initial commit, 4.5 stable

thirdparty/sdl/thread/pthread/SDL_sysmutex.c

@@ -0,0 +1,154 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "SDL_internal.h"
+
+#include <errno.h>
+#include <pthread.h>
+
+#include "SDL_sysmutex_c.h"
+
+SDL_Mutex *SDL_CreateMutex(void)
+{
+    SDL_Mutex *mutex;
+    pthread_mutexattr_t attr;
+
+    // Allocate the structure
+    mutex = (SDL_Mutex *)SDL_calloc(1, sizeof(*mutex));
+    if (mutex) {
+        pthread_mutexattr_init(&attr);
+#ifdef SDL_THREAD_PTHREAD_RECURSIVE_MUTEX
+        pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
+#elif defined(SDL_THREAD_PTHREAD_RECURSIVE_MUTEX_NP)
+        pthread_mutexattr_setkind_np(&attr, PTHREAD_MUTEX_RECURSIVE_NP);
+#else
+        // No extra attributes necessary
+#endif
+        if (pthread_mutex_init(&mutex->id, &attr) != 0) {
+            SDL_SetError("pthread_mutex_init() failed");
+            SDL_free(mutex);
+            mutex = NULL;
+        }
+    }
+    return mutex;
+}
+
+void SDL_DestroyMutex(SDL_Mutex *mutex)
+{
+    if (mutex) {
+        pthread_mutex_destroy(&mutex->id);
+        SDL_free(mutex);
+    }
+}
+
+void SDL_LockMutex(SDL_Mutex *mutex) SDL_NO_THREAD_SAFETY_ANALYSIS // clang doesn't know about NULL mutexes
+{
+    if (mutex) {
+#ifdef FAKE_RECURSIVE_MUTEX
+        pthread_t this_thread = pthread_self();
+        if (mutex->owner == this_thread) {
+            ++mutex->recursive;
+        } else {
+            /* The order of operations is important.
+               We set the locking thread id after we obtain the lock
+               so unlocks from other threads will fail.
+             */
+            const int rc = pthread_mutex_lock(&mutex->id);
+            SDL_assert(rc == 0);  // assume we're in a lot of trouble if this assert fails.
+            mutex->owner = this_thread;
+            mutex->recursive = 0;
+        }
+#else
+        const int rc = pthread_mutex_lock(&mutex->id);
+        SDL_assert(rc == 0);  // assume we're in a lot of trouble if this assert fails.
+#endif
+    }
+}
+
+bool SDL_TryLockMutex(SDL_Mutex *mutex)
+{
+    bool result = true;
+
+    if (mutex) {
+#ifdef FAKE_RECURSIVE_MUTEX
+        pthread_t this_thread = pthread_self();
+        if (mutex->owner == this_thread) {
+            ++mutex->recursive;
+        } else {
+            /* The order of operations is important.
+               We set the locking thread id after we obtain the lock
+               so unlocks from other threads will fail.
+             */
+            const int rc = pthread_mutex_trylock(&mutex->id);
+            if (rc == 0) {
+                mutex->owner = this_thread;
+                mutex->recursive = 0;
+            } else if (rc == EBUSY) {
+                result = false;
+            } else {
+                SDL_assert(!"Error trying to lock mutex");  // assume we're in a lot of trouble if this assert fails.
+                result = false;
+            }
+        }
+#else
+        const int rc = pthread_mutex_trylock(&mutex->id);
+        if (rc != 0) {
+            if (rc == EBUSY) {
+                result = false;
+            } else {
+                SDL_assert(!"Error trying to lock mutex");  // assume we're in a lot of trouble if this assert fails.
+                result = false;
+            }
+        }
+#endif
+    }
+
+    return result;
+}
+
+void SDL_UnlockMutex(SDL_Mutex *mutex) SDL_NO_THREAD_SAFETY_ANALYSIS // clang doesn't know about NULL mutexes
+{
+    if (mutex) {
+#ifdef FAKE_RECURSIVE_MUTEX
+        // We can only unlock the mutex if we own it
+        if (pthread_self() == mutex->owner) {
+            if (mutex->recursive) {
+                --mutex->recursive;
+            } else {
+                /* The order of operations is important.
+                   First reset the owner so another thread doesn't lock
+                   the mutex and set the ownership before we reset it,
+                   then release the lock semaphore.
+                 */
+                mutex->owner = 0;
+                pthread_mutex_unlock(&mutex->id);
+            }
+        } else {
+            SDL_SetError("mutex not owned by this thread");
+            return;
+        }
+
+#else
+        const int rc = pthread_mutex_unlock(&mutex->id);
+        SDL_assert(rc == 0);  // assume we're in a lot of trouble if this assert fails.
+#endif // FAKE_RECURSIVE_MUTEX
+    }
+}
+