# libSceAppContent technical debt

### Unknown function info

- [sceAppContentDownloadDataGetAvailableSpaceKb](../../../core/libs/prx/libSceAppContent/Export.cpp) (libSceAppContent) - a title whose `param.json` declares `downloadDataSize` 0 gets 0 KB and OK; the console's behaviour for a title without a download data area is unverified (it may return an error instead). KytyPS5 does not special-case it, and shadPS4 stubs 1048576 KB. One disassembled title (PPSA15246) calls it with the `/download0` mount point and a zeroed 64-bit output, ignores the return value and multiplies the output by 1024, so for that title an error that leaves the output untouched and an OK with 0 KB look the same
- [sceAppContentDownloadDataFormat](../../../core/libs/prx/libSceAppContent/Export.cpp) (libSceAppContent) - empties the `/download0` directory, creating it if needed. Imported by PPSA01317. A null mount point returns `PARAMETER` and another mount point returns `NOT_MOUNTED` as in `sceAppContentTemporaryDataFormat` and `sceAppContentDownloadDataGetAvailableSpaceKb`; the console's error codes for both and its behaviour with files still open are unverified


- [libSceAppContent pending exports](../../../core/libs/prx/libSceAppContent/Export.cpp) - 15 named callable exports are listed in the [PS5 3.20 export table](https://github.com/DNNDHH/PS5-3.20_Libs/blob/b2a77c09cd71c01f34c790cfbe98c751a13262ad/libSceAppContent.c) and were cross-checked against the same module in PS5 firmware 13.60. Their signatures and behaviour are unverified; the declarations use the no-parameter unknown-signature convention and throw through `NotImplemented_nid_no_patch`.
### Functional

- [Initialization](../../../core/libs/prx/libSceAppContent/Export.cpp) - service readiness and boot attributes are not modeled; successful initialization returns a zero boot record. Initialization-state guards, SDK 0x01500000 repeated-initialization errors and reserved-field checks are recovered. SDK-dependent service-error translation remains incomplete.

- [Additional content](../../../core/libs/prx/libSceAppContent/Export.cpp) (libSceAppContent) is not installed or mounted: `sceAppContentAddcontMount` answers `NOT_FOUND` for every entitlement label and `sceAppContentAddcontUnmount` for every mount point, as no add-content mount is ever handed out; `sceAppContentGetAddcontInfo` answers `DRM_NO_ENTITLEMENT` for every label and `sceAppContentGetAddcontInfoList` reports 0 entries; `sceAppContentAddcontEnqueueDownload` answers `PARAMETER` for a null label and `NOT_FOUND` otherwise, since no download is ever queued; `sceAppContentAddcontDelete` answers `PARAMETER` for a null label and `NOT_FOUND` otherwise, since no additional content is ever installed. `sceAppContentGetAddcontDownloadProgress` answers `PARAMETER` for a null label or progress and `NOT_FOUND` otherwise, as [dlc_emu](https://github.com/drakmor/dlc_emu/blob/fcf69b16d46a9850578bce19dc2c1b4dc867cbb5/src/dlc_modules/dlc_content.cpp#L2328-L2341) does for a label that is not installed additional content, and never writes the progress. Its 16-byte layout (`DataSize`, then `DownloadedSize`, both 64-bit) follows [SharpProspero](https://github.com/SvenGDK/SharpProspero/blob/5dfdb4b0b166e83dc9ae275001afb695f12c7174/src/SharpProspero/Interop/AppContent/AppContent.cs#L45-L54) and is unused here. The signatures of `sceAppContentAddcontEnqueueDownload` and `sceAppContentGetAddcontDownloadProgress` follow [SharpProspero](https://github.com/SvenGDK/SharpProspero/blob/5dfdb4b0b166e83dc9ae275001afb695f12c7174/src/SharpProspero/Interop/AppContent/AppContent.cs#L140-L148), and the signature of `sceAppContentAddcontDelete` follows [dlc_emu](https://github.com/drakmor/dlc_emu/blob/fcf69b16d46a9850578bce19dc2c1b4dc867cbb5/src/dlc_modules/dlc_content.h#L91-L92); dlc_emu is not a console measurement and no console source gives the error codes, so the signatures and the error codes are unverified
- [sceAppContentGetEntitlementKey](../../../core/libs/prx/libSceAppContent/Export.cpp) (libSceAppContent) - the service result without an entitlement is unverified: this model returns `DRM_NO_ENTITLEMENT` and leaves the 16-byte key unchanged. Initialization, null-pointer and SDK 0x01500000 label-padding checks match the reported [firmware 13.42 module probe](https://github.com/boykopovar/AnyPS5/pull/9638#issuecomment-6390573735), run in an emulator, not on hardware. That module forwards service labels 0, 7, 8 and 0xFFFFFFFF without checking them; this library ignores the service label. The system service's own validation and errors remain unknown.
- [Temporary app-content storage](../../../core/libs/prx/libSceAppContent/Export.cpp) console behaviour and hardware return values are unverified, including behaviour with open files across unmount; host filesystem failures throw. Storage models one `/temp0` mount, preserving files on unmount while rejecting new path resolutions until remount, and leaving existing open host descriptors usable. `sceAppContentTemporaryDataMount` delegates to `sceAppContentTemporaryDataMount2` with option 1 (`TEMPORARY_DATA_OPTION_FORMAT`) to format on mount as [shadPS4](https://github.com/shadps4-emu/shadPS4/blob/main/src/core/libraries/app_content/app_content.cpp#L550-L553) does. Mount, format, space-query and unmount errors follow [fpPS4](https://github.com/red-prig/fpPS4/blob/04cefd43e6fddd1ab033e7980cd356d14c964905/sys/sys_path.pas); pointer ABI follows [SharpProspero](https://github.com/SvenGDK/SharpProspero/blob/main/src/SharpProspero/Interop/AppContent/AppContent.cs).