fix(vfs): harden getdirentries and APR filepath resolution#77
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fix(vfs): harden getdirentries and APR filepath resolution#77MikeSaito wants to merge 2 commits into
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Follow-up VFS hardening task applying the same guest-writes-first discipline established in the time subsystem to directory enumeration.
Deferred Commit in KernelGetdirentriesCore:
- Reordered guest output so the 512-byte dirent buffer is written first via TryWriteCompat, basep is updated second (when non-null) via TryWriteUInt64Compat, and directory.NextIndex is advanced only after both guest writes succeed.
- Removed the early basep write at method entry that could mutate guest memory before buffer validation and advance the host cursor before a successful dirent delivery, causing permanent entry loss on MEMORY_FAULT at bufferAddress.
- EOF handling: when currentIndex >= Entries.Length, write basep with the final offset and return 0 without mutating NextIndex, matching FreeBSD getdirentries(2) semantics and preventing infinite retry loops.
KernelGetdents path: basePointerAddress is passed as 0, so the transaction collapses to buffer write then host cursor advance with no basep side effect.
Out of scope: coalesced {id, size} writes in sceKernelAprResolveFilepathsToIdsAndFileSizes; NetCtl connected-state stubs.
Files: KernelMemoryCompatExports.cs
Refactored sceKernelAprResolveFilepathsToIdsAndFileSizes to stop writing ids and sizes into guest memory one element at a time. - Removed the uint.MaxValue placeholder write at the start of each loop iteration. - Path resolution and file size lookup now fill host-side buffers first; on EFAULT or NOT_FOUND the guest ids/sizes arrays are left untouched. - ids and sizes are packed into contiguous byte buffers and written with one TryWriteCompat call per output array instead of separate TryWriteUInt32Compat / TryWriteUInt64Compat per index. - AmprFileRegistry.Register is called only after guest writes succeed. - AmprFileRegistry.ComputeFileId is internal so ids can be computed without registering paths during the resolve loop. Files: KernelMemoryCompatExports.cs, AmprFileRegistry.cs
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Follow-up VFS hardening applying the same guest-writes-first discipline from the time subsystem to directory enumeration and APR filepath resolution.
Getdirentries (
KernelGetdirentriesCore):TryWriteCompat, updatebasepsecond (when non-null) viaTryWriteUInt64Compat, and advancedirectory.NextIndexonly after both guest writes succeed.basepwrite at method entry that could mutate guest memory before buffer validation and advance the host cursor before a successful dirent delivery, causing permanent entry loss onMEMORY_FAULTatbufferAddress.currentIndex >= Entries.Length), writebasepwith the final offset and return 0 without mutatingNextIndex, matching FreeBSDgetdirentries(2)semantics. ForKernelGetdents,basePointerAddressis 0, so only the buffer write and host cursor advance run.APR (
sceKernelAprResolveFilepathsToIdsAndFileSizes):EFAULTorNOT_FOUND, guest arrays are untouched andAmprFileRegistryis not updated.localSizesandlocalIdsinto contiguous byte buffers and write each output array with oneTryWriteCompatcall instead of per-elementTryWriteUInt32Compat/TryWriteUInt64Compatpairs.AmprFileRegistry.Registerruns only after guest writes succeed.AmprFileRegistry.ComputeFileIdis internal so ids can be computed during the resolve loop without premature registry mutation. Removed theuint.MaxValueplaceholder pre-write.Out of scope: NetCtl connected-state stubs; writable range validation pre-probes for split outputs.
Files:
KernelMemoryCompatExports.cs,AmprFileRegistry.cs