1 files changed, 127 insertions, 0 deletions
diff --git a/lib/windows-recmutex.c b/lib/windows-recmutex.c
new file mode 100644
index 00000000..d8087ac1
--- /dev/null
+++ b/lib/windows-recmutex.c
@@ -0,0 +1,127 @@
+/* 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;
+}