HLE: Revamp error handling throrough the HLE code

All service calls in the CTR OS return result codes indicating the
success or failure of the call. Previous to this commit, Citra's HLE
emulation of services and the kernel universally either ignored errors
or returned dummy -1 error codes.

This commit makes an initial effort to provide an infrastructure for
error reporting and propagation which can be use going forward to make
HLE calls accurately return errors as the original system. A few parts
of the code have been updated to use the new system where applicable.

One part of this effort is the definition of the `ResultCode` type,
which provides facilities for constructing and parsing error codes in
the structured format used by the CTR.

The `ResultVal` type builds on `ResultCode` by providing a container for
values returned by function that can report errors. It enforces that
correct error checking will be done on function returns by preventing
the use of the return value if the function returned an error code.

Currently this change is mostly internal since errors are still
suppressed on the ARM<->HLE border, as a temporary compatibility hack.
As functionality is implemented and tested this hack can be eventually
removed.

1 files changed, 13 insertions, 12 deletions

diff --git a/src/core/hle/kernel/mutex.cpp b/src/core/hle/kernel/mutex.cpp
index 31129fd86..e4ff1ef40 100644
--- a/src/core/hle/kernel/mutex.cpp
+++ b/src/core/hle/kernel/mutex.cpp
@@ -32,10 +32,10 @@ public:
      * @param wait Boolean wait set if current thread should wait as a result of sync operation
      * @return Result of operation, 0 on success, otherwise error code
      */
-    Result SyncRequest(bool* wait) override {
+    ResultVal<bool> SyncRequest() override {
         // TODO(bunnei): ImplementMe
         locked = true;
-        return 0;
+        return MakeResult<bool>(false);
     }
 
     /**
@@ -43,15 +43,14 @@ public:
      * @param wait Boolean wait set if current thread should wait as a result of sync operation
      * @return Result of operation, 0 on success, otherwise error code
      */
-    Result WaitSynchronization(bool* wait) override {
+    ResultVal<bool> WaitSynchronization() override {
         // TODO(bunnei): ImplementMe
-        *wait = locked;
-
+        bool wait = locked;
         if (locked) {
             Kernel::WaitCurrentThread(WAITTYPE_MUTEX, GetHandle());
         }
 
-        return 0;
+        return MakeResult<bool>(wait);
     }
 };
 
@@ -119,15 +118,17 @@ bool ReleaseMutex(Mutex* mutex) {
  * Releases a mutex
  * @param handle Handle to mutex to release
  */
-Result ReleaseMutex(Handle handle) {
-    Mutex* mutex = Kernel::g_object_pool.GetFast<Mutex>(handle);
-
-    _assert_msg_(KERNEL, (mutex != nullptr), "ReleaseMutex tried to release a nullptr mutex!");
+ResultCode ReleaseMutex(Handle handle) {
+    Mutex* mutex = Kernel::g_object_pool.Get<Mutex>(handle);
+    if (mutex == nullptr) return InvalidHandle(ErrorModule::Kernel);
 
     if (!ReleaseMutex(mutex)) {
-        return -1;
+        // TODO(yuriks): Verify error code, this one was pulled out of thin air. I'm not even sure
+        // what error condition this is supposed to be signaling.
+        return ResultCode(ErrorDescription::AlreadyDone, ErrorModule::Kernel,
+                ErrorSummary::NothingHappened, ErrorLevel::Temporary);
     }
-    return 0;
+    return RESULT_SUCCESS;
 }
 
 /**