FS subfiles are created with File::OpenSubFile, they have a start offset that must be added to all read/write operations.
The implementation in this commit is done using a new FileBackend that wraps the FS::File along with the start offset.
There were a few places where nested namespace specifiers weren't being
used where they could be within the service code. This amends that to
make the namespacing a tiny bit more compact.
Some services can have multiple clients at the same time, and they identify the different clients using the server session as a key.
This parameter (if present) should be a structure that contains the per-session data for each service.
The data can be retrieved using ServiceFramework::GetSessionData(session)
The File class now holds a list of connected sessions along with data unique to each session.
A subfile is a window into an existing file. They have a few limitations compared to normal files:
* They can't be written to.
* They can't be flushed.
* Their size can not be changed.
* New subfiles can't be created from another subfile.
The loaders now register each loaded ROM with the SelfNCCH factory, which keeps the data around for the duration of the emulation session.
When opening the SelfNCCH archive, the factory queries the current program's programid and uses that as a key to the map that contains the NCCHData structure (RomFS, Icon, Banner, etc).
3dsx files do not have a programid and will use a default of 0 for this value, thus, only 1 3dsx file with RomFS is loadable at the same time.
This allows attaching a HLE handle to a ServerPort at any point after it
is created, allowing port/session creation to be generic between HLE and
regular services.
Sessions and Ports are now detached from each other.
HLE services are handled by means of a SessionRequestHandler class, Interface now inherits from this class.
The File and Directory classes are no longer kernel objects, but SessionRequestHandlers instead, bound to a ServerSession when requested.
File::OpenLinkFile now creates a new session pair and binds the File instance to it.
All handles obtained via srv::GetServiceHandle or svcConnectToPort are references to ClientSessions.
Service modules will wait on the counterpart of those ClientSessions (Called ServerSessions) using svcReplyAndReceive or svcWaitSynchronization[1|N], and will be awoken when a SyncRequest is performed.
HLE Interfaces are now ClientPorts which override the HandleSyncRequest virtual member function to perform command handling immediately.
Format information is currently only implemented for the ExtSaveData, SharedExtSaveData and SaveData archives, the information is stored in a file alongside the root folder of the archive.
Each archive now takes a mount point of either NAND or SDMC, and builds its own directory structure there, trying to simulate an HLE-friendly hardware layout
This allows Steel Diver to boot further, some files are needed.
This is still not ready and needs a big cleanup, this will possibly be delayed until the way we handle archives is fixed (with factory classes instead of ahead-of-time creation of archives)
