ThreadManager angefangen; Logger laeuft jetzt in eigenem Thread

7 files changed, 3525 insertions, 0 deletions

diff --git a/lib/glthread/cond.c b/lib/glthread/cond.c
new file mode 100644
index 0000000..909eb71
--- /dev/null
+++ b/lib/glthread/cond.c
@@ -0,0 +1,464 @@
+/* Condition variables for multithreading.
+   Copyright (C) 2008 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by Yoann Vandoorselaere <yoann@prelude-ids.org>, 2008,
+   and Bruno Haible <bruno@clisp.org>, 2008.  */
+
+#include <config.h>
+
+#include "glthread/cond.h"
+
+/* ========================================================================= */
+
+#if USE_PTH_THREADS
+
+/* -------------------------- gl_cond_t datatype -------------------------- */
+
+int
+glthread_cond_timedwait_multithreaded (gl_cond_t *cond,
+				       gl_lock_t *lock,
+				       struct timespec *abstime)
+{
+  int ret, status;
+  pth_event_t ev;
+
+  ev = pth_event (PTH_EVENT_TIME, pth_time (abstime->tv_sec, abstime->tv_nsec / 1000));
+  ret = pth_cond_await (cond, lock, ev);
+
+  status = pth_event_status (ev);
+  pth_event_free (ev, PTH_FREE_THIS);
+
+  if (status == PTH_STATUS_OCCURRED)
+    return ETIMEDOUT;
+
+  return ret;
+}
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_SOLARIS_THREADS
+
+/* -------------------------- gl_cond_t datatype -------------------------- */
+
+int
+glthread_cond_timedwait_multithreaded (gl_cond_t *cond,
+				       gl_lock_t *lock,
+				       struct timespec *abstime)
+{
+  int ret;
+
+  ret = cond_timedwait (cond, lock, abstime);
+  if (ret == ETIME)
+    return ETIMEDOUT;
+  return ret;
+}
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_WIN32_THREADS
+
+#include <sys/time.h>
+
+/* -------------------------- gl_cond_t datatype -------------------------- */
+
+/* In this file, the waitqueues are implemented as linked lists.  */
+#define gl_waitqueue_t gl_linked_waitqueue_t
+
+/* All links of a circular list, except the anchor, are of this type, carrying
+   a payload.  */
+struct gl_waitqueue_element
+{
+  struct gl_waitqueue_link link; /* must be the first field! */
+  HANDLE event; /* Waiting thread, represented by an event.
+                   This field is immutable once initialized. */
+};
+
+static inline void
+gl_waitqueue_init (gl_waitqueue_t *wq)
+{
+  wq->wq_list.wql_next = &wq->wq_list;
+  wq->wq_list.wql_prev = &wq->wq_list;
+}
+
+/* Enqueues the current thread, represented by an event, in a wait queue.
+   Returns NULL if an allocation failure occurs.  */
+static struct gl_waitqueue_element *
+gl_waitqueue_add (gl_waitqueue_t *wq)
+{
+  struct gl_waitqueue_element *elt;
+  HANDLE event;
+
+  /* Allocate the memory for the waitqueue element on the heap, not on the
+     thread's stack.  If the thread exits unexpectedly, we prefer to leak
+     some memory rather than to access unavailable memory and crash.  */
+  elt =
+    (struct gl_waitqueue_element *)
+    malloc (sizeof (struct gl_waitqueue_element));
+  if (elt == NULL)
+    /* No more memory.  */
+    return NULL;
+
+  /* Whether the created event is a manual-reset one or an auto-reset one,
+     does not matter, since we will wait on it only once.  */
+  event = CreateEvent (NULL, TRUE, FALSE, NULL);
+  if (event == INVALID_HANDLE_VALUE)
+    {
+      /* No way to allocate an event.  */
+      free (elt);
+      return NULL;
+    }
+  elt->event = event;
+  /* Insert elt at the end of the circular list.  */
+  (elt->link.wql_prev = wq->wq_list.wql_prev)->wql_next = &elt->link;
+  (elt->link.wql_next = &wq->wq_list)->wql_prev = &elt->link;
+  return elt;
+}
+
+/* Removes the current thread, represented by a 'struct gl_waitqueue_element *',
+   from a wait queue.
+   Returns true if is was found and removed, false if it was not present.  */
+static inline bool
+gl_waitqueue_remove (gl_waitqueue_t *wq, struct gl_waitqueue_element *elt)
+{
+  if (elt->link.wql_next != NULL && elt->link.wql_prev != NULL)
+    {
+      /* Remove elt from the circular list.  */
+      struct gl_waitqueue_link *prev = elt->link.wql_prev;
+      struct gl_waitqueue_link *next = elt->link.wql_next;
+      prev->wql_next = next;
+      next->wql_prev = prev;
+      elt->link.wql_next = NULL;
+      elt->link.wql_prev = NULL;
+      return true;
+    }
+  else
+    return false;
+}
+
+/* Notifies the first thread from a wait queue and dequeues it.  */
+static inline void
+gl_waitqueue_notify_first (gl_waitqueue_t *wq)
+{
+  if (wq->wq_list.wql_next != &wq->wq_list)
+    {
+      struct gl_waitqueue_element *elt =
+	(struct gl_waitqueue_element *) wq->wq_list.wql_next;
+      struct gl_waitqueue_link *prev;
+      struct gl_waitqueue_link *next;
+
+      /* Remove elt from the circular list.  */
+      prev = &wq->wq_list; /* = elt->link.wql_prev; */
+      next = elt->link.wql_next;
+      prev->wql_next = next;
+      next->wql_prev = prev;
+      elt->link.wql_next = NULL;
+      elt->link.wql_prev = NULL;
+
+      SetEvent (elt->event);
+      /* After the SetEvent, this thread cannot access *elt any more, because
+	 the woken-up thread will quickly call  free (elt).  */
+    }
+}
+
+/* Notifies all threads from a wait queue and dequeues them all.  */
+static inline void
+gl_waitqueue_notify_all (gl_waitqueue_t *wq)
+{
+  struct gl_waitqueue_link *l;
+
+  for (l = wq->wq_list.wql_next; l != &wq->wq_list; )
+    {
+      struct gl_waitqueue_element *elt = (struct gl_waitqueue_element *) l;
+      struct gl_waitqueue_link *prev;
+      struct gl_waitqueue_link *next;
+
+      /* Remove elt from the circular list.  */
+      prev = &wq->wq_list; /* = elt->link.wql_prev; */
+      next = elt->link.wql_next;
+      prev->wql_next = next;
+      next->wql_prev = prev;
+      elt->link.wql_next = NULL;
+      elt->link.wql_prev = NULL;
+
+      SetEvent (elt->event);
+      /* After the SetEvent, this thread cannot access *elt any more, because
+	 the woken-up thread will quickly call  free (elt).  */
+
+      l = next;
+    }
+  if (!(wq->wq_list.wql_next == &wq->wq_list
+        && wq->wq_list.wql_prev == &wq->wq_list))
+    abort ();
+}
+
+int
+glthread_cond_init_func (gl_cond_t *cond)
+{
+  InitializeCriticalSection (&cond->lock);
+  gl_waitqueue_init (&cond->waiters);
+
+  cond->guard.done = 1;
+  return 0;
+}
+
+int
+glthread_cond_wait_func (gl_cond_t *cond, gl_lock_t *lock)
+{
+  if (!cond->guard.done)
+    {
+      if (InterlockedIncrement (&cond->guard.started) == 0)
+	/* This thread is the first one to need this condition variable.
+	   Initialize it.  */
+	glthread_cond_init (cond);
+      else
+	/* Yield the CPU while waiting for another thread to finish
+	   initializing this condition variable.  */
+	while (!cond->guard.done)
+	  Sleep (0);
+    }
+
+  EnterCriticalSection (&cond->lock);
+  {
+    struct gl_waitqueue_element *elt = gl_waitqueue_add (&cond->waiters);
+    LeaveCriticalSection (&cond->lock);
+    if (elt == NULL)
+      {
+	/* Allocation failure.  Weird.  */
+	return EAGAIN;
+      }
+    else
+      {
+	HANDLE event = elt->event;
+	int err;
+	DWORD result;
+
+	/* Now release the lock and let any other thread take it.  */
+	err = glthread_lock_unlock (lock);
+	if (err != 0)
+	  {
+	    EnterCriticalSection (&cond->lock);
+	    gl_waitqueue_remove (&cond->waiters, elt);
+	    LeaveCriticalSection (&cond->lock);
+	    CloseHandle (event);
+	    free (elt);
+	    return err;
+	  }
+	/* POSIX says:
+	    "If another thread is able to acquire the mutex after the
+	     about-to-block thread has released it, then a subsequent call to
+	     pthread_cond_broadcast() or pthread_cond_signal() in that thread
+	     shall behave as if it were issued after the about-to-block thread
+	     has blocked."
+	   This is fulfilled here, because the thread signalling is done
+	   through SetEvent, not PulseEvent.  */
+	/* Wait until another thread signals this event.  */
+	result = WaitForSingleObject (event, INFINITE);
+	if (result == WAIT_FAILED || result == WAIT_TIMEOUT)
+	  abort ();
+	CloseHandle (event);
+	free (elt);
+	/* The thread which signalled the event already did the bookkeeping:
+	   removed us from the waiters.  */
+	return glthread_lock_lock (lock);
+      }
+  }
+}
+
+int
+glthread_cond_timedwait_func (gl_cond_t *cond, gl_lock_t *lock, struct timespec *abstime)
+{
+  struct timeval currtime;
+
+  gettimeofday (&currtime, NULL);
+  if (currtime.tv_sec > abstime->tv_sec
+      || (currtime.tv_sec == abstime->tv_sec
+	  && currtime.tv_usec * 1000 >= abstime->tv_nsec))
+    return ETIMEDOUT;
+
+  if (!cond->guard.done)
+    {
+      if (InterlockedIncrement (&cond->guard.started) == 0)
+	/* This thread is the first one to need this condition variable.
+	   Initialize it.  */
+	glthread_cond_init (cond);
+      else
+	/* Yield the CPU while waiting for another thread to finish
+	   initializing this condition variable.  */
+	while (!cond->guard.done)
+	  Sleep (0);
+    }
+
+  EnterCriticalSection (&cond->lock);
+  {
+    struct gl_waitqueue_element *elt = gl_waitqueue_add (&cond->waiters);
+    LeaveCriticalSection (&cond->lock);
+    if (elt == NULL)
+      {
+	/* Allocation failure.  Weird.  */
+	return EAGAIN;
+      }
+    else
+      {
+	HANDLE event = elt->event;
+	int err;
+	DWORD timeout;
+	DWORD result;
+
+	/* Now release the lock and let any other thread take it.  */
+	err = glthread_lock_unlock (lock);
+	if (err != 0)
+	  {
+	    EnterCriticalSection (&cond->lock);
+	    gl_waitqueue_remove (&cond->waiters, elt);
+	    LeaveCriticalSection (&cond->lock);
+	    CloseHandle (event);
+	    free (elt);
+	    return err;
+	  }
+	/* POSIX says:
+	    "If another thread is able to acquire the mutex after the
+	     about-to-block thread has released it, then a subsequent call to
+	     pthread_cond_broadcast() or pthread_cond_signal() in that thread
+	     shall behave as if it were issued after the about-to-block thread
+	     has blocked."
+	   This is fulfilled here, because the thread signalling is done
+	   through SetEvent, not PulseEvent.  */
+	/* Wait until another thread signals this event or until the abstime
+	   passes.  */
+	gettimeofday (&currtime, NULL);
+	if (currtime.tv_sec > abstime->tv_sec)
+	  timeout = 0;
+	else
+	  {
+	    unsigned long seconds = abstime->tv_sec - currtime.tv_sec;
+	    timeout = seconds * 1000;
+	    if (timeout / 1000 != seconds) /* overflow? */
+	      timeout = INFINITE;
+	    else
+	      {
+		long milliseconds =
+		  abstime->tv_nsec / 1000000 - currtime.tv_usec / 1000;
+		if (milliseconds >= 0)
+		  {
+		    timeout += milliseconds;
+		    if (timeout < milliseconds) /* overflow? */
+		      timeout = INFINITE;
+		  }
+		else
+		  {
+		    if (timeout >= - milliseconds)
+		      timeout -= (- milliseconds);
+		    else
+		      timeout = 0;
+		  }
+	      }
+	  }
+	result = WaitForSingleObject (event, timeout);
+	if (result == WAIT_FAILED)
+	  abort ();
+	if (result == WAIT_TIMEOUT)
+	  {
+	    EnterCriticalSection (&cond->lock);
+	    if (gl_waitqueue_remove (&cond->waiters, elt))
+	      {
+		/* The event was not signaled between the WaitForSingleObject
+		   call and the EnterCriticalSection call.  */
+		if (!(WaitForSingleObject (event, 0) == WAIT_TIMEOUT))
+		  abort ();
+	      }
+	    else
+	      {
+		/* The event was signaled between the WaitForSingleObject
+		   call and the EnterCriticalSection call.  */
+		if (!(WaitForSingleObject (event, 0) == WAIT_OBJECT_0))
+		  abort ();
+		/* Produce the right return value.  */
+		result = WAIT_OBJECT_0;
+	      }
+	    LeaveCriticalSection (&cond->lock);
+	  }
+	else
+	  {
+	    /* The thread which signalled the event already did the
+	       bookkeeping: removed us from the waiters.  */
+	  }
+	CloseHandle (event);
+	free (elt);
+	/* Take the lock again.  It does not matter whether this is done
+	   before or after the bookkeeping for WAIT_TIMEOUT.  */
+	err = glthread_lock_lock (lock);
+	return (err ? err :
+		result == WAIT_OBJECT_0 ? 0 :
+		result == WAIT_TIMEOUT ? ETIMEDOUT :
+		/* WAIT_FAILED shouldn't happen */ EAGAIN);
+      }
+  }
+}
+
+int
+glthread_cond_signal_func (gl_cond_t *cond)
+{
+  if (!cond->guard.done)
+    return EINVAL;
+
+  EnterCriticalSection (&cond->lock);
+  /* POSIX says:
+      "The pthread_cond_broadcast() and pthread_cond_signal() functions shall
+       have no effect if there are no threads currently blocked on cond."  */
+  if (cond->waiters.wq_list.wql_next != &cond->waiters.wq_list)
+    gl_waitqueue_notify_first (&cond->waiters);
+  LeaveCriticalSection (&cond->lock);
+
+  return 0;
+}
+
+int
+glthread_cond_broadcast_func (gl_cond_t *cond)
+{
+  if (!cond->guard.done)
+    return EINVAL;
+
+  EnterCriticalSection (&cond->lock);
+  /* POSIX says:
+      "The pthread_cond_broadcast() and pthread_cond_signal() functions shall
+       have no effect if there are no threads currently blocked on cond."
+     gl_waitqueue_notify_all is a nop in this case.  */
+  gl_waitqueue_notify_all (&cond->waiters);
+  LeaveCriticalSection (&cond->lock);
+
+  return 0;
+}
+
+int
+glthread_cond_destroy_func (gl_cond_t *cond)
+{
+  if (!cond->guard.done)
+    return EINVAL;
+  if (cond->waiters.wq_list.wql_next != &cond->waiters.wq_list)
+    return EBUSY;
+  DeleteCriticalSection (&cond->lock);
+  cond->guard.done = 0;
+  return 0;
+}
+
+#endif
+
+/* ========================================================================= */
diff --git a/lib/glthread/cond.h b/lib/glthread/cond.h
new file mode 100644
index 0000000..f5462db
--- /dev/null
+++ b/lib/glthread/cond.h
@@ -0,0 +1,408 @@
+/* Condition variables for multithreading.
+   Copyright (C) 2005-2008 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by Yoann Vandoorselaere <yoann@prelude-ids.org>, 2008.
+   Based on Bruno Haible <bruno@clisp.org> lock.h */
+
+/*
+   Condition variables can be used for waiting until a condition
+   becomes true. In this respect, they are similar to wait queues. But
+   contrary to wait queues, condition variables have different
+   semantics that allows events to be lost when there is no thread
+   waiting for them.
+
+   Condition variable:
+     Type:                gl_cond_t
+     Declaration:         gl_cond_define(extern, name)
+     Initializer:         gl_cond_define_initialized(, name)
+     Initialization:      gl_cond_init (name);
+     Waiting:             gl_cond_wait (name, lock);
+     Timed wait:          bool timedout = gl_cond_timedwait (name, lock, abstime);
+                          where lock is a gl_lock_t variable (cf. <glthread/lock.h>)
+     Signaling:           gl_cond_signal (name);
+     Broadcasting:        gl_cond_broadcast (name);
+     De-initialization:   gl_cond_destroy (name);
+   Equivalent functions with control of error handling:
+     Initialization:      err = glthread_cond_init (&name);
+     Waiting:             err = glthread_cond_wait (&name);
+     Timed wait:          err = glthread_cond_timedwait (&name, &lock, abstime);
+     Signaling:           err = glthread_cond_signal (&name);
+     Broadcasting:        err = glthread_cond_broadcast (&name);
+     De-initialization:   err = glthread_cond_destroy (&name);
+*/
+
+
+#ifndef _GLTHREAD_COND_H
+#define _GLTHREAD_COND_H
+
+#include <errno.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <time.h>
+
+#include "glthread/lock.h"
+
+/* ========================================================================= */
+
+#if USE_POSIX_THREADS
+
+/* Use the POSIX threads library.  */
+
+# include <pthread.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+# if PTHREAD_IN_USE_DETECTION_HARD
+
+/* The pthread_in_use() detection needs to be done at runtime.  */
+#  define pthread_in_use() \
+     glthread_in_use ()
+extern int glthread_in_use (void);
+
+# endif
+
+# if USE_POSIX_THREADS_WEAK
+
+/* Use weak references to the POSIX threads library.  */
+
+/* Weak references avoid dragging in external libraries if the other parts
+   of the program don't use them.  Here we use them, because we don't want
+   every program that uses libintl to depend on libpthread.  This assumes
+   that libpthread would not be loaded after libintl; i.e. if libintl is
+   loaded first, by an executable that does not depend on libpthread, and
+   then a module is dynamically loaded that depends on libpthread, libintl
+   will not be multithread-safe.  */
+
+/* The way to test at runtime whether libpthread is present is to test
+   whether a function pointer's value, such as &pthread_mutex_init, is
+   non-NULL.  However, some versions of GCC have a bug through which, in
+   PIC mode, &foo != NULL always evaluates to true if there is a direct
+   call to foo(...) in the same function.  To avoid this, we test the
+   address of a function in libpthread that we don't use.  */
+
+#  pragma weak pthread_cond_init
+#  pragma weak pthread_cond_wait
+#  pragma weak pthread_cond_timedwait
+#  pragma weak pthread_cond_signal
+#  pragma weak pthread_cond_broadcast
+#  pragma weak pthread_cond_destroy
+#  ifndef pthread_self
+#   pragma weak pthread_self
+#  endif
+
+#  if !PTHREAD_IN_USE_DETECTION_HARD
+#   pragma weak pthread_cancel
+#   define pthread_in_use() (pthread_cancel != NULL)
+#  endif
+
+# else
+
+#  if !PTHREAD_IN_USE_DETECTION_HARD
+#   define pthread_in_use() 1
+#  endif
+
+# endif
+
+/* -------------------------- gl_cond_t datatype -------------------------- */
+
+typedef pthread_cond_t gl_cond_t;
+# define gl_cond_define(STORAGECLASS, NAME) \
+    STORAGECLASS gl_cond_t NAME;
+# define gl_cond_define_initialized(STORAGECLASS, NAME) \
+    STORAGECLASS gl_cond_t NAME = gl_cond_initializer;
+# define gl_cond_initializer \
+    PTHREAD_COND_INITIALIZER
+# define glthread_cond_init(COND) \
+    (pthread_in_use () ? pthread_cond_init (COND, NULL) : 0)
+# define glthread_cond_wait(COND, LOCK) \
+    (pthread_in_use () ? pthread_cond_wait (COND, LOCK) : 0)
+# define glthread_cond_timedwait(COND, LOCK, ABSTIME) \
+    (pthread_in_use () ? pthread_cond_timedwait (COND, LOCK, ABSTIME) : 0)
+# define glthread_cond_signal(COND) \
+    (pthread_in_use () ? pthread_cond_signal (COND) : 0)
+# define glthread_cond_broadcast(COND) \
+    (pthread_in_use () ? pthread_cond_broadcast (COND) : 0)
+# define glthread_cond_destroy(COND) \
+    (pthread_in_use () ? pthread_cond_destroy (COND) : 0)
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_PTH_THREADS
+
+/* Use the GNU Pth threads library.  */
+
+# include <pth.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+# if USE_PTH_THREADS_WEAK
+
+/* Use weak references to the GNU Pth threads library.  */
+
+#  pragma weak pth_cond_init
+#  pragma weak pth_cond_await
+#  pragma weak pth_cond_notify
+#  pragma weak pth_event
+#  pragma weak pth_timeout
+
+#  pragma weak pth_cancel
+#  define pth_in_use() (pth_cancel != NULL)
+
+# else
+
+#  define pth_in_use() 1
+
+# endif
+
+/* -------------------------- gl_cond_t datatype -------------------------- */
+
+typedef pth_cond_t gl_cond_t;
+# define gl_cond_define(STORAGECLASS, NAME) \
+    STORAGECLASS gl_cond_t NAME;
+# define gl_cond_define_initialized(STORAGECLASS, NAME) \
+    STORAGECLASS gl_cond_t NAME = gl_cond_initializer;
+# define gl_cond_initializer \
+    PTH_COND_INIT
+# define glthread_cond_init(COND) \
+    (pth_in_use () && !pth_cond_init (COND) ? errno : 0)
+# define glthread_cond_wait(COND, LOCK) \
+    (pth_in_use () && !pth_cond_await (COND, LOCK, NULL) ? errno : 0)
+# define glthread_cond_timedwait(COND, LOCK, ABSTIME) \
+    (pth_in_use () ? glthread_cond_timedwait_multithreaded (COND, LOCK, ABSTIME) : 0)
+# define glthread_cond_signal(COND) \
+    (pth_in_use () && !pth_cond_notify (COND, FALSE) ? errno : 0)
+# define glthread_cond_broadcast(COND) \
+    (pth_in_use () && !pth_cond_notify (COND, TRUE) ? errno : 0)
+# define glthread_cond_destroy(COND) 0
+extern int glthread_cond_timedwait_multithreaded (gl_cond_t *cond, gl_lock_t *lock, struct timespec *abstime);
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_SOLARIS_THREADS
+
+/* Use the old Solaris threads library.  */
+
+# include <thread.h>
+# include <synch.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+# if USE_SOLARIS_THREADS_WEAK
+
+/* Use weak references to the old Solaris threads library.  */
+
+#  pragma weak cond_init
+#  pragma weak cond_wait
+#  pragma weak cond_timedwait
+#  pragma weak cond_signal
+#  pragma weak cond_broadcast
+#  pragma weak cond_destroy
+#  pragma weak thr_suspend
+#  define thread_in_use() (thr_suspend != NULL)
+
+# else
+
+#  define thread_in_use() 1
+
+# endif
+
+/* -------------------------- gl_cond_t datatype -------------------------- */
+
+typedef cond_t gl_cond_t;
+# define gl_cond_define(STORAGECLASS, NAME) \
+    STORAGECLASS gl_cond_t NAME;
+# define gl_cond_define_initialized(STORAGECLASS, NAME) \
+    STORAGECLASS gl_cond_t NAME = gl_cond_initializer;
+# define gl_cond_initializer \
+    DEFAULTCV
+# define glthread_cond_init(COND) \
+    (pthread_in_use () ? cond_init (COND, USYNC_THREAD, NULL) : 0)
+# define glthread_cond_wait(COND, LOCK) \
+    (pthread_in_use () ? cond_wait (COND, LOCK) : 0)
+# define glthread_cond_timedwait(COND, LOCK, ABSTIME) \
+    (pthread_in_use () ? glthread_cond_timedwait_multithreaded (COND, LOCK, ABSTIME) : 0)
+# define glthread_cond_signal(COND) \
+    (pthread_in_use () ? cond_signal (COND) : 0)
+# define glthread_cond_broadcast(COND) \
+    (pthread_in_use () ? cond_broadcast (COND) : 0)
+# define glthread_cond_destroy(COND) \
+    (pthread_in_use () ? cond_destroy (COND) : 0)
+extern int glthread_cond_timedwait_multithreaded (gl_cond_t *cond, gl_lock_t *lock, struct timespec *abstime);
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_WIN32_THREADS
+
+# include <windows.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+/* -------------------------- gl_cond_t datatype -------------------------- */
+
+struct gl_waitqueue_link
+{
+  struct gl_waitqueue_link *wql_next;
+  struct gl_waitqueue_link *wql_prev;
+};
+typedef struct
+        {
+          struct gl_waitqueue_link wq_list; /* circular list of waiting threads */
+        }
+        gl_linked_waitqueue_t;
+typedef struct
+        {
+          gl_spinlock_t guard; /* protects the initialization */
+          CRITICAL_SECTION lock; /* protects the remaining fields */
+          gl_linked_waitqueue_t waiters; /* waiting threads */
+        }
+        gl_cond_t;
+# define gl_cond_define(STORAGECLASS, NAME) \
+    STORAGECLASS gl_cond_t NAME;
+# define gl_cond_define_initialized(STORAGECLASS, NAME) \
+    STORAGECLASS gl_cond_t NAME = gl_cond_initializer;
+# define gl_cond_initializer \
+    { { 0, -1 } }
+# define glthread_cond_init(COND) \
+    glthread_cond_init_func (COND)
+# define glthread_cond_wait(COND, LOCK) \
+    glthread_cond_wait_func (COND, LOCK)
+# define glthread_cond_timedwait(COND, LOCK, ABSTIME) \
+    glthread_cond_timedwait_func (COND, LOCK, ABSTIME)
+# define glthread_cond_signal(COND) \
+    glthread_cond_signal_func (COND)
+# define glthread_cond_broadcast(COND) \
+    glthread_cond_broadcast_func (COND)
+# define glthread_cond_destroy(COND) \
+    glthread_cond_destroy_func (COND)
+extern int glthread_cond_init_func (gl_cond_t *cond);
+extern int glthread_cond_wait_func (gl_cond_t *cond, gl_lock_t *lock);
+extern int glthread_cond_timedwait_func (gl_cond_t *cond, gl_lock_t *lock, struct timespec *abstime);
+extern int glthread_cond_signal_func (gl_cond_t *cond);
+extern int glthread_cond_broadcast_func (gl_cond_t *cond);
+extern int glthread_cond_destroy_func (gl_cond_t *cond);
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif
+
+/* ========================================================================= */
+
+#if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_SOLARIS_THREADS || USE_WIN32_THREADS)
+
+/* Provide dummy implementation if threads are not supported.  */
+
+typedef int gl_cond_t;
+# define gl_cond_define(STORAGECLASS, NAME)
+# define gl_cond_define_initialized(STORAGECLASS, NAME)
+# define glthread_cond_init(COND) 0
+# define glthread_cond_wait(COND, LOCK) 0
+# define glthread_cond_timedwait(COND, LOCK, ABSTIME) 0
+# define glthread_cond_signal(COND) 0
+# define glthread_cond_broadcast(COND) 0
+# define glthread_cond_destroy(COND) 0
+
+#endif
+
+/* ========================================================================= */
+
+/* Macros with built-in error handling.  */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define gl_cond_init(COND)             \
+   do                                  \
+     {                                 \
+       if (glthread_cond_init (&COND)) \
+         abort ();                     \
+     }                                 \
+   while (0)
+#define gl_cond_wait(COND, LOCK)              \
+   do                                         \
+     {                                        \
+       if (glthread_cond_wait (&COND, &LOCK)) \
+         abort ();                            \
+     }                                        \
+   while (0)
+#define gl_cond_timedwait(COND, LOCK, ABSTIME) \
+  gl_cond_timedwait_func (&COND, &LOCK, ABSTIME)
+static inline bool
+gl_cond_timedwait_func (gl_cond_t *cond, gl_lock_t *lock, struct timespec *abstime)
+{
+  int err = glthread_cond_timedwait (cond, lock, abstime);
+  if (err == ETIMEDOUT)
+    return true;
+  if (err != 0)
+    abort ();
+  return false;
+}
+#define gl_cond_signal(COND)             \
+   do                                    \
+     {                                   \
+       if (glthread_cond_signal (&COND)) \
+         abort ();                       \
+     }                                   \
+   while (0)
+#define gl_cond_broadcast(COND)             \
+   do                                       \
+     {                                      \
+       if (glthread_cond_broadcast (&COND)) \
+         abort ();                          \
+     }                                      \
+   while (0)
+#define gl_cond_destroy(COND)             \
+   do                                     \
+     {                                    \
+       if (glthread_cond_destroy (&COND)) \
+         abort ();                        \
+     }                                    \
+   while (0)
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _GLTHREAD_COND_H */
diff --git a/lib/glthread/lock.c b/lib/glthread/lock.c
new file mode 100644
index 0000000..7db6426
--- /dev/null
+++ b/lib/glthread/lock.c
@@ -0,0 +1,1058 @@
+/* Locking in multithreaded situations.
+   Copyright (C) 2005-2008 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2005.
+   Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-solaris.h,
+   gthr-win32.h.  */
+
+#include <config.h>
+
+#include "glthread/lock.h"
+
+/* ========================================================================= */
+
+#if USE_POSIX_THREADS
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+# if HAVE_PTHREAD_RWLOCK
+
+#  if !defined PTHREAD_RWLOCK_INITIALIZER
+
+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.  */
+  /* POSIX says: "It is implementation-defined whether the calling thread
+     acquires the lock when a writer does not hold the lock and there are
+     writers blocked on the lock."  Let's say, no: give the writers a higher
+     priority.  */
+  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;
+}
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_PTH_THREADS
+
+/* Use the GNU Pth threads library.  */
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+/* --------------------- gl_recursive_lock_t datatype --------------------- */
+
+/* -------------------------- gl_once_t datatype -------------------------- */
+
+static void
+glthread_once_call (void *arg)
+{
+  void (**gl_once_temp_addr) (void) = (void (**) (void)) arg;
+  void (*initfunction) (void) = *gl_once_temp_addr;
+  initfunction ();
+}
+
+int
+glthread_once_multithreaded (pth_once_t *once_control, void (*initfunction) (void))
+{
+  void (*temp) (void) = initfunction;
+  return (!pth_once (once_control, glthread_once_call, &temp) ? errno : 0);
+}
+
+int
+glthread_once_singlethreaded (pth_once_t *once_control)
+{
+  /* We know that pth_once_t is an integer type.  */
+  if (*once_control == PTH_ONCE_INIT)
+    {
+      /* First time use of once_control.  Invert the marker.  */
+      *once_control = ~ PTH_ONCE_INIT;
+      return 1;
+    }
+  else
+    return 0;
+}
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_SOLARIS_THREADS
+
+/* Use the old Solaris threads library.  */
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+/* --------------------- gl_recursive_lock_t datatype --------------------- */
+
+int
+glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock)
+{
+  int err;
+
+  err = mutex_init (&lock->mutex, USYNC_THREAD, NULL);
+  if (err != 0)
+    return err;
+  lock->owner = (thread_t) 0;
+  lock->depth = 0;
+  return 0;
+}
+
+int
+glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock)
+{
+  thread_t self = thr_self ();
+  if (lock->owner != self)
+    {
+      int err;
+
+      err = 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 != thr_self ())
+    return EPERM;
+  if (lock->depth == 0)
+    return EINVAL;
+  if (--(lock->depth) == 0)
+    {
+      lock->owner = (thread_t) 0;
+      return mutex_unlock (&lock->mutex);
+    }
+  else
+    return 0;
+}
+
+int
+glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock)
+{
+  if (lock->owner != (thread_t) 0)
+    return EBUSY;
+  return mutex_destroy (&lock->mutex);
+}
+
+/* -------------------------- gl_once_t datatype -------------------------- */
+
+int
+glthread_once_multithreaded (gl_once_t *once_control, void (*initfunction) (void))
+{
+  if (!once_control->inited)
+    {
+      int err;
+
+      /* Use the mutex to guarantee that if another thread is already calling
+	 the initfunction, this thread waits until it's finished.  */
+      err = mutex_lock (&once_control->mutex);
+      if (err != 0)
+	return err;
+      if (!once_control->inited)
+	{
+	  once_control->inited = 1;
+	  initfunction ();
+	}
+      return mutex_unlock (&once_control->mutex);
+    }
+  else
+    return 0;
+}
+
+int
+glthread_once_singlethreaded (gl_once_t *once_control)
+{
+  /* We know that gl_once_t contains an integer type.  */
+  if (!once_control->inited)
+    {
+      /* First time use of once_control.  Invert the marker.  */
+      once_control->inited = ~ 0;
+      return 1;
+    }
+  else
+    return 0;
+}
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_WIN32_THREADS
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+void
+glthread_lock_init_func (gl_lock_t *lock)
+{
+  InitializeCriticalSection (&lock->lock);
+  lock->guard.done = 1;
+}
+
+int
+glthread_lock_lock_func (gl_lock_t *lock)
+{
+  if (!lock->guard.done)
+    {
+      if (InterlockedIncrement (&lock->guard.started) == 0)
+	/* This thread is the first one to need this lock.  Initialize it.  */
+	glthread_lock_init (lock);
+      else
+	/* Yield the CPU while waiting for another thread to finish
+	   initializing this lock.  */
+	while (!lock->guard.done)
+	  Sleep (0);
+    }
+  EnterCriticalSection (&lock->lock);
+  return 0;
+}
+
+int
+glthread_lock_unlock_func (gl_lock_t *lock)
+{
+  if (!lock->guard.done)
+    return EINVAL;
+  LeaveCriticalSection (&lock->lock);
+  return 0;
+}
+
+int
+glthread_lock_destroy_func (gl_lock_t *lock)
+{
+  if (!lock->guard.done)
+    return EINVAL;
+  DeleteCriticalSection (&lock->lock);
+  lock->guard.done = 0;
+  return 0;
+}
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+/* In this file, the waitqueues are implemented as circular arrays.  */
+#define gl_waitqueue_t gl_carray_waitqueue_t
+
+static inline void
+gl_waitqueue_init (gl_waitqueue_t *wq)
+{
+  wq->array = NULL;
+  wq->count = 0;
+  wq->alloc = 0;
+  wq->offset = 0;
+}
+
+/* Enqueues the current thread, represented by an event, in a wait queue.
+   Returns INVALID_HANDLE_VALUE if an allocation failure occurs.  */
+static HANDLE
+gl_waitqueue_add (gl_waitqueue_t *wq)
+{
+  HANDLE event;
+  unsigned int index;
+
+  if (wq->count == wq->alloc)
+    {
+      unsigned int new_alloc = 2 * wq->alloc + 1;
+      HANDLE *new_array =
+	(HANDLE *) realloc (wq->array, new_alloc * sizeof (HANDLE));
+      if (new_array == NULL)
+	/* No more memory.  */
+	return INVALID_HANDLE_VALUE;
+      /* Now is a good opportunity to rotate the array so that its contents
+	 starts at offset 0.  */
+      if (wq->offset > 0)
+	{
+	  unsigned int old_count = wq->count;
+	  unsigned int old_alloc = wq->alloc;
+	  unsigned int old_offset = wq->offset;
+	  unsigned int i;
+	  if (old_offset + old_count > old_alloc)
+	    {
+	      unsigned int limit = old_offset + old_count - old_alloc;
+	      for (i = 0; i < limit; i++)
+		new_array[old_alloc + i] = new_array[i];
+	    }
+	  for (i = 0; i < old_count; i++)
+	    new_array[i] = new_array[old_offset + i];
+	  wq->offset = 0;
+	}
+      wq->array = new_array;
+      wq->alloc = new_alloc;
+    }
+  /* Whether the created event is a manual-reset one or an auto-reset one,
+     does not matter, since we will wait on it only once.  */
+  event = CreateEvent (NULL, TRUE, FALSE, NULL);
+  if (event == INVALID_HANDLE_VALUE)
+    /* No way to allocate an event.  */
+    return INVALID_HANDLE_VALUE;
+  index = wq->offset + wq->count;
+  if (index >= wq->alloc)
+    index -= wq->alloc;
+  wq->array[index] = event;
+  wq->count++;
+  return event;
+}
+
+/* Notifies the first thread from a wait queue and dequeues it.  */
+static inline void
+gl_waitqueue_notify_first (gl_waitqueue_t *wq)
+{
+  SetEvent (wq->array[wq->offset + 0]);
+  wq->offset++;
+  wq->count--;
+  if (wq->count == 0 || wq->offset == wq->alloc)
+    wq->offset = 0;
+}
+
+/* Notifies all threads from a wait queue and dequeues them all.  */
+static inline void
+gl_waitqueue_notify_all (gl_waitqueue_t *wq)
+{
+  unsigned int i;
+
+  for (i = 0; i < wq->count; i++)
+    {
+      unsigned int index = wq->offset + i;
+      if (index >= wq->alloc)
+	index -= wq->alloc;
+      SetEvent (wq->array[index]);
+    }
+  wq->count = 0;
+  wq->offset = 0;
+}
+
+void
+glthread_rwlock_init_func (gl_rwlock_t *lock)
+{
+  InitializeCriticalSection (&lock->lock);
+  gl_waitqueue_init (&lock->waiting_readers);
+  gl_waitqueue_init (&lock->waiting_writers);
+  lock->runcount = 0;
+  lock->guard.done = 1;
+}
+
+int
+glthread_rwlock_rdlock_func (gl_rwlock_t *lock)
+{
+  if (!lock->guard.done)
+    {
+      if (InterlockedIncrement (&lock->guard.started) == 0)
+	/* This thread is the first one to need this lock.  Initialize it.  */
+	glthread_rwlock_init (lock);
+      else
+	/* Yield the CPU while waiting for another thread to finish
+	   initializing this lock.  */
+	while (!lock->guard.done)
+	  Sleep (0);
+    }
+  EnterCriticalSection (&lock->lock);
+  /* Test whether only readers are currently running, and whether the runcount
+     field will not overflow.  */
+  if (!(lock->runcount + 1 > 0))
+    {
+      /* This thread has to wait for a while.  Enqueue it among the
+	 waiting_readers.  */
+      HANDLE event = gl_waitqueue_add (&lock->waiting_readers);
+      if (event != INVALID_HANDLE_VALUE)
+	{
+	  DWORD result;
+	  LeaveCriticalSection (&lock->lock);
+	  /* Wait until another thread signals this event.  */
+	  result = WaitForSingleObject (event, INFINITE);
+	  if (result == WAIT_FAILED || result == WAIT_TIMEOUT)
+	    abort ();
+	  CloseHandle (event);
+	  /* The thread which signalled the event already did the bookkeeping:
+	     removed us from the waiting_readers, incremented lock->runcount.  */
+	  if (!(lock->runcount > 0))
+	    abort ();
+	  return 0;
+	}
+      else
+	{
+	  /* Allocation failure.  Weird.  */
+	  do
+	    {
+	      LeaveCriticalSection (&lock->lock);
+	      Sleep (1);
+	      EnterCriticalSection (&lock->lock);
+	    }
+	  while (!(lock->runcount + 1 > 0));
+	}
+    }
+  lock->runcount++;
+  LeaveCriticalSection (&lock->lock);
+  return 0;
+}
+
+int
+glthread_rwlock_wrlock_func (gl_rwlock_t *lock)
+{
+  if (!lock->guard.done)
+    {
+      if (InterlockedIncrement (&lock->guard.started) == 0)
+	/* This thread is the first one to need this lock.  Initialize it.  */
+	glthread_rwlock_init (lock);
+      else
+	/* Yield the CPU while waiting for another thread to finish
+	   initializing this lock.  */
+	while (!lock->guard.done)
+	  Sleep (0);
+    }
+  EnterCriticalSection (&lock->lock);
+  /* Test whether no readers or writers are currently running.  */
+  if (!(lock->runcount == 0))
+    {
+      /* This thread has to wait for a while.  Enqueue it among the
+	 waiting_writers.  */
+      HANDLE event = gl_waitqueue_add (&lock->waiting_writers);
+      if (event != INVALID_HANDLE_VALUE)
+	{
+	  DWORD result;
+	  LeaveCriticalSection (&lock->lock);
+	  /* Wait until another thread signals this event.  */
+	  result = WaitForSingleObject (event, INFINITE);
+	  if (result == WAIT_FAILED || result == WAIT_TIMEOUT)
+	    abort ();
+	  CloseHandle (event);
+	  /* The thread which signalled the event already did the bookkeeping:
+	     removed us from the waiting_writers, set lock->runcount = -1.  */
+	  if (!(lock->runcount == -1))
+	    abort ();
+	  return 0;
+	}
+      else
+	{
+	  /* Allocation failure.  Weird.  */
+	  do
+	    {
+	      LeaveCriticalSection (&lock->lock);
+	      Sleep (1);
+	      EnterCriticalSection (&lock->lock);
+	    }
+	  while (!(lock->runcount == 0));
+	}
+    }
+  lock->runcount--; /* runcount becomes -1 */
+  LeaveCriticalSection (&lock->lock);
+  return 0;
+}
+
+int
+glthread_rwlock_unlock_func (gl_rwlock_t *lock)
+{
+  if (!lock->guard.done)
+    return EINVAL;
+  EnterCriticalSection (&lock->lock);
+  if (lock->runcount < 0)
+    {
+      /* Drop a writer lock.  */
+      if (!(lock->runcount == -1))
+	abort ();
+      lock->runcount = 0;
+    }
+  else
+    {
+      /* Drop a reader lock.  */
+      if (!(lock->runcount > 0))
+	{
+	  LeaveCriticalSection (&lock->lock);
+	  return EPERM;
+	}
+      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.  */
+	  lock->runcount--;
+	  gl_waitqueue_notify_first (&lock->waiting_writers);
+	}
+      else
+	{
+	  /* Wake up all waiting readers.  */
+	  lock->runcount += lock->waiting_readers.count;
+	  gl_waitqueue_notify_all (&lock->waiting_readers);
+	}
+    }
+  LeaveCriticalSection (&lock->lock);
+  return 0;
+}
+
+int
+glthread_rwlock_destroy_func (gl_rwlock_t *lock)
+{
+  if (!lock->guard.done)
+    return EINVAL;
+  if (lock->runcount != 0)
+    return EBUSY;
+  DeleteCriticalSection (&lock->lock);
+  if (lock->waiting_readers.array != NULL)
+    free (lock->waiting_readers.array);
+  if (lock->waiting_writers.array != NULL)
+    free (lock->waiting_writers.array);
+  lock->guard.done = 0;
+  return 0;
+}
+
+/* --------------------- gl_recursive_lock_t datatype --------------------- */
+
+void
+glthread_recursive_lock_init_func (gl_recursive_lock_t *lock)
+{
+  lock->owner = 0;
+  lock->depth = 0;
+  InitializeCriticalSection (&lock->lock);
+  lock->guard.done = 1;
+}
+
+int
+glthread_recursive_lock_lock_func (gl_recursive_lock_t *lock)
+{
+  if (!lock->guard.done)
+    {
+      if (InterlockedIncrement (&lock->guard.started) == 0)
+	/* This thread is the first one to need this lock.  Initialize it.  */
+	glthread_recursive_lock_init (lock);
+      else
+	/* Yield the CPU while waiting for another thread to finish
+	   initializing this lock.  */
+	while (!lock->guard.done)
+	  Sleep (0);
+    }
+  {
+    DWORD self = GetCurrentThreadId ();
+    if (lock->owner != self)
+      {
+	EnterCriticalSection (&lock->lock);
+	lock->owner = self;
+      }
+    if (++(lock->depth) == 0) /* wraparound? */
+      {
+	lock->depth--;
+	return EAGAIN;
+      }
+  }
+  return 0;
+}
+
+int
+glthread_recursive_lock_unlock_func (gl_recursive_lock_t *lock)
+{
+  if (lock->owner != GetCurrentThreadId ())
+    return EPERM;
+  if (lock->depth == 0)
+    return EINVAL;
+  if (--(lock->depth) == 0)
+    {
+      lock->owner = 0;
+      LeaveCriticalSection (&lock->lock);
+    }
+  return 0;
+}
+
+int
+glthread_recursive_lock_destroy_func (gl_recursive_lock_t *lock)
+{
+  if (lock->owner != 0)
+    return EBUSY;
+  DeleteCriticalSection (&lock->lock);
+  lock->guard.done = 0;
+  return 0;
+}
+
+/* -------------------------- gl_once_t datatype -------------------------- */
+
+void
+glthread_once_func (gl_once_t *once_control, void (*initfunction) (void))
+{
+  if (once_control->inited <= 0)
+    {
+      if (InterlockedIncrement (&once_control->started) == 0)
+	{
+	  /* This thread is the first one to come to this once_control.  */
+	  InitializeCriticalSection (&once_control->lock);
+	  EnterCriticalSection (&once_control->lock);
+	  once_control->inited = 0;
+	  initfunction ();
+	  once_control->inited = 1;
+	  LeaveCriticalSection (&once_control->lock);
+	}
+      else
+	{
+	  /* Undo last operation.  */
+	  InterlockedDecrement (&once_control->started);
+	  /* Some other thread has already started the initialization.
+	     Yield the CPU while waiting for the other thread to finish
+	     initializing and taking the lock.  */
+	  while (once_control->inited < 0)
+	    Sleep (0);
+	  if (once_control->inited <= 0)
+	    {
+	      /* Take the lock.  This blocks until the other thread has
+		 finished calling the initfunction.  */
+	      EnterCriticalSection (&once_control->lock);
+	      LeaveCriticalSection (&once_control->lock);
+	      if (!(once_control->inited > 0))
+		abort ();
+	    }
+	}
+    }
+}
+
+#endif
+
+/* ========================================================================= */
diff --git a/lib/glthread/lock.h b/lib/glthread/lock.h
new file mode 100644
index 0000000..0cfb30e
--- /dev/null
+++ b/lib/glthread/lock.h
@@ -0,0 +1,927 @@
+/* Locking in multithreaded situations.
+   Copyright (C) 2005-2008 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2005.
+   Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-solaris.h,
+   gthr-win32.h.  */
+
+/* This file contains locking primitives for use with a given thread library.
+   It does not contain primitives for creating threads or for other
+   synchronization primitives.
+
+   Normal (non-recursive) locks:
+     Type:                gl_lock_t
+     Declaration:         gl_lock_define(extern, name)
+     Initializer:         gl_lock_define_initialized(, name)
+     Initialization:      gl_lock_init (name);
+     Taking the lock:     gl_lock_lock (name);
+     Releasing the lock:  gl_lock_unlock (name);
+     De-initialization:   gl_lock_destroy (name);
+   Equivalent functions with control of error handling:
+     Initialization:      err = glthread_lock_init (&name);
+     Taking the lock:     err = glthread_lock_lock (&name);
+     Releasing the lock:  err = glthread_lock_unlock (&name);
+     De-initialization:   err = glthread_lock_destroy (&name);
+
+   Read-Write (non-recursive) locks:
+     Type:                gl_rwlock_t
+     Declaration:         gl_rwlock_define(extern, name)
+     Initializer:         gl_rwlock_define_initialized(, name)
+     Initialization:      gl_rwlock_init (name);
+     Taking the lock:     gl_rwlock_rdlock (name);
+                          gl_rwlock_wrlock (name);
+     Releasing the lock:  gl_rwlock_unlock (name);
+     De-initialization:   gl_rwlock_destroy (name);
+   Equivalent functions with control of error handling:
+     Initialization:      err = glthread_rwlock_init (&name);
+     Taking the lock:     err = glthread_rwlock_rdlock (&name);
+                          err = glthread_rwlock_wrlock (&name);
+     Releasing the lock:  err = glthread_rwlock_unlock (&name);
+     De-initialization:   err = glthread_rwlock_destroy (&name);
+
+   Recursive locks:
+     Type:                gl_recursive_lock_t
+     Declaration:         gl_recursive_lock_define(extern, name)
+     Initializer:         gl_recursive_lock_define_initialized(, name)
+     Initialization:      gl_recursive_lock_init (name);
+     Taking the lock:     gl_recursive_lock_lock (name);
+     Releasing the lock:  gl_recursive_lock_unlock (name);
+     De-initialization:   gl_recursive_lock_destroy (name);
+   Equivalent functions with control of error handling:
+     Initialization:      err = glthread_recursive_lock_init (&name);
+     Taking the lock:     err = glthread_recursive_lock_lock (&name);
+     Releasing the lock:  err = glthread_recursive_lock_unlock (&name);
+     De-initialization:   err = glthread_recursive_lock_destroy (&name);
+
+  Once-only execution:
+     Type:                gl_once_t
+     Initializer:         gl_once_define(extern, name)
+     Execution:           gl_once (name, initfunction);
+   Equivalent functions with control of error handling:
+     Execution:           err = glthread_once (&name, initfunction);
+*/
+
+
+#ifndef _LOCK_H
+#define _LOCK_H
+
+#include <errno.h>
+#include <stdlib.h>
+
+/* ========================================================================= */
+
+#if USE_POSIX_THREADS
+
+/* Use the POSIX threads library.  */
+
+# include <pthread.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+# if PTHREAD_IN_USE_DETECTION_HARD
+
+/* The pthread_in_use() detection needs to be done at runtime.  */
+#  define pthread_in_use() \
+     glthread_in_use ()
+extern int glthread_in_use (void);
+
+# endif
+
+# if USE_POSIX_THREADS_WEAK
+
+/* Use weak references to the POSIX threads library.  */
+
+/* Weak references avoid dragging in external libraries if the other parts
+   of the program don't use them.  Here we use them, because we don't want
+   every program that uses libintl to depend on libpthread.  This assumes
+   that libpthread would not be loaded after libintl; i.e. if libintl is
+   loaded first, by an executable that does not depend on libpthread, and
+   then a module is dynamically loaded that depends on libpthread, libintl
+   will not be multithread-safe.  */
+
+/* The way to test at runtime whether libpthread is present is to test
+   whether a function pointer's value, such as &pthread_mutex_init, is
+   non-NULL.  However, some versions of GCC have a bug through which, in
+   PIC mode, &foo != NULL always evaluates to true if there is a direct
+   call to foo(...) in the same function.  To avoid this, we test the
+   address of a function in libpthread that we don't use.  */
+
+#  pragma weak pthread_mutex_init
+#  pragma weak pthread_mutex_lock
+#  pragma weak pthread_mutex_unlock
+#  pragma weak pthread_mutex_destroy
+#  pragma weak pthread_rwlock_init
+#  pragma weak pthread_rwlock_rdlock
+#  pragma weak pthread_rwlock_wrlock
+#  pragma weak pthread_rwlock_unlock
+#  pragma weak pthread_rwlock_destroy
+#  pragma weak pthread_once
+#  pragma weak pthread_cond_init
+#  pragma weak pthread_cond_wait
+#  pragma weak pthread_cond_signal
+#  pragma weak pthread_cond_broadcast
+#  pragma weak pthread_cond_destroy
+#  pragma weak pthread_mutexattr_init
+#  pragma weak pthread_mutexattr_settype
+#  pragma weak pthread_mutexattr_destroy
+#  ifndef pthread_self
+#   pragma weak pthread_self
+#  endif
+
+#  if !PTHREAD_IN_USE_DETECTION_HARD
+#   pragma weak pthread_cancel
+#   define pthread_in_use() (pthread_cancel != NULL)
+#  endif
+
+# else
+
+#  if !PTHREAD_IN_USE_DETECTION_HARD
+#   define pthread_in_use() 1
+#  endif
+
+# endif
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+typedef pthread_mutex_t gl_lock_t;
+# define gl_lock_define(STORAGECLASS, NAME) \
+    STORAGECLASS pthread_mutex_t NAME;
+# define gl_lock_define_initialized(STORAGECLASS, NAME) \
+    STORAGECLASS pthread_mutex_t NAME = gl_lock_initializer;
+# define gl_lock_initializer \
+    PTHREAD_MUTEX_INITIALIZER
+# define glthread_lock_init(LOCK) \
+    (pthread_in_use () ? pthread_mutex_init (LOCK, NULL) : 0)
+# define glthread_lock_lock(LOCK) \
+    (pthread_in_use () ? pthread_mutex_lock (LOCK) : 0)
+# define glthread_lock_unlock(LOCK) \
+    (pthread_in_use () ? pthread_mutex_unlock (LOCK) : 0)
+# define glthread_lock_destroy(LOCK) \
+    (pthread_in_use () ? pthread_mutex_destroy (LOCK) : 0)
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+# if HAVE_PTHREAD_RWLOCK
+
+#  ifdef PTHREAD_RWLOCK_INITIALIZER
+
+typedef pthread_rwlock_t gl_rwlock_t;
+#   define gl_rwlock_define(STORAGECLASS, NAME) \
+      STORAGECLASS pthread_rwlock_t NAME;
+#   define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
+      STORAGECLASS pthread_rwlock_t NAME = gl_rwlock_initializer;
+#   define gl_rwlock_initializer \
+      PTHREAD_RWLOCK_INITIALIZER
+#   define glthread_rwlock_init(LOCK) \
+      (pthread_in_use () ? pthread_rwlock_init (LOCK, NULL) : 0)
+#   define glthread_rwlock_rdlock(LOCK) \
+      (pthread_in_use () ? pthread_rwlock_rdlock (LOCK) : 0)
+#   define glthread_rwlock_wrlock(LOCK) \
+      (pthread_in_use () ? pthread_rwlock_wrlock (LOCK) : 0)
+#   define glthread_rwlock_unlock(LOCK) \
+      (pthread_in_use () ? pthread_rwlock_unlock (LOCK) : 0)
+#   define glthread_rwlock_destroy(LOCK) \
+      (pthread_in_use () ? pthread_rwlock_destroy (LOCK) : 0)
+
+#  else
+
+typedef struct
+        {
+          int initialized;
+          pthread_mutex_t guard;   /* protects the initialization */
+          pthread_rwlock_t rwlock; /* read-write lock */
+        }
+        gl_rwlock_t;
+#   define gl_rwlock_define(STORAGECLASS, NAME) \
+      STORAGECLASS gl_rwlock_t NAME;
+#   define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
+      STORAGECLASS gl_rwlock_t NAME = gl_rwlock_initializer;
+#   define gl_rwlock_initializer \
+      { 0, PTHREAD_MUTEX_INITIALIZER }
+#   define glthread_rwlock_init(LOCK) \
+      (pthread_in_use () ? glthread_rwlock_init_multithreaded (LOCK) : 0)
+#   define glthread_rwlock_rdlock(LOCK) \
+      (pthread_in_use () ? glthread_rwlock_rdlock_multithreaded (LOCK) : 0)
+#   define glthread_rwlock_wrlock(LOCK) \
+      (pthread_in_use () ? glthread_rwlock_wrlock_multithreaded (LOCK) : 0)
+#   define glthread_rwlock_unlock(LOCK) \
+      (pthread_in_use () ? glthread_rwlock_unlock_multithreaded (LOCK) : 0)
+#   define glthread_rwlock_destroy(LOCK) \
+      (pthread_in_use () ? glthread_rwlock_destroy_multithreaded (LOCK) : 0)
+extern int glthread_rwlock_init_multithreaded (gl_rwlock_t *lock);
+extern int glthread_rwlock_rdlock_multithreaded (gl_rwlock_t *lock);
+extern int glthread_rwlock_wrlock_multithreaded (gl_rwlock_t *lock);
+extern int glthread_rwlock_unlock_multithreaded (gl_rwlock_t *lock);
+extern int glthread_rwlock_destroy_multithreaded (gl_rwlock_t *lock);
+
+#  endif
+
+# else
+
+typedef struct
+        {
+          pthread_mutex_t lock; /* protects the remaining fields */
+          pthread_cond_t waiting_readers; /* waiting readers */
+          pthread_cond_t waiting_writers; /* waiting writers */
+          unsigned int waiting_writers_count; /* number of waiting writers */
+          int runcount; /* number of readers running, or -1 when a writer runs */
+        }
+        gl_rwlock_t;
+# define gl_rwlock_define(STORAGECLASS, NAME) \
+    STORAGECLASS gl_rwlock_t NAME;
+# define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
+    STORAGECLASS gl_rwlock_t NAME = gl_rwlock_initializer;
+# define gl_rwlock_initializer \
+    { PTHREAD_MUTEX_INITIALIZER, PTHREAD_COND_INITIALIZER, PTHREAD_COND_INITIALIZER, 0, 0 }
+# define glthread_rwlock_init(LOCK) \
+    (pthread_in_use () ? glthread_rwlock_init_multithreaded (LOCK) : 0)
+# define glthread_rwlock_rdlock(LOCK) \
+    (pthread_in_use () ? glthread_rwlock_rdlock_multithreaded (LOCK) : 0)
+# define glthread_rwlock_wrlock(LOCK) \
+    (pthread_in_use () ? glthread_rwlock_wrlock_multithreaded (LOCK) : 0)
+# define glthread_rwlock_unlock(LOCK) \
+    (pthread_in_use () ? glthread_rwlock_unlock_multithreaded (LOCK) : 0)
+# define glthread_rwlock_destroy(LOCK) \
+    (pthread_in_use () ? glthread_rwlock_destroy_multithreaded (LOCK) : 0)
+extern int glthread_rwlock_init_multithreaded (gl_rwlock_t *lock);
+extern int glthread_rwlock_rdlock_multithreaded (gl_rwlock_t *lock);
+extern int glthread_rwlock_wrlock_multithreaded (gl_rwlock_t *lock);
+extern int glthread_rwlock_unlock_multithreaded (gl_rwlock_t *lock);
+extern int glthread_rwlock_destroy_multithreaded (gl_rwlock_t *lock);
+
+# endif
+
+/* --------------------- gl_recursive_lock_t datatype --------------------- */
+
+# if HAVE_PTHREAD_MUTEX_RECURSIVE
+
+#  if defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER || defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
+
+typedef pthread_mutex_t gl_recursive_lock_t;
+#   define gl_recursive_lock_define(STORAGECLASS, NAME) \
+      STORAGECLASS pthread_mutex_t NAME;
+#   define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
+      STORAGECLASS pthread_mutex_t NAME = gl_recursive_lock_initializer;
+#   ifdef PTHREAD_RECURSIVE_MUTEX_INITIALIZER
+#    define gl_recursive_lock_initializer \
+       PTHREAD_RECURSIVE_MUTEX_INITIALIZER
+#   else
+#    define gl_recursive_lock_initializer \
+       PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
+#   endif
+#   define glthread_recursive_lock_init(LOCK) \
+      (pthread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
+#   define glthread_recursive_lock_lock(LOCK) \
+      (pthread_in_use () ? pthread_mutex_lock (LOCK) : 0)
+#   define glthread_recursive_lock_unlock(LOCK) \
+      (pthread_in_use () ? pthread_mutex_unlock (LOCK) : 0)
+#   define glthread_recursive_lock_destroy(LOCK) \
+      (pthread_in_use () ? pthread_mutex_destroy (LOCK) : 0)
+extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
+
+#  else
+
+typedef struct
+        {
+          pthread_mutex_t recmutex; /* recursive mutex */
+          pthread_mutex_t guard;    /* protects the initialization */
+          int initialized;
+        }
+        gl_recursive_lock_t;
+#   define gl_recursive_lock_define(STORAGECLASS, NAME) \
+      STORAGECLASS gl_recursive_lock_t NAME;
+#   define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
+      STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
+#   define gl_recursive_lock_initializer \
+      { PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, 0 }
+#   define glthread_recursive_lock_init(LOCK) \
+      (pthread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
+#   define glthread_recursive_lock_lock(LOCK) \
+      (pthread_in_use () ? glthread_recursive_lock_lock_multithreaded (LOCK) : 0)
+#   define glthread_recursive_lock_unlock(LOCK) \
+      (pthread_in_use () ? glthread_recursive_lock_unlock_multithreaded (LOCK) : 0)
+#   define glthread_recursive_lock_destroy(LOCK) \
+      (pthread_in_use () ? glthread_recursive_lock_destroy_multithreaded (LOCK) : 0)
+extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
+extern int glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock);
+extern int glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock);
+extern int glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock);
+
+#  endif
+
+# else
+
+/* Old versions of POSIX threads on Solaris did not have recursive locks.
+   We have to implement them ourselves.  */
+
+typedef struct
+        {
+          pthread_mutex_t mutex;
+          pthread_t owner;
+          unsigned long depth;
+        }
+        gl_recursive_lock_t;
+#  define gl_recursive_lock_define(STORAGECLASS, NAME) \
+     STORAGECLASS gl_recursive_lock_t NAME;
+#  define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
+     STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
+#  define gl_recursive_lock_initializer \
+     { PTHREAD_MUTEX_INITIALIZER, (pthread_t) 0, 0 }
+#  define glthread_recursive_lock_init(LOCK) \
+     (pthread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
+#  define glthread_recursive_lock_lock(LOCK) \
+     (pthread_in_use () ? glthread_recursive_lock_lock_multithreaded (LOCK) : 0)
+#  define glthread_recursive_lock_unlock(LOCK) \
+     (pthread_in_use () ? glthread_recursive_lock_unlock_multithreaded (LOCK) : 0)
+#  define glthread_recursive_lock_destroy(LOCK) \
+     (pthread_in_use () ? glthread_recursive_lock_destroy_multithreaded (LOCK) : 0)
+extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
+extern int glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock);
+extern int glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock);
+extern int glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock);
+
+# endif
+
+/* -------------------------- gl_once_t datatype -------------------------- */
+
+typedef pthread_once_t gl_once_t;
+# define gl_once_define(STORAGECLASS, NAME) \
+    STORAGECLASS pthread_once_t NAME = PTHREAD_ONCE_INIT;
+# define glthread_once(ONCE_CONTROL, INITFUNCTION) \
+    (pthread_in_use ()                                                         \
+     ? pthread_once (ONCE_CONTROL, INITFUNCTION)                               \
+     : (glthread_once_singlethreaded (ONCE_CONTROL) ? (INITFUNCTION (), 0) : 0))
+extern int glthread_once_singlethreaded (pthread_once_t *once_control);
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_PTH_THREADS
+
+/* Use the GNU Pth threads library.  */
+
+# include <pth.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+# if USE_PTH_THREADS_WEAK
+
+/* Use weak references to the GNU Pth threads library.  */
+
+#  pragma weak pth_mutex_init
+#  pragma weak pth_mutex_acquire
+#  pragma weak pth_mutex_release
+#  pragma weak pth_rwlock_init
+#  pragma weak pth_rwlock_acquire
+#  pragma weak pth_rwlock_release
+#  pragma weak pth_once
+
+#  pragma weak pth_cancel
+#  define pth_in_use() (pth_cancel != NULL)
+
+# else
+
+#  define pth_in_use() 1
+
+# endif
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+typedef pth_mutex_t gl_lock_t;
+# define gl_lock_define(STORAGECLASS, NAME) \
+    STORAGECLASS pth_mutex_t NAME;
+# define gl_lock_define_initialized(STORAGECLASS, NAME) \
+    STORAGECLASS pth_mutex_t NAME = gl_lock_initializer;
+# define gl_lock_initializer \
+    PTH_MUTEX_INIT
+# define glthread_lock_init(LOCK) \
+    (pth_in_use() && !pth_mutex_init (LOCK) ? errno : 0)
+# define glthread_lock_lock(LOCK) \
+    (pth_in_use() && !pth_mutex_acquire (LOCK, 0, NULL) ? errno : 0)
+# define glthread_lock_unlock(LOCK) \
+    (pth_in_use() && !pth_mutex_release (LOCK) ? errno : 0)
+# define glthread_lock_destroy(LOCK) \
+    ((void)(LOCK), 0)
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+typedef pth_rwlock_t gl_rwlock_t;
+#  define gl_rwlock_define(STORAGECLASS, NAME) \
+     STORAGECLASS pth_rwlock_t NAME;
+#  define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
+     STORAGECLASS pth_rwlock_t NAME = gl_rwlock_initializer;
+#  define gl_rwlock_initializer \
+     PTH_RWLOCK_INIT
+#  define glthread_rwlock_init(LOCK) \
+     (pth_in_use() && !pth_rwlock_init (LOCK) ? errno : 0)
+#  define glthread_rwlock_rdlock(LOCK) \
+     (pth_in_use() && !pth_rwlock_acquire (LOCK, PTH_RWLOCK_RD, 0, NULL) ? errno : 0)
+#  define glthread_rwlock_wrlock(LOCK) \
+     (pth_in_use() && !pth_rwlock_acquire (LOCK, PTH_RWLOCK_RW, 0, NULL) ? errno : 0)
+#  define glthread_rwlock_unlock(LOCK) \
+     (pth_in_use() && !pth_rwlock_release (LOCK) ? errno : 0)
+#  define glthread_rwlock_destroy(LOCK) \
+     ((void)(LOCK), 0)
+
+/* --------------------- gl_recursive_lock_t datatype --------------------- */
+
+/* In Pth, mutexes are recursive by default.  */
+typedef pth_mutex_t gl_recursive_lock_t;
+#  define gl_recursive_lock_define(STORAGECLASS, NAME) \
+     STORAGECLASS pth_mutex_t NAME;
+#  define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
+     STORAGECLASS pth_mutex_t NAME = gl_recursive_lock_initializer;
+#  define gl_recursive_lock_initializer \
+     PTH_MUTEX_INIT
+#  define glthread_recursive_lock_init(LOCK) \
+     (pth_in_use() && !pth_mutex_init (LOCK) ? errno : 0)
+#  define glthread_recursive_lock_lock(LOCK) \
+     (pth_in_use() && !pth_mutex_acquire (LOCK, 0, NULL) ? errno : 0)
+#  define glthread_recursive_lock_unlock(LOCK) \
+     (pth_in_use() && !pth_mutex_release (LOCK) ? errno : 0)
+#  define glthread_recursive_lock_destroy(LOCK) \
+     ((void)(LOCK), 0)
+
+/* -------------------------- gl_once_t datatype -------------------------- */
+
+typedef pth_once_t gl_once_t;
+# define gl_once_define(STORAGECLASS, NAME) \
+    STORAGECLASS pth_once_t NAME = PTH_ONCE_INIT;
+# define glthread_once(ONCE_CONTROL, INITFUNCTION) \
+    (pth_in_use ()                                                             \
+     ? glthread_once_multithreaded (ONCE_CONTROL, INITFUNCTION)                \
+     : (glthread_once_singlethreaded (ONCE_CONTROL) ? (INITFUNCTION (), 0) : 0))
+extern int glthread_once_multithreaded (pth_once_t *once_control, void (*initfunction) (void));
+extern int glthread_once_singlethreaded (pth_once_t *once_control);
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_SOLARIS_THREADS
+
+/* Use the old Solaris threads library.  */
+
+# include <thread.h>
+# include <synch.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+# if USE_SOLARIS_THREADS_WEAK
+
+/* Use weak references to the old Solaris threads library.  */
+
+#  pragma weak mutex_init
+#  pragma weak mutex_lock
+#  pragma weak mutex_unlock
+#  pragma weak mutex_destroy
+#  pragma weak rwlock_init
+#  pragma weak rw_rdlock
+#  pragma weak rw_wrlock
+#  pragma weak rw_unlock
+#  pragma weak rwlock_destroy
+#  pragma weak thr_self
+
+#  pragma weak thr_suspend
+#  define thread_in_use() (thr_suspend != NULL)
+
+# else
+
+#  define thread_in_use() 1
+
+# endif
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+typedef mutex_t gl_lock_t;
+# define gl_lock_define(STORAGECLASS, NAME) \
+    STORAGECLASS mutex_t NAME;
+# define gl_lock_define_initialized(STORAGECLASS, NAME) \
+    STORAGECLASS mutex_t NAME = gl_lock_initializer;
+# define gl_lock_initializer \
+    DEFAULTMUTEX
+# define glthread_lock_init(LOCK) \
+    (thread_in_use () ? mutex_init (LOCK, USYNC_THREAD, NULL) : 0)
+# define glthread_lock_lock(LOCK) \
+    (thread_in_use () ? mutex_lock (LOCK) : 0)
+# define glthread_lock_unlock(LOCK) \
+    (thread_in_use () ? mutex_unlock (LOCK) : 0)
+# define glthread_lock_destroy(LOCK) \
+    (thread_in_use () ? mutex_destroy (LOCK) : 0)
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+typedef rwlock_t gl_rwlock_t;
+# define gl_rwlock_define(STORAGECLASS, NAME) \
+    STORAGECLASS rwlock_t NAME;
+# define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
+    STORAGECLASS rwlock_t NAME = gl_rwlock_initializer;
+# define gl_rwlock_initializer \
+    DEFAULTRWLOCK
+# define glthread_rwlock_init(LOCK) \
+    (thread_in_use () ? rwlock_init (LOCK, USYNC_THREAD, NULL) : 0)
+# define glthread_rwlock_rdlock(LOCK) \
+    (thread_in_use () ? rw_rdlock (LOCK) : 0)
+# define glthread_rwlock_wrlock(LOCK) \
+    (thread_in_use () ? rw_wrlock (LOCK) : 0)
+# define glthread_rwlock_unlock(LOCK) \
+    (thread_in_use () ? rw_unlock (LOCK) : 0)
+# define glthread_rwlock_destroy(LOCK) \
+    (thread_in_use () ? rwlock_destroy (LOCK) : 0)
+
+/* --------------------- gl_recursive_lock_t datatype --------------------- */
+
+/* Old Solaris threads did not have recursive locks.
+   We have to implement them ourselves.  */
+
+typedef struct
+        {
+          mutex_t mutex;
+          thread_t owner;
+          unsigned long depth;
+        }
+        gl_recursive_lock_t;
+# define gl_recursive_lock_define(STORAGECLASS, NAME) \
+    STORAGECLASS gl_recursive_lock_t NAME;
+# define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
+    STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
+# define gl_recursive_lock_initializer \
+    { DEFAULTMUTEX, (thread_t) 0, 0 }
+# define glthread_recursive_lock_init(LOCK) \
+    (thread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
+# define glthread_recursive_lock_lock(LOCK) \
+    (thread_in_use () ? glthread_recursive_lock_lock_multithreaded (LOCK) : 0)
+# define glthread_recursive_lock_unlock(LOCK) \
+    (thread_in_use () ? glthread_recursive_lock_unlock_multithreaded (LOCK) : 0)
+# define glthread_recursive_lock_destroy(LOCK) \
+    (thread_in_use () ? glthread_recursive_lock_destroy_multithreaded (LOCK) : 0)
+extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
+extern int glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock);
+extern int glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock);
+extern int glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock);
+
+/* -------------------------- gl_once_t datatype -------------------------- */
+
+typedef struct
+        {
+          volatile int inited;
+          mutex_t mutex;
+        }
+        gl_once_t;
+# define gl_once_define(STORAGECLASS, NAME) \
+    STORAGECLASS gl_once_t NAME = { 0, DEFAULTMUTEX };
+# define glthread_once(ONCE_CONTROL, INITFUNCTION) \
+    (thread_in_use ()                                                          \
+     ? glthread_once_multithreaded (ONCE_CONTROL, INITFUNCTION)                \
+     : (glthread_once_singlethreaded (ONCE_CONTROL) ? (INITFUNCTION (), 0) : 0))
+extern int glthread_once_multithreaded (gl_once_t *once_control, void (*initfunction) (void));
+extern int glthread_once_singlethreaded (gl_once_t *once_control);
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_WIN32_THREADS
+
+# include <windows.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+/* We can use CRITICAL_SECTION directly, rather than the Win32 Event, Mutex,
+   Semaphore types, because
+     - we need only to synchronize inside a single process (address space),
+       not inter-process locking,
+     - we don't need to support trylock operations.  (TryEnterCriticalSection
+       does not work on Windows 95/98/ME.  Packages that need trylock usually
+       define their own mutex type.)  */
+
+/* There is no way to statically initialize a CRITICAL_SECTION.  It needs
+   to be done lazily, once only.  For this we need spinlocks.  */
+
+typedef struct { volatile int done; volatile long started; } gl_spinlock_t;
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+typedef struct
+        {
+          gl_spinlock_t guard; /* protects the initialization */
+          CRITICAL_SECTION lock;
+        }
+        gl_lock_t;
+# define gl_lock_define(STORAGECLASS, NAME) \
+    STORAGECLASS gl_lock_t NAME;
+# define gl_lock_define_initialized(STORAGECLASS, NAME) \
+    STORAGECLASS gl_lock_t NAME = gl_lock_initializer;
+# define gl_lock_initializer \
+    { { 0, -1 } }
+# define glthread_lock_init(LOCK) \
+    (glthread_lock_init_func (LOCK), 0)
+# define glthread_lock_lock(LOCK) \
+    glthread_lock_lock_func (LOCK)
+# define glthread_lock_unlock(LOCK) \
+    glthread_lock_unlock_func (LOCK)
+# define glthread_lock_destroy(LOCK) \
+    glthread_lock_destroy_func (LOCK)
+extern void glthread_lock_init_func (gl_lock_t *lock);
+extern int glthread_lock_lock_func (gl_lock_t *lock);
+extern int glthread_lock_unlock_func (gl_lock_t *lock);
+extern int glthread_lock_destroy_func (gl_lock_t *lock);
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+/* It is impossible to implement read-write locks using plain locks, without
+   introducing an extra thread dedicated to managing read-write locks.
+   Therefore here we need to use the low-level Event type.  */
+
+typedef struct
+        {
+          HANDLE *array; /* array of waiting threads, each represented by an event */
+          unsigned int count; /* number of waiting threads */
+          unsigned int alloc; /* length of allocated array */
+          unsigned int offset; /* index of first waiting thread in array */
+        }
+        gl_carray_waitqueue_t;
+typedef struct
+        {
+          gl_spinlock_t guard; /* protects the initialization */
+          CRITICAL_SECTION lock; /* protects the remaining fields */
+          gl_carray_waitqueue_t waiting_readers; /* waiting readers */
+          gl_carray_waitqueue_t waiting_writers; /* waiting writers */
+          int runcount; /* number of readers running, or -1 when a writer runs */
+        }
+        gl_rwlock_t;
+# define gl_rwlock_define(STORAGECLASS, NAME) \
+    STORAGECLASS gl_rwlock_t NAME;
+# define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
+    STORAGECLASS gl_rwlock_t NAME = gl_rwlock_initializer;
+# define gl_rwlock_initializer \
+    { { 0, -1 } }
+# define glthread_rwlock_init(LOCK) \
+    (glthread_rwlock_init_func (LOCK), 0)
+# define glthread_rwlock_rdlock(LOCK) \
+    glthread_rwlock_rdlock_func (LOCK)
+# define glthread_rwlock_wrlock(LOCK) \
+    glthread_rwlock_wrlock_func (LOCK)
+# define glthread_rwlock_unlock(LOCK) \
+    glthread_rwlock_unlock_func (LOCK)
+# define glthread_rwlock_destroy(LOCK) \
+    glthread_rwlock_destroy_func (LOCK)
+extern void glthread_rwlock_init_func (gl_rwlock_t *lock);
+extern int glthread_rwlock_rdlock_func (gl_rwlock_t *lock);
+extern int glthread_rwlock_wrlock_func (gl_rwlock_t *lock);
+extern int glthread_rwlock_unlock_func (gl_rwlock_t *lock);
+extern int glthread_rwlock_destroy_func (gl_rwlock_t *lock);
+
+/* --------------------- gl_recursive_lock_t datatype --------------------- */
+
+/* The Win32 documentation says that CRITICAL_SECTION already implements a
+   recursive lock.  But we need not rely on it: It's easy to implement a
+   recursive lock without this assumption.  */
+
+typedef struct
+        {
+          gl_spinlock_t guard; /* protects the initialization */
+          DWORD owner;
+          unsigned long depth;
+          CRITICAL_SECTION lock;
+        }
+        gl_recursive_lock_t;
+# define gl_recursive_lock_define(STORAGECLASS, NAME) \
+    STORAGECLASS gl_recursive_lock_t NAME;
+# define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
+    STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
+# define gl_recursive_lock_initializer \
+    { { 0, -1 }, 0, 0 }
+# define glthread_recursive_lock_init(LOCK) \
+    (glthread_recursive_lock_init_func (LOCK), 0)
+# define glthread_recursive_lock_lock(LOCK) \
+    glthread_recursive_lock_lock_func (LOCK)
+# define glthread_recursive_lock_unlock(LOCK) \
+    glthread_recursive_lock_unlock_func (LOCK)
+# define glthread_recursive_lock_destroy(LOCK) \
+    glthread_recursive_lock_destroy_func (LOCK)
+extern void glthread_recursive_lock_init_func (gl_recursive_lock_t *lock);
+extern int glthread_recursive_lock_lock_func (gl_recursive_lock_t *lock);
+extern int glthread_recursive_lock_unlock_func (gl_recursive_lock_t *lock);
+extern int glthread_recursive_lock_destroy_func (gl_recursive_lock_t *lock);
+
+/* -------------------------- gl_once_t datatype -------------------------- */
+
+typedef struct
+        {
+          volatile int inited;
+          volatile long started;
+          CRITICAL_SECTION lock;
+        }
+        gl_once_t;
+# define gl_once_define(STORAGECLASS, NAME) \
+    STORAGECLASS gl_once_t NAME = { -1, -1 };
+# define glthread_once(ONCE_CONTROL, INITFUNCTION) \
+    (glthread_once_func (ONCE_CONTROL, INITFUNCTION), 0)
+extern void glthread_once_func (gl_once_t *once_control, void (*initfunction) (void));
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif
+
+/* ========================================================================= */
+
+#if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_SOLARIS_THREADS || USE_WIN32_THREADS)
+
+/* Provide dummy implementation if threads are not supported.  */
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+typedef int gl_lock_t;
+# define gl_lock_define(STORAGECLASS, NAME)
+# define gl_lock_define_initialized(STORAGECLASS, NAME)
+# define glthread_lock_init(NAME) 0
+# define glthread_lock_lock(NAME) 0
+# define glthread_lock_unlock(NAME) 0
+# define glthread_lock_destroy(NAME) 0
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+typedef int gl_rwlock_t;
+# define gl_rwlock_define(STORAGECLASS, NAME)
+# define gl_rwlock_define_initialized(STORAGECLASS, NAME)
+# define glthread_rwlock_init(NAME) 0
+# define glthread_rwlock_rdlock(NAME) 0
+# define glthread_rwlock_wrlock(NAME) 0
+# define glthread_rwlock_unlock(NAME) 0
+# define glthread_rwlock_destroy(NAME) 0
+
+/* --------------------- gl_recursive_lock_t datatype --------------------- */
+
+typedef int gl_recursive_lock_t;
+# define gl_recursive_lock_define(STORAGECLASS, NAME)
+# define gl_recursive_lock_define_initialized(STORAGECLASS, NAME)
+# define glthread_recursive_lock_init(NAME) 0
+# define glthread_recursive_lock_lock(NAME) 0
+# define glthread_recursive_lock_unlock(NAME) 0
+# define glthread_recursive_lock_destroy(NAME) 0
+
+/* -------------------------- gl_once_t datatype -------------------------- */
+
+typedef int gl_once_t;
+# define gl_once_define(STORAGECLASS, NAME) \
+    STORAGECLASS gl_once_t NAME = 0;
+# define glthread_once(ONCE_CONTROL, INITFUNCTION) \
+    (*(ONCE_CONTROL) == 0 ? (*(ONCE_CONTROL) = ~ 0, INITFUNCTION (), 0) : 0)
+
+#endif
+
+/* ========================================================================= */
+
+/* Macros with built-in error handling.  */
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+#define gl_lock_init(NAME) \
+   do                                  \
+     {                                 \
+       if (glthread_lock_init (&NAME)) \
+         abort ();                     \
+     }                                 \
+   while (0)
+#define gl_lock_lock(NAME) \
+   do                                  \
+     {                                 \
+       if (glthread_lock_lock (&NAME)) \
+         abort ();                     \
+     }                                 \
+   while (0)
+#define gl_lock_unlock(NAME) \
+   do                                    \
+     {                                   \
+       if (glthread_lock_unlock (&NAME)) \
+         abort ();                       \
+     }                                   \
+   while (0)
+#define gl_lock_destroy(NAME) \
+   do                                     \
+     {                                    \
+       if (glthread_lock_destroy (&NAME)) \
+         abort ();                        \
+     }                                    \
+   while (0)
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+#define gl_rwlock_init(NAME) \
+   do                                    \
+     {                                   \
+       if (glthread_rwlock_init (&NAME)) \
+         abort ();                       \
+     }                                   \
+   while (0)
+#define gl_rwlock_rdlock(NAME) \
+   do                                      \
+     {                                     \
+       if (glthread_rwlock_rdlock (&NAME)) \
+         abort ();                         \
+     }                                     \
+   while (0)
+#define gl_rwlock_wrlock(NAME) \
+   do                                      \
+     {                                     \
+       if (glthread_rwlock_wrlock (&NAME)) \
+         abort ();                         \
+     }                                     \
+   while (0)
+#define gl_rwlock_unlock(NAME) \
+   do                                      \
+     {                                     \
+       if (glthread_rwlock_unlock (&NAME)) \
+         abort ();                         \
+     }                                     \
+   while (0)
+#define gl_rwlock_destroy(NAME) \
+   do                                       \
+     {                                      \
+       if (glthread_rwlock_destroy (&NAME)) \
+         abort ();                          \
+     }                                      \
+   while (0)
+
+/* --------------------- gl_recursive_lock_t datatype --------------------- */
+
+#define gl_recursive_lock_init(NAME) \
+   do                                            \
+     {                                           \
+       if (glthread_recursive_lock_init (&NAME)) \
+         abort ();                               \
+     }                                           \
+   while (0)
+#define gl_recursive_lock_lock(NAME) \
+   do                                            \
+     {                                           \
+       if (glthread_recursive_lock_lock (&NAME)) \
+         abort ();                               \
+     }                                           \
+   while (0)
+#define gl_recursive_lock_unlock(NAME) \
+   do                                              \
+     {                                             \
+       if (glthread_recursive_lock_unlock (&NAME)) \
+         abort ();                                 \
+     }                                             \
+   while (0)
+#define gl_recursive_lock_destroy(NAME) \
+   do                                               \
+     {                                              \
+       if (glthread_recursive_lock_destroy (&NAME)) \
+         abort ();                                  \
+     }                                              \
+   while (0)
+
+/* -------------------------- gl_once_t datatype -------------------------- */
+
+#define gl_once(NAME, INITFUNCTION) \
+   do                                           \
+     {                                          \
+       if (glthread_once (&NAME, INITFUNCTION)) \
+         abort ();                              \
+     }                                          \
+   while (0)
+
+/* ========================================================================= */
+
+#endif /* _LOCK_H */
diff --git a/lib/glthread/thread.c b/lib/glthread/thread.c
new file mode 100644
index 0000000..82d2ad4
--- /dev/null
+++ b/lib/glthread/thread.c
@@ -0,0 +1,218 @@
+/* Creating and controlling threads.
+   Copyright (C) 2005-2008 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2005.
+   Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-solaris.h,
+   gthr-win32.h.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "glthread/thread.h"
+
+#include <stdlib.h>
+#include "glthread/lock.h"
+
+/* ========================================================================= */
+
+#if USE_WIN32_THREADS
+
+#include <process.h>
+
+/* -------------------------- gl_thread_t datatype -------------------------- */
+
+/* The Thread-Local Storage (TLS) key that allows to access each thread's
+   'struct gl_thread_struct *' pointer.  */
+static DWORD self_key = (DWORD)-1;
+
+/* Initializes self_key.  This function must only be called once.  */
+static void
+do_init_self_key (void)
+{
+  self_key = TlsAlloc ();
+  /* If this fails, we're hosed.  */
+  if (self_key == (DWORD)-1)
+    abort ();
+}
+
+/* Initializes self_key.  */
+static void
+init_self_key (void)
+{
+  gl_once_define(static, once)
+  gl_once (once, do_init_self_key);
+}
+
+/* This structure contains information about a thread.
+   It is stored in TLS under key self_key.  */
+struct gl_thread_struct
+{
+  /* Fields for managing the handle.  */
+  HANDLE volatile handle;
+  CRITICAL_SECTION handle_lock;
+  /* Fields for managing the exit value.  */
+  void * volatile result;
+  /* Fields for managing the thread start.  */
+  void * (*func) (void *);
+  void *arg;
+};
+
+/* Return a real HANDLE object for the current thread.  */
+static inline HANDLE
+get_current_thread_handle (void)
+{
+  HANDLE this_handle;
+
+  /* GetCurrentThread() returns a pseudo-handle, i.e. only a symbolic
+     identifier, not a real handle.  */
+  if (!DuplicateHandle (GetCurrentProcess (), GetCurrentThread (),
+			GetCurrentProcess (), &this_handle,
+			0, FALSE, DUPLICATE_SAME_ACCESS))
+    abort ();
+  return this_handle;
+}
+
+gl_thread_t
+gl_thread_self_func (void)
+{
+  gl_thread_t thread;
+
+  if (self_key == (DWORD)-1)
+    init_self_key ();
+  thread = TlsGetValue (self_key);
+  if (thread == NULL)
+    {
+      /* This happens only in threads that have not been created through
+	 glthread_create(), such as the main thread.  */
+      for (;;)
+	{
+	  thread =
+	    (struct gl_thread_struct *)
+	    malloc (sizeof (struct gl_thread_struct));
+	  if (thread != NULL)
+	    break;
+	  /* Memory allocation failed.  There is not much we can do.  Have to
+	     busy-loop, waiting for the availability of memory.  */
+	  Sleep (1);
+	}
+
+      thread->handle = get_current_thread_handle ();
+      InitializeCriticalSection (&thread->handle_lock);
+      thread->result = NULL; /* just to be deterministic */
+      TlsSetValue (self_key, thread);
+    }
+  return thread;
+}
+
+/* The main function of a freshly creating thread.  It's a wrapper around
+   the FUNC and ARG arguments passed to glthread_create_func.  */
+static unsigned int WINAPI
+wrapper_func (void *varg)
+{
+  struct gl_thread_struct *thread = (struct gl_thread_struct *)varg;
+
+  EnterCriticalSection (&thread->handle_lock);
+  /* Create a new handle for the thread only if the parent thread did not yet
+     fill in the handle.  */
+  if (thread->handle == NULL)
+    thread->handle = get_current_thread_handle ();
+  LeaveCriticalSection (&thread->handle_lock);
+
+  if (self_key == (DWORD)-1)
+    init_self_key ();
+  TlsSetValue (self_key, thread);
+
+  /* Run the thread.  Store the exit value if the thread was not terminated
+     otherwise.  */
+  thread->result = thread->func (thread->arg);
+  return 0;
+}
+
+int
+glthread_create_func (gl_thread_t *threadp, void * (*func) (void *), void *arg)
+{
+  struct gl_thread_struct *thread =
+    (struct gl_thread_struct *) malloc (sizeof (struct gl_thread_struct));
+  if (thread == NULL)
+    return ENOMEM;
+  thread->handle = NULL;
+  InitializeCriticalSection (&thread->handle_lock);
+  thread->result = NULL; /* just to be deterministic */
+  thread->func = func;
+  thread->arg = arg;
+
+  {
+    unsigned int thread_id;
+    HANDLE thread_handle;
+
+    thread_handle = (HANDLE)
+      _beginthreadex (NULL, 100000, wrapper_func, thread, 0, &thread_id);
+      /* calls CreateThread with the same arguments */
+    if (thread_handle == NULL)
+      {
+	DeleteCriticalSection (&thread->handle_lock);
+	free (thread);
+	return EAGAIN;
+      }
+
+    EnterCriticalSection (&thread->handle_lock);
+    if (thread->handle == NULL)
+      thread->handle = thread_handle;
+    else
+      /* thread->handle was already set by the thread itself.  */
+      CloseHandle (thread_handle);
+    LeaveCriticalSection (&thread->handle_lock);
+
+    *threadp = thread;
+    return 0;
+  }
+}
+
+int
+glthread_join_func (gl_thread_t thread, void **retvalp)
+{
+  if (thread == NULL)
+    return EINVAL;
+
+  if (thread == gl_thread_self ())
+    return EDEADLK;
+
+  if (WaitForSingleObject (thread->handle, INFINITE) == WAIT_FAILED)
+    return EINVAL;
+
+  if (retvalp != NULL)
+    *retvalp = thread->result;
+
+  DeleteCriticalSection (&thread->handle_lock);
+  CloseHandle (thread->handle);
+  free (thread);
+
+  return 0;
+}
+
+int
+gl_thread_exit_func (void *retval)
+{
+  gl_thread_t thread = gl_thread_self ();
+  thread->result = retval;
+  _endthreadex (0); /* calls ExitThread (0) */
+  abort ();
+}
+
+#endif
+
+/* ========================================================================= */
diff --git a/lib/glthread/thread.h b/lib/glthread/thread.h
new file mode 100644
index 0000000..c47a82e
--- /dev/null
+++ b/lib/glthread/thread.h
@@ -0,0 +1,376 @@
+/* Creating and controlling threads.
+   Copyright (C) 2005-2008 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2005.
+   Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-solaris.h,
+   gthr-win32.h.  */
+
+/* This file contains primitives for creating and controlling threads.
+
+   Thread data type: gl_thread_t.
+
+   Creating a thread:
+       thread = gl_thread_create (func, arg);
+   Or with control of error handling:
+       err = glthread_create (&thread, func, arg);
+       extern int glthread_create (gl_thread_t *result,
+                                   void *(*func) (void *), void *arg);
+
+   Querying and changing the signal mask of a thread (not supported on all
+   platforms):
+       gl_thread_sigmask (how, newmask, oldmask);
+   Or with control of error handling:
+       err = glthread_sigmask (how, newmask, oldmask);
+       extern int glthread_sigmask (int how, const sigset_t *newmask, sigset_t *oldmask);
+
+   Waiting for termination of another thread:
+       gl_thread_join (thread, &return_value);
+   Or with control of error handling:
+       err = glthread_join (thread, &return_value);
+       extern int glthread_join (gl_thread_t thread, void **return_value_ptr);
+
+   Getting a reference to the current thread:
+       current = gl_thread_self ();
+       extern gl_thread_t gl_thread_self (void);
+
+   Terminating the current thread:
+       gl_thread_exit (return_value);
+       extern void gl_thread_exit (void *return_value) __attribute__ ((noreturn));
+
+   Requesting custom code to be executed at fork() time(not supported on all
+   platforms):
+       gl_thread_atfork (prepare_func, parent_func, child_func);
+   Or with control of error handling:
+       err = glthread_atfork (prepare_func, parent_func, child_func);
+       extern int glthread_atfork (void (*prepare_func) (void),
+                                   void (*parent_func) (void),
+                                   void (*child_func) (void));
+   Note that even on platforms where this is supported, use of fork() and
+   threads together is problematic, see
+     <http://lists.gnu.org/archive/html/bug-gnulib/2008-08/msg00062.html>
+ */
+
+
+#ifndef _GLTHREAD_THREAD_H
+#define _GLTHREAD_THREAD_H
+
+#include <errno.h>
+#include <stdlib.h>
+
+/* ========================================================================= */
+
+#if USE_POSIX_THREADS
+
+/* Use the POSIX threads library.  */
+
+# include <pthread.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+# if PTHREAD_IN_USE_DETECTION_HARD
+
+/* The pthread_in_use() detection needs to be done at runtime.  */
+#  define pthread_in_use() \
+     glthread_in_use ()
+extern int glthread_in_use (void);
+
+# endif
+
+# if USE_POSIX_THREADS_WEAK
+
+/* Use weak references to the POSIX threads library.  */
+
+/* Weak references avoid dragging in external libraries if the other parts
+   of the program don't use them.  Here we use them, because we don't want
+   every program that uses libintl to depend on libpthread.  This assumes
+   that libpthread would not be loaded after libintl; i.e. if libintl is
+   loaded first, by an executable that does not depend on libpthread, and
+   then a module is dynamically loaded that depends on libpthread, libintl
+   will not be multithread-safe.  */
+
+/* The way to test at runtime whether libpthread is present is to test
+   whether a function pointer's value, such as &pthread_mutex_init, is
+   non-NULL.  However, some versions of GCC have a bug through which, in
+   PIC mode, &foo != NULL always evaluates to true if there is a direct
+   call to foo(...) in the same function.  To avoid this, we test the
+   address of a function in libpthread that we don't use.  */
+
+#  pragma weak pthread_create
+#  pragma weak pthread_sigmask
+#  pragma weak pthread_join
+#  ifndef pthread_self
+#   pragma weak pthread_self
+#  endif
+#  pragma weak pthread_exit
+#  if HAVE_PTHREAD_ATFORK
+#   pragma weak pthread_atfork
+#  endif
+
+#  if !PTHREAD_IN_USE_DETECTION_HARD
+#   pragma weak pthread_cancel
+#   define pthread_in_use() (pthread_cancel != NULL)
+#  endif
+
+# else
+
+#  if !PTHREAD_IN_USE_DETECTION_HARD
+#   define pthread_in_use() 1
+#  endif
+
+# endif
+
+/* -------------------------- gl_thread_t datatype -------------------------- */
+
+/* This choice of gl_thread_t assumes that
+     pthread_equal (a, b)  is equivalent to  ((a) == (b)).
+   This is the case on all platforms in use in 2008.  */
+typedef pthread_t gl_thread_t;
+# define glthread_create(THREADP, FUNC, ARG) \
+    (pthread_in_use () ? pthread_create (THREADP, NULL, FUNC, ARG) : ENOSYS)
+# define glthread_sigmask(HOW, SET, OSET) \
+    (pthread_in_use () ? pthread_sigmask (HOW, SET, OSET) : 0)
+# define glthread_join(THREAD, RETVALP) \
+    (pthread_in_use () ? pthread_join (THREAD, RETVALP) : 0)
+# define gl_thread_self() \
+    (pthread_in_use () ? (void *) pthread_self () : NULL)
+# define gl_thread_exit(RETVAL) \
+    (pthread_in_use () ? pthread_exit (RETVAL) : 0)
+
+# if HAVE_PTHREAD_ATFORK
+#  define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) \
+     (pthread_in_use () ? pthread_atfork (PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) : 0)
+# else
+#  define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
+# endif
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_PTH_THREADS
+
+/* Use the GNU Pth threads library.  */
+
+# include <pth.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+# if USE_PTH_THREADS_WEAK
+
+/* Use weak references to the GNU Pth threads library.  */
+
+#  pragma weak pth_spawn
+#  pragma weak pth_sigmask
+#  pragma weak pth_join
+#  pragma weak pth_self
+#  pragma weak pth_exit
+
+#  pragma weak pth_cancel
+#  define pth_in_use() (pth_cancel != NULL)
+
+# else
+
+#  define pth_in_use() 1
+
+# endif
+/* -------------------------- gl_thread_t datatype -------------------------- */
+
+typedef pth_t gl_thread_t;
+# define glthread_create(THREADP, FUNC, ARG) \
+    (pth_in_use () ? ((*(THREADP) = pth_spawn (NULL, FUNC, ARG)) ? 0 : errno) : 0)
+# define glthread_sigmask(HOW, SET, OSET) \
+    (pth_in_use () && !pth_sigmask (HOW, SET, OSET) ? errno : 0)
+# define glthread_join(THREAD, RETVALP) \
+    (pth_in_use () && !pth_join (THREAD, RETVALP) ? errno : 0)
+# define gl_thread_self() \
+    (pth_in_use () ? (void *) pth_self () : 0)
+# define gl_thread_exit(RETVAL) \
+    (pth_in_use () ? pth_exit (RETVAL) : 0)
+# define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_SOLARIS_THREADS
+
+/* Use the old Solaris threads library.  */
+
+# include <thread.h>
+# include <synch.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+# if USE_SOLARIS_THREADS_WEAK
+
+/* Use weak references to the old Solaris threads library.  */
+
+#  pragma weak thr_create
+#  pragma weak thr_join
+#  pragma weak thr_self
+#  pragma weak thr_exit
+
+#  pragma weak thr_suspend
+#  define thread_in_use() (thr_suspend != NULL)
+
+# else
+
+#  define thread_in_use() 1
+
+# endif
+
+/* -------------------------- gl_thread_t datatype -------------------------- */
+
+typedef thread_t gl_thread_t;
+# define glthread_create(THREADP, FUNC, ARG) \
+    (thread_in_use () ? thr_create (NULL, 0, FUNC, ARG, 0, THREADP) : 0)
+# define glthread_sigmask(HOW, SET, OSET) \
+    (thread_in_use () ? sigprocmask (HOW, SET, OSET) : 0)
+# define glthread_join(THREAD, RETVALP) \
+    (thread_in_use () ? thr_join (THREAD, NULL, RETVALP) : 0)
+# define gl_thread_self() \
+    (thread_in_use () ? (void *) thr_self () : 0)
+# define gl_thread_exit(RETVAL) \
+    (thread_in_use () ? thr_exit (RETVAL) : 0)
+# define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_WIN32_THREADS
+
+# include <windows.h>
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+/* -------------------------- gl_thread_t datatype -------------------------- */
+
+/* The gl_thread_t is a pointer to a structure in memory.
+   Why not the thread handle?  If it were the thread handle, it would be hard
+   to implement gl_thread_self() (since GetCurrentThread () returns a pseudo-
+   handle, DuplicateHandle (GetCurrentThread ()) returns a handle that must be
+   closed afterwards, and there is no function for quickly retrieving a thread
+   handle from its id).
+   Why not the thread id?  I tried it.  It did not work: Sometimes ids appeared
+   that did not belong to running threads, and glthread_join failed with ESRCH.
+ */
+typedef struct gl_thread_struct *gl_thread_t;
+# define glthread_create(THREADP, FUNC, ARG) \
+    glthread_create_func (THREADP, FUNC, ARG)
+# define glthread_sigmask(HOW, SET, OSET) \
+    /* unsupported */ 0
+# define glthread_join(THREAD, RETVALP) \
+    glthread_join_func (THREAD, RETVALP)
+# define gl_thread_self() \
+    gl_thread_self_func ()
+# define gl_thread_exit(RETVAL) \
+    gl_thread_exit_func (RETVAL)
+# define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
+extern int glthread_create_func (gl_thread_t *threadp, void * (*func) (void *), void *arg);
+extern int glthread_join_func (gl_thread_t thread, void **retvalp);
+extern gl_thread_t gl_thread_self_func (void);
+extern int gl_thread_exit_func (void *retval);
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif
+
+/* ========================================================================= */
+
+#if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_SOLARIS_THREADS || USE_WIN32_THREADS)
+
+/* Provide dummy implementation if threads are not supported.  */
+
+typedef int gl_thread_t;
+# define glthread_create(THREADP, FUNC, ARG) ENOSYS
+# define glthread_sigmask(HOW, SET, OSET) 0
+# define glthread_join(THREAD, RETVALP) 0
+# define gl_thread_self() NULL
+# define gl_thread_exit(RETVAL) 0
+# define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
+
+#endif
+
+/* ========================================================================= */
+
+/* Macros with built-in error handling.  */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+static inline gl_thread_t
+gl_thread_create (void *(*func) (void *arg), void *arg)
+{
+  gl_thread_t thread;
+  int ret;
+
+  ret = glthread_create (&thread, func, arg);
+  if (ret != 0)
+    abort ();
+  return thread;
+}
+#define gl_thread_sigmask(HOW, SET, OSET)     \
+   do                                         \
+     {                                        \
+       if (glthread_sigmask (HOW, SET, OSET)) \
+         abort ();                            \
+     }                                        \
+   while (0)
+#define gl_thread_join(THREAD, RETVAL)     \
+   do                                      \
+     {                                     \
+       if (glthread_join (THREAD, RETVAL)) \
+         abort ();                         \
+     }                                     \
+   while (0)
+#define gl_thread_atfork(PREPARE, PARENT, CHILD)     \
+   do                                                \
+     {                                               \
+       if (glthread_atfork (PREPARE, PARENT, CHILD)) \
+         abort ();                                   \
+     }                                               \
+   while (0)
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _GLTHREAD_THREAD_H */
diff --git a/lib/glthread/threadlib.c b/lib/glthread/threadlib.c
new file mode 100644
index 0000000..5feb304
--- /dev/null
+++ b/lib/glthread/threadlib.c
@@ -0,0 +1,74 @@
+/* Multithreading primitives.
+   Copyright (C) 2005-2009 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2005.  */
+
+#include <config.h>
+
+/* ========================================================================= */
+
+#if USE_POSIX_THREADS
+
+/* Use the POSIX threads library.  */
+
+# include <pthread.h>
+# include <stdlib.h>
+
+# if PTHREAD_IN_USE_DETECTION_HARD
+
+/* The function to be executed by a dummy thread.  */
+static void *
+dummy_thread_func (void *arg)
+{
+  return arg;
+}
+
+int
+glthread_in_use (void)
+{
+  static int tested;
+  static int result; /* 1: linked with -lpthread, 0: only with libc */
+
+  if (!tested)
+    {
+      pthread_t thread;
+
+      if (pthread_create (&thread, NULL, dummy_thread_func, NULL) != 0)
+	/* Thread creation failed.  */
+	result = 0;
+      else
+	{
+	  /* Thread creation works.  */
+	  void *retval;
+	  if (pthread_join (thread, &retval) != 0)
+	    abort ();
+	  result = 1;
+	}
+      tested = 1;
+    }
+  return result;
+}
+
+# endif
+
+#endif
+
+/* ========================================================================= */
+
+/* This declaration is solely to ensure that after preprocessing
+   this file is never empty.  */
+typedef int dummy;