1 files changed, 138 insertions, 0 deletions

diff --git a/src/microhttpd/mhd_sem.c b/src/microhttpd/mhd_sem.c
new file mode 100644
index 00000000..fdd5dbe4
--- /dev/null
+++ b/src/microhttpd/mhd_sem.c
@@ -0,0 +1,138 @@
+/*
+  This file is part of libmicrohttpd
+  Copyright (C) 2016 Christian Grothoff
+
+  This library 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 library 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 library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+
+*/
+
+/**
+ * @file microhttpd/mhd_sem.c
+ * @brief  implementation of semaphores
+ * @author Christian Grothoff
+ */
+#include "internal.h"
+#include "mhd_locks.h"
+
+/**
+ * A semaphore.
+ */
+struct MHD_Semaphore
+{
+  /**
+   * Mutex we use internally.
+   */
+  pthread_mutex_t mutex;
+
+  /**
+   * Condition variable used to implement the semaphore.
+   */
+  pthread_cond_t cv;
+
+  /**
+   * Current value of the semaphore.
+   */
+  unsigned int counter;
+};
+
+
+/**
+ * Create a semaphore with an initial counter of @a init
+ *
+ * @param init initial counter
+ * @return the semaphore, NULL on error
+ */
+struct MHD_Semaphore *
+MHD_semaphore_create (unsigned int init)
+{
+  struct MHD_Semaphore *sem;
+
+  sem = malloc (sizeof (struct MHD_Semaphore));
+  if (NULL == sem)
+    return NULL;
+  sem->counter = init;
+  if (0 != pthread_mutex_init (&sem->mutex,
+                               NULL))
+    {
+      free (sem);
+      return NULL;
+    }
+  if (0 != pthread_cond_init (&sem->cv,
+                              NULL))
+    {
+      (void) pthread_mutex_destroy (&sem->mutex);
+      free (sem);
+      return NULL;
+    }
+  return sem;
+}
+
+
+/**
+ * Count down the semaphore, block if necessary.
+ *
+ * @param sem semaphore to count down.
+ */
+void
+MHD_semaphore_down (struct MHD_Semaphore *sem)
+{
+  if (! pthread_mutex_lock (&sem->mutex))
+    MHD_PANIC ("pthread_mutex_lock for semaphore failed\n");
+  while (0 == sem->counter)
+    {
+      if (0 != pthread_cond_wait (&sem->cv,
+                                  &sem->mutex))
+        MHD_PANIC ("pthread_cond_wait failed\n");
+    }
+  sem->counter--;
+  if (! pthread_mutex_unlock (&sem->mutex))
+    MHD_PANIC ("pthread_mutex_unlock for semaphore failed\n");
+}
+
+
+/**
+ * Increment the semaphore.
+ *
+ * @param sem semaphore to increment.
+ */
+void
+MHD_semaphore_up (struct MHD_Semaphore *sem)
+{
+  if (! pthread_mutex_lock (&sem->mutex))
+    MHD_PANIC ("pthread_mutex_lock for semaphore failed\n");
+  sem->counter++;
+  pthread_cond_signal (&sem->cv);
+  if (! pthread_mutex_unlock (&sem->mutex))
+    MHD_PANIC ("pthread_mutex_unlock for semaphore failed\n");
+}
+
+
+/**
+ * Destroys the semaphore.
+ *
+ * @param sem semaphore to destroy.
+ */
+void
+MHD_semaphore_destroy (struct MHD_Semaphore *sem)
+{
+  if (0 != pthread_cond_destroy (&sem->cv))
+    MHD_PANIC ("pthread_cond_destroy failed\n");
+  if (0 != pthread_mutex_destroy (&sem->mutex))
+    MHD_PANIC ("pthread_mutex_destroy failed\n");
+  free (sem);
+}
+
+
+/* end of mhd_sem.c */