NCM services

NCM contains services for internal file path and content management.

Location Resolver services

lr

This is "nn::lr::ILocationResolverManager".

Cmd	Name	Arguments	Notes
0	GetLocationResolver	StorageID
1	GetRegisteredLocationResolver	None
2	CheckStorage	StorageID
3	GetAddOnContentLocationResolver	None

The only sysmodules which use this service are FS, Loader, and NS. boot2 has access but doesn't use it.

ILocationResolver

This is "nn::lr::ILocationResolver".

Cmd	Name	Arguments	Notes
0	GetProgramNcaPath	u64 TID + C descriptor	Used for NCA-type1.
1	SetProgramNcaPath	u64 TID + X descriptor ContentPath	Used for NCA-type1.
2	GetUserControlNcaPath	u64 TID + C descriptor	Used for NCA-type3 (gamecard only?).
3	GetDocHtmlNcaPath	u64 TID + C descriptor	Used for NCA-type4.
4	GetControlNcaPath	u64 TID + C descriptor	Used for NCA-type3. Stubbed, only returns error 0x608.
5	SetControlNcaPath	u64 TID + X descriptor ContentPath	Used for NCA-type3.
6	SetDocHtmlNcaPath	u64 TID + X descriptor ContentPath	Used for NCA-type4.
7	GetInfoHtmlNcaPath	u64 TID + C descriptor	Used for NCA-type5.
8	SetInfoHtmlNcaPath	u64 TID + X descriptor ContentPath	Used for NCA-type5.
9	ClearLocationResolver	None	Clears all NCA paths set.

These get-commands load the ContentPath from linked-lists in memory using the input titleID. The set-commands add a new entry to the list, if a matching entry is found it's removed first. ClearLocationResolver frees all entries in all of these linked-lists. The ContentPath is only used with memcpy() here with size=0x300, nothing more.

The set commands always return 0. When the get-commands fail to find an entry for the specified titleID, 0x408 is returned for GetProgramNcaPath, while the rest of the commands return 0xA08.

IRegisteredLocationResolver

This is "nn::lr::IRegisteredLocationResolver".

This works like #ILocationResolver, but only two types of NCA paths can be gotten/set. In addition, each type has a fallback path that can be set for a single title ID at a time.

Cmd	Name	Arguments	Notes
0	GetPatchType0NcaPath	u64 TID + C descriptor	Used for NCA-type1.
1	RegisterPatchType0FallbackPath	u64 TID + X descriptor ContentPath	Sets the Type 0 fallback TID and path to the provided arguments.
2	UnregisterPatchType0FallbackPath	u64 TID	If the Type 0 fallback TID is == argument TID, unregisters the fallback path. Otherwise, noop.
3	SetPatchType0NcaPath	u64 TID + X descriptor ContentPath
(2.0.0+) 4	GetPatchType1NcaPath	u64 TID + C descriptor
(2.0.0+) 5	RegisterPatchType1FallbackPath	u64 TID + X descriptor ContentPath	Sets the Type 1 fallback TID and path to the provided arguments.
(2.0.0+) 6	UnregisterPatchType1FallbackPath	u64 TID	If the Type 1 fallback TID is == argument TID, unregisters the fallback path. Otherwise, noop.
(2.0.0+) 7	SetPatchType1NcaPath	u64 TID + X descriptor ContentPath

IAddOnContentLocationResolver

This is "nn::lr::IAddOnContentLocationResolver".

Cmd	Name	Arguments	Notes
0	GetAddOnContentNcaPath	u64 TID + C descriptor
1	RegisterAddOnContent	StorageID + u64 TID
2	ClearAddOnContentLocationResolver	None	Clears all registered titles here.

Content Manager services

ncm

This is "nn::ncm::IContentManager".

Cmd	Name	Notes
0	CreatePlaceholderAndRegisteredDirectoriesForMediaId	Takes a StorageID.
1	CreateSaveDataDirectoryForMediaId	Takes a StorageID.
2	GetExistsPlaceholderAndRegisteredDirectoriesForMediaId	Takes a StorageID.
3	GetExistsSaveDataDirectoryForMediaId	Takes a StorageID.
4	GetIContentStorage	Takes a StorageID.
5	GetIContentMetaDatabase	Takes a StorageID.
(1.0.0) 6	CloseAndLockIContentStorage	Takes a StorageID. Calls IContentStorage->CloseAndFlushStorage().
(1.0.0) 7	CloseAndLockIContentMetaDatabase	Takes a StorageID. Calls IContentMetaDatabase->CloseMetaDatabase().
8	DeleteSaveDataForMediaId	Takes a StorageID, and deletes the associated savedata.
(2.0.0+?) 9	MountStorageForMediaId
(2.0.0+?) 10	UnmountStorageForMediaId
(2.0.0+?) 11	MountDatabaseForMediaId
(2.0.0+?) 12	UnmountDatabaseForMediaId

All of the above cmds takes a u8 as input.

IContentStorage

This is "nn::ncm::IContentStorage".

Cmd	Name	Notes
0	#GetUUID	Returns a random UUID for the Content Storage.
1	CreatePlaceholderEntryAndRegisteredDirectoryEntry	Takes two #NcaIDs, and a u64 filesize.
2	DeletePlaceholderEntry	Takes a #NcaID.
3	DoesPlaceholderEntryExist	Takes a #NcaID.
4	WritePlaceholderEntry	Takes a #NcaID, a u64-offset, and type 5 buffer. Writes the buffer to the file for the NcaID's placeholder path at the specified offset.
5	MovePlaceholderToRegistered	Takes two #NcaIDs, moves the Placeholder NCA content to the registered NCA path.
6	DeleteRegisteredEntry	Takes a #NcaID.
7	DoesRegisteredEntryExist	Takes a #NcaID.
8	GetPathForRegisteredEntry	Takes a #NcaID. Returns a Content Path.
9	GetPathForPlaceholderEntry	Takes a #NcaID. Returns a Content Path.
10	CleanPlaceholderDirectory	Deletes and re-creates the Placeholder directory.
11	GetNumberOfRegisteredEntries	This is like #GetRegisteredEntries, but for the Placeholder directory.
12	#GetNumberOfRegisteredEntries
13	#GetRegisteredEntries
14	#GetRegisteredEntrySize
15	CloseAndFlushStorage	Closes/Flushes all resources for the storage, and causes all future IPC commands to the current session to return error 0xC805.
16		Takes three 0x10-sized entries.
17	SetPlaceholderEntrySize	Takes a #NcaID, and a u64 size
18	#ReadRegisteredEntryRaw
19	GetPlaceholderEntryRightsID	Gets the Rights ID for the #NcaID's placeholder path.
20	GetRegisteredEntryRightsID	Gets the Rights ID for the #NcaID's registered path
21	WriteRegisteredPathForDebug	Takes a #NcaID, a u64 offset, and a type 5 buffer. On debug units, writes the buffer to the NCA's registered path. On retail units, this just aborts.
22	GetFreeSpace	Gets free space for the storage.
23	GetTotalSpace	Gets total space for the storage.
24	FlushStorage	Flushes resources for the storage without closing it.

GetUUID

Calls nn::util::GenerateUuid(), which internally calls nn::os::GenerateRandomBytes(16);

GetNumberOfRegisteredEntries

Writes the total number of entries which can be read by GetEntries, to cmdreply <SFCO_offset>+0x10.

GetRegisteredEntries

Takes an output buffer, u32 offset and gets all entries starting at that offset. Returns number of entries read.

Each entry is a #NcaID.

The total read entries is exactly the same as the number of "<hex>.nca" directories in the storage FS(or at least under the "registered" directory?).

GetRegisteredEntrySize

Takes a #NcaID as input.

Returns the total size readable by ReadEntryRaw. This is the same as the size-field in the NAX0 "<NcaID>.nca/00" file.

ReadRegisteredEntryRaw

Takes an output buffer, a #NcaID as input, and a u64 file offset.

Returns encrypted looking data from the content in the NAX0. Doesn't match the encrypted raw data in the NAX0 "<NcaID>.nca/00" file. Seems to be at least one crypto layer below the initial NAX0 layer, since the data doesn't change after NAX0 recreation.

Manually modifying the content in the NAX0(starting at offset 0x4000) results in different output data being returned by this cmd. Changing any data within the first 0x10-bytes results in the entire 0x10-byte block changing. Likewise for offset 0x4010 size 0x1, entire 0x10-byte block at 0x4010 changes. Changing the first 0x20-bytes at 0x4000 to zeros has the same combined changed output, as when offset 0x4000 size 0x10 and offset 0x4010 size 0x10 were changed to zeros separately. Output BlockA and BlockB are completely different, where the raw NAX0 data for those blocks are all-zero.

Overwriting the entire raw NAX0 content with zeros results in output data which doesn't seem to have any duplicate blocks/data. When changing the previously mentioned raw content for the first 8 blocks to last-block-byte = 1<<i, where i is 0-7, none of the changed output blocks match any output blocks from the previously mentioned output(all-zero raw content).

This implies that that an AES mode is being used which isn't CTR, where changing data in one block doesn't affect other blocks.

See GetEntrySize for the total size readable with this.

IContentMetaDatabase

This is "nn::ncm::IContentMetaDatabase".

Note the official name for Meta Record is "ContentMetaKey".

Cmd	Name	Notes
0	InsertEntryContentRecords	Takes a Meta Record, a type-5 Content Records buffer and a u64 size.
1	ReadEntryContentRecords	Takes a Meta Record, a type-6 buffer to write Content Records to and a u64 size. Returns the actual Content Records size read.
2	RemoveEntryContentRecords	Takes a Meta Record, and removes the associated record.
3	GetEntryContentNcaId	Takes a Meta Record and a u8 Title Type. Returns a #NcaID.
4	ReadEntryContentRecordEntries	Takes a type-6 buffer to write Content Record entries to, a Meta Record, and a u32 index into the Content Record entries to start copying from. Returns a u32 entries_read.
5	List	Takes a type-6 buffer to write Meta Records to, a u32 Title Type, a u64 TID, a u64 TID_LOW, and u64 TID_HIGH. Writes into the buffer all Meta Records with low <= record->title_id <= high, and record->type == type. Additionally requires record->title_id == TID, if record->type is Application, Patch, Add-On, or Delta.
6	GetMetaRecord	Takes a u64 title id, and returns the Meta Record with the highest version field for that title id.
7	#ListApplication
8	IsEntryPresent	Takes a Meta Record and returns whether that record is present in the database.
9	AreEntriesPresent	Takes a type-5 buffer containing Meta Records (code assumes there are size/sizeof(meta_record) records in the buffer), and returns whether all of those records are present in the database.
10	GetEntryContentRecordsSize	Takes a Meta Record, and returns the size of the associated Content Records.
11	GetEntryUnknownRecordSize	Takes a Meta Record, and returns u32 from ContentRecords + 16 (only if the Meta record has type Application or Patch).
12	GetEntryUpdateTitleId	Takes a Meta Record, and returns the update title id for that record.
13	CloseMetaDatabase	Closes the meta database, and causes all future IPC commands to the current session to return error 0xDC05.
14	#CheckNcaIDsPresent	Takes a type-6 byte buffer, and a type-5 buffer of #NcaIDs.
15	SaveMetaDatabase	Flushes the in-memory database to savedata.
16	CheckEntryHasNcaId	Takes a Meta Record and an #NcaID. Returns whether the content records for that meta record contain the NcaID.
17	ReadEntryMetaRecords	Takes a type-6 Meta Record output buffer, a u32 eoffset into that buffer, and an input Meta Record.
18	GetEntryUnknown6	Takes a Meta Record, and returns u8 from ContentRecords + 6.
19	GetAddOnContentEntryUnknownRecordSize	Does the same thing as GetEntryUnknownRecordSize, but for AddOnContents.

ListApplication

Each 24-byte entry (officially "ApplicationContentMetaKey") is as follows:

 meta_record meta_record;
 u64    base_title_id;

This function takes in a type 6 buffer to write entries to, and a u8 "filter" type. If filter is zero, all update records will be copied to to the output buffer (space permitting). Otherwise, only titles with type == filter_type will be copied to the output buffer.

This func returns a u32 num_entries_written, and a u32 num_entries_total.

ReadEntryMetaRecords

Takes a type-6 Meta Record output buffer, a u32 eoffset into that buffer, and an input Meta Record entry. Returns a u32 for total_read_entries.

Reads the meta records stored in the entry's content records into the output buffer.

This is used, for example, with System Update title 0100000000000816, which contains Meta Records for all other systitles in its Content Records.

CheckEntryNcaIDsPresent

Takes a type-6 byte buffer, and a type-5 buffer containing #NcaIDs.

This function was stubbed to return 0xDC05 in 2.0.0.

On 1.0.0: Initialized the output buffer to all 1s. Then, for each #NcaID in the input buffer, it checks if that NcaID is present anywhere in the database, and if so writes 0 to the corresponding output byte.

In pseudocode, the function basically does the following:

for i in range(len(out_buf)):

   out_buf[i] = 1

for i, NcaID in NcaIDs:

   if is_present_in_database(NcaID):
       out_buf[i] = 0

NcaID

This is a 0x10-byte entry. This is originally from the hex portion of "<hex>.nca" directory-names from this storage FS(like SD).

The NcaID is the same as the first 0x10-bytes from the calculated SHA256 hash, from hashing the entire output from ReadEntryRaw.

Enums

Title Types

Value	Description
0x01	System Programs (System Modules or System Applets)
0x02	System Data Archives
0x03	System Update
0x04	Firmware package A
0x05	Firmware package B
0x80	Regular application
0x81	Update title
0x82	Add-on content
0x83	Delta title