This makes it possible to catch errors earlier so that file systems
simply fail to load instead of behaving oddly. It also makes it possible
to check for errors that weren't checkable before, like the end of a
directory being after the end of the parent directory.
Instead of expecting callers to know how the size of directory file infos
relates to which files are in which directories, filesystems now offer a
GetRoot() method, and file infos offer a way to get their children. As
a bonus, m_FileInfoVector no longer has to be created and kept around
in RAM. Only the file info objects that actually are used are created.
Not initializing until the filesystem is used is good when
a filesystem is constructed and then never used, but nobody does that.
This simplifies the code a little and lets all methods be const.
Instead of using lots of small scattered reads to read the FST,
only one big read is used, which is more efficient.
This also means that the FST only allocates memory once and stores all
strings close to each other - good for the CPU cache. The file info
objects use pointers to this FST memory of containing data themselves.
Keeping around the big m_FileInfoVector containing objects with only
pointers is a bit unnecessary, but that will be fixed soon.
Instead of calling GetPathFromFSTOffset for every file info, FindFileInfo
now only looks at names in directories that are included in the path.
For the common case of searching for "opening.bnr", this means that
only root-level files and directories have to be searched through.
Some callers already have the file info, making the relatively slow
FindFileInfo calls unnecessary. Callers that didn't have the file info
will now need to call FindFileInfo on their own.
Some callers (i.e. ISOProperties) don't want the full path, so giving them
it is unnecessary. Those that do want it can use GetPathFromFSTOffset.
Not storing full paths everywhere also saves a small bit of RAM and is
necessary for a later commit. The code isn't especially pretty right now
(callers need to use FST offsets...) but it'll become better later.
GC/Wii filesystem internals shouldn't be exposed to other classes.
This change isn't especially useful by itself, but it opens up the
way for some neat stuff in the following commits.
You may want to read the PR #2047 comments before reading this.
Dolphin attempts to support an unencrypted type of Wii discs
that apparently is identified by a 4-byte integer at 0x60
being non-zero. I don't know what discs (if any) would be
using that format, so I haven't been able to test Dolphin's
support for it, but it has probably been broken for a while.
The old implementation is very short but also strange.
In CreateVolumeFromFilename, we read a 4-byte integer from
0x60, and if it's non-zero, we create a CVolumeGC object
instead of a CVolumeWiiCrypted object. This might seem like
it makes no sense, but it presumably worked in the past
because IsVolumeWiiDisc used to check the volume type by
reading the magic word for Wii straight from the disc,
meaning that CVolumeGC objects representing unencrypted Wii
discs would be treated as Wii discs by pretty much all of
Dolphin's code except for the volume implementation code.
(It wasn't possible to simply use CVolumeWiiCrypted, because
that class only handled encrypted discs, like the name says.)
However, that stopped working as intended because of ace0607.
And furthermore, bb93336 made it even more broken by making
parts of Dolphin expect that data read from Wii discs needed
to be decrypted (rather than the volume implementation
implicitly deciding whether to decrypt when Read was called).
Disclaimer: Like I said before, I haven't been able to test
any of this because I don't have any discs that use this
unencrypted Wii disc format, so this is all theoretical.
Later, PR #2047 tried to remove Dolphin's support for
the unencrypted Wii disc format because seemingly no
discs used it, but the PR got closed without being merged.
At the end of that PR, I said that I would make a new PR
with a better implementation for the format after PR #2353
was merged. Now that PR #2353 is merged (two years later...)
and PR #5521 is merged, the new implementation was easy to
make, and here it is!
Untested.
Leo LamandGitHub
JosJuice
Shawn Hoffman
Léo Lam