1 files changed, 749 insertions, 0 deletions

diff --git a/lib/glthread/lock.c b/lib/glthread/lock.c
new file mode 100644
index 0000000..10af6f2
--- /dev/null
+++ b/lib/glthread/lock.c
@@ -0,0 +1,749 @@
+/* Locking in multithreaded situations.
+   Copyright (C) 2005-2020 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU 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-posix.h, gthr-posix95.h.  */
+
+#include <config.h>
+
+#include "glthread/lock.h"
+
+/* ========================================================================= */
+
+#if USE_ISOC_THREADS || USE_ISOC_AND_POSIX_THREADS
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+int
+glthread_lock_init (gl_lock_t *lock)
+{
+  if (mtx_init (&lock->mutex, mtx_plain) != thrd_success)
+    return ENOMEM;
+  lock->init_needed = 0;
+  return 0;
+}
+
+int
+glthread_lock_lock (gl_lock_t *lock)
+{
+  if (lock->init_needed)
+    call_once (&lock->init_once, lock->init_func);
+  if (mtx_lock (&lock->mutex) != thrd_success)
+    return EAGAIN;
+  return 0;
+}
+
+int
+glthread_lock_unlock (gl_lock_t *lock)
+{
+  if (lock->init_needed)
+    call_once (&lock->init_once, lock->init_func);
+  if (mtx_unlock (&lock->mutex) != thrd_success)
+    return EINVAL;
+  return 0;
+}
+
+int
+glthread_lock_destroy (gl_lock_t *lock)
+{
+  if (lock->init_needed)
+    call_once (&lock->init_once, lock->init_func);
+  mtx_destroy (&lock->mutex);
+  return 0;
+}
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+int
+glthread_rwlock_init (gl_rwlock_t *lock)
+{
+  if (mtx_init (&lock->lock, mtx_plain) != thrd_success
+      || cnd_init (&lock->waiting_readers) != thrd_success
+      || cnd_init (&lock->waiting_writers) != thrd_success)
+    return ENOMEM;
+  lock->waiting_writers_count = 0;
+  lock->runcount = 0;
+  lock->init_needed = 0;
+  return 0;
+}
+
+int
+glthread_rwlock_rdlock (gl_rwlock_t *lock)
+{
+  if (lock->init_needed)
+    call_once (&lock->init_once, lock->init_func);
+  if (mtx_lock (&lock->lock) != thrd_success)
+    return EAGAIN;
+  /* Test whether only readers are currently running, and whether the runcount
+     field will not overflow, and whether no writer is waiting.  The latter
+     condition is because POSIX recommends that "write locks shall take
+     precedence over read locks", to avoid "writer starvation".  */
+  while (!(lock->runcount + 1 > 0 && lock->waiting_writers_count == 0))
+    {
+      /* This thread has to wait for a while.  Enqueue it among the
+         waiting_readers.  */
+      if (cnd_wait (&lock->waiting_readers, &lock->lock) != thrd_success)
+        {
+          mtx_unlock (&lock->lock);
+          return EINVAL;
+        }
+    }
+  lock->runcount++;
+  if (mtx_unlock (&lock->lock) != thrd_success)
+    return EINVAL;
+  return 0;
+}
+
+int
+glthread_rwlock_wrlock (gl_rwlock_t *lock)
+{
+  if (lock->init_needed)
+    call_once (&lock->init_once, lock->init_func);
+  if (mtx_lock (&lock->lock) != thrd_success)
+    return EAGAIN;
+  /* Test whether no readers or writers are currently running.  */
+  while (!(lock->runcount == 0))
+    {
+      /* This thread has to wait for a while.  Enqueue it among the
+         waiting_writers.  */
+      lock->waiting_writers_count++;
+      if (cnd_wait (&lock->waiting_writers, &lock->lock) != thrd_success)
+        {
+          lock->waiting_writers_count--;
+          mtx_unlock (&lock->lock);
+          return EINVAL;
+        }
+      lock->waiting_writers_count--;
+    }
+  lock->runcount--; /* runcount becomes -1 */
+  if (mtx_unlock (&lock->lock) != thrd_success)
+    return EINVAL;
+  return 0;
+}
+
+int
+glthread_rwlock_unlock (gl_rwlock_t *lock)
+{
+  if (lock->init_needed)
+    call_once (&lock->init_once, lock->init_func);
+  if (mtx_lock (&lock->lock) != thrd_success)
+    return EAGAIN;
+  if (lock->runcount < 0)
+    {
+      /* Drop a writer lock.  */
+      if (!(lock->runcount == -1))
+        {
+          mtx_unlock (&lock->lock);
+          return EINVAL;
+        }
+      lock->runcount = 0;
+    }
+  else
+    {
+      /* Drop a reader lock.  */
+      if (!(lock->runcount > 0))
+        {
+          mtx_unlock (&lock->lock);
+          return EINVAL;
+        }
+      lock->runcount--;
+    }
+  if (lock->runcount == 0)
+    {
+      /* POSIX recommends that "write locks shall take precedence over read
+         locks", to avoid "writer starvation".  */
+      if (lock->waiting_writers_count > 0)
+        {
+          /* Wake up one of the waiting writers.  */
+          if (cnd_signal (&lock->waiting_writers) != thrd_success)
+            {
+              mtx_unlock (&lock->lock);
+              return EINVAL;
+            }
+        }
+      else
+        {
+          /* Wake up all waiting readers.  */
+          if (cnd_broadcast (&lock->waiting_readers) != thrd_success)
+            {
+              mtx_unlock (&lock->lock);
+              return EINVAL;
+            }
+        }
+    }
+  if (mtx_unlock (&lock->lock) != thrd_success)
+    return EINVAL;
+  return 0;
+}
+
+int
+glthread_rwlock_destroy (gl_rwlock_t *lock)
+{
+  if (lock->init_needed)
+    call_once (&lock->init_once, lock->init_func);
+  mtx_destroy (&lock->lock);
+  cnd_destroy (&lock->waiting_readers);
+  cnd_destroy (&lock->waiting_writers);
+  return 0;
+}
+
+/* --------------------- gl_recursive_lock_t datatype --------------------- */
+
+int
+glthread_recursive_lock_init (gl_recursive_lock_t *lock)
+{
+  if (mtx_init (&lock->mutex, mtx_plain | mtx_recursive) != thrd_success)
+    return ENOMEM;
+  lock->init_needed = 0;
+  return 0;
+}
+
+int
+glthread_recursive_lock_lock (gl_recursive_lock_t *lock)
+{
+  if (lock->init_needed)
+    call_once (&lock->init_once, lock->init_func);
+  if (mtx_lock (&lock->mutex) != thrd_success)
+    return EAGAIN;
+  return 0;
+}
+
+int
+glthread_recursive_lock_unlock (gl_recursive_lock_t *lock)
+{
+  if (lock->init_needed)
+    call_once (&lock->init_once, lock->init_func);
+  if (mtx_unlock (&lock->mutex) != thrd_success)
+    return EINVAL;
+  return 0;
+}
+
+int
+glthread_recursive_lock_destroy (gl_recursive_lock_t *lock)
+{
+  if (lock->init_needed)
+    call_once (&lock->init_once, lock->init_func);
+  mtx_destroy (&lock->mutex);
+  return 0;
+}
+
+/* -------------------------- gl_once_t datatype -------------------------- */
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_POSIX_THREADS
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+# if HAVE_PTHREAD_RWLOCK && (HAVE_PTHREAD_RWLOCK_RDLOCK_PREFER_WRITER || (defined PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP && (__GNU_LIBRARY__ > 1)))
+
+#  if defined PTHREAD_RWLOCK_INITIALIZER || defined PTHREAD_RWLOCK_INITIALIZER_NP
+
+#   if !HAVE_PTHREAD_RWLOCK_RDLOCK_PREFER_WRITER
+     /* glibc with bug https://sourceware.org/bugzilla/show_bug.cgi?id=13701 */
+
+int
+glthread_rwlock_init_for_glibc (pthread_rwlock_t *lock)
+{
+  pthread_rwlockattr_t attributes;
+  int err;
+
+  err = pthread_rwlockattr_init (&attributes);
+  if (err != 0)
+    return err;
+  /* Note: PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP is the only value that
+     causes the writer to be preferred. PTHREAD_RWLOCK_PREFER_WRITER_NP does not
+     do this; see
+     http://man7.org/linux/man-pages/man3/pthread_rwlockattr_setkind_np.3.html */
+  err = pthread_rwlockattr_setkind_np (&attributes,
+                                       PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
+  if (err == 0)
+    err = pthread_rwlock_init(lock, &attributes);
+  /* pthread_rwlockattr_destroy always returns 0.  It cannot influence the
+     return value.  */
+  pthread_rwlockattr_destroy (&attributes);
+  return err;
+}
+
+#   endif
+#  else
+
+int
+glthread_rwlock_init_multithreaded (gl_rwlock_t *lock)
+{
+  int err;
+
+  err = pthread_rwlock_init (&lock->rwlock, NULL);
+  if (err != 0)
+    return err;
+  lock->initialized = 1;
+  return 0;
+}
+
+int
+glthread_rwlock_rdlock_multithreaded (gl_rwlock_t *lock)
+{
+  if (!lock->initialized)
+    {
+      int err;
+
+      err = pthread_mutex_lock (&lock->guard);
+      if (err != 0)
+        return err;
+      if (!lock->initialized)
+        {
+          err = glthread_rwlock_init_multithreaded (lock);
+          if (err != 0)
+            {
+              pthread_mutex_unlock (&lock->guard);
+              return err;
+            }
+        }
+      err = pthread_mutex_unlock (&lock->guard);
+      if (err != 0)
+        return err;
+    }
+  return pthread_rwlock_rdlock (&lock->rwlock);
+}
+
+int
+glthread_rwlock_wrlock_multithreaded (gl_rwlock_t *lock)
+{
+  if (!lock->initialized)
+    {
+      int err;
+
+      err = pthread_mutex_lock (&lock->guard);
+      if (err != 0)
+        return err;
+      if (!lock->initialized)
+        {
+          err = glthread_rwlock_init_multithreaded (lock);
+          if (err != 0)
+            {
+              pthread_mutex_unlock (&lock->guard);
+              return err;
+            }
+        }
+      err = pthread_mutex_unlock (&lock->guard);
+      if (err != 0)
+        return err;
+    }
+  return pthread_rwlock_wrlock (&lock->rwlock);
+}
+
+int
+glthread_rwlock_unlock_multithreaded (gl_rwlock_t *lock)
+{
+  if (!lock->initialized)
+    return EINVAL;
+  return pthread_rwlock_unlock (&lock->rwlock);
+}
+
+int
+glthread_rwlock_destroy_multithreaded (gl_rwlock_t *lock)
+{
+  int err;
+
+  if (!lock->initialized)
+    return EINVAL;
+  err = pthread_rwlock_destroy (&lock->rwlock);
+  if (err != 0)
+    return err;
+  lock->initialized = 0;
+  return 0;
+}
+
+#  endif
+
+# else
+
+int
+glthread_rwlock_init_multithreaded (gl_rwlock_t *lock)
+{
+  int err;
+
+  err = pthread_mutex_init (&lock->lock, NULL);
+  if (err != 0)
+    return err;
+  err = pthread_cond_init (&lock->waiting_readers, NULL);
+  if (err != 0)
+    return err;
+  err = pthread_cond_init (&lock->waiting_writers, NULL);
+  if (err != 0)
+    return err;
+  lock->waiting_writers_count = 0;
+  lock->runcount = 0;
+  return 0;
+}
+
+int
+glthread_rwlock_rdlock_multithreaded (gl_rwlock_t *lock)
+{
+  int err;
+
+  err = pthread_mutex_lock (&lock->lock);
+  if (err != 0)
+    return err;
+  /* Test whether only readers are currently running, and whether the runcount
+     field will not overflow, and whether no writer is waiting.  The latter
+     condition is because POSIX recommends that "write locks shall take
+     precedence over read locks", to avoid "writer starvation".  */
+  while (!(lock->runcount + 1 > 0 && lock->waiting_writers_count == 0))
+    {
+      /* This thread has to wait for a while.  Enqueue it among the
+         waiting_readers.  */
+      err = pthread_cond_wait (&lock->waiting_readers, &lock->lock);
+      if (err != 0)
+        {
+          pthread_mutex_unlock (&lock->lock);
+          return err;
+        }
+    }
+  lock->runcount++;
+  return pthread_mutex_unlock (&lock->lock);
+}
+
+int
+glthread_rwlock_wrlock_multithreaded (gl_rwlock_t *lock)
+{
+  int err;
+
+  err = pthread_mutex_lock (&lock->lock);
+  if (err != 0)
+    return err;
+  /* Test whether no readers or writers are currently running.  */
+  while (!(lock->runcount == 0))
+    {
+      /* This thread has to wait for a while.  Enqueue it among the
+         waiting_writers.  */
+      lock->waiting_writers_count++;
+      err = pthread_cond_wait (&lock->waiting_writers, &lock->lock);
+      if (err != 0)
+        {
+          lock->waiting_writers_count--;
+          pthread_mutex_unlock (&lock->lock);
+          return err;
+        }
+      lock->waiting_writers_count--;
+    }
+  lock->runcount--; /* runcount becomes -1 */
+  return pthread_mutex_unlock (&lock->lock);
+}
+
+int
+glthread_rwlock_unlock_multithreaded (gl_rwlock_t *lock)
+{
+  int err;
+
+  err = pthread_mutex_lock (&lock->lock);
+  if (err != 0)
+    return err;
+  if (lock->runcount < 0)
+    {
+      /* Drop a writer lock.  */
+      if (!(lock->runcount == -1))
+        {
+          pthread_mutex_unlock (&lock->lock);
+          return EINVAL;
+        }
+      lock->runcount = 0;
+    }
+  else
+    {
+      /* Drop a reader lock.  */
+      if (!(lock->runcount > 0))
+        {
+          pthread_mutex_unlock (&lock->lock);
+          return EINVAL;
+        }
+      lock->runcount--;
+    }
+  if (lock->runcount == 0)
+    {
+      /* POSIX recommends that "write locks shall take precedence over read
+         locks", to avoid "writer starvation".  */
+      if (lock->waiting_writers_count > 0)
+        {
+          /* Wake up one of the waiting writers.  */
+          err = pthread_cond_signal (&lock->waiting_writers);
+          if (err != 0)
+            {
+              pthread_mutex_unlock (&lock->lock);
+              return err;
+            }
+        }
+      else
+        {
+          /* Wake up all waiting readers.  */
+          err = pthread_cond_broadcast (&lock->waiting_readers);
+          if (err != 0)
+            {
+              pthread_mutex_unlock (&lock->lock);
+              return err;
+            }
+        }
+    }
+  return pthread_mutex_unlock (&lock->lock);
+}
+
+int
+glthread_rwlock_destroy_multithreaded (gl_rwlock_t *lock)
+{
+  int err;
+
+  err = pthread_mutex_destroy (&lock->lock);
+  if (err != 0)
+    return err;
+  err = pthread_cond_destroy (&lock->waiting_readers);
+  if (err != 0)
+    return err;
+  err = pthread_cond_destroy (&lock->waiting_writers);
+  if (err != 0)
+    return err;
+  return 0;
+}
+
+# endif
+
+/* --------------------- gl_recursive_lock_t datatype --------------------- */
+
+# if HAVE_PTHREAD_MUTEX_RECURSIVE
+
+#  if defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER || defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
+
+int
+glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock)
+{
+  pthread_mutexattr_t attributes;
+  int err;
+
+  err = pthread_mutexattr_init (&attributes);
+  if (err != 0)
+    return err;
+  err = pthread_mutexattr_settype (&attributes, PTHREAD_MUTEX_RECURSIVE);
+  if (err != 0)
+    {
+      pthread_mutexattr_destroy (&attributes);
+      return err;
+    }
+  err = pthread_mutex_init (lock, &attributes);
+  if (err != 0)
+    {
+      pthread_mutexattr_destroy (&attributes);
+      return err;
+    }
+  err = pthread_mutexattr_destroy (&attributes);
+  if (err != 0)
+    return err;
+  return 0;
+}
+
+#  else
+
+int
+glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock)
+{
+  pthread_mutexattr_t attributes;
+  int err;
+
+  err = pthread_mutexattr_init (&attributes);
+  if (err != 0)
+    return err;
+  err = pthread_mutexattr_settype (&attributes, PTHREAD_MUTEX_RECURSIVE);
+  if (err != 0)
+    {
+      pthread_mutexattr_destroy (&attributes);
+      return err;
+    }
+  err = pthread_mutex_init (&lock->recmutex, &attributes);
+  if (err != 0)
+    {
+      pthread_mutexattr_destroy (&attributes);
+      return err;
+    }
+  err = pthread_mutexattr_destroy (&attributes);
+  if (err != 0)
+    return err;
+  lock->initialized = 1;
+  return 0;
+}
+
+int
+glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock)
+{
+  if (!lock->initialized)
+    {
+      int err;
+
+      err = pthread_mutex_lock (&lock->guard);
+      if (err != 0)
+        return err;
+      if (!lock->initialized)
+        {
+          err = glthread_recursive_lock_init_multithreaded (lock);
+          if (err != 0)
+            {
+              pthread_mutex_unlock (&lock->guard);
+              return err;
+            }
+        }
+      err = pthread_mutex_unlock (&lock->guard);
+      if (err != 0)
+        return err;
+    }
+  return pthread_mutex_lock (&lock->recmutex);
+}
+
+int
+glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock)
+{
+  if (!lock->initialized)
+    return EINVAL;
+  return pthread_mutex_unlock (&lock->recmutex);
+}
+
+int
+glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock)
+{
+  int err;
+
+  if (!lock->initialized)
+    return EINVAL;
+  err = pthread_mutex_destroy (&lock->recmutex);
+  if (err != 0)
+    return err;
+  lock->initialized = 0;
+  return 0;
+}
+
+#  endif
+
+# else
+
+int
+glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock)
+{
+  int err;
+
+  err = pthread_mutex_init (&lock->mutex, NULL);
+  if (err != 0)
+    return err;
+  lock->owner = (pthread_t) 0;
+  lock->depth = 0;
+  return 0;
+}
+
+int
+glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock)
+{
+  pthread_t self = pthread_self ();
+  if (lock->owner != self)
+    {
+      int err;
+
+      err = pthread_mutex_lock (&lock->mutex);
+      if (err != 0)
+        return err;
+      lock->owner = self;
+    }
+  if (++(lock->depth) == 0) /* wraparound? */
+    {
+      lock->depth--;
+      return EAGAIN;
+    }
+  return 0;
+}
+
+int
+glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock)
+{
+  if (lock->owner != pthread_self ())
+    return EPERM;
+  if (lock->depth == 0)
+    return EINVAL;
+  if (--(lock->depth) == 0)
+    {
+      lock->owner = (pthread_t) 0;
+      return pthread_mutex_unlock (&lock->mutex);
+    }
+  else
+    return 0;
+}
+
+int
+glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock)
+{
+  if (lock->owner != (pthread_t) 0)
+    return EBUSY;
+  return pthread_mutex_destroy (&lock->mutex);
+}
+
+# endif
+
+/* -------------------------- gl_once_t datatype -------------------------- */
+
+static const pthread_once_t fresh_once = PTHREAD_ONCE_INIT;
+
+int
+glthread_once_singlethreaded (pthread_once_t *once_control)
+{
+  /* We don't know whether pthread_once_t is an integer type, a floating-point
+     type, a pointer type, or a structure type.  */
+  char *firstbyte = (char *)once_control;
+  if (*firstbyte == *(const char *)&fresh_once)
+    {
+      /* First time use of once_control.  Invert the first byte.  */
+      *firstbyte = ~ *(const char *)&fresh_once;
+      return 1;
+    }
+  else
+    return 0;
+}
+
+# if !(PTHREAD_IN_USE_DETECTION_HARD || USE_POSIX_THREADS_WEAK)
+
+int
+glthread_once_multithreaded (pthread_once_t *once_control,
+                             void (*init_function) (void))
+{
+  int err = pthread_once (once_control, init_function);
+  if (err == ENOSYS)
+    {
+      /* This happens on FreeBSD 11: The pthread_once function in libc returns
+         ENOSYS.  */
+      if (glthread_once_singlethreaded (once_control))
+        init_function ();
+      return 0;
+    }
+  return err;
+}
+
+# endif
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_WINDOWS_THREADS
+
+#endif
+
+/* ========================================================================= */