loader/ECS: don't clear ECS on failure, add ClearExternalContentSource command

docs/modules/loader.md

@@ -67,16 +67,35 @@ For example, `override_key=!R` will run the game only while holding down R when
 
 When the Stratosphere implementation of loader creates a new process, it notifies [sm](sm.md) through the `AtmosphereAssociatePidTidForMitm` command to notify any MITM services of new processes' identities.
 
-### IPC: AtmosphereSetExternalContentSource
+### IPC: AtmosphereSetExternalContentSource and AtmosphereClearExternalContentSource
 
-An additional command is added to the [`ldr:shel`](https://reswitched.github.io/SwIPC/ifaces.html#nn::ro::detail::ILdrShellInterface) interface, called `AtmosphereSetExternalContentSource`. It's command ID is `65000` on all system firmware versions. It takes a `u64 tid` and returns a server-side session handle. The client is expected to implement the `IFileSystem` interface on the returned handle. The next time the title specified by the given title ID is launched, its ExeFS contents will be loaded from the custom `IFileSystem` instead of from SD card or original ExeFS. NSOs loaded from external content source may still be subject to exefs IPS patches. After the title is launched, the `IFileSystem` is closed and the external content source override is removed. If `AtmosphereSetExternalContentSource` is called on a title that already has an external content source set for it, the existing one will be removed and replaced with the new one. It is illegal to call `AtmosphereSetExternalContentSource` while the title is being launched.
+Two additional commands are added to the [`ldr:shel`](https://reswitched.github.io/SwIPC/ifaces.html#nn::ro::detail::ILdrShellInterface) interface, called `AtmosphereSetExternalContentSource` and `AtmosphereClearExternalContentSource`.
+Their command IDs are `65000` and `65001` on all system firmware versions.
 
-The `IFileSystem` only needs to implement `OpenFile`. The paths received by the `IFileSystem`'s `OpenFile` command begin with slashes, as in `/main`, `/rtld`, and `/main.npdm`. A result code of 0x202 should be returned if the file does not exist. The `IFile`s returned from `OpenFile` only need to implement `Read` and `GetSize`.
+`AtmosphereSetExternalContentSource` takes a `u64 tid` and returns a server-side session handle.
+The client is expected to implement the `IFileSystem` interface on the returned handle. The next
+time the title specified by the given title ID is launched, its ExeFS contents will be loaded from
+the custom `IFileSystem` instead of from SD card or original ExeFS. NSOs loaded from external
+content source may still be subject to exefs IPS patches. After the title is launched successfuly,
+the `IFileSystem` is closed and the external content source override is removed. If
+`AtmosphereSetExternalContentSource` is called on a title that already has an external content
+source set for it, the existing one will be removed and replaced with the new one. It is illegal to
+call `AtmosphereSetExternalContentSource` while the title is being launched.
 
-The SwIPC definition for the `AtmosphereSetExternalContentSource` command follows.
+If title launching fails, the external content source remains registered. The
+`AtmosphereClearExternalContentSource` command can be used to clear an external content source if
+title launch fails.
+
+The `IFileSystem` only needs to implement `OpenFile` and `GetFileTimeStampRaw`. The paths received
+by the `IFileSystem`'s `OpenFile` command begin with slashes, as in `/main`, `/rtld`, and `/main.npdm`.
+A result code of 0x202 should be returned if the file does not exist. `GetFileTimeStampRaw` can just
+be a stub. The `IFile`s returned from `OpenFile` only need to implement `Read` and `GetSize`.
+
+The SwIPC definitions for the extension commands follow.
 ```
 interface nn::ldr::detail::IShellInterface is ldr:shel {
   ...
   [65000] AtmosphereSetExternalContentSource(u64 tid) -> handle<copy, session_server> ifilesystem_handle;
+  [65001] AtmosphereClearExternalContentSource(u64 tid);
 }
 ```

stratosphere/loader/source/ldr_process_creation.cpp

@@ -214,8 +214,8 @@ Result ProcessCreation::CreateProcess(Handle *out_process_h, u64 index, char *nc
     Registration::AssociatePidTidForMitM(index);
     
     rc = 0;  
-CREATE_PROCESS_END:
+
-    /* ECS is a one-shot operation. */
+    /* ECS is a one-shot operation, but we don't clear on failure. */
     ContentManagement::ClearExternalContentSource(target_process->tid_sid.title_id);
     if (mounted_code) {
         if (R_SUCCEEDED(rc) && target_process->tid_sid.storage_id != FsStorageId_None) {
@@ -224,6 +224,8 @@ CREATE_PROCESS_END:
             ContentManagement::UnmountCode();
         }
     }
+
+CREATE_PROCESS_END:
     if (R_SUCCEEDED(rc)) {
         *out_process_h = process_h;
     } else {

stratosphere/loader/source/ldr_shell.cpp

@@ -45,3 +45,7 @@ Result ShellService::SetExternalContentSource(Out<MovedHandle> out, u64 tid) {
     out.SetValue(server_h);
     return 0;
 }
+
+void ShellService::ClearExternalContentSource(u64 tid) {
+    ContentManagement::ClearExternalContentSource(tid);
+}

stratosphere/loader/source/ldr_shell.hpp

@@ -23,6 +23,7 @@ enum ShellServiceCmd {
     Shell_Cmd_ClearLaunchQueue = 1,
 
     Shell_Cmd_AtmosphereSetExternalContentSource = 65000,
+    Shell_Cmd_AtmosphereClearExternalContentSource = 65001,
 };
 
 class ShellService final : public IServiceObject {
@@ -33,10 +34,12 @@ class ShellService final : public IServiceObject {
         
         /* Atmosphere commands. */
         Result SetExternalContentSource(Out<MovedHandle> out, u64 tid);
+        void ClearExternalContentSource(u64 tid);
     public:
         DEFINE_SERVICE_DISPATCH_TABLE {
             MakeServiceCommandMeta<Shell_Cmd_AddTitleToLaunchQueue, &ShellService::AddTitleToLaunchQueue>(),
             MakeServiceCommandMeta<Shell_Cmd_ClearLaunchQueue, &ShellService::ClearLaunchQueue>(),
             MakeServiceCommandMeta<Shell_Cmd_AtmosphereSetExternalContentSource, &ShellService::SetExternalContentSource>(),
+            MakeServiceCommandMeta<Shell_Cmd_AtmosphereClearExternalContentSource, &ShellService::ClearExternalContentSource>(),
         };
 };