SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.
This improves the speed of verifying Wii WIA/RVZ files.
For me, the verification speed for LZMA2-compressed files
has gone from 11-12 MiB/s to 13-14 MiB/s.
One thing VolumeVerifier does to achieve parallelism is to
compute hashes for one chunk of data while reading the next
chunk of data. In master, when reading data from a Wii
partition, each such chunk is 32 KiB. This is normally fine,
but with WIA and RVZ it leads to rather lopsided read times
(without the compute times being lopsided): The first 32 KiB
of each 2 MiB takes a long time to read, and the remaining
part of the 2 MiB can be read nearly instantly. (The WIA/RVZ
code has to read the entire 2 MiB in order to compute hashes
which appear at the beginning of the 2 MiB, and then caches
the result afterwards.) This leads to us at times not doing
much reading and at other times not doing much computation.
To improve this, this change makes us use 2 MiB chunks
instead of 32 KiB chunks when reading from Wii partitions.
(block = 32 KiB, group = 2 MiB)
The performance gains of doing this aren't too important since you
normally wouldn't run into any disc image that has overlapping blocks
(which by extension means overlapping partitions), but this change also
lets us get rid of things like VolumeVerifier's mutex that used to
exist just for the sake of handling overlapping blocks.
When I first made VolumeVerifier, I figured that the distinction
between an unsigned ticket and an unsigned TMD was a technical
detail that users would have no reason to care about. However,
while this might be true for discs, it isn't equally true for
WADs, due to the widespread practice of fakesigning tickets to
set the console ID to 0. This practice does not require
fakesigning the TMD (though apparently people do it anyway,
at least sometimes...), and the presence of a correctly signed
TMD is a useful indicator that the contents have not been
tampered with, even if the ticket isn't correctly signed.
This happens if someone manually downloads a regular datfile from
redump.org and puts it where Dolphin stores datfiles. Dolphin needs
"special" datfiles that contain fields for serials and versions.
Before this change, all discs (except Datel discs) would show up as
"Unknown disc" when using a regular datfile.
The old implementation of this was not able to distinguish between
a title that had the common key index set to 1 because it actually
was Korean and a title that had the common key index set to 1 due to
fakesigning. This new implementation solves the problem by
decrypting a content with each possible common key and checking
which result matches the provided SHA-1 hash.
The problem that the old implementation causes has only been reported
to affect a certain pirated WAD of Chronos Twins DX (WC6EUP), but it's
possible that the problem would start affecting more WADs if we add
support for the vWii common key (which uses index 2). Adding support
for the vWii common key would also prevent us from using the simpler
solution of always forcing the index to 0 if the title is not Korean.
Removes redundant initializers from the constructor and provides
initializers for all members that don't already have one for consistency
(and deterministic initial state).
Given the volume verifier has quite a few non-trivial object within it,
it's best to default the destructor within the cpp file to prevent
inlining complex destruction logic elsewhere, while also making it nicer
if a forward-declared type is ever used in a member variable.
Pierre Bourdon