docs(debt): note the result structure a title passes to sceSaveDataDirNameSearch2

docs/dev/debt/libSceSaveData.native.md

@@ -16,7 +16,7 @@
 ### Functional
 
 - [sceSaveDataDirNameSearch, sceSaveDataDirNameSearch2](../../../core/libs/prx/libSceSaveData.native/Export.cpp) (libSceSaveData.native) - only the running title's saves are kept, so a search with another title's `title_id` reports zero hits, as [shadPS4](https://github.com/shadps4-emu/shadPS4/blob/ec334904604ba41f5d4753f4a2498ec82540e5d6/src/core/libraries/save_data/savedata.cpp#L791-L802) and [KytyPS5](https://github.com/KytyPS5/KytyPS5/blob/569ec04d1a77127c601eed522ad5bba187173f9d/src/libs/libSaveData.cpp#L592-L596) do when that title has no save directory; what a console returns for another title's saves is not verified. The running title's ID is the `titleId` in its `param.json`
-- [sceSaveDataDirNameSearch2](../../../core/libs/prx/libSceSaveData.native/Export.cpp) (libSceSaveData.native) runs the same search as `sceSaveDataDirNameSearch` with the same condition and result structures, as [SharpEmu](https://github.com/sharpemu/sharpemu/blob/main/src/SharpEmu.Libs/SaveData/SaveDataExports.cs) does, its only source; what distinguishes it on the console is unknown.
+- [sceSaveDataDirNameSearch2](../../../core/libs/prx/libSceSaveData.native/Export.cpp) (libSceSaveData.native) runs the same search as `sceSaveDataDirNameSearch` with the same condition and result structures, as [SharpEmu](https://github.com/sharpemu/sharpemu/blob/main/src/SharpEmu.Libs/SaveData/SaveDataExports.cs) does, its only source; what distinguishes it on the console is unknown. One title (PPSA35669, in a plugin) disassembled for this entry has one call site (0x2eda71); it clears 56 bytes for the result structure first (the size of the structure used here), puts a value returned by a call with the argument 0x8000 at offset 8 and 0x400 at offset 0x10, and afterwards branches on a negative result and reads the 32-bit field at offset 0, skipping its loop when it is 0. That agrees with the result structure of `sceSaveDataDirNameSearch`. The condition structure was not read.
 - [sceSaveDataMount3](../../../core/libs/prx/libSceSaveData.native/Export.cpp) (libSceSaveData.native) - a failed mount (BUSY, EXISTS, NOT_FOUND, MOUNT_FULL) leaves the result as it was, as shadPS4 does; not checked on hardware. Animal Well (PPSA22520) depends on it: it checks for its save with a mount it never unmounts, then saves with a second mount of the same directory, ignores its BUSY and keeps using the first mount point for `sceSaveDataPrepare`, its file and `sceSaveDataUmount2`
 - [sceSaveDataMount3](../../../core/libs/prx/libSceSaveData.native/Export.cpp) (libSceSaveData.native) - an unterminated or empty directory name, `.`, `..`, or a name containing `/`, `\` or `:` returns `SAVE_DATA_ERROR_PARAMETER`, which the [SDK 12.000 reference](https://github.com/peterpuppy/bm/blob/3f9d1ba6b896a53080460c903f5c15af8affb80d/features/ps5/document/output/psn_12/System/Save_Data/SaveData-Reference/sce-save-data-mount3.md#L196-L204) lists for an invalid parameter, and leaves the result as it was, as [KytyPS5](https://github.com/KytyPS5/KytyPS5/blob/569ec04d1a77127c601eed522ad5bba187173f9d/src/libs/libSaveData.cpp#L652-L658) does. The [SDK](https://github.com/peterpuppy/bm/blob/3f9d1ba6b896a53080460c903f5c15af8affb80d/features/ps5/document/output/psn_12/System/Save_Data/SaveData-Reference/sce-save-data-dir-name.md#L32-L36) lets an application use only letters, digits, `-`, `.` and `@` in a name, and KytyPS5 also accepts `_` ([`valid_path_component`](https://github.com/KytyPS5/KytyPS5/blob/569ec04d1a77127c601eed522ad5bba187173f9d/src/libs/libSaveData.cpp#L276-L287)); which other names the console's mount rejects is not checked on hardware
 - [sceSaveDataGetMountInfo, sceSaveDataGetParam, sceSaveDataLoadIcon, sceSaveDataSaveIcon, sceSaveDataSetParam, sceSaveDataUmount2](../../../core/libs/prx/libSceSaveData.native/Export.cpp) (libSceSaveData.native) - null pointer arguments return `SAVE_DATA_ERROR_PARAMETER` instead of throwing C++ exceptions; unmounted targets return `SAVE_DATA_ERROR_NOT_MOUNTED`, and parameter type or buffer size violations return `SAVE_DATA_ERROR_PARAMETER` after slot lookup