pthread_mutex_timedlock: New module.

* lib/pthread.in.h (pthread_mutex_timedlock): New dummy function and
new declaration.
* lib/pthread_mutex_timedlock.c: New file.
* m4/pthread_mutex_timedlock.m4: New file.
* m4/pthread.m4 (gl_PTHREAD_CHECK): Don't call AC_LIBOBJ here. Test
whether pthread_mutex_timedlock is declared.
(gl_PTHREAD_MODULE_INDICATOR): New macro.
(gl_PTHREAD_DEFAULTS): Initialize GNULIB_PTHREAD_MUTEX_TIMEDLOCK,
HAVE_PTHREAD_MUTEX_TIMEDLOCK.
* modules/pthread (configure.ac): Call AC_LIBOBJ here.
(Makefile.am): Substitute GNULIB_PTHREAD_MUTEX_TIMEDLOCK,
HAVE_PTHREAD_MUTEX_TIMEDLOCK.
* modules/pthread_mutex_timedlock: New file.
* doc/posix-functions/pthread_mutex_timedlock.texi: Mention the new
module.

8 files changed, 207 insertions, 13 deletions

diff --git a/ChangeLog b/ChangeLog
index a9fe91ef8f..d9afc4efb8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,24 @@
 2019-06-20  Bruno Haible  <bruno@clisp.org>
 
+	pthread_mutex_timedlock: New module.
+	* lib/pthread.in.h (pthread_mutex_timedlock): New dummy function and
+	new declaration.
+	* lib/pthread_mutex_timedlock.c: New file.
+	* m4/pthread_mutex_timedlock.m4: New file.
+	* m4/pthread.m4 (gl_PTHREAD_CHECK): Don't call AC_LIBOBJ here. Test
+	whether pthread_mutex_timedlock is declared.
+	(gl_PTHREAD_MODULE_INDICATOR): New macro.
+	(gl_PTHREAD_DEFAULTS): Initialize GNULIB_PTHREAD_MUTEX_TIMEDLOCK,
+	HAVE_PTHREAD_MUTEX_TIMEDLOCK.
+	* modules/pthread (configure.ac): Call AC_LIBOBJ here.
+	(Makefile.am): Substitute GNULIB_PTHREAD_MUTEX_TIMEDLOCK,
+	HAVE_PTHREAD_MUTEX_TIMEDLOCK.
+	* modules/pthread_mutex_timedlock: New file.
+	* doc/posix-functions/pthread_mutex_timedlock.texi: Mention the new
+	module.
+
+2019-06-20  Bruno Haible  <bruno@clisp.org>
+
 	thread, lock, cond, tls: Recognize C11 multithreaded applications.
 	* m4/threadlib.m4 (gl_THREADLIB_BODY): Test for <threads.h>.
 	* lib/glthread/thread.h (c11_threads_in_use): New macro.
diff --git a/doc/posix-functions/pthread_mutex_timedlock.texi b/doc/posix-functions/pthread_mutex_timedlock.texi
index 888b310a0c..aaa76eb2c9 100644
--- a/doc/posix-functions/pthread_mutex_timedlock.texi
+++ b/doc/posix-functions/pthread_mutex_timedlock.texi
@@ -4,15 +4,17 @@
 
 POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/pthread_mutex_timedlock.html}
 
-Gnulib module: ---
+Gnulib module: pthread_mutex_timedlock
 
 Portability problems fixed by Gnulib:
 @itemize
+@item
+This function is missing on some platforms:
+Mac OS X 10.5, FreeBSD 5.2.1, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 9, Cygwin, mingw, MSVC 14, BeOS, Android 4.4.
+But the provided replacement is just a dummy on some of these platforms:
+Minix 3.1.8, HP-UX 11, IRIX 5.3, Solaris 2.4, mingw, MSVC 14, BeOS.
 @end itemize
 
 Portability problems not fixed by Gnulib:
 @itemize
-@item
-This function is missing on some platforms:
-Mac OS X 10.5, FreeBSD 5.2.1, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 9, Cygwin, mingw, MSVC 14, BeOS, Android 4.4.
 @end itemize
diff --git a/lib/pthread.in.h b/lib/pthread.in.h
index 1deef7dcf4..cd3cf1fd03 100644
--- a/lib/pthread.in.h
+++ b/lib/pthread.in.h
@@ -252,6 +252,14 @@ pthread_mutex_trylock (pthread_mutex_t *mutex)
 }
 
 _GL_PTHREAD_INLINE int
+pthread_mutex_timedlock (pthread_mutex_t *mutex, const struct timespec *abstime)
+{
+  /* There is only one thread, so it always gets the lock.  This
+     implementation does not support PTHREAD_MUTEX_ERRORCHECK.  */
+  return 0;
+}
+
+_GL_PTHREAD_INLINE int
 pthread_mutex_unlock (pthread_mutex_t *mutex)
 {
   /* There is only one thread, so it always unlocks successfully.
@@ -263,6 +271,24 @@ pthread_mutex_unlock (pthread_mutex_t *mutex)
 #  define GNULIB_defined_pthread_functions 1
 # endif
 
+#else
+
+# if @GNULIB_PTHREAD_MUTEX_TIMEDLOCK@
+#  if !@HAVE_PTHREAD_MUTEX_TIMEDLOCK@
+_GL_FUNCDECL_SYS (pthread_mutex_timedlock, int,
+                  (pthread_mutex_t *, const struct timespec *));
+#  endif
+_GL_CXXALIAS_SYS (pthread_mutex_timedlock, int,
+                  (pthread_mutex_t *, const struct timespec *));
+_GL_CXXALIASWARN (pthread_mutex_timedlock);
+# elif defined GNULIB_POSIXCHECK
+#  undef pthread_mutex_timedlock
+#  if HAVE_RAW_DECL_PTHREAD_MUTEX_TIMEDLOCK
+_GL_WARN_ON_USE (pthread_mutex_timedlock, "pthread_mutex_timedlock is unportable - "
+                 "use gnulib module pthread_mutex_timedlock for portability");
+#  endif
+# endif
+
 #endif
 
 #if ! @HAVE_PTHREAD_SPINLOCK_T@
diff --git a/lib/pthread_mutex_timedlock.c b/lib/pthread_mutex_timedlock.c
new file mode 100644
index 0000000000..9b6bc6355c
--- /dev/null
+++ b/lib/pthread_mutex_timedlock.c
@@ -0,0 +1,87 @@
+/* Lock a mutex, abandoning after a certain time.
+   Copyright (C) 2019 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 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <pthread.h>
+
+#include <errno.h>
+#include <limits.h>
+#include <sys/time.h>
+#include <time.h>
+
+int
+pthread_mutex_timedlock (pthread_mutex_t *mutex, const struct timespec *abstime)
+{
+  /* Poll the mutex's state in regular intervals.  Ugh.  */
+  /* POSIX says:
+      "Under no circumstance shall the function fail with a timeout if
+       the mutex can be locked immediately. The validity of the abstime
+       parameter need not be checked if the mutex can be locked
+       immediately."
+     Therefore start the loop with a pthread_mutex_trylock call.  */
+  for (;;)
+    {
+      int err;
+      struct timeval currtime;
+      unsigned long remaining;
+      struct timespec duration;
+
+      err = pthread_mutex_trylock (mutex);
+      if (err != EBUSY)
+        return err;
+
+      gettimeofday (&currtime, NULL);
+
+      if (currtime.tv_sec > abstime->tv_sec)
+        remaining = 0;
+      else
+        {
+          unsigned long seconds = abstime->tv_sec - currtime.tv_sec;
+          remaining = seconds * 1000000000;
+          if (remaining / 1000000000 != seconds) /* overflow? */
+            remaining = ULONG_MAX;
+          else
+            {
+              long nanoseconds =
+                abstime->tv_nsec - currtime.tv_usec * 1000;
+              if (nanoseconds >= 0)
+                {
+                  remaining += nanoseconds;
+                  if (remaining < nanoseconds) /* overflow? */
+                    remaining = ULONG_MAX;
+                }
+              else
+                {
+                  if (remaining >= - nanoseconds)
+                    remaining -= (- nanoseconds);
+                  else
+                    remaining = 0;
+                }
+            }
+        }
+      if (remaining == 0)
+        return ETIMEDOUT;
+
+      /* Sleep 1 ms.  */
+      duration.tv_sec = 0;
+      duration.tv_nsec = 1000000;
+      if (duration.tv_nsec > remaining)
+        duration.tv_nsec = remaining;
+      nanosleep (&duration, NULL);
+    }
+}
diff --git a/m4/pthread.m4 b/m4/pthread.m4
index 0a219d7389..bccac96206 100644
--- a/m4/pthread.m4
+++ b/m4/pthread.m4
@@ -1,4 +1,4 @@
-# pthread.m4 serial 10
+# pthread.m4 serial 11
 dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -39,19 +39,22 @@ AC_DEFUN([gl_PTHREAD_CHECK],
      HAVE_PTHREAD_SPINLOCK_T=0
    fi
 
-   if test $ac_cv_header_pthread_h != yes ||
-      test $ac_cv_type_pthread_t != yes ||
-      test $ac_cv_type_pthread_spinlock_t != yes; then
+   if test $HAVE_PTHREAD_H = 0 || test $HAVE_PTHREAD_T = 0 || test $HAVE_PTHREAD_SPINLOCK_T = 0; then
      PTHREAD_H='pthread.h'
-     AC_LIBOBJ([pthread])
    elif test $gl_cv_header_pthread_h_pollution = yes; then
-     PTHREAD_H=pthread.h
+     PTHREAD_H='pthread.h'
    else
      PTHREAD_H=
    fi
    AC_SUBST([PTHREAD_H])
    AM_CONDITIONAL([GL_GENERATE_PTHREAD_H], [test -n "$PTHREAD_H"])
 
+   dnl Check for declarations of anything we want to poison if the
+   dnl corresponding gnulib module is not in use, if it is not common
+   dnl enough to be declared everywhere.
+   gl_WARN_ON_USE_PREPARE([[#include <pthread.h>
+     ]], [pthread_mutex_timedlock])
+
    LIB_PTHREAD=
    if test $ac_cv_header_pthread_h = yes; then
      dnl We cannot use AC_SEARCH_LIBS here, because on OSF/1 5.1 pthread_join
@@ -91,10 +94,21 @@ AC_DEFUN([gl_PTHREAD_CHECK],
    AC_REQUIRE([AC_C_RESTRICT])
 ])
 
+AC_DEFUN([gl_PTHREAD_MODULE_INDICATOR],
+[
+  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
+  AC_REQUIRE([gl_PTHREAD_DEFAULTS])
+  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
+  dnl Define it also as a C macro, for the benefit of the unit tests.
+  gl_MODULE_INDICATOR_FOR_TESTS([$1])
+])
+
 AC_DEFUN([gl_PTHREAD_DEFAULTS],
 [
+  GNULIB_PTHREAD_MUTEX_TIMEDLOCK=0; AC_SUBST([GNULIB_PTHREAD_MUTEX_TIMEDLOCK])
   dnl Assume proper GNU behavior unless another module says otherwise.
-  HAVE_PTHREAD_H=1;              AC_SUBST([HAVE_PTHREAD_H])
-  HAVE_PTHREAD_T=1;              AC_SUBST([HAVE_PTHREAD_T])
-  HAVE_PTHREAD_SPINLOCK_T=1;     AC_SUBST([HAVE_PTHREAD_SPINLOCK_T])
+  HAVE_PTHREAD_H=1;                 AC_SUBST([HAVE_PTHREAD_H])
+  HAVE_PTHREAD_T=1;                 AC_SUBST([HAVE_PTHREAD_T])
+  HAVE_PTHREAD_SPINLOCK_T=1;        AC_SUBST([HAVE_PTHREAD_SPINLOCK_T])
+  HAVE_PTHREAD_MUTEX_TIMEDLOCK=1;   AC_SUBST([HAVE_PTHREAD_MUTEX_TIMEDLOCK])
 ])
diff --git a/m4/pthread_mutex_timedlock.m4 b/m4/pthread_mutex_timedlock.m4
new file mode 100644
index 0000000000..664670f2bb
--- /dev/null
+++ b/m4/pthread_mutex_timedlock.m4
@@ -0,0 +1,13 @@
+# pthread_mutex_timedlock.m4 serial 1
+dnl Copyright (C) 2019 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_PTHREAD_MUTEX_TIMEDLOCK],
+[
+  AC_REQUIRE([gl_PTHREAD_DEFAULTS])
+
+  AC_CHECK_DECL([pthread_mutex_timedlock], , [HAVE_PTHREAD_MUTEX_TIMEDLOCK=0],
+    [[#include <pthread.h>]])
+])
diff --git a/modules/pthread b/modules/pthread
index 3fb39208ab..81e2aad384 100644
--- a/modules/pthread
+++ b/modules/pthread
@@ -18,6 +18,9 @@ AC_DEFINE([_THREAD_SAFE], 1, [For thread-safety on AIX, FreeBSD.])
 
 configure.ac:
 gl_PTHREAD_CHECK
+if test $HAVE_PTHREAD_H = 0 || test $HAVE_PTHREAD_T = 0 || test $HAVE_PTHREAD_SPINLOCK_T = 0; then
+  AC_LIBOBJ([pthread])
+fi
 gl_MODULE_INDICATOR([pthread])
 
 Makefile.am:
@@ -35,8 +38,10 @@ pthread.h: pthread.in.h $(top_builddir)/config.status
 	      -e 's|@''PRAGMA_SYSTEM_HEADER''@|@PRAGMA_SYSTEM_HEADER@|g' \
 	      -e 's|@''PRAGMA_COLUMNS''@|@PRAGMA_COLUMNS@|g' \
 	      -e 's|@''NEXT_PTHREAD_H''@|$(NEXT_PTHREAD_H)|g' \
+	      -e 's/@''GNULIB_PTHREAD_MUTEX_TIMEDLOCK''@/$(GNULIB_PTHREAD_MUTEX_TIMEDLOCK)/g' \
 	      -e 's|@''HAVE_PTHREAD_T''@|$(HAVE_PTHREAD_T)|g' \
 	      -e 's|@''HAVE_PTHREAD_SPINLOCK_T''@|$(HAVE_PTHREAD_SPINLOCK_T)|g' \
+	      -e 's|@''HAVE_PTHREAD_MUTEX_TIMEDLOCK''@|$(HAVE_PTHREAD_MUTEX_TIMEDLOCK)|g' \
 	      < $(srcdir)/pthread.in.h; \
 	} > $@-t && \
 	mv $@-t $@
diff --git a/modules/pthread_mutex_timedlock b/modules/pthread_mutex_timedlock
new file mode 100644
index 0000000000..2ae39f497e
--- /dev/null
+++ b/modules/pthread_mutex_timedlock
@@ -0,0 +1,28 @@
+Description:
+Lock a mutex, abandoning after a certain time.
+
+Files:
+lib/pthread_mutex_timedlock.c
+m4/pthread_mutex_timedlock.m4
+
+Depends-on:
+pthread
+nanosleep       [test $HAVE_PTHREAD_T = 1 && test $HAVE_PTHREAD_MUTEX_TIMEDLOCK = 0]
+
+configure.ac:
+gl_FUNC_PTHREAD_MUTEX_TIMEDLOCK
+if test $HAVE_PTHREAD_T = 1 && test $HAVE_PTHREAD_MUTEX_TIMEDLOCK = 0; then
+  AC_LIBOBJ([pthread_mutex_timedlock])
+fi
+gl_PTHREAD_MODULE_INDICATOR([pthread_mutex_timedlock])
+
+Makefile.am:
+
+Include:
+<pthread.h>
+
+License:
+LGPLv2+
+
+Maintainer:
+all