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diff --git a/lib/windows-recmutex.c b/lib/windows-recmutex.c
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+/* Plain recursive mutexes (native Windows implementation).
+ Copyright (C) 2005-2022 Free Software Foundation, Inc.
+
+ This file is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ This file is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2005.
+ Based on GCC's gthr-win32.h. */
+
+#include <config.h>
+
+/* Specification. */
+#include "windows-recmutex.h"
+
+#include <errno.h>
+
+void
+glwthread_recmutex_init (glwthread_recmutex_t *mutex)
+{
+ mutex->owner = 0;
+ mutex->depth = 0;
+ InitializeCriticalSection (&mutex->lock);
+ mutex->guard.done = 1;
+}
+
+int
+glwthread_recmutex_lock (glwthread_recmutex_t *mutex)
+{
+ if (!mutex->guard.done)
+ {
+ if (InterlockedIncrement (&mutex->guard.started) == 0)
+ /* This thread is the first one to need this mutex. Initialize it. */
+ glwthread_recmutex_init (mutex);
+ else
+ {
+ /* Don't let mutex->guard.started grow and wrap around. */
+ InterlockedDecrement (&mutex->guard.started);
+ /* Yield the CPU while waiting for another thread to finish
+ initializing this mutex. */
+ while (!mutex->guard.done)
+ Sleep (0);
+ }
+ }
+ {
+ DWORD self = GetCurrentThreadId ();
+ if (mutex->owner != self)
+ {
+ EnterCriticalSection (&mutex->lock);
+ mutex->owner = self;
+ }
+ if (++(mutex->depth) == 0) /* wraparound? */
+ {
+ mutex->depth--;
+ return EAGAIN;
+ }
+ }
+ return 0;
+}
+
+int
+glwthread_recmutex_trylock (glwthread_recmutex_t *mutex)
+{
+ if (!mutex->guard.done)
+ {
+ if (InterlockedIncrement (&mutex->guard.started) == 0)
+ /* This thread is the first one to need this mutex. Initialize it. */
+ glwthread_recmutex_init (mutex);
+ else
+ {
+ /* Don't let mutex->guard.started grow and wrap around. */
+ InterlockedDecrement (&mutex->guard.started);
+ /* Let another thread finish initializing this mutex, and let it also
+ lock this mutex. */
+ return EBUSY;
+ }
+ }
+ {
+ DWORD self = GetCurrentThreadId ();
+ if (mutex->owner != self)
+ {
+ if (!TryEnterCriticalSection (&mutex->lock))
+ return EBUSY;
+ mutex->owner = self;
+ }
+ if (++(mutex->depth) == 0) /* wraparound? */
+ {
+ mutex->depth--;
+ return EAGAIN;
+ }
+ }
+ return 0;
+}
+
+int
+glwthread_recmutex_unlock (glwthread_recmutex_t *mutex)
+{
+ if (mutex->owner != GetCurrentThreadId ())
+ return EPERM;
+ if (mutex->depth == 0)
+ return EINVAL;
+ if (--(mutex->depth) == 0)
+ {
+ mutex->owner = 0;
+ LeaveCriticalSection (&mutex->lock);
+ }
+ return 0;
+}
+
+int
+glwthread_recmutex_destroy (glwthread_recmutex_t *mutex)
+{
+ if (mutex->owner != 0)
+ return EBUSY;
+ DeleteCriticalSection (&mutex->lock);
+ mutex->guard.done = 0;
+ return 0;
+}