == NULL)
return -1;
if (in->left != 0)
return 0;
in->next = in->buf;
do {
len = (long)read(in->fd, in->buf + in->left, CHUNK - in->left);
if (len < 0)
return -1;
in->left += (unsigned)len;
} while (len != 0 && in->left < CHUNK);
return len == 0 ? 1 : 0;
}
/* get a byte from the file, bail if end of file */
#define bget(in) (in->left ? 0 : bload(in), \
in->left ? (in->left--, *(in->next)++) : \
bail("unexpected end of file on ", in->name))
/* get a four-byte little-endian unsigned integer from file */
local unsigned long bget4(bin *in)
{
unsigned long val;
val = bget(in);
val += (unsigned long)(bget(in)) << 8;
val += (unsigned long)(bget(in)) << 16;
val += (unsigned long)(bget(in)) << 24;
return val;
}
/* skip bytes in file */
local void bskip(bin *in, unsigned skip)
{
/* check pointer */
if (in == NULL)
return;
/* easy case -- skip bytes in buffer */
if (skip <= in->left) {
in->left -= skip;
in->next += skip;
return;
}
/* skip what's in buffer, discard buffer contents */
skip -= in->left;
in->left = 0;
/* seek past multiples of CHUNK bytes */
if (skip > CHUNK) {
unsigned left;
left = skip & (CHUNK - 1);
if (left == 0) {
/* exact number of chunks: seek all the way minus one byte to check
for end-of-file with a read */
lseek(in->fd, skip - 1, SEEK_CUR);
if (read(in->fd, in->buf, 1) != 1)
bail("unexpected end of file on ", in->name);
return;
}
/* skip the integral chunks, update skip with remainder */
lseek(in->fd, skip - left, SEEK_CUR);
skip = left;
}
/* read more input and skip remainder */
bload(in);
if (skip > in->left)
bail("unexpected end of file on ", in->name);
in->left -= skip;
in->next += skip;
}
/* -- end of buffered input functions -- */
/* skip the gzip header from file in */
local void gzhead(bin *in)
{
int flags;
/* verify gzip magic header and compression method */
if (bget(in) != 0x1f || bget(in) != 0x8b || bget(in) != 8)
bail(in->name, " is not a valid gzip file");
/* get and verify flags */
flags = bget(in);
if ((flags & 0xe0) != 0)
bail("unknown reserved bits set in ", in->name);
/* skip modification time, extra flags, and os */
bskip(in, 6);
/* skip extra field if present */
if (flags & 4) {
unsigned len;
len = bget(in);
len += (unsigned)(bget(in)) << 8;
bskip(in, len);
}
/* skip file name if present */
if (flags & 8)
while (bget(in) != 0)
;
/* skip comment if present */
if (flags & 16)
while (bget(in) != 0)
;
/* skip header crc if present */
if (flags & 2)
bskip(in, 2);
}
/* write a four-byte little-endian unsigned integer to out */
local void put4(unsigned long val, FILE *out)
{
putc(val & 0xff, out);
putc((val >> 8) & 0xff, out);
putc((val >> 16) & 0xff, out);
putc((val >> 24) & 0xff, out);
}
/* Load up zlib stream from buffered input, bail if end of file */
local void zpull(z_streamp strm, bin *in)
{
if (in->left == 0)
bload(in);
if (in->left == 0)
bail("unexpected end of file on ", in->name);
strm->avail_in = in->left;
strm->next_in = in->next;
}
/* Write header for gzip file to out and initialize trailer. */
local void gzinit(unsigned long *crc, unsigned long *tot, FILE *out)
{
fwrite("\x1f\x8b\x08\0\0\0\0\0\0\xff", 1, 10, out);
*crc = crc32(0L, Z_NULL, 0);
*tot = 0;
}
/* Copy the compressed data from name, zeroing the last block bit of the last
block if clr is true, and adding empty blocks as needed to get to a byte
boundary. If clr is false, then the last block becomes the last block of
the output, and the gzip trailer is written. crc and tot maintains the
crc and length (modulo 2^32) of the output for the trailer. The resulting
gzip file is written to out. gzinit() must be called before the first call
of gzcopy() to write the gzip header and to initialize crc and tot. */
local void gzcopy(char *name, int clr, unsigned long *crc, unsigned long *tot,
FILE *out)
{
int ret; /* return value from zlib functions */
int pos; /* where the "last block" bit is in byte */
int last; /* true if processing the last block */
bin *in; /* buffered input file */
unsigned char *start; /* start of compressed data in buffer */
unsigned char *junk; /* buffer for uncompressed data -- discarded */
z_off_t len; /* length of uncompressed data (support > 4 GB) */
z_stream strm; /* zlib inflate stream */
/* open gzip file and skip header */
in = bopen(name);
if (in == NULL)
bail("could not open ", name);
gzhead(in);
/* allocate buffer for uncompressed data and initialize raw inflate
stream */
junk = malloc(CHUNK);
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = 0;
strm.next_in = Z_NULL;
ret = inflateInit2(&strm, -15);
if (junk == NULL || ret != Z_OK)
bail("out of memory", "");
/* inflate and copy compressed data, clear last-block bit if requested */
len = 0;
zpull(&strm, in);
start = in->next;
last = start[0] & 1;
if (last && clr)
start[0] &= ~1;
strm.avail_out = 0;
for (;;) {
/* if input used and output done, write used input and get more */
if (strm.avail_in == 0 && strm.avail_out != 0) {
fwrite(start, 1, strm.next_in - start, out);
start = in->buf;
in->left = 0;
zpull(&strm, in);
}
/* decompress -- return early when end-of-block reached */
strm.avail_out = CHUNK;
strm.next_out = junk;
ret = inflate(&strm, Z_BLOCK);
switch (ret) {
case Z_MEM_ERROR:
bail("out of memory", "");
case Z_DATA_ERROR:
bail("invalid compressed data in ", in->name);
}
/* update length of uncompressed data */
len += CHUNK - strm.avail_out;
/* check for block boundary (only get this when block copied out) */
if (strm.data_type & 128) {
/* if that was the last block, then done */
if (last)
break;
/* number of unused bits in last byte */
pos = strm.data_type & 7;
/* find the next last-block bit */
if (pos != 0) {
/* next last-block bit is in last used byte */
pos = 0x100 >> pos;
last = strm.next_in[-1] & pos;
if (last && clr)
in->buf[strm.next_in - in->buf - 1] &= ~pos;
}
else {
/* next last-block bit is in next unused byte */
if (strm.avail_in == 0) {
/* don't have that byte yet -- get it */
fwrite(start, 1, strm.next_in - start, out);
start = in->buf;
in->left = 0;
zpull(&strm, in);
}
last = strm.next_in[0] & 1;
if (last && clr)
in->buf[strm.next_in - in->buf] &= ~1;
}
}
}
/* update buffer with unused input */
in->left = strm.avail_in;
in->next = in->buf + (strm.next_in - in->buf);
/* copy used input, write empty blocks to get to byte boundary */
pos = strm.data_type & 7;
fwrite(start, 1, in->next - start - 1, out);
last = in->next[-1];
if (pos == 0 || !clr)
/* already at byte boundary, or last file: write last byte */
putc(last, out);
else {
/* append empty blocks to last byte */
last &= ((0x100 >> pos) - 1); /* assure unused bits are zero */
if (pos & 1) {
/* odd -- append an empty stored block */
putc(last, out);
if (pos == 1)
putc(0, out); /* two more bits in block header */
fwrite("\0\0\xff\xff", 1, 4, out);
}
else {
/* even -- append 1, 2, or 3 empty fixed blocks */
switch (pos) {
case 6:
putc(last | 8, out);
last = 0;
case 4:
putc(last | 0x20, out);
last = 0;
case 2:
putc(last | 0x80, out);
putc(0, out);
}
}
}
/* update crc and tot */
*crc = crc32_combine(*crc, bget4(in), len);
*tot += (unsigned long)len;
/* clean up */
inflateEnd(&strm);
free(junk);
bclose(in);
/* write trailer if this is the last gzip file */
if (!clr) {
put4(*crc, out);
put4(*tot, out);
}
}
/* join the gzip files on the command line, write result to stdout */
int main(int argc, char **argv)
{
unsigned long crc, tot; /* running crc and total uncompressed length */
/* skip command name */
argc--;
argv++;
/* show usage if no arguments */
if (argc == 0) {
fputs("gzjoin usage: gzjoin f1.gz [f2.gz [f3.gz ...]] > fjoin.gz\n",
stderr);
return 0;
}
/* join gzip files on command line and write to stdout */
gzinit(&crc, &tot, stdout);
while (argc--)
gzcopy(*argv++, argc, &crc, &tot, stdout);
/* done */
return 0;
}

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/* gzlog.h
Copyright (C) 2004, 2008, 2012 Mark Adler, all rights reserved
version 2.2, 14 Aug 2012
This software is provided 'as-is', without any express or implied
warranty. In no event will the author be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
Mark Adler madler@alumni.caltech.edu
*/
/* Version History:
1.0 26 Nov 2004 First version
2.0 25 Apr 2008 Complete redesign for recovery of interrupted operations
Interface changed slightly in that now path is a prefix
Compression now occurs as needed during gzlog_write()
gzlog_write() now always leaves the log file as valid gzip
2.1 8 Jul 2012 Fix argument checks in gzlog_compress() and gzlog_write()
2.2 14 Aug 2012 Clean up signed comparisons
*/
/*
The gzlog object allows writing short messages to a gzipped log file,
opening the log file locked for small bursts, and then closing it. The log
object works by appending stored (uncompressed) data to the gzip file until
1 MB has been accumulated. At that time, the stored data is compressed, and
replaces the uncompressed data in the file. The log file is truncated to
its new size at that time. After each write operation, the log file is a
valid gzip file that can decompressed to recover what was written.
The gzlog operations can be interupted at any point due to an application or
system crash, and the log file will be recovered the next time the log is
opened with gzlog_open().
*/
#ifndef GZLOG_H
#define GZLOG_H
/* gzlog object type */
typedef void gzlog;
/* Open a gzlog object, creating the log file if it does not exist. Return
NULL on error. Note that gzlog_open() could take a while to complete if it
has to wait to verify that a lock is stale (possibly for five minutes), or
if there is significant contention with other instantiations of this object
when locking the resource. path is the prefix of the file names created by
this object. If path is "foo", then the log file will be "foo.gz", and
other auxiliary files will be created and destroyed during the process:
"foo.dict" for a compression dictionary, "foo.temp" for a temporary (next)
dictionary, "foo.add" for data being added or compressed, "foo.lock" for the
lock file, and "foo.repairs" to log recovery operations performed due to
interrupted gzlog operations. A gzlog_open() followed by a gzlog_close()
will recover a previously interrupted operation, if any. */
gzlog *gzlog_open(char *path);
/* Write to a gzlog object. Return zero on success, -1 if there is a file i/o
error on any of the gzlog files (this should not happen if gzlog_open()
succeeded, unless the device has run out of space or leftover auxiliary
files have permissions or ownership that prevent their use), -2 if there is
a memory allocation failure, or -3 if the log argument is invalid (e.g. if
it was not created by gzlog_open()). This function will write data to the
file uncompressed, until 1 MB has been accumulated, at which time that data
will be compressed. The log file will be a valid gzip file upon successful
return. */
int gzlog_write(gzlog *log, void *data, size_t len);
/* Force compression of any uncompressed data in the log. This should be used
sparingly, if at all. The main application would be when a log file will
not be appended to again. If this is used to compress frequently while
appending, it will both significantly increase the execution time and
reduce the compression ratio. The return codes are the same as for
gzlog_write(). */
int gzlog_compress(gzlog *log);
/* Close a gzlog object. Return zero on success, -3 if the log argument is
invalid. The log object is freed, and so cannot be referenced again. */
int gzlog_close(gzlog *log);
#endif

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
"http://www.w3.org/TR/REC-html40/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>zlib Usage Example</title>
<!-- Copyright (c) 2004, 2005 Mark Adler. -->
</head>
<body bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#00A000">
<h2 align="center"> zlib Usage Example </h2>
We often get questions about how the <tt>deflate()</tt> and <tt>inflate()</tt> functions should be used.
Users wonder when they should provide more input, when they should use more output,
what to do with a <tt>Z_BUF_ERROR</tt>, how to make sure the process terminates properly, and
so on. So for those who have read <tt>zlib.h</tt> (a few times), and
would like further edification, below is an annotated example in C of simple routines to compress and decompress
from an input file to an output file using <tt>deflate()</tt> and <tt>inflate()</tt> respectively. The
annotations are interspersed between lines of the code. So please read between the lines.
We hope this helps explain some of the intricacies of <em>zlib</em>.
<p>
Without further adieu, here is the program <a href="zpipe.c"><tt>zpipe.c</tt></a>:
<pre><b>
/* zpipe.c: example of proper use of zlib's inflate() and deflate()
Not copyrighted -- provided to the public domain
Version 1.4 11 December 2005 Mark Adler */
/* Version history:
1.0 30 Oct 2004 First version
1.1 8 Nov 2004 Add void casting for unused return values
Use switch statement for inflate() return values
1.2 9 Nov 2004 Add assertions to document zlib guarantees
1.3 6 Apr 2005 Remove incorrect assertion in inf()
1.4 11 Dec 2005 Add hack to avoid MSDOS end-of-line conversions
Avoid some compiler warnings for input and output buffers
*/
</b></pre><!-- -->
We now include the header files for the required definitions. From
<tt>stdio.h</tt> we use <tt>fopen()</tt>, <tt>fread()</tt>, <tt>fwrite()</tt>,
<tt>feof()</tt>, <tt>ferror()</tt>, and <tt>fclose()</tt> for file i/o, and
<tt>fputs()</tt> for error messages. From <tt>string.h</tt> we use
<tt>strcmp()</tt> for command line argument processing.
From <tt>assert.h</tt> we use the <tt>assert()</tt> macro.
From <tt>zlib.h</tt>
we use the basic compression functions <tt>deflateInit()</tt>,
<tt>deflate()</tt>, and <tt>deflateEnd()</tt>, and the basic decompression
functions <tt>inflateInit()</tt>, <tt>inflate()</tt>, and
<tt>inflateEnd()</tt>.
<pre><b>
#include &lt;stdio.h&gt;
#include &lt;string.h&gt;
#include &lt;assert.h&gt;
#include "zlib.h"
</b></pre><!-- -->
This is an ugly hack required to avoid corruption of the input and output data on
Windows/MS-DOS systems. Without this, those systems would assume that the input and output
files are text, and try to convert the end-of-line characters from one standard to
another. That would corrupt binary data, and in particular would render the compressed data unusable.
This sets the input and output to binary which suppresses the end-of-line conversions.
<tt>SET_BINARY_MODE()</tt> will be used later on <tt>stdin</tt> and <tt>stdout</tt>, at the beginning of <tt>main()</tt>.
<pre><b>
#if defined(MSDOS) || defined(OS2) || defined(WIN32) || defined(__CYGWIN__)
# include &lt;fcntl.h&gt;
# include &lt;io.h&gt;
# define SET_BINARY_MODE(file) setmode(fileno(file), O_BINARY)
#else
# define SET_BINARY_MODE(file)
#endif
</b></pre><!-- -->
<tt>CHUNK</tt> is simply the buffer size for feeding data to and pulling data
from the <em>zlib</em> routines. Larger buffer sizes would be more efficient,
especially for <tt>inflate()</tt>. If the memory is available, buffers sizes
on the order of 128K or 256K bytes should be used.
<pre><b>
#define CHUNK 16384
</b></pre><!-- -->
The <tt>def()</tt> routine compresses data from an input file to an output file. The output data
will be in the <em>zlib</em> format, which is different from the <em>gzip</em> or <em>zip</em>
formats. The <em>zlib</em> format has a very small header of only two bytes to identify it as
a <em>zlib</em> stream and to provide decoding information, and a four-byte trailer with a fast
check value to verify the integrity of the uncompressed data after decoding.
<pre><b>
/* Compress from file source to file dest until EOF on source.
def() returns Z_OK on success, Z_MEM_ERROR if memory could not be
allocated for processing, Z_STREAM_ERROR if an invalid compression
level is supplied, Z_VERSION_ERROR if the version of zlib.h and the
version of the library linked do not match, or Z_ERRNO if there is
an error reading or writing the files. */
int def(FILE *source, FILE *dest, int level)
{
</b></pre>
Here are the local variables for <tt>def()</tt>. <tt>ret</tt> will be used for <em>zlib</em>
return codes. <tt>flush</tt> will keep track of the current flushing state for <tt>deflate()</tt>,
which is either no flushing, or flush to completion after the end of the input file is reached.
<tt>have</tt> is the amount of data returned from <tt>deflate()</tt>. The <tt>strm</tt> structure
is used to pass information to and from the <em>zlib</em> routines, and to maintain the
<tt>deflate()</tt> state. <tt>in</tt> and <tt>out</tt> are the input and output buffers for
<tt>deflate()</tt>.
<pre><b>
int ret, flush;
unsigned have;
z_stream strm;
unsigned char in[CHUNK];
unsigned char out[CHUNK];
</b></pre><!-- -->
The first thing we do is to initialize the <em>zlib</em> state for compression using
<tt>deflateInit()</tt>. This must be done before the first use of <tt>deflate()</tt>.
The <tt>zalloc</tt>, <tt>zfree</tt>, and <tt>opaque</tt> fields in the <tt>strm</tt>
structure must be initialized before calling <tt>deflateInit()</tt>. Here they are
set to the <em>zlib</em> constant <tt>Z_NULL</tt> to request that <em>zlib</em> use
the default memory allocation routines. An application may also choose to provide
custom memory allocation routines here. <tt>deflateInit()</tt> will allocate on the
order of 256K bytes for the internal state.
(See <a href="zlib_tech.html"><em>zlib Technical Details</em></a>.)
<p>
<tt>deflateInit()</tt> is called with a pointer to the structure to be initialized and
the compression level, which is an integer in the range of -1 to 9. Lower compression
levels result in faster execution, but less compression. Higher levels result in
greater compression, but slower execution. The <em>zlib</em> constant Z_DEFAULT_COMPRESSION,
equal to -1,
provides a good compromise between compression and speed and is equivalent to level 6.
Level 0 actually does no compression at all, and in fact expands the data slightly to produce
the <em>zlib</em> format (it is not a byte-for-byte copy of the input).
More advanced applications of <em>zlib</em>
may use <tt>deflateInit2()</tt> here instead. Such an application may want to reduce how
much memory will be used, at some price in compression. Or it may need to request a
<em>gzip</em> header and trailer instead of a <em>zlib</em> header and trailer, or raw
encoding with no header or trailer at all.
<p>
We must check the return value of <tt>deflateInit()</tt> against the <em>zlib</em> constant
<tt>Z_OK</tt> to make sure that it was able to
allocate memory for the internal state, and that the provided arguments were valid.
<tt>deflateInit()</tt> will also check that the version of <em>zlib</em> that the <tt>zlib.h</tt>
file came from matches the version of <em>zlib</em> actually linked with the program. This
is especially important for environments in which <em>zlib</em> is a shared library.
<p>
Note that an application can initialize multiple, independent <em>zlib</em> streams, which can
operate in parallel. The state information maintained in the structure allows the <em>zlib</em>
routines to be reentrant.
<pre><b>
/* allocate deflate state */
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
ret = deflateInit(&amp;strm, level);
if (ret != Z_OK)
return ret;
</b></pre><!-- -->
With the pleasantries out of the way, now we can get down to business. The outer <tt>do</tt>-loop
reads all of the input file and exits at the bottom of the loop once end-of-file is reached.
This loop contains the only call of <tt>deflate()</tt>. So we must make sure that all of the
input data has been processed and that all of the output data has been generated and consumed
before we fall out of the loop at the bottom.
<pre><b>
/* compress until end of file */
do {
</b></pre>
We start off by reading data from the input file. The number of bytes read is put directly
into <tt>avail_in</tt>, and a pointer to those bytes is put into <tt>next_in</tt>. We also
check to see if end-of-file on the input has been reached. If we are at the end of file, then <tt>flush</tt> is set to the
<em>zlib</em> constant <tt>Z_FINISH</tt>, which is later passed to <tt>deflate()</tt> to
indicate that this is the last chunk of input data to compress. We need to use <tt>feof()</tt>
to check for end-of-file as opposed to seeing if fewer than <tt>CHUNK</tt> bytes have been read. The
reason is that if the input file length is an exact multiple of <tt>CHUNK</tt>, we will miss
the fact that we got to the end-of-file, and not know to tell <tt>deflate()</tt> to finish
up the compressed stream. If we are not yet at the end of the input, then the <em>zlib</em>
constant <tt>Z_NO_FLUSH</tt> will be passed to <tt>deflate</tt> to indicate that we are still
in the middle of the uncompressed data.
<p>
If there is an error in reading from the input file, the process is aborted with
<tt>deflateEnd()</tt> being called to free the allocated <em>zlib</em> state before returning
the error. We wouldn't want a memory leak, now would we? <tt>deflateEnd()</tt> can be called
at any time after the state has been initialized. Once that's done, <tt>deflateInit()</tt> (or
<tt>deflateInit2()</tt>) would have to be called to start a new compression process. There is
no point here in checking the <tt>deflateEnd()</tt> return code. The deallocation can't fail.
<pre><b>
strm.avail_in = fread(in, 1, CHUNK, source);
if (ferror(source)) {
(void)deflateEnd(&amp;strm);
return Z_ERRNO;
}
flush = feof(source) ? Z_FINISH : Z_NO_FLUSH;
strm.next_in = in;
</b></pre><!-- -->
The inner <tt>do</tt>-loop passes our chunk of input data to <tt>deflate()</tt>, and then
keeps calling <tt>deflate()</tt> until it is done producing output. Once there is no more
new output, <tt>deflate()</tt> is guaranteed to have consumed all of the input, i.e.,
<tt>avail_in</tt> will be zero.
<pre><b>
/* run deflate() on input until output buffer not full, finish
compression if all of source has been read in */
do {
</b></pre>
Output space is provided to <tt>deflate()</tt> by setting <tt>avail_out</tt> to the number
of available output bytes and <tt>next_out</tt> to a pointer to that space.
<pre><b>
strm.avail_out = CHUNK;
strm.next_out = out;
</b></pre>
Now we call the compression engine itself, <tt>deflate()</tt>. It takes as many of the
<tt>avail_in</tt> bytes at <tt>next_in</tt> as it can process, and writes as many as
<tt>avail_out</tt> bytes to <tt>next_out</tt>. Those counters and pointers are then
updated past the input data consumed and the output data written. It is the amount of
output space available that may limit how much input is consumed.
Hence the inner loop to make sure that
all of the input is consumed by providing more output space each time. Since <tt>avail_in</tt>
and <tt>next_in</tt> are updated by <tt>deflate()</tt>, we don't have to mess with those
between <tt>deflate()</tt> calls until it's all used up.
<p>
The parameters to <tt>deflate()</tt> are a pointer to the <tt>strm</tt> structure containing
the input and output information and the internal compression engine state, and a parameter
indicating whether and how to flush data to the output. Normally <tt>deflate</tt> will consume
several K bytes of input data before producing any output (except for the header), in order
to accumulate statistics on the data for optimum compression. It will then put out a burst of
compressed data, and proceed to consume more input before the next burst. Eventually,
<tt>deflate()</tt>
must be told to terminate the stream, complete the compression with provided input data, and
write out the trailer check value. <tt>deflate()</tt> will continue to compress normally as long
as the flush parameter is <tt>Z_NO_FLUSH</tt>. Once the <tt>Z_FINISH</tt> parameter is provided,
<tt>deflate()</tt> will begin to complete the compressed output stream. However depending on how
much output space is provided, <tt>deflate()</tt> may have to be called several times until it
has provided the complete compressed stream, even after it has consumed all of the input. The flush
parameter must continue to be <tt>Z_FINISH</tt> for those subsequent calls.
<p>
There are other values of the flush parameter that are used in more advanced applications. You can
force <tt>deflate()</tt> to produce a burst of output that encodes all of the input data provided
so far, even if it wouldn't have otherwise, for example to control data latency on a link with
compressed data. You can also ask that <tt>deflate()</tt> do that as well as erase any history up to
that point so that what follows can be decompressed independently, for example for random access
applications. Both requests will degrade compression by an amount depending on how often such
requests are made.
<p>
<tt>deflate()</tt> has a return value that can indicate errors, yet we do not check it here. Why
not? Well, it turns out that <tt>deflate()</tt> can do no wrong here. Let's go through
<tt>deflate()</tt>'s return values and dispense with them one by one. The possible values are
<tt>Z_OK</tt>, <tt>Z_STREAM_END</tt>, <tt>Z_STREAM_ERROR</tt>, or <tt>Z_BUF_ERROR</tt>. <tt>Z_OK</tt>
is, well, ok. <tt>Z_STREAM_END</tt> is also ok and will be returned for the last call of
<tt>deflate()</tt>. This is already guaranteed by calling <tt>deflate()</tt> with <tt>Z_FINISH</tt>
until it has no more output. <tt>Z_STREAM_ERROR</tt> is only possible if the stream is not
initialized properly, but we did initialize it properly. There is no harm in checking for
<tt>Z_STREAM_ERROR</tt> here, for example to check for the possibility that some
other part of the application inadvertently clobbered the memory containing the <em>zlib</em> state.
<tt>Z_BUF_ERROR</tt> will be explained further below, but
suffice it to say that this is simply an indication that <tt>deflate()</tt> could not consume
more input or produce more output. <tt>deflate()</tt> can be called again with more output space
or more available input, which it will be in this code.
<pre><b>
ret = deflate(&amp;strm, flush); /* no bad return value */
assert(ret != Z_STREAM_ERROR); /* state not clobbered */
</b></pre>
Now we compute how much output <tt>deflate()</tt> provided on the last call, which is the
difference between how much space was provided before the call, and how much output space
is still available after the call. Then that data, if any, is written to the output file.
We can then reuse the output buffer for the next call of <tt>deflate()</tt>. Again if there
is a file i/o error, we call <tt>deflateEnd()</tt> before returning to avoid a memory leak.
<pre><b>
have = CHUNK - strm.avail_out;
if (fwrite(out, 1, have, dest) != have || ferror(dest)) {
(void)deflateEnd(&amp;strm);
return Z_ERRNO;
}
</b></pre>
The inner <tt>do</tt>-loop is repeated until the last <tt>deflate()</tt> call fails to fill the
provided output buffer. Then we know that <tt>deflate()</tt> has done as much as it can with
the provided input, and that all of that input has been consumed. We can then fall out of this
loop and reuse the input buffer.
<p>
The way we tell that <tt>deflate()</tt> has no more output is by seeing that it did not fill
the output buffer, leaving <tt>avail_out</tt> greater than zero. However suppose that
<tt>deflate()</tt> has no more output, but just so happened to exactly fill the output buffer!
<tt>avail_out</tt> is zero, and we can't tell that <tt>deflate()</tt> has done all it can.
As far as we know, <tt>deflate()</tt>
has more output for us. So we call it again. But now <tt>deflate()</tt> produces no output
at all, and <tt>avail_out</tt> remains unchanged as <tt>CHUNK</tt>. That <tt>deflate()</tt> call
wasn't able to do anything, either consume input or produce output, and so it returns
<tt>Z_BUF_ERROR</tt>. (See, I told you I'd cover this later.) However this is not a problem at
all. Now we finally have the desired indication that <tt>deflate()</tt> is really done,
and so we drop out of the inner loop to provide more input to <tt>deflate()</tt>.
<p>
With <tt>flush</tt> set to <tt>Z_FINISH</tt>, this final set of <tt>deflate()</tt> calls will
complete the output stream. Once that is done, subsequent calls of <tt>deflate()</tt> would return
<tt>Z_STREAM_ERROR</tt> if the flush parameter is not <tt>Z_FINISH</tt>, and do no more processing
until the state is reinitialized.
<p>
Some applications of <em>zlib</em> have two loops that call <tt>deflate()</tt>
instead of the single inner loop we have here. The first loop would call
without flushing and feed all of the data to <tt>deflate()</tt>. The second loop would call
<tt>deflate()</tt> with no more
data and the <tt>Z_FINISH</tt> parameter to complete the process. As you can see from this
example, that can be avoided by simply keeping track of the current flush state.
<pre><b>
} while (strm.avail_out == 0);
assert(strm.avail_in == 0); /* all input will be used */
</b></pre><!-- -->
Now we check to see if we have already processed all of the input file. That information was
saved in the <tt>flush</tt> variable, so we see if that was set to <tt>Z_FINISH</tt>. If so,
then we're done and we fall out of the outer loop. We're guaranteed to get <tt>Z_STREAM_END</tt>
from the last <tt>deflate()</tt> call, since we ran it until the last chunk of input was
consumed and all of the output was generated.
<pre><b>
/* done when last data in file processed */
} while (flush != Z_FINISH);
assert(ret == Z_STREAM_END); /* stream will be complete */
</b></pre><!-- -->
The process is complete, but we still need to deallocate the state to avoid a memory leak
(or rather more like a memory hemorrhage if you didn't do this). Then
finally we can return with a happy return value.
<pre><b>
/* clean up and return */
(void)deflateEnd(&amp;strm);
return Z_OK;
}
</b></pre><!-- -->
Now we do the same thing for decompression in the <tt>inf()</tt> routine. <tt>inf()</tt>
decompresses what is hopefully a valid <em>zlib</em> stream from the input file and writes the
uncompressed data to the output file. Much of the discussion above for <tt>def()</tt>
applies to <tt>inf()</tt> as well, so the discussion here will focus on the differences between
the two.
<pre><b>
/* Decompress from file source to file dest until stream ends or EOF.
inf() returns Z_OK on success, Z_MEM_ERROR if memory could not be
allocated for processing, Z_DATA_ERROR if the deflate data is
invalid or incomplete, Z_VERSION_ERROR if the version of zlib.h and
the version of the library linked do not match, or Z_ERRNO if there
is an error reading or writing the files. */
int inf(FILE *source, FILE *dest)
{
</b></pre>
The local variables have the same functionality as they do for <tt>def()</tt>. The
only difference is that there is no <tt>flush</tt> variable, since <tt>inflate()</tt>
can tell from the <em>zlib</em> stream itself when the stream is complete.
<pre><b>
int ret;
unsigned have;
z_stream strm;
unsigned char in[CHUNK];
unsigned char out[CHUNK];
</b></pre><!-- -->
The initialization of the state is the same, except that there is no compression level,
of course, and two more elements of the structure are initialized. <tt>avail_in</tt>
and <tt>next_in</tt> must be initialized before calling <tt>inflateInit()</tt>. This
is because the application has the option to provide the start of the zlib stream in
order for <tt>inflateInit()</tt> to have access to information about the compression
method to aid in memory allocation. In the current implementation of <em>zlib</em>
(up through versions 1.2.x), the method-dependent memory allocations are deferred to the first call of
<tt>inflate()</tt> anyway. However those fields must be initialized since later versions
of <em>zlib</em> that provide more compression methods may take advantage of this interface.
In any case, no decompression is performed by <tt>inflateInit()</tt>, so the
<tt>avail_out</tt> and <tt>next_out</tt> fields do not need to be initialized before calling.
<p>
Here <tt>avail_in</tt> is set to zero and <tt>next_in</tt> is set to <tt>Z_NULL</tt> to
indicate that no input data is being provided.
<pre><b>
/* allocate inflate state */
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = 0;
strm.next_in = Z_NULL;
ret = inflateInit(&amp;strm);
if (ret != Z_OK)
return ret;
</b></pre><!-- -->
The outer <tt>do</tt>-loop decompresses input until <tt>inflate()</tt> indicates
that it has reached the end of the compressed data and has produced all of the uncompressed
output. This is in contrast to <tt>def()</tt> which processes all of the input file.
If end-of-file is reached before the compressed data self-terminates, then the compressed
data is incomplete and an error is returned.
<pre><b>
/* decompress until deflate stream ends or end of file */
do {
</b></pre>
We read input data and set the <tt>strm</tt> structure accordingly. If we've reached the
end of the input file, then we leave the outer loop and report an error, since the
compressed data is incomplete. Note that we may read more data than is eventually consumed
by <tt>inflate()</tt>, if the input file continues past the <em>zlib</em> stream.
For applications where <em>zlib</em> streams are embedded in other data, this routine would
need to be modified to return the unused data, or at least indicate how much of the input
data was not used, so the application would know where to pick up after the <em>zlib</em> stream.
<pre><b>
strm.avail_in = fread(in, 1, CHUNK, source);
if (ferror(source)) {
(void)inflateEnd(&amp;strm);
return Z_ERRNO;
}
if (strm.avail_in == 0)
break;
strm.next_in = in;
</b></pre><!-- -->
The inner <tt>do</tt>-loop has the same function it did in <tt>def()</tt>, which is to
keep calling <tt>inflate()</tt> until has generated all of the output it can with the
provided input.
<pre><b>
/* run inflate() on input until output buffer not full */
do {
</b></pre>
Just like in <tt>def()</tt>, the same output space is provided for each call of <tt>inflate()</tt>.
<pre><b>
strm.avail_out = CHUNK;
strm.next_out = out;
</b></pre>
Now we run the decompression engine itself. There is no need to adjust the flush parameter, since
the <em>zlib</em> format is self-terminating. The main difference here is that there are
return values that we need to pay attention to. <tt>Z_DATA_ERROR</tt>
indicates that <tt>inflate()</tt> detected an error in the <em>zlib</em> compressed data format,
which means that either the data is not a <em>zlib</em> stream to begin with, or that the data was
corrupted somewhere along the way since it was compressed. The other error to be processed is
<tt>Z_MEM_ERROR</tt>, which can occur since memory allocation is deferred until <tt>inflate()</tt>
needs it, unlike <tt>deflate()</tt>, whose memory is allocated at the start by <tt>deflateInit()</tt>.
<p>
Advanced applications may use
<tt>deflateSetDictionary()</tt> to prime <tt>deflate()</tt> with a set of likely data to improve the
first 32K or so of compression. This is noted in the <em>zlib</em> header, so <tt>inflate()</tt>
requests that that dictionary be provided before it can start to decompress. Without the dictionary,
correct decompression is not possible. For this routine, we have no idea what the dictionary is,
so the <tt>Z_NEED_DICT</tt> indication is converted to a <tt>Z_DATA_ERROR</tt>.
<p>
<tt>inflate()</tt> can also return <tt>Z_STREAM_ERROR</tt>, which should not be possible here,
but could be checked for as noted above for <tt>def()</tt>. <tt>Z_BUF_ERROR</tt> does not need to be
checked for here, for the same reasons noted for <tt>def()</tt>. <tt>Z_STREAM_END</tt> will be
checked for later.
<pre><b>
ret = inflate(&amp;strm, Z_NO_FLUSH);
assert(ret != Z_STREAM_ERROR); /* state not clobbered */
switch (ret) {
case Z_NEED_DICT:
ret = Z_DATA_ERROR; /* and fall through */
case Z_DATA_ERROR:
case Z_MEM_ERROR:
(void)inflateEnd(&amp;strm);
return ret;
}
</b></pre>
The output of <tt>inflate()</tt> is handled identically to that of <tt>deflate()</tt>.
<pre><b>
have = CHUNK - strm.avail_out;
if (fwrite(out, 1, have, dest) != have || ferror(dest)) {
(void)inflateEnd(&amp;strm);
return Z_ERRNO;
}
</b></pre>
The inner <tt>do</tt>-loop ends when <tt>inflate()</tt> has no more output as indicated
by not filling the output buffer, just as for <tt>deflate()</tt>. In this case, we cannot
assert that <tt>strm.avail_in</tt> will be zero, since the deflate stream may end before the file
does.
<pre><b>
} while (strm.avail_out == 0);
</b></pre><!-- -->
The outer <tt>do</tt>-loop ends when <tt>inflate()</tt> reports that it has reached the
end of the input <em>zlib</em> stream, has completed the decompression and integrity
check, and has provided all of the output. This is indicated by the <tt>inflate()</tt>
return value <tt>Z_STREAM_END</tt>. The inner loop is guaranteed to leave <tt>ret</tt>
equal to <tt>Z_STREAM_END</tt> if the last chunk of the input file read contained the end
of the <em>zlib</em> stream. So if the return value is not <tt>Z_STREAM_END</tt>, the
loop continues to read more input.
<pre><b>
/* done when inflate() says it's done */
} while (ret != Z_STREAM_END);
</b></pre><!-- -->
At this point, decompression successfully completed, or we broke out of the loop due to no
more data being available from the input file. If the last <tt>inflate()</tt> return value
is not <tt>Z_STREAM_END</tt>, then the <em>zlib</em> stream was incomplete and a data error
is returned. Otherwise, we return with a happy return value. Of course, <tt>inflateEnd()</tt>
is called first to avoid a memory leak.
<pre><b>
/* clean up and return */
(void)inflateEnd(&amp;strm);
return ret == Z_STREAM_END ? Z_OK : Z_DATA_ERROR;
}
</b></pre><!-- -->
That ends the routines that directly use <em>zlib</em>. The following routines make this
a command-line program by running data through the above routines from <tt>stdin</tt> to
<tt>stdout</tt>, and handling any errors reported by <tt>def()</tt> or <tt>inf()</tt>.
<p>
<tt>zerr()</tt> is used to interpret the possible error codes from <tt>def()</tt>
and <tt>inf()</tt>, as detailed in their comments above, and print out an error message.
Note that these are only a subset of the possible return values from <tt>deflate()</tt>
and <tt>inflate()</tt>.
<pre><b>
/* report a zlib or i/o error */
void zerr(int ret)
{
fputs("zpipe: ", stderr);
switch (ret) {
case Z_ERRNO:
if (ferror(stdin))
fputs("error reading stdin\n", stderr);
if (ferror(stdout))
fputs("error writing stdout\n", stderr);
break;
case Z_STREAM_ERROR:
fputs("invalid compression level\n", stderr);
break;
case Z_DATA_ERROR:
fputs("invalid or incomplete deflate data\n", stderr);
break;
case Z_MEM_ERROR:
fputs("out of memory\n", stderr);
break;
case Z_VERSION_ERROR:
fputs("zlib version mismatch!\n", stderr);
}
}
</b></pre><!-- -->
Here is the <tt>main()</tt> routine used to test <tt>def()</tt> and <tt>inf()</tt>. The
<tt>zpipe</tt> command is simply a compression pipe from <tt>stdin</tt> to <tt>stdout</tt>, if
no arguments are given, or it is a decompression pipe if <tt>zpipe -d</tt> is used. If any other
arguments are provided, no compression or decompression is performed. Instead a usage
message is displayed. Examples are <tt>zpipe < foo.txt > foo.txt.z</tt> to compress, and
<tt>zpipe -d < foo.txt.z > foo.txt</tt> to decompress.
<pre><b>
/* compress or decompress from stdin to stdout */
int main(int argc, char **argv)
{
int ret;
/* avoid end-of-line conversions */
SET_BINARY_MODE(stdin);
SET_BINARY_MODE(stdout);
/* do compression if no arguments */
if (argc == 1) {
ret = def(stdin, stdout, Z_DEFAULT_COMPRESSION);
if (ret != Z_OK)
zerr(ret);
return ret;
}
/* do decompression if -d specified */
else if (argc == 2 &amp;&amp; strcmp(argv[1], "-d") == 0) {
ret = inf(stdin, stdout);
if (ret != Z_OK)
zerr(ret);
return ret;
}
/* otherwise, report usage */
else {
fputs("zpipe usage: zpipe [-d] &lt; source &gt; dest\n", stderr);
return 1;
}
}
</b></pre>
<hr>
<i>Copyright (c) 2004, 2005 by Mark Adler<br>Last modified 11 December 2005</i>
</body>
</html>

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/* zpipe.c: example of proper use of zlib's inflate() and deflate()
Not copyrighted -- provided to the public domain
Version 1.4 11 December 2005 Mark Adler */
/* Version history:
1.0 30 Oct 2004 First version
1.1 8 Nov 2004 Add void casting for unused return values
Use switch statement for inflate() return values
1.2 9 Nov 2004 Add assertions to document zlib guarantees
1.3 6 Apr 2005 Remove incorrect assertion in inf()
1.4 11 Dec 2005 Add hack to avoid MSDOS end-of-line conversions
Avoid some compiler warnings for input and output buffers
*/
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include "zlib.h"
#if defined(MSDOS) || defined(OS2) || defined(WIN32) || defined(__CYGWIN__)
# include <fcntl.h>
# include <io.h>
# define SET_BINARY_MODE(file) setmode(fileno(file), O_BINARY)
#else
# define SET_BINARY_MODE(file)
#endif
#define CHUNK 16384
/* Compress from file source to file dest until EOF on source.
def() returns Z_OK on success, Z_MEM_ERROR if memory could not be
allocated for processing, Z_STREAM_ERROR if an invalid compression
level is supplied, Z_VERSION_ERROR if the version of zlib.h and the
version of the library linked do not match, or Z_ERRNO if there is
an error reading or writing the files. */
int def(FILE *source, FILE *dest, int level)
{
int ret, flush;
unsigned have;
z_stream strm;
unsigned char in[CHUNK];
unsigned char out[CHUNK];
/* allocate deflate state */
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
ret = deflateInit(&strm, level);
if (ret != Z_OK)
return ret;
/* compress until end of file */
do {
strm.avail_in = fread(in, 1, CHUNK, source);
if (ferror(source)) {
(void)deflateEnd(&strm);
return Z_ERRNO;
}
flush = feof(source) ? Z_FINISH : Z_NO_FLUSH;
strm.next_in = in;
/* run deflate() on input until output buffer not full, finish
compression if all of source has been read in */
do {
strm.avail_out = CHUNK;
strm.next_out = out;
ret = deflate(&strm, flush); /* no bad return value */
assert(ret != Z_STREAM_ERROR); /* state not clobbered */
have = CHUNK - strm.avail_out;
if (fwrite(out, 1, have, dest) != have || ferror(dest)) {
(void)deflateEnd(&strm);
return Z_ERRNO;
}
} while (strm.avail_out == 0);
assert(strm.avail_in == 0); /* all input will be used */
/* done when last data in file processed */
} while (flush != Z_FINISH);
assert(ret == Z_STREAM_END); /* stream will be complete */
/* clean up and return */
(void)deflateEnd(&strm);
return Z_OK;
}
/* Decompress from file source to file dest until stream ends or EOF.
inf() returns Z_OK on success, Z_MEM_ERROR if memory could not be
allocated for processing, Z_DATA_ERROR if the deflate data is
invalid or incomplete, Z_VERSION_ERROR if the version of zlib.h and
the version of the library linked do not match, or Z_ERRNO if there
is an error reading or writing the files. */
int inf(FILE *source, FILE *dest)
{
int ret;
unsigned have;
z_stream strm;
unsigned char in[CHUNK];
unsigned char out[CHUNK];
/* allocate inflate state */
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = 0;
strm.next_in = Z_NULL;
ret = inflateInit(&strm);
if (ret != Z_OK)
return ret;
/* decompress until deflate stream ends or end of file */
do {
strm.avail_in = fread(in, 1, CHUNK, source);
if (ferror(source)) {
(void)inflateEnd(&strm);
return Z_ERRNO;
}
if (strm.avail_in == 0)
break;
strm.next_in = in;
/* run inflate() on input until output buffer not full */
do {
strm.avail_out = CHUNK;
strm.next_out = out;
ret = inflate(&strm, Z_NO_FLUSH);
assert(ret != Z_STREAM_ERROR); /* state not clobbered */
switch (ret) {
case Z_NEED_DICT:
ret = Z_DATA_ERROR; /* and fall through */
case Z_DATA_ERROR:
case Z_MEM_ERROR:
(void)inflateEnd(&strm);
return ret;
}
have = CHUNK - strm.avail_out;
if (fwrite(out, 1, have, dest) != have || ferror(dest)) {
(void)inflateEnd(&strm);
return Z_ERRNO;
}
} while (strm.avail_out == 0);
/* done when inflate() says it's done */
} while (ret != Z_STREAM_END);
/* clean up and return */
(void)inflateEnd(&strm);
return ret == Z_STREAM_END ? Z_OK : Z_DATA_ERROR;
}
/* report a zlib or i/o error */
void zerr(int ret)
{
fputs("zpipe: ", stderr);
switch (ret) {
case Z_ERRNO:
if (ferror(stdin))
fputs("error reading stdin\n", stderr);
if (ferror(stdout))
fputs("error writing stdout\n", stderr);
break;
case Z_STREAM_ERROR:
fputs("invalid compression level\n", stderr);
break;
case Z_DATA_ERROR:
fputs("invalid or incomplete deflate data\n", stderr);
break;
case Z_MEM_ERROR:
fputs("out of memory\n", stderr);
break;
case Z_VERSION_ERROR:
fputs("zlib version mismatch!\n", stderr);
}
}
/* compress or decompress from stdin to stdout */
int main(int argc, char **argv)
{
int ret;
/* avoid end-of-line conversions */
SET_BINARY_MODE(stdin);
SET_BINARY_MODE(stdout);
/* do compression if no arguments */
if (argc == 1) {
ret = def(stdin, stdout, Z_DEFAULT_COMPRESSION);
if (ret != Z_OK)
zerr(ret);
return ret;
}
/* do decompression if -d specified */
else if (argc == 2 && strcmp(argv[1], "-d") == 0) {
ret = inf(stdin, stdout);
if (ret != Z_OK)
zerr(ret);
return ret;
}
/* otherwise, report usage */
else {
fputs("zpipe usage: zpipe [-d] < source > dest\n", stderr);
return 1;
}
}

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/* zran.c -- example of zlib/gzip stream indexing and random access
* Copyright (C) 2005, 2012 Mark Adler
* For conditions of distribution and use, see copyright notice in zlib.h
Version 1.1 29 Sep 2012 Mark Adler */
/* Version History:
1.0 29 May 2005 First version
1.1 29 Sep 2012 Fix memory reallocation error
*/
/* Illustrate the use of Z_BLOCK, inflatePrime(), and inflateSetDictionary()
for random access of a compressed file. A file containing a zlib or gzip
stream is provided on the command line. The compressed stream is decoded in
its entirety, and an index built with access points about every SPAN bytes
in the uncompressed output. The compressed file is left open, and can then
be read randomly, having to decompress on the average SPAN/2 uncompressed
bytes before getting to the desired block of data.
An access point can be created at the start of any deflate block, by saving
the starting file offset and bit of that block, and the 32K bytes of
uncompressed data that precede that block. Also the uncompressed offset of
that block is saved to provide a referece for locating a desired starting
point in the uncompressed stream. build_index() works by decompressing the
input zlib or gzip stream a block at a time, and at the end of each block
deciding if enough uncompressed data has gone by to justify the creation of
a new access point. If so, that point is saved in a data structure that
grows as needed to accommodate the points.
To use the index, an offset in the uncompressed data is provided, for which
the latest accees point at or preceding that offset is located in the index.
The input file is positioned to the specified location in the index, and if
necessary the first few bits of the compressed data is read from the file.
inflate is initialized with those bits and the 32K of uncompressed data, and
the decompression then proceeds until the desired offset in the file is
reached. Then the decompression continues to read the desired uncompressed
data from the file.
Another approach would be to generate the index on demand. In that case,
requests for random access reads from the compressed data would try to use
the index, but if a read far enough past the end of the index is required,
then further index entries would be generated and added.
There is some fair bit of overhead to starting inflation for the random
access, mainly copying the 32K byte dictionary. So if small pieces of the
file are being accessed, it would make sense to implement a cache to hold
some lookahead and avoid many calls to extract() for small lengths.
Another way to build an index would be to use inflateCopy(). That would
not be constrained to have access points at block boundaries, but requires
more memory per access point, and also cannot be saved to file due to the
use of pointers in the state. The approach here allows for storage of the
index in a file.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "zlib.h"
#define local static
#define SPAN 1048576L /* desired distance between access points */
#define WINSIZE 32768U /* sliding window size */
#define CHUNK 16384 /* file input buffer size */
/* access point entry */
struct point {
off_t out; /* corresponding offset in uncompressed data */
off_t in; /* offset in input file of first full byte */
int bits; /* number of bits (1-7) from byte at in - 1, or 0 */
unsigned char window[WINSIZE]; /* preceding 32K of uncompressed data */
};
/* access point list */
struct access {
int have; /* number of list entries filled in */
int size; /* number of list entries allocated */
struct point *list; /* allocated list */
};
/* Deallocate an index built by build_index() */
local void free_index(struct access *index)
{
if (index != NULL) {
free(index->list);
free(index);
}
}
/* Add an entry to the access point list. If out of memory, deallocate the
existing list and return NULL. */
local struct access *addpoint(struct access *index, int bits,
off_t in, off_t out, unsigned left, unsigned char *window)
{
struct point *next;
/* if list is empty, create it (start with eight points) */
if (index == NULL) {
index = malloc(sizeof(struct access));
if (index == NULL) return NULL;
index->list = malloc(sizeof(struct point) << 3);
if (index->list == NULL) {
free(index);
return NULL;
}
index->size = 8;
index->have = 0;
}
/* if list is full, make it bigger */
else if (index->have == index->size) {
index->size <<= 1;
next = realloc(index->list, sizeof(struct point) * index->size);
if (next == NULL) {
free_index(index);
return NULL;
}
index->list = next;
}
/* fill in entry and increment how many we have */
next = index->list + index->have;
next->bits = bits;
next->in = in;
next->out = out;
if (left)
memcpy(next->window, window + WINSIZE - left, left);
if (left < WINSIZE)
memcpy(next->window + left, window, WINSIZE - left);
index->have++;
/* return list, possibly reallocated */
return index;
}
/* Make one entire pass through the compressed stream and build an index, with
access points about every span bytes of uncompressed output -- span is
chosen to balance the speed of random access against the memory requirements
of the list, about 32K bytes per access point. Note that data after the end
of the first zlib or gzip stream in the file is ignored. build_index()
returns the number of access points on success (>= 1), Z_MEM_ERROR for out
of memory, Z_DATA_ERROR for an error in the input file, or Z_ERRNO for a
file read error. On success, *built points to the resulting index. */
local int build_index(FILE *in, off_t span, struct access **built)
{
int ret;
off_t totin, totout; /* our own total counters to avoid 4GB limit */
off_t last; /* totout value of last access point */
struct access *index; /* access points being generated */
z_stream strm;
unsigned char input[CHUNK];
unsigned char window[WINSIZE];
/* initialize inflate */
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = 0;
strm.next_in = Z_NULL;
ret = inflateInit2(&strm, 47); /* automatic zlib or gzip decoding */
if (ret != Z_OK)
return ret;
/* inflate the input, maintain a sliding window, and build an index -- this
also validates the integrity of the compressed data using the check
information at the end of the gzip or zlib stream */
totin = totout = last = 0;
index = NULL; /* will be allocated by first addpoint() */
strm.avail_out = 0;
do {
/* get some compressed data from input file */
strm.avail_in = fread(input, 1, CHUNK, in);
if (ferror(in)) {
ret = Z_ERRNO;
goto build_index_error;
}
if (strm.avail_in == 0) {
ret = Z_DATA_ERROR;
goto build_index_error;
}
strm.next_in = input;
/* process all of that, or until end of stream */
do {
/* reset sliding window if necessary */
if (strm.avail_out == 0) {
strm.avail_out = WINSIZE;
strm.next_out = window;
}
/* inflate until out of input, output, or at end of block --
update the total input and output counters */
totin += strm.avail_in;
totout += strm.avail_out;
ret = inflate(&strm, Z_BLOCK); /* return at end of block */
totin -= strm.avail_in;
totout -= strm.avail_out;
if (ret == Z_NEED_DICT)
ret = Z_DATA_ERROR;
if (ret == Z_MEM_ERROR || ret == Z_DATA_ERROR)
goto build_index_error;
if (ret == Z_STREAM_END)
break;
/* if at end of block, consider adding an index entry (note that if
data_type indicates an end-of-block, then all of the
uncompressed data from that block has been delivered, and none
of the compressed data after that block has been consumed,
except for up to seven bits) -- the totout == 0 provides an
entry point after the zlib or gzip header, and assures that the
index always has at least one access point; we avoid creating an
access point after the last block by checking bit 6 of data_type
*/
if ((strm.data_type & 128) && !(strm.data_type & 64) &&
(totout == 0 || totout - last > span)) {
index = addpoint(index, strm.data_type & 7, totin,
totout, strm.avail_out, window);
if (index == NULL) {
ret = Z_MEM_ERROR;
goto build_index_error;
}
last = totout;
}
} while (strm.avail_in != 0);
} while (ret != Z_STREAM_END);
/* clean up and return index (release unused entries in list) */
(void)inflateEnd(&strm);
index->list = realloc(index->list, sizeof(struct point) * index->have);
index->size = index->have;
*built = index;
return index->size;
/* return error */
build_index_error:
(void)inflateEnd(&strm);
if (index != NULL)
free_index(index);
return ret;
}
/* Use the index to read len bytes from offset into buf, return bytes read or
negative for error (Z_DATA_ERROR or Z_MEM_ERROR). If data is requested past
the end of the uncompressed data, then extract() will return a value less
than len, indicating how much as actually read into buf. This function
should not return a data error unless the file was modified since the index
was generated. extract() may also return Z_ERRNO if there is an error on
reading or seeking the input file. */
local int extract(FILE *in, struct access *index, off_t offset,
unsigned char *buf, int len)
{
int ret, skip;
z_stream strm;
struct point *here;
unsigned char input[CHUNK];
unsigned char discard[WINSIZE];
/* proceed only if something reasonable to do */
if (len < 0)
return 0;
/* find where in stream to start */
here = index->list;
ret = index->have;
while (--ret && here[1].out <= offset)
here++;
/* initialize file and inflate state to start there */
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = 0;
strm.next_in = Z_NULL;
ret = inflateInit2(&strm, -15); /* raw inflate */
if (ret != Z_OK)
return ret;
ret = fseeko(in, here->in - (here->bits ? 1 : 0), SEEK_SET);
if (ret == -1)
goto extract_ret;
if (here->bits) {
ret = getc(in);
if (ret == -1) {
ret = ferror(in) ? Z_ERRNO : Z_DATA_ERROR;
goto extract_ret;
}
(void)inflatePrime(&strm, here->bits, ret >> (8 - here->bits));
}
(void)inflateSetDictionary(&strm, here->window, WINSIZE);
/* skip uncompressed bytes until offset reached, then satisfy request */
offset -= here->out;
strm.avail_in = 0;
skip = 1; /* while skipping to offset */
do {
/* define where to put uncompressed data, and how much */
if (offset == 0 && skip) { /* at offset now */
strm.avail_out = len;
strm.next_out = buf;
skip = 0; /* only do this once */
}
if (offset > WINSIZE) { /* skip WINSIZE bytes */
strm.avail_out = WINSIZE;
strm.next_out = discard;
offset -= WINSIZE;
}
else if (offset != 0) { /* last skip */
strm.avail_out = (unsigned)offset;
strm.next_out = discard;
offset = 0;
}
/* uncompress until avail_out filled, or end of stream */
do {
if (strm.avail_in == 0) {
strm.avail_in = fread(input, 1, CHUNK, in);
if (ferror(in)) {
ret = Z_ERRNO;
goto extract_ret;
}
if (strm.avail_in == 0) {
ret = Z_DATA_ERROR;
goto extract_ret;
}
strm.next_in = input;
}
ret = inflate(&strm, Z_NO_FLUSH); /* normal inflate */
if (ret == Z_NEED_DICT)
ret = Z_DATA_ERROR;
if (ret == Z_MEM_ERROR || ret == Z_DATA_ERROR)
goto extract_ret;
if (ret == Z_STREAM_END)
break;
} while (strm.avail_out != 0);
/* if reach end of stream, then don't keep trying to get more */
if (ret == Z_STREAM_END)
break;
/* do until offset reached and requested data read, or stream ends */
} while (skip);
/* compute number of uncompressed bytes read after offset */
ret = skip ? 0 : len - strm.avail_out;
/* clean up and return bytes read or error */
extract_ret:
(void)inflateEnd(&strm);
return ret;
}
/* Demonstrate the use of build_index() and extract() by processing the file
provided on the command line, and the extracting 16K from about 2/3rds of
the way through the uncompressed output, and writing that to stdout. */
int main(int argc, char **argv)
{
int len;
off_t offset;
FILE *in;
struct access *index = NULL;
unsigned char buf[CHUNK];
/* open input file */
if (argc != 2) {
fprintf(stderr, "usage: zran file.gz\n");
return 1;
}
in = fopen(argv[1], "rb");
if (in == NULL) {
fprintf(stderr, "zran: could not open %s for reading\n", argv[1]);
return 1;
}
/* build index */
len = build_index(in, SPAN, &index);
if (len < 0) {
fclose(in);
switch (len) {
case Z_MEM_ERROR:
fprintf(stderr, "zran: out of memory\n");
break;
case Z_DATA_ERROR:
fprintf(stderr, "zran: compressed data error in %s\n", argv[1]);
break;
case Z_ERRNO:
fprintf(stderr, "zran: read error on %s\n", argv[1]);
break;
default:
fprintf(stderr, "zran: error %d while building index\n", len);
}
return 1;
}
fprintf(stderr, "zran: built index with %d access points\n", len);
/* use index by reading some bytes from an arbitrary offset */
offset = (index->list[index->have - 1].out << 1) / 3;
len = extract(in, index, offset, buf, CHUNK);
if (len < 0)
fprintf(stderr, "zran: extraction failed: %s error\n",
len == Z_MEM_ERROR ? "out of memory" : "input corrupted");
else {
fwrite(buf, 1, len, stdout);
fprintf(stderr, "zran: extracted %d bytes at %llu\n", len, offset);
}
/* clean up and exit */
free_index(index);
fclose(in);
return 0;
}

409
pcsx2/CDVD/zlib_indexed.c Normal file
View File

@ -0,0 +1,409 @@
/* zran.c -- example of zlib/gzip stream indexing and random access
* Copyright (C) 2005, 2012 Mark Adler
* For conditions of distribution and use, see copyright notice in zlib.h
Version 1.1 29 Sep 2012 Mark Adler */
/* Version History:
1.0 29 May 2005 First version
1.1 29 Sep 2012 Fix memory reallocation error
*/
/* Illustrate the use of Z_BLOCK, inflatePrime(), and inflateSetDictionary()
for random access of a compressed file. A file containing a zlib or gzip
stream is provided on the command line. The compressed stream is decoded in
its entirety, and an index built with access points about every SPAN bytes
in the uncompressed output. The compressed file is left open, and can then
be read randomly, having to decompress on the average SPAN/2 uncompressed
bytes before getting to the desired block of data.
An access point can be created at the start of any deflate block, by saving
the starting file offset and bit of that block, and the 32K bytes of
uncompressed data that precede that block. Also the uncompressed offset of
that block is saved to provide a referece for locating a desired starting
point in the uncompressed stream. build_index() works by decompressing the
input zlib or gzip stream a block at a time, and at the end of each block
deciding if enough uncompressed data has gone by to justify the creation of
a new access point. If so, that point is saved in a data structure that
grows as needed to accommodate the points.
To use the index, an offset in the uncompressed data is provided, for which
the latest accees point at or preceding that offset is located in the index.
The input file is positioned to the specified location in the index, and if
necessary the first few bits of the compressed data is read from the file.
inflate is initialized with those bits and the 32K of uncompressed data, and
the decompression then proceeds until the desired offset in the file is
reached. Then the decompression continues to read the desired uncompressed
data from the file.
Another approach would be to generate the index on demand. In that case,
requests for random access reads from the compressed data would try to use
the index, but if a read far enough past the end of the index is required,
then further index entries would be generated and added.
There is some fair bit of overhead to starting inflation for the random
access, mainly copying the 32K byte dictionary. So if small pieces of the
file are being accessed, it would make sense to implement a cache to hold
some lookahead and avoid many calls to extract() for small lengths.
Another way to build an index would be to use inflateCopy(). That would
not be constrained to have access points at block boundaries, but requires
more memory per access point, and also cannot be saved to file due to the
use of pointers in the state. The approach here allows for storage of the
index in a file.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "zlib.h"
#define local static
#define SPAN 1048576L /* desired distance between access points */
#define WINSIZE 32768U /* sliding window size */
#define CHUNK 16384 /* file input buffer size */
/* access point entry */
struct point {
off_t out; /* corresponding offset in uncompressed data */
off_t in; /* offset in input file of first full byte */
int bits; /* number of bits (1-7) from byte at in - 1, or 0 */
unsigned char window[WINSIZE]; /* preceding 32K of uncompressed data */
};
/* access point list */
struct access {
int have; /* number of list entries filled in */
int size; /* number of list entries allocated */
struct point *list; /* allocated list */
};
/* Deallocate an index built by build_index() */
local void free_index(struct access *index)
{
if (index != NULL) {
free(index->list);
free(index);
}
}
/* Add an entry to the access point list. If out of memory, deallocate the
existing list and return NULL. */
local struct access *addpoint(struct access *index, int bits,
off_t in, off_t out, unsigned left, unsigned char *window)
{
struct point *next;
/* if list is empty, create it (start with eight points) */
if (index == NULL) {
index = malloc(sizeof(struct access));
if (index == NULL) return NULL;
index->list = malloc(sizeof(struct point) << 3);
if (index->list == NULL) {
free(index);
return NULL;
}
index->size = 8;
index->have = 0;
}
/* if list is full, make it bigger */
else if (index->have == index->size) {
index->size <<= 1;
next = realloc(index->list, sizeof(struct point) * index->size);
if (next == NULL) {
free_index(index);
return NULL;
}
index->list = next;
}
/* fill in entry and increment how many we have */
next = index->list + index->have;
next->bits = bits;
next->in = in;
next->out = out;
if (left)
memcpy(next->window, window + WINSIZE - left, left);
if (left < WINSIZE)
memcpy(next->window + left, window, WINSIZE - left);
index->have++;
/* return list, possibly reallocated */
return index;
}
/* Make one entire pass through the compressed stream and build an index, with
access points about every span bytes of uncompressed output -- span is
chosen to balance the speed of random access against the memory requirements
of the list, about 32K bytes per access point. Note that data after the end
of the first zlib or gzip stream in the file is ignored. build_index()
returns the number of access points on success (>= 1), Z_MEM_ERROR for out
of memory, Z_DATA_ERROR for an error in the input file, or Z_ERRNO for a
file read error. On success, *built points to the resulting index. */
local int build_index(FILE *in, off_t span, struct access **built)
{
int ret;
off_t totin, totout; /* our own total counters to avoid 4GB limit */
off_t last; /* totout value of last access point */
struct access *index; /* access points being generated */
z_stream strm;
unsigned char input[CHUNK];
unsigned char window[WINSIZE];
/* initialize inflate */
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = 0;
strm.next_in = Z_NULL;
ret = inflateInit2(&strm, 47); /* automatic zlib or gzip decoding */
if (ret != Z_OK)
return ret;
/* inflate the input, maintain a sliding window, and build an index -- this
also validates the integrity of the compressed data using the check
information at the end of the gzip or zlib stream */
totin = totout = last = 0;
index = NULL; /* will be allocated by first addpoint() */
strm.avail_out = 0;
do {
/* get some compressed data from input file */
strm.avail_in = fread(input, 1, CHUNK, in);
if (ferror(in)) {
ret = Z_ERRNO;
goto build_index_error;
}
if (strm.avail_in == 0) {
ret = Z_DATA_ERROR;
goto build_index_error;
}
strm.next_in = input;
/* process all of that, or until end of stream */
do {
/* reset sliding window if necessary */
if (strm.avail_out == 0) {
strm.avail_out = WINSIZE;
strm.next_out = window;
}
/* inflate until out of input, output, or at end of block --
update the total input and output counters */
totin += strm.avail_in;
totout += strm.avail_out;
ret = inflate(&strm, Z_BLOCK); /* return at end of block */
totin -= strm.avail_in;
totout -= strm.avail_out;
if (ret == Z_NEED_DICT)
ret = Z_DATA_ERROR;
if (ret == Z_MEM_ERROR || ret == Z_DATA_ERROR)
goto build_index_error;
if (ret == Z_STREAM_END)
break;
/* if at end of block, consider adding an index entry (note that if
data_type indicates an end-of-block, then all of the
uncompressed data from that block has been delivered, and none
of the compressed data after that block has been consumed,
except for up to seven bits) -- the totout == 0 provides an
entry point after the zlib or gzip header, and assures that the
index always has at least one access point; we avoid creating an
access point after the last block by checking bit 6 of data_type
*/
if ((strm.data_type & 128) && !(strm.data_type & 64) &&
(totout == 0 || totout - last > span)) {
index = addpoint(index, strm.data_type & 7, totin,
totout, strm.avail_out, window);
if (index == NULL) {
ret = Z_MEM_ERROR;
goto build_index_error;
}
last = totout;
}
} while (strm.avail_in != 0);
} while (ret != Z_STREAM_END);
/* clean up and return index (release unused entries in list) */
(void)inflateEnd(&strm);
index->list = realloc(index->list, sizeof(struct point) * index->have);
index->size = index->have;
*built = index;
return index->size;
/* return error */
build_index_error:
(void)inflateEnd(&strm);
if (index != NULL)
free_index(index);
return ret;
}
/* Use the index to read len bytes from offset into buf, return bytes read or
negative for error (Z_DATA_ERROR or Z_MEM_ERROR). If data is requested past
the end of the uncompressed data, then extract() will return a value less
than len, indicating how much as actually read into buf. This function
should not return a data error unless the file was modified since the index
was generated. extract() may also return Z_ERRNO if there is an error on
reading or seeking the input file. */
local int extract(FILE *in, struct access *index, off_t offset,
unsigned char *buf, int len)
{
int ret, skip;
z_stream strm;
struct point *here;
unsigned char input[CHUNK];
unsigned char discard[WINSIZE];
/* proceed only if something reasonable to do */
if (len < 0)
return 0;
/* find where in stream to start */
here = index->list;
ret = index->have;
while (--ret && here[1].out <= offset)
here++;
/* initialize file and inflate state to start there */
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = 0;
strm.next_in = Z_NULL;
ret = inflateInit2(&strm, -15); /* raw inflate */
if (ret != Z_OK)
return ret;
ret = fseeko(in, here->in - (here->bits ? 1 : 0), SEEK_SET);
if (ret == -1)
goto extract_ret;
if (here->bits) {
ret = getc(in);
if (ret == -1) {
ret = ferror(in) ? Z_ERRNO : Z_DATA_ERROR;
goto extract_ret;
}
(void)inflatePrime(&strm, here->bits, ret >> (8 - here->bits));
}
(void)inflateSetDictionary(&strm, here->window, WINSIZE);
/* skip uncompressed bytes until offset reached, then satisfy request */
offset -= here->out;
strm.avail_in = 0;
skip = 1; /* while skipping to offset */
do {
/* define where to put uncompressed data, and how much */
if (offset == 0 && skip) { /* at offset now */
strm.avail_out = len;
strm.next_out = buf;
skip = 0; /* only do this once */
}
if (offset > WINSIZE) { /* skip WINSIZE bytes */
strm.avail_out = WINSIZE;
strm.next_out = discard;
offset -= WINSIZE;
}
else if (offset != 0) { /* last skip */
strm.avail_out = (unsigned)offset;
strm.next_out = discard;
offset = 0;
}
/* uncompress until avail_out filled, or end of stream */
do {
if (strm.avail_in == 0) {
strm.avail_in = fread(input, 1, CHUNK, in);
if (ferror(in)) {
ret = Z_ERRNO;
goto extract_ret;
}
if (strm.avail_in == 0) {
ret = Z_DATA_ERROR;
goto extract_ret;
}
strm.next_in = input;
}
ret = inflate(&strm, Z_NO_FLUSH); /* normal inflate */
if (ret == Z_NEED_DICT)
ret = Z_DATA_ERROR;
if (ret == Z_MEM_ERROR || ret == Z_DATA_ERROR)
goto extract_ret;
if (ret == Z_STREAM_END)
break;
} while (strm.avail_out != 0);
/* if reach end of stream, then don't keep trying to get more */
if (ret == Z_STREAM_END)
break;
/* do until offset reached and requested data read, or stream ends */
} while (skip);
/* compute number of uncompressed bytes read after offset */
ret = skip ? 0 : len - strm.avail_out;
/* clean up and return bytes read or error */
extract_ret:
(void)inflateEnd(&strm);
return ret;
}
/* Demonstrate the use of build_index() and extract() by processing the file
provided on the command line, and the extracting 16K from about 2/3rds of
the way through the uncompressed output, and writing that to stdout. */
int main(int argc, char **argv)
{
int len;
off_t offset;
FILE *in;
struct access *index = NULL;
unsigned char buf[CHUNK];
/* open input file */
if (argc != 2) {
fprintf(stderr, "usage: zran file.gz\n");
return 1;
}
in = fopen(argv[1], "rb");
if (in == NULL) {
fprintf(stderr, "zran: could not open %s for reading\n", argv[1]);
return 1;
}
/* build index */
len = build_index(in, SPAN, &index);
if (len < 0) {
fclose(in);
switch (len) {
case Z_MEM_ERROR:
fprintf(stderr, "zran: out of memory\n");
break;
case Z_DATA_ERROR:
fprintf(stderr, "zran: compressed data error in %s\n", argv[1]);
break;
case Z_ERRNO:
fprintf(stderr, "zran: read error on %s\n", argv[1]);
break;
default:
fprintf(stderr, "zran: error %d while building index\n", len);
}
return 1;
}
fprintf(stderr, "zran: built index with %d access points\n", len);
/* use index by reading some bytes from an arbitrary offset */
offset = (index->list[index->have - 1].out << 1) / 3;
len = extract(in, index, offset, buf, CHUNK);
if (len < 0)
fprintf(stderr, "zran: extraction failed: %s error\n",
len == Z_MEM_ERROR ? "out of memory" : "input corrupted");
else {
fwrite(buf, 1, len, stdout);
fprintf(stderr, "zran: extracted %d bytes at %llu\n", len, offset);
}
/* clean up and exit */
free_index(index);
fclose(in);
return 0;
}