Implement in-memory savestates (#1693)

* Refactor Savestate::Var{8,16,32,64}

- They now delegate to VarArray
- They're declared in the class header so they're likely to be inlined

* First crack at refactoring Savestate to work in-memory

- Well, third, but who's counting?

* Implement Savestate::Finish

* Remove the VersionMajor and VersionMinor fields

- Instead, pull their values directly from the savestate buffer

* Mark a new constructor as explicit

* Rename Reset to Rewind

* Fix a linebreak

* Implement Savestate::Rewind

* Add ROMManager::ClearBackupState

* Refactor ROMManager to use the refactored Savestate

* Capitalize "Least"

- It was driving me nuts

* Add a log call

* Increase default Savestate buffer length to 32MB

* Use C-style file I/O instead of C++-style

- Dumping bytes to a file with C++'s standard library is a MONSTROUS PAIN IN THE ASS

* Quote the savestate's file path for clarity

* Write the savestate's length into the header

* Add some extra logging calls

* Fix section-loading

* Remove the deprecated Savestate constructor

* Convert a char* to a u32 with memcpy, not a cast

* Fix section-handling in loads

* Include <cstring> in Savestate.h

- This was causing a build error on Linux
This commit is contained in:
Jesse Talavera-Greenberg 2023-06-12 17:56:09 -04:00 committed by GitHub
parent ca7fb4f55e
commit 391ad8c95e
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
6 changed files with 437 additions and 225 deletions

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@ -562,7 +562,7 @@ void DoSavestate(Savestate* file)
file->Bool32(&poly->IsShadowMask);
file->Bool32(&poly->IsShadow);
if (file->IsAtleastVersion(4, 1))
if (file->IsAtLeastVersion(4, 1))
file->Var32((u32*)&poly->Type);
else
poly->Type = 0;

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@ -815,7 +815,10 @@ bool DoSavestate(Savestate* file)
u32 console;
file->Var32(&console);
if (console != ConsoleType)
{
Log(LogLevel::Error, "savestate: Expected console type %d, got console type %d. cannot load.\n", ConsoleType, console);
return false;
}
}
file->VarArray(MainRAM, MainRAMMaxSize);
@ -870,7 +873,11 @@ bool DoSavestate(Savestate* file)
file->VarArray(DMA9Fill, 4*sizeof(u32));
if (!DoSavestate_Scheduler(file)) return false;
if (!DoSavestate_Scheduler(file))
{
Platform::Log(Platform::LogLevel::Error, "savestate: failed to %s scheduler state\n", file->Saving ? "save" : "load");
return false;
}
file->Var32(&SchedListMask);
file->Var64(&ARM9Timestamp);
file->Var64(&ARM9Target);
@ -937,6 +944,8 @@ bool DoSavestate(Savestate* file)
}
#endif
file->Finish();
return true;
}

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@ -17,12 +17,16 @@
*/
#include <stdio.h>
#include <cassert>
#include <cstring>
#include "Savestate.h"
#include "Platform.h"
using Platform::Log;
using Platform::LogLevel;
static const char* SAVESTATE_MAGIC = "MELN";
/*
Savestate format
@ -46,230 +50,148 @@ using Platform::LogLevel;
* different minor means adjustments may have to be made
*/
// TODO: buffering system! or something of that sort
// repeated fread/fwrite is slow on Switch
Savestate::Savestate(const std::string& filename, bool save)
Savestate::Savestate(void *buffer, u32 size, bool save) :
Error(false),
Saving(save),
CurSection(NO_SECTION),
buffer(static_cast<u8 *>(buffer)),
buffer_offset(0),
buffer_length(size),
buffer_owned(false),
finished(false)
{
const char* magic = "MELN";
Error = false;
if (save)
if (Saving)
{
Saving = true;
file = Platform::OpenLocalFile(filename, "wb");
if (!file)
{
Log(LogLevel::Error, "savestate: file %s doesn't exist\n", filename.c_str());
Error = true;
return;
}
VersionMajor = SAVESTATE_MAJOR;
VersionMinor = SAVESTATE_MINOR;
fwrite(magic, 4, 1, file);
fwrite(&VersionMajor, 2, 1, file);
fwrite(&VersionMinor, 2, 1, file);
fseek(file, 8, SEEK_CUR); // length to be fixed later
WriteSavestateHeader();
}
else
{
Saving = false;
file = Platform::OpenFile(filename, "rb");
if (!file)
// Ensure that the file starts with "MELN"
u32 read_magic = 0;
Var32(&read_magic);
if (read_magic != *((u32*)SAVESTATE_MAGIC))
{
Log(LogLevel::Error, "savestate: file %s doesn't exist\n", filename.c_str());
Log(LogLevel::Error, "savestate: expected magic number %#08x (%s), got %#08x\n",
*((u32*)SAVESTATE_MAGIC),
SAVESTATE_MAGIC,
read_magic
);
Error = true;
return;
}
u32 len;
fseek(file, 0, SEEK_END);
len = (u32)ftell(file);
fseek(file, 0, SEEK_SET);
u32 buf = 0;
fread(&buf, 4, 1, file);
if (buf != ((u32*)magic)[0])
u16 major = 0;
Var16(&major);
if (major != SAVESTATE_MAJOR)
{
Log(LogLevel::Error, "savestate: invalid magic %08X\n", buf);
Log(LogLevel::Error, "savestate: bad version major %d, expecting %d\n", major, SAVESTATE_MAJOR);
Error = true;
return;
}
VersionMajor = 0;
VersionMinor = 0;
fread(&VersionMajor, 2, 1, file);
if (VersionMajor != SAVESTATE_MAJOR)
u16 minor = 0;
Var16(&minor);
if (minor > SAVESTATE_MINOR)
{
Log(LogLevel::Error, "savestate: bad version major %d, expecting %d\n", VersionMajor, SAVESTATE_MAJOR);
Log(LogLevel::Error, "savestate: state from the future, %d > %d\n", minor, SAVESTATE_MINOR);
Error = true;
return;
}
fread(&VersionMinor, 2, 1, file);
if (VersionMinor > SAVESTATE_MINOR)
u32 read_length = 0;
Var32(&read_length);
if (read_length != buffer_length)
{
Log(LogLevel::Error, "savestate: state from the future, %d > %d\n", VersionMinor, SAVESTATE_MINOR);
Log(LogLevel::Error, "savestate: expected a length of %d, got %d\n", buffer_length, read_length);
Error = true;
return;
}
buf = 0;
fread(&buf, 4, 1, file);
if (buf != len)
{
Log(LogLevel::Error, "savestate: bad length %d\n", buf);
Error = true;
return;
}
// The next 4 bytes are reserved
buffer_offset += 4;
}
}
fseek(file, 4, SEEK_CUR);
Savestate::Savestate(u32 initial_size) :
Error(false),
Saving(true), // Can't load from an empty buffer
CurSection(NO_SECTION),
buffer(nullptr),
buffer_offset(0),
buffer_length(initial_size),
buffer_owned(true),
finished(false)
{
buffer = static_cast<u8 *>(malloc(buffer_length));
if (buffer == nullptr)
{
Log(LogLevel::Error, "savestate: failed to allocate %d bytes\n", buffer_length);
Error = true;
return;
}
CurSection = -1;
WriteSavestateHeader();
}
Savestate::~Savestate()
{
if (Error) return;
if (Saving)
{
if (CurSection != 0xFFFFFFFF)
{
u32 pos = (u32)ftell(file);
fseek(file, CurSection+4, SEEK_SET);
u32 len = pos - CurSection;
fwrite(&len, 4, 1, file);
fseek(file, pos, SEEK_SET);
}
fseek(file, 0, SEEK_END);
u32 len = (u32)ftell(file);
fseek(file, 8, SEEK_SET);
fwrite(&len, 4, 1, file);
if (Saving && !finished && !buffer_owned && !Error)
{ // If we haven't finished saving, and there hasn't been an error...
Finish();
// No need to close the active section for an owned buffer,
// it's about to be thrown out.
}
if (file) fclose(file);
if (buffer_owned)
{
free(buffer);
}
}
void Savestate::Section(const char* magic)
{
if (Error) return;
if (Error || finished) return;
if (Saving)
{
if (CurSection != 0xFFFFFFFF)
// Go back to the current section's header and write the length
CloseCurrentSection();
CurSection = buffer_offset;
// Write the new section's magic number
VarArray((void*)magic, 4);
// The next 4 bytes are the length, which we'll come back to later.
u32 zero = 0;
Var32(&zero);
// The 8 bytes afterward are reserved, so we skip them.
Var32(&zero);
Var32(&zero);
}
else
{
u32 section_offset = FindSection(magic);
if (section_offset != NO_SECTION)
{
u32 pos = (u32)ftell(file);
fseek(file, CurSection+4, SEEK_SET);
u32 len = pos - CurSection;
fwrite(&len, 4, 1, file);
fseek(file, pos, SEEK_SET);
buffer_offset = section_offset;
}
CurSection = (u32)ftell(file);
fwrite(magic, 4, 1, file);
fseek(file, 12, SEEK_CUR);
}
else
{
fseek(file, 0x10, SEEK_SET);
for (;;)
else
{
u32 buf = 0;
fread(&buf, 4, 1, file);
if (buf != ((u32*)magic)[0])
{
if (buf == 0)
{
Log(LogLevel::Error, "savestate: section %s not found. blarg\n", magic);
return;
}
buf = 0;
fread(&buf, 4, 1, file);
fseek(file, buf-8, SEEK_CUR);
continue;
}
fseek(file, 12, SEEK_CUR);
break;
Log(LogLevel::Error, "savestate: section %s not found. blarg\n", magic);
Error = true;
}
}
}
void Savestate::Var8(u8* var)
{
if (Error) return;
if (Saving)
{
fwrite(var, 1, 1, file);
}
else
{
fread(var, 1, 1, file);
}
}
void Savestate::Var16(u16* var)
{
if (Error) return;
if (Saving)
{
fwrite(var, 2, 1, file);
}
else
{
fread(var, 2, 1, file);
}
}
void Savestate::Var32(u32* var)
{
if (Error) return;
if (Saving)
{
fwrite(var, 4, 1, file);
}
else
{
fread(var, 4, 1, file);
}
}
void Savestate::Var64(u64* var)
{
if (Error) return;
if (Saving)
{
fwrite(var, 8, 1, file);
}
else
{
fread(var, 8, 1, file);
}
}
void Savestate::Bool32(bool* var)
{
// for compability
// for compatibility
if (Saving)
{
u32 val = *var;
@ -285,14 +207,175 @@ void Savestate::Bool32(bool* var)
void Savestate::VarArray(void* data, u32 len)
{
if (Error) return;
if (Error || finished) return;
assert(buffer_offset <= buffer_length);
if (Saving)
{
fwrite(data, len, 1, file);
if (buffer_offset + len > buffer_length)
{ // If writing the given data would take us past the buffer's end...
Log(LogLevel::Warn, "savestate: %u-byte write would exceed %u-byte savestate buffer\n", len, buffer_length);
if (!(buffer_owned && Resize(buffer_length * 2 + len)))
{ // If we're not allowed to resize this buffer, or if we are but failed...
Log(LogLevel::Error, "savestate: Failed to write %d bytes to savestate\n", len);
Error = true;
return;
}
// The buffer's length is doubled, plus however much memory is needed for this write.
// This way we can write the data and reduce the chance of needing to resize again.
}
memcpy(buffer + buffer_offset, data, len);
}
else
{
fread(data, len, 1, file);
if (buffer_offset + len > buffer_length)
{ // If reading the requested amount of data would take us past the buffer's edge...
Log(LogLevel::Error, "savestate: %u-byte read would exceed %u-byte savestate buffer\n", len, buffer_length);
Error = true;
return;
// Can't realloc here.
// Not only do we not own the buffer pointer (when loading a state),
// but we can't magically make the desired data appear.
}
memcpy(data, buffer + buffer_offset, len);
}
buffer_offset += len;
}
void Savestate::Finish()
{
if (Error || finished) return;
CloseCurrentSection();
WriteStateLength();
finished = true;
}
void Savestate::Rewind(bool save)
{
Error = false;
Saving = save;
CurSection = NO_SECTION;
buffer_offset = 0;
finished = false;
}
void Savestate::CloseCurrentSection()
{
if (CurSection != NO_SECTION && !finished)
{ // If we're in the middle of writing a section...
// Go back to the section's header
// Get the length of the section we've written thus far
u32 section_length = buffer_offset - CurSection;
// Write the length in the section's header
// (specifically the first 4 bytes after the magic number)
memcpy(buffer + CurSection + 4, &section_length, sizeof(section_length));
CurSection = NO_SECTION;
}
}
bool Savestate::Resize(u32 new_length)
{
if (!buffer_owned)
{ // If we're not allowed to resize this buffer...
Log(LogLevel::Error, "savestate: Buffer is externally-owned, cannot resize it\n");
return false;
}
u32 old_length = buffer_length;
void* resized = realloc(buffer, new_length);
if (!resized)
{ // If the buffer couldn't be expanded...
Log(LogLevel::Error, "savestate: Failed to resize owned savestate buffer from %dB to %dB\n", old_length, new_length);
return false;
}
u32 length_diff = new_length - old_length;
buffer = static_cast<u8 *>(resized);
buffer_length = new_length;
Log(LogLevel::Debug, "savestate: Expanded %uB savestate buffer to %uB\n", old_length, new_length);
// Zero out the newly-allocated memory (to ensure we don't introduce a security hole)
memset(buffer + old_length, 0, length_diff);
return true;
}
void Savestate::WriteSavestateHeader()
{
// The magic number
VarArray((void *) SAVESTATE_MAGIC, 4);
// The major and minor versions
u16 major = SAVESTATE_MAJOR;
Var16(&major);
u16 minor = SAVESTATE_MINOR;
Var16(&minor);
// The next 4 bytes are the file's length, which will be filled in at the end
u32 zero = 0;
Var32(&zero);
// The following 4 bytes are reserved
Var32(&zero);
}
void Savestate::WriteStateLength()
{
// Not to be confused with the buffer length.
// The buffer might not be full,
// so we don't want to write out the extra stuff.
u32 state_length = buffer_offset;
// Write the length in the header
memcpy(buffer + 0x08, &state_length, sizeof(state_length));
}
u32 Savestate::FindSection(const char* magic) const
{
if (!magic) return NO_SECTION;
// Start looking at the savestate's beginning, right after its global header
// (we can't start from the current offset because then we'd lose the ability to rearrange sections)
for (u32 offset = 0x10; offset < buffer_length;)
{ // Until we've found the desired section...
// Get this section's magic number
char read_magic[4] = {0};
memcpy(read_magic, buffer + offset, sizeof(read_magic));
if (memcmp(read_magic, magic, sizeof(read_magic)) == 0)
{ // If this is the right section...
return offset + 16; // ...return the offset of the first byte of the section after the header
}
// Haven't found our section yet. Let's move on to the next one.
u32 section_length_offset = offset + sizeof(read_magic);
if (section_length_offset >= buffer_length)
{ // If trying to read the section length would take us past the file's end...
break;
}
// First we need to find out how big this section is...
u32 section_length = 0;
memcpy(&section_length, buffer + section_length_offset, sizeof(section_length));
// ...then skip it. (The section length includes the 16-byte header.)
offset += section_length;
}
// We've reached the end of the file without finding the requested section...
Log(LogLevel::Error, "savestate: section %s not found. blarg\n", magic);
return NO_SECTION;
}

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@ -19,6 +19,7 @@
#ifndef SAVESTATE_H
#define SAVESTATE_H
#include <cstring>
#include <string>
#include <stdio.h>
#include "types.h"
@ -29,37 +30,92 @@
class Savestate
{
public:
Savestate(const std::string& filename, bool save);
static constexpr u32 DEFAULT_SIZE = 32 * 1024 * 1024; // 32 MB
Savestate(void* buffer, u32 size, bool save);
explicit Savestate(u32 initial_size = DEFAULT_SIZE);
~Savestate();
bool Error;
bool Saving;
u32 VersionMajor;
u32 VersionMinor;
u32 CurSection;
void Section(const char* magic);
void Var8(u8* var);
void Var16(u16* var);
void Var32(u32* var);
void Var64(u64* var);
void Var8(u8* var)
{
VarArray(var, sizeof(*var));
}
void Var16(u16* var)
{
VarArray(var, sizeof(*var));
}
void Var32(u32* var)
{
VarArray(var, sizeof(*var));
}
void Var64(u64* var)
{
VarArray(var, sizeof(*var));
}
void Bool32(bool* var);
void VarArray(void* data, u32 len);
bool IsAtleastVersion(u32 major, u32 minor)
void Finish();
// TODO rewinds the stream
void Rewind(bool save);
bool IsAtLeastVersion(u32 major, u32 minor)
{
if (VersionMajor > major) return true;
if (VersionMajor == major && VersionMinor >= minor) return true;
u16 major_version = MajorVersion();
if (MajorVersion() > major) return true;
if (major_version == major && MinorVersion() >= minor) return true;
return false;
}
void* Buffer() { return buffer; }
[[nodiscard]] const void* Buffer() const { return buffer; }
[[nodiscard]] u32 BufferLength() const { return buffer_length; }
[[nodiscard]] u32 Length() const { return buffer_offset; }
[[nodiscard]] u16 MajorVersion() const
{
// major version is stored at offset 0x04
u16 major = 0;
memcpy(&major, buffer + 0x04, sizeof(major));
return major;
}
[[nodiscard]] u16 MinorVersion() const
{
// minor version is stored at offset 0x06
u16 minor = 0;
memcpy(&minor, buffer + 0x06, sizeof(minor));
return minor;
}
private:
FILE* file;
static constexpr u32 NO_SECTION = 0xffffffff;
void CloseCurrentSection();
bool Resize(u32 new_length);
void WriteSavestateHeader();
void WriteStateLength();
u32 FindSection(const char* magic) const;
u8* buffer;
u32 buffer_offset;
u32 buffer_length;
bool buffer_owned;
bool finished;
};
#endif // SAVESTATE_H

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@ -21,6 +21,7 @@
#include <string>
#include <utility>
#include <fstream>
#include <zstd.h>
#ifdef ARCHIVE_SUPPORT_ENABLED
@ -52,6 +53,7 @@ std::string BaseGBAAssetName = "";
SaveManager* NDSSave = nullptr;
SaveManager* GBASave = nullptr;
std::unique_ptr<Savestate> BackupState = nullptr;
bool SavestateLoaded = false;
std::string PreviousSaveFile = "";
@ -304,35 +306,62 @@ bool SavestateExists(int slot)
bool LoadState(const std::string& filename)
{
// backup
Savestate* backup = new Savestate("timewarp.mln", true);
NDS::DoSavestate(backup);
delete backup;
bool failed = false;
Savestate* state = new Savestate(filename, false);
if (state->Error)
{
delete state;
// current state might be crapoed, so restore from sane backup
state = new Savestate("timewarp.mln", false);
failed = true;
FILE* file = fopen(filename.c_str(), "rb");
if (file == nullptr)
{ // If we couldn't open the state file...
Platform::Log(Platform::LogLevel::Error, "Failed to open state file \"%s\"\n", filename.c_str());
return false;
}
bool res = NDS::DoSavestate(state);
delete state;
if (!res)
{
failed = true;
state = new Savestate("timewarp.mln", false);
NDS::DoSavestate(state);
delete state;
std::unique_ptr<Savestate> backup = std::make_unique<Savestate>(Savestate::DEFAULT_SIZE);
if (backup->Error)
{ // If we couldn't allocate memory for the backup...
Platform::Log(Platform::LogLevel::Error, "Failed to allocate memory for state backup\n");
fclose(file);
return false;
}
if (failed) return false;
if (!NDS::DoSavestate(backup.get()) || backup->Error)
{ // Back up the emulator's state. If that failed...
Platform::Log(Platform::LogLevel::Error, "Failed to back up state, aborting load (from \"%s\")\n", filename.c_str());
fclose(file);
return false;
}
// We'll store the backup once we're sure that the state was loaded.
// Now that we know the file and backup are both good, let's load the new state.
// Get the size of the file that we opened
if (fseek(file, 0, SEEK_END) != 0)
{
Platform::Log(Platform::LogLevel::Error, "Failed to seek to end of state file \"%s\"\n", filename.c_str());
fclose(file);
return false;
}
size_t size = ftell(file);
rewind(file); // reset the filebuf's position
// Allocate exactly as much memory as we need for the savestate
std::vector<u8> buffer(size);
if (fread(buffer.data(), size, 1, file) == 0)
{ // Read the state file into the buffer. If that failed...
Platform::Log(Platform::LogLevel::Error, "Failed to read %u-byte state file \"%s\"\n", size, filename.c_str());
fclose(file);
return false;
}
fclose(file); // done with the file now
// Get ready to load the state from the buffer into the emulator
std::unique_ptr<Savestate> state = std::make_unique<Savestate>(buffer.data(), size, false);
if (!NDS::DoSavestate(state.get()) || state->Error)
{ // If we couldn't load the savestate from the buffer...
Platform::Log(Platform::LogLevel::Error, "Failed to load state file \"%s\" into emulator\n", filename.c_str());
return false;
}
// The backup was made and the state was loaded, so we can store the backup now.
BackupState = std::move(backup); // This will clean up any existing backup
assert(backup == nullptr);
if (Config::SavestateRelocSRAM && NDSSave)
{
@ -351,15 +380,41 @@ bool LoadState(const std::string& filename)
bool SaveState(const std::string& filename)
{
Savestate* state = new Savestate(filename, true);
if (state->Error)
{
delete state;
FILE* file = fopen(filename.c_str(), "wb");
if (file == nullptr)
{ // If the file couldn't be opened...
return false;
}
NDS::DoSavestate(state);
delete state;
Savestate state;
if (state.Error)
{ // If there was an error creating the state (and allocating its memory)...
fclose(file);
return false;
}
// Write the savestate to the in-memory buffer
NDS::DoSavestate(&state);
if (state.Error)
{
fclose(file);
return false;
}
if (fwrite(state.Buffer(), state.Length(), 1, file) == 0)
{ // Write the Savestate buffer to the file. If that fails...
Platform::Log(Platform::Error,
"Failed to write %d-byte savestate to %s\n",
state.Length(),
filename.c_str()
);
fclose(file);
return false;
}
fclose(file);
if (Config::SavestateRelocSRAM && NDSSave)
{
@ -374,14 +429,14 @@ bool SaveState(const std::string& filename)
void UndoStateLoad()
{
if (!SavestateLoaded) return;
if (!SavestateLoaded || !BackupState) return;
// Rewind the backup state and put it in load mode
BackupState->Rewind(false);
// pray that this works
// what do we do if it doesn't???
// but it should work.
Savestate* backup = new Savestate("timewarp.mln", false);
NDS::DoSavestate(backup);
delete backup;
NDS::DoSavestate(BackupState.get());
if (NDSSave && (!PreviousSaveFile.empty()))
{
@ -514,6 +569,14 @@ u32 DecompressROM(const u8* inContent, const u32 inSize, u8** outContent)
return realSize;
}
void ClearBackupState()
{
if (BackupState != nullptr)
{
BackupState = nullptr;
}
}
bool LoadROM(QStringList filepath, bool reset)
{
if (filepath.empty()) return false;

View File

@ -35,6 +35,7 @@ extern SaveManager* GBASave;
QString VerifySetup();
void Reset();
bool LoadBIOS();
void ClearBackupState();
bool LoadROM(QStringList filepath, bool reset);
void EjectCart();