--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2011-07-07  Bruno Haible  <bruno@clisp.org>
+
+	pthread_sigmask: Fix return value.
+	* lib/signal.in.h (pthread_sigmask): Declare. Don't define as a macro.
+	* lib/pthread_sigmask.c: New file.
+	* modules/pthread_sigmask (Files): Add it.
+	(configure.ac): Invoke AC_LIBOBJ.
+
 2011-07-07  Eric Blake  <eblake@redhat.com>
 
 	getopt: more portable argv creation

new file mode 100644
--- /dev/null
+++ b/lib/pthread_sigmask.c
@@ -0,0 +1,29 @@
+/* POSIX compatible signal blocking for threads.
+   Copyright (C) 2011 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 <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <signal.h>
+
+#include <errno.h>
+
+int
+pthread_sigmask (int how, const sigset_t *new_mask, sigset_t *old_mask)
+{
+  int ret = sigprocmask (how, new_mask, old_mask);
+  return (ret < 0 ? errno : 0);
+}

--- a/lib/signal.in.h
+++ b/lib/signal.in.h
@@ -104,8 +104,8 @@
 
 #if @GNULIB_PTHREAD_SIGMASK@
 # if @REPLACE_PTHREAD_SIGMASK@
-#  undef pthread_sigmask
-#  define pthread_sigmask sigprocmask
+_GL_FUNCDECL_SYS (pthread_sigmask, int,
+                  (int how, const sigset_t *new_mask, sigset_t *old_mask));
 # endif
 #elif defined GNULIB_POSIXCHECK
 # undef pthread_sigmask

--- a/modules/pthread_sigmask
+++ b/modules/pthread_sigmask
@@ -2,6 +2,7 @@
 POSIX compatible signal blocking for threads.
 
 Files:
+lib/pthread_sigmask.c
 m4/pthread_sigmask.m4
 
 Depends-on:
@@ -10,6 +11,9 @@
 
 configure.ac:
 gl_PTHREAD_SIGMASK
+if test $REPLACE_PTHREAD_SIGMASK = 1; then
+  AC_LIBOBJ([pthread_sigmask])
+fi
 gl_SIGNAL_MODULE_INDICATOR([pthread_sigmask])
 
 Makefile.am: