IOS/FS: Reimplement many functions in a more accurate way #8539

They will be used in more places than just HostBackend/FS.cpp. Also fix the check and make it accurate while we're at it.

Some official titles rely on implementation details of Nintendo's FS sysmodule and will not work properly if those are changed. Notably, some games and older versions of the System Menu appear to be relying on the order of files returned by FS::ReadDirectory and will either fail to find their save data (for Bolt) or outright crash (for the System Menu). Some titles also actually expect filesystem metadata to be correct. One title that has been confirmed to do this is DQX, which generates paths based on the GID of files within its own title directory. While it is easy to make workarounds for these issues -- and in fact we already do have some for the sysmenu and DQX, having hacks is obviously nonideal and adding yet another hack would be required to fix Bolt -- one that would be even uglier. Furthermore, while it is currently unknown whether any official title cares about permissions, the lack of FS metadata means that we are unable to implement them if that turns out to be desirable or necessary. By adding a FST, we can implement things correctly and solve all those problems without hacks. Apart from DQX, the sysmenu and Bolt, this changeset also fixes the Photo Channel complaining about corrupted system files on the initial launch. This first commit adds the basic structures and functions that are necessary to load, save, query and update our version of the FST. For simplicity, a binary format that is inspired from Nintendo's FST structure was chosen for serialization. It is not expected to ever receive an update. PS: an update on the NAND image backend: A long time ago I had planned to add another FS backend which would be using a NAND image/blob as the storage. While I have already written an implementation that has been tested, solves all the aforementioned issues and more, produces images that are fully compatible with IOS's FS driver, I feel like NAND images raise too many issues: savestate sizes, code complexity and maintenance cost. Since many fixes and additions that are part of that implementation (e.g. FS timings, utility structures, FST) have already been merged or will be submitted as part of this changeset, I will likely not submit the branch.

Prevents /tmp from being cleared unnecessarily; clearing /tmp is normally only done once every time IOS is reloaded.

Previously, the FS root directory would get created as a side effect of calling CreateDirectory during boot (since the implementation was sloppy and used File::CreateFullDir). Since CreateDirectory no longer does that, it is necessary to ensure that the FS root directory does exist by creating it explicitly.

CreateDirectory does not create missing parent directories. If that behaviour is desired, CreateFullPath should be used instead. (These small misuses went unnoticed since the previous implementation of CreateDirectory automatically created parent directories.)

With the CreateFile/CreateDirectory fix and this commit, we can finally return correct results in ReadDirectory and the sorting hack -- whose purpose was to prevent certain versions of the System Menu from crashing -- can be removed too.

Now that all FS functions that create new inodes are properly implemented, we can make GetMetadata actually return correct file metadata rather than giving fixed information. The hack for the DQX installer can also be removed now since our ES and FS keep track of caller UID/GIDs now.

Files cannot be given a different file name, only moved across directories. Add a test for that behaviour and fix the existing RenameWithExistingTargetFile test.

* Test recursive directory deletion * Test "in use" check for both files and directories

ES now uses FS to access the filesystem and FS's ReadDirectory now returns file lists that are correctly ordered.

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IOS/FS: Reimplement many functions in a more accurate way #8539

IOS/FS: Reimplement many functions in a more accurate way #8539

Commits on Jan 25, 2020