Add gpgrt_lock_ functions.

* src/gpg-error.h.in (GPGRT_LOCK_DEFINE): New.
(gpgrt_lock_init): New.
(gpgrt_lock_lock): New.
(gpgrt_lock_unlock): New.
(gpgrt_lock_destroy): New.
(gpgrt_yield): New.
* src/gpg-error.def.in: Add new functions.
* m4/lock.m4, m4/threadlib.m4: New. Taken from current gnulib.
* configure.ac: Call gl_LOCK.  Check size of pthread_mutex_t. Add
LIBTHREAD to GPG_ERROR_CONFIG_LIBS.
* src/err-codes.h.in (GPG_ERR_INV_LOCK_OBJ): New.
* src/gen-posix-lock-obj.c: New.
* src/gen-w32-lock-obj.c: New.
* src/lock.h, src/thread.h: New.
* src/posix-lock-obj.h, src/w32-lock-obj.h: New.
* src/posix-lock.c, src/w32-lock.c: New.
* src/posix-thread.c, src/w32-thread.c:
* src/w32-lock-obj-pub.in: New.
* src/mkheader.c (include_file): Support build time include files.
(write_special): Add keyword "include:lock-obj".
* src/Makefile.am:
(posix-lock-obj-pub.in): New rule.
(noinst_PROGRAMS): Add gen-*-lock-obj helpers.

* tests/t-common.h: New.
* tests/t-lock.c: New.
* tests/Makefile.am (t_lock_LDADD): Add new test.

--

This patch introduces the gpgrt_ functions which will be extended over
time to provide a library of commonly used code in GnuPG and
Libgcrypt.  Having them in a library named libgpg-error is a misnomer
but this way we can achieve a smooth upgrade path.

In contrasts to other GnuPG libraries, the gpgrt_ functions return a
simple gpg_err_code_t and not gpg_error_t.  The rationale for this is
that a source of error identifier does not make sense here; it is
better to use the source of error identifier of the caller.  This can
easily be achieved in a component by wrapping these function in a
gpg_error macro/inline.

There is no cross-compiling support for Posix platforms; the
gen-posix-lock-obj tool must be run on the target system.

Note that the gen-w32-lock-obj tool is not needed at build time but
was used to figure out ABI definitions for Windows.

Signed-off-by: Werner Koch <[email protected]>

24 files changed, 1665 insertions, 298 deletions

diff --git a/NEWS b/NEWS
index 2600b4e..c7f666b 100644
--- a/NEWS
+++ b/NEWS
@@ -1,9 +1,20 @@
 Noteworthy changes in version 1.13 (unreleased)
 -----------------------------------------------
 
- * Interface changes relative to the 1.11 release:
+ Add a portable mutex API.
+
+ * Interface changes relative to the 1.12 release:
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  GPG_ERR_MAC_ALGO             NEW.
+ GPG_ERR_INV_LOCK_OBJ         NEW.
+ gpgrt_lock_t                 NEW.
+ GPGRT_LOCK_INITIALIZER       NEW.
+ GPGRT_LOCK_DEFINE            NEW.
+ gpgrt_lock_init              NEW.
+ gpgrt_lock_lock              NEW.
+ gpgrt_lock_unlock            NEW.
+ gpgrt_lock_destroy           NEW.
+ gpgrt_yield                  NEW.
 
 
 Noteworthy changes in version 1.12 (2013-06-24)
diff --git a/configure.ac b/configure.ac
index 73de716..3d1e12f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -85,6 +85,9 @@ AC_PROG_AWK
 AC_CHECK_TOOL(AR, ar, :)
 AC_GNU_SOURCE
 
+gl_THREADLIB_EARLY
+
+
 LT_PREREQ([2.2.6])
 LT_INIT([win32-dll disable-static])
 LT_LANG([Windows Resource])
@@ -156,11 +159,26 @@ AC_MSG_WARN([[Without strerror_r, gpg_strerror_r might not be thread-safe]]))
      ;;
 esac
 
+AC_CHECK_FUNCS([flockfile])
+
+
 # Checks for typedefs, structures, and compiler characteristics.
 AC_C_CONST
 
+
+# Check for thread library
+gl_LOCK
+if test "$gl_threads_api" = posix; then
+  AC_CHECK_SIZEOF(pthread_mutex_t,,[AC_INCLUDES_DEFAULT
+                                    #include <pthread.h>])
+fi
+
+
 # Substitution used for gpg-error-config
 GPG_ERROR_CONFIG_LIBS="-lgpg-error"
+if test "x$LIBTHREAD" != x; then
+  GPG_ERROR_CONFIG_LIBS="${GPG_ERROR_CONFIG_LIBS} ${LIBTHREAD}"
+fi
 GPG_ERROR_CONFIG_CFLAGS=""
 GPG_ERROR_CONFIG_ISUBDIRAFTER=""
 GPG_ERROR_CONFIG_HOST="$host"
diff --git a/m4/lock.m4 b/m4/lock.m4
index d1ea1ca..73a3c54 100644
--- a/m4/lock.m4
+++ b/m4/lock.m4
@@ -1,289 +1,42 @@
-# lock.m4 serial 2 (gettext-0.15)
-dnl Copyright (C) 2005 Free Software Foundation, Inc.
+# lock.m4 serial 13 (gettext-0.18.2)
+dnl Copyright (C) 2005-2014 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.
 
 dnl From Bruno Haible.
 
-dnl Tests for a multithreading library to be used.
-dnl Defines at most one of the macros USE_POSIX_THREADS, USE_SOLARIS_THREADS,
-dnl USE_PTH_THREADS, USE_WIN32_THREADS
-dnl Sets the variables LIBTHREAD and LTLIBTHREAD to the linker options for use
-dnl in a Makefile (LIBTHREAD for use without libtool, LTLIBTHREAD for use with
-dnl libtool).
-dnl Sets the variables LIBMULTITHREAD and LTLIBMULTITHREAD similarly, for
-dnl programs that really need multithread functionality. The difference
-dnl between LIBTHREAD and LIBMULTITHREAD is that on platforms supporting weak
-dnl symbols, typically LIBTHREAD="" whereas LIBMULTITHREAD="-lpthread".
-dnl Adds to CPPFLAGS the flag -D_REENTRANT or -D_THREAD_SAFE if needed for
-dnl multithread-safe programs.
-
 AC_DEFUN([gl_LOCK],
 [
-  AC_REQUIRE([gl_LOCK_BODY])
-])
-
-dnl The guts of gl_LOCK. Needs to be expanded only once.
-
-AC_DEFUN([gl_LOCK_BODY],
-[
-  dnl Ordering constraints: This macro modifies CPPFLAGS in a way that
-  dnl influences the result of the autoconf tests that test for *_unlocked
-  dnl declarations, on AIX 5 at least. Therefore it must come early.
-  AC_BEFORE([$0], [gl_FUNC_GLIBC_UNLOCKED_IO])dnl
-  AC_BEFORE([$0], [gl_ARGP])dnl
-
-  AC_REQUIRE([AC_CANONICAL_HOST])
-  AC_REQUIRE([AC_GNU_SOURCE]) dnl needed for pthread_rwlock_t on glibc systems
-  dnl Check for multithreading.
-  AC_ARG_ENABLE(threads,
-AC_HELP_STRING([--enable-threads={posix|solaris|pth|win32}], [specify multithreading API])
-AC_HELP_STRING([--disable-threads], [build without multithread safety]),
-    gl_use_threads=$enableval, gl_use_threads=yes)
-  gl_threads_api=none
-  LIBTHREAD=
-  LTLIBTHREAD=
-  LIBMULTITHREAD=
-  LTLIBMULTITHREAD=
-  if test "$gl_use_threads" != no; then
-    dnl Check whether the compiler and linker support weak declarations.
-    AC_MSG_CHECKING([whether imported symbols can be declared weak])
-    gl_have_weak=no
-    AC_TRY_LINK([extern void xyzzy ();
-#pragma weak xyzzy], [xyzzy();], [gl_have_weak=yes])
-    AC_MSG_RESULT([$gl_have_weak])
-    if test "$gl_use_threads" = yes || test "$gl_use_threads" = posix; then
-      # On OSF/1, the compiler needs the flag -pthread or -D_REENTRANT so that
-      # it groks <pthread.h>.
-      gl_save_CPPFLAGS="$CPPFLAGS"
-      CPPFLAGS="$CPPFLAGS -D_REENTRANT"
-      AC_CHECK_HEADER(pthread.h, gl_have_pthread_h=yes, gl_have_pthread_h=no)
-      CPPFLAGS="$gl_save_CPPFLAGS"
-      if test "$gl_have_pthread_h" = yes; then
-        # Other possible tests:
-        #   -lpthreads (FSU threads, PCthreads)
-        #   -lgthreads
-        case "$host_os" in
-          osf*)
-            # On OSF/1, the compiler needs the flag -D_REENTRANT so that it
-            # groks <pthread.h>. cc also understands the flag -pthread, but
-            # we don't use it because 1. gcc-2.95 doesn't understand -pthread,
-            # 2. putting a flag into CPPFLAGS that has an effect on the linker
-            # causes the AC_TRY_LINK test below to succeed unexpectedly,
-            # leading to wrong values of LIBTHREAD and LTLIBTHREAD.
-            CPPFLAGS="$CPPFLAGS -D_REENTRANT"
-            ;;
-        esac
-        gl_have_pthread=
-        # Test whether both pthread_mutex_lock and pthread_mutexattr_init exist
-        # in libc. IRIX 6.5 has the first one in both libc and libpthread, but
-        # the second one only in libpthread, and lock.c needs it.
-        AC_TRY_LINK([#include <pthread.h>],
-          [pthread_mutex_lock((pthread_mutex_t*)0);
-           pthread_mutexattr_init((pthread_mutexattr_t*)0);],
-          [gl_have_pthread=yes])
-        # Test for libpthread by looking for pthread_kill. (Not pthread_self,
-        # since it is defined as a macro on OSF/1.)
-        if test -n "$gl_have_pthread"; then
-          # The program links fine without libpthread. But it may actually
-          # need to link with libpthread in order to create multiple threads.
-          AC_CHECK_LIB(pthread, pthread_kill,
-            [LIBMULTITHREAD=-lpthread LTLIBMULTITHREAD=-lpthread
-             # On Solaris and HP-UX, most pthread functions exist also in libc.
-             # Therefore pthread_in_use() needs to actually try to create a
-             # thread: pthread_create from libc will fail, whereas
-             # pthread_create will actually create a thread.
-             case "$host_os" in
-               solaris* | hpux*)
-                 AC_DEFINE([PTHREAD_IN_USE_DETECTION_HARD], 1,
-                   [Define if the pthread_in_use() detection is hard.])
-             esac
-            ])
-        else
-          # Some library is needed. Try libpthread and libc_r.
-          AC_CHECK_LIB(pthread, pthread_kill,
-            [gl_have_pthread=yes
-             LIBTHREAD=-lpthread LTLIBTHREAD=-lpthread
-             LIBMULTITHREAD=-lpthread LTLIBMULTITHREAD=-lpthread])
-          if test -z "$gl_have_pthread"; then
-            # For FreeBSD 4.
-            AC_CHECK_LIB(c_r, pthread_kill,
-              [gl_have_pthread=yes
-               LIBTHREAD=-lc_r LTLIBTHREAD=-lc_r
-               LIBMULTITHREAD=-lc_r LTLIBMULTITHREAD=-lc_r])
-          fi
-        fi
-        if test -n "$gl_have_pthread"; then
-          gl_threads_api=posix
-          AC_DEFINE([USE_POSIX_THREADS], 1,
-            [Define if the POSIX multithreading library can be used.])
-          if test -n "$LIBMULTITHREAD" || test -n "$LTLIBMULTITHREAD"; then
-            if test $gl_have_weak = yes; then
-              AC_DEFINE([USE_POSIX_THREADS_WEAK], 1,
-                [Define if references to the POSIX multithreading library should be made weak.])
-              LIBTHREAD=
-              LTLIBTHREAD=
-            fi
-          fi
-          # OSF/1 4.0 and MacOS X 10.1 lack the pthread_rwlock_t type and the
-          # pthread_rwlock_* functions.
-          AC_CHECK_TYPE([pthread_rwlock_t],
-            [AC_DEFINE([HAVE_PTHREAD_RWLOCK], 1,
-               [Define if the POSIX multithreading library has read/write locks.])],
-            [],
-            [#include <pthread.h>])
-          # glibc defines PTHREAD_MUTEX_RECURSIVE as enum, not as a macro.
-          AC_TRY_COMPILE([#include <pthread.h>],
-            [#if __FreeBSD__ == 4
+  AC_REQUIRE([gl_THREADLIB])
+  if test "$gl_threads_api" = posix; then
+    # OSF/1 4.0 and Mac OS X 10.1 lack the pthread_rwlock_t type and the
+    # pthread_rwlock_* functions.
+    AC_CHECK_TYPE([pthread_rwlock_t],
+      [AC_DEFINE([HAVE_PTHREAD_RWLOCK], [1],
+         [Define if the POSIX multithreading library has read/write locks.])],
+      [],
+      [#include <pthread.h>])
+    # glibc defines PTHREAD_MUTEX_RECURSIVE as enum, not as a macro.
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM(
+        [[#include <pthread.h>]],
+        [[
+#if __FreeBSD__ == 4
 error "No, in FreeBSD 4.0 recursive mutexes actually don't work."
+#elif (defined __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ \
+       && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 1070)
+error "No, in Mac OS X < 10.7 recursive mutexes actually don't work."
 #else
 int x = (int)PTHREAD_MUTEX_RECURSIVE;
-#endif],
-            [AC_DEFINE([HAVE_PTHREAD_MUTEX_RECURSIVE], 1,
-               [Define if the <pthread.h> defines PTHREAD_MUTEX_RECURSIVE.])])
-          # Some systems optimize for single-threaded programs by default, and
-          # need special flags to disable these optimizations. For example, the
-          # definition of 'errno' in <errno.h>.
-          case "$host_os" in
-            aix* | freebsd*) CPPFLAGS="$CPPFLAGS -D_THREAD_SAFE" ;;
-            solaris*) CPPFLAGS="$CPPFLAGS -D_REENTRANT" ;;
-          esac
-        fi
-      fi
-    fi
-    if test -z "$gl_have_pthread"; then
-      if test "$gl_use_threads" = yes || test "$gl_use_threads" = solaris; then
-        gl_have_solaristhread=
-        gl_save_LIBS="$LIBS"
-        LIBS="$LIBS -lthread"
-        AC_TRY_LINK([#include <thread.h>
-#include <synch.h>],
-          [thr_self();],
-          [gl_have_solaristhread=yes])
-        LIBS="$gl_save_LIBS"
-        if test -n "$gl_have_solaristhread"; then
-          gl_threads_api=solaris
-          LIBTHREAD=-lthread
-          LTLIBTHREAD=-lthread
-          LIBMULTITHREAD="$LIBTHREAD"
-          LTLIBMULTITHREAD="$LTLIBTHREAD"
-          AC_DEFINE([USE_SOLARIS_THREADS], 1,
-            [Define if the old Solaris multithreading library can be used.])
-          if test $gl_have_weak = yes; then
-            AC_DEFINE([USE_SOLARIS_THREADS_WEAK], 1,
-              [Define if references to the old Solaris multithreading library should be made weak.])
-            LIBTHREAD=
-            LTLIBTHREAD=
-          fi
-        fi
-      fi
-    fi
-    if test "$gl_use_threads" = pth; then
-      gl_save_CPPFLAGS="$CPPFLAGS"
-      AC_LIB_LINKFLAGS(pth)
-      gl_have_pth=
-      gl_save_LIBS="$LIBS"
-      LIBS="$LIBS -lpth"
-      AC_TRY_LINK([#include <pth.h>], [pth_self();], gl_have_pth=yes)
-      LIBS="$gl_save_LIBS"
-      if test -n "$gl_have_pth"; then
-        gl_threads_api=pth
-        LIBTHREAD="$LIBPTH"
-        LTLIBTHREAD="$LTLIBPTH"
-        LIBMULTITHREAD="$LIBTHREAD"
-        LTLIBMULTITHREAD="$LTLIBTHREAD"
-        AC_DEFINE([USE_PTH_THREADS], 1,
-          [Define if the GNU Pth multithreading library can be used.])
-        if test -n "$LIBMULTITHREAD" || test -n "$LTLIBMULTITHREAD"; then
-          if test $gl_have_weak = yes; then
-            AC_DEFINE([USE_PTH_THREADS_WEAK], 1,
-              [Define if references to the GNU Pth multithreading library should be made weak.])
-            LIBTHREAD=
-            LTLIBTHREAD=
-          fi
-        fi
-      else
-        CPPFLAGS="$gl_save_CPPFLAGS"
-      fi
-    fi
-    if test -z "$gl_have_pthread"; then
-      if test "$gl_use_threads" = yes || test "$gl_use_threads" = win32; then
-        if { case "$host_os" in
-               mingw*) true;;
-               *) false;;
-             esac
-           }; then
-          gl_threads_api=win32
-          AC_DEFINE([USE_WIN32_THREADS], 1,
-            [Define if the Win32 multithreading API can be used.])
-        fi
-      fi
-    fi
+return !x;
+#endif
+        ]])],
+      [AC_DEFINE([HAVE_PTHREAD_MUTEX_RECURSIVE], [1],
+         [Define if the <pthread.h> defines PTHREAD_MUTEX_RECURSIVE.])])
   fi
-  AC_MSG_CHECKING([for multithread API to use])
-  AC_MSG_RESULT([$gl_threads_api])
-  AC_SUBST(LIBTHREAD)
-  AC_SUBST(LTLIBTHREAD)
-  AC_SUBST(LIBMULTITHREAD)
-  AC_SUBST(LTLIBMULTITHREAD)
   gl_PREREQ_LOCK
 ])
 
-# Prerequisites of lib/lock.c.
-AC_DEFUN([gl_PREREQ_LOCK], [
-  AC_REQUIRE([AC_C_INLINE])
-])
-
-dnl Survey of platforms:
-dnl
-dnl Platform          Available   Compiler    Supports   test-lock
-dnl                   flavours    option      weak       result
-dnl ---------------   ---------   ---------   --------   ---------
-dnl Linux 2.4/glibc   posix       -lpthread       Y      OK
-dnl
-dnl GNU Hurd/glibc    posix
-dnl
-dnl FreeBSD 5.3       posix       -lc_r           Y
-dnl                   posix       -lkse ?         Y
-dnl                   posix       -lpthread ?     Y
-dnl                   posix       -lthr           Y
-dnl
-dnl FreeBSD 5.2       posix       -lc_r           Y
-dnl                   posix       -lkse           Y
-dnl                   posix       -lthr           Y
-dnl
-dnl FreeBSD 4.0,4.10  posix       -lc_r           Y      OK
-dnl
-dnl NetBSD 1.6        --
-dnl
-dnl OpenBSD 3.4       posix       -lpthread       Y      OK
-dnl
-dnl MacOS X 10.[123]  posix       -lpthread       Y      OK
-dnl
-dnl Solaris 7,8,9     posix       -lpthread       Y      Sol 7,8: 0.0; Sol 9: OK
-dnl                   solaris     -lthread        Y      Sol 7,8: 0.0; Sol 9: OK
-dnl
-dnl HP-UX 11          posix       -lpthread       N (cc) OK
-dnl                                               Y (gcc)
-dnl
-dnl IRIX 6.5          posix       -lpthread       Y      0.5
-dnl
-dnl AIX 4.3,5.1       posix       -lpthread       N      AIX 4: 0.5; AIX 5: OK
-dnl
-dnl OSF/1 4.0,5.1     posix       -pthread (cc)   N      OK
-dnl                               -lpthread (gcc) Y
-dnl
-dnl Cygwin            posix       -lpthread       Y      OK
-dnl
-dnl Any of the above  pth         -lpth                  0.0
-dnl
-dnl Mingw             win32                       N      OK
-dnl
-dnl BeOS 5            --
-dnl
-dnl The test-lock result shows what happens if in test-lock.c EXPLICIT_YIELD is
-dnl turned off:
-dnl   OK if all three tests terminate OK,
-dnl   0.5 if the first test terminates OK but the second one loops endlessly,
-dnl   0.0 if the first test already loops endlessly.
+# Prerequisites of lib/glthread/lock.c.
+AC_DEFUN([gl_PREREQ_LOCK], [:])
diff --git a/m4/threadlib.m4 b/m4/threadlib.m4
new file mode 100644
index 0000000..a91e819
--- /dev/null
+++ b/m4/threadlib.m4
@@ -0,0 +1,341 @@
+# threadlib.m4 serial 10 (gettext-0.18.2) modified by wk 2014-01-15.
+dnl Copyright (C) 2005-2014 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.
+
+dnl From Bruno Haible.
+
+dnl gl_THREADLIB
+dnl ------------
+dnl Tests for a multithreading library to be used.
+dnl If the configure.ac contains a definition of the gl_THREADLIB_DEFAULT_NO
+dnl (it must be placed before the invocation of gl_THREADLIB_EARLY!), then the
+dnl default is 'no', otherwise it is system dependent. In both cases, the user
+dnl can change the choice through the options --enable-threads=choice or
+dnl --disable-threads.
+dnl Defines at most one of the macros USE_POSIX_THREADS, USE_SOLARIS_THREADS,
+dnl USE_WINDOWS_THREADS
+dnl Sets the variables LIBTHREAD and LTLIBTHREAD to the linker options for use
+dnl in a Makefile (LIBTHREAD for use without libtool, LTLIBTHREAD for use with
+dnl libtool).
+dnl Sets the variables LIBMULTITHREAD and LTLIBMULTITHREAD similarly, for
+dnl programs that really need multithread functionality. The difference
+dnl between LIBTHREAD and LIBMULTITHREAD is that on platforms supporting weak
+dnl symbols, typically LIBTHREAD="" whereas LIBMULTITHREAD="-lpthread".
+dnl Adds to CPPFLAGS the flag -D_REENTRANT or -D_THREAD_SAFE if needed for
+dnl multithread-safe programs.
+
+AC_DEFUN([gl_THREADLIB_EARLY],
+[
+  AC_REQUIRE([gl_THREADLIB_EARLY_BODY])
+])
+
+dnl The guts of gl_THREADLIB_EARLY. Needs to be expanded only once.
+
+AC_DEFUN([gl_THREADLIB_EARLY_BODY],
+[
+  dnl Ordering constraints: This macro modifies CPPFLAGS in a way that
+  dnl influences the result of the autoconf tests that test for *_unlocked
+  dnl declarations, on AIX 5 at least. Therefore it must come early.
+  AC_BEFORE([$0], [gl_FUNC_GLIBC_UNLOCKED_IO])dnl
+  AC_BEFORE([$0], [gl_ARGP])dnl
+
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  dnl _GNU_SOURCE is needed for pthread_rwlock_t on glibc systems.
+  dnl AC_USE_SYSTEM_EXTENSIONS was introduced in autoconf 2.60 and obsoletes
+  dnl AC_GNU_SOURCE.
+  m4_ifdef([AC_USE_SYSTEM_EXTENSIONS],
+    [AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])],
+    [AC_REQUIRE([AC_GNU_SOURCE])])
+  dnl Check for multithreading.
+  m4_ifdef([gl_THREADLIB_DEFAULT_NO],
+    [m4_divert_text([DEFAULTS], [gl_use_threads_default=no])],
+    [m4_divert_text([DEFAULTS], [gl_use_threads_default=])])
+  AC_ARG_ENABLE([threads],
+AC_HELP_STRING([--enable-threads={posix|solaris|windows}], [specify multithreading API])m4_ifdef([gl_THREADLIB_DEFAULT_NO], [], [
+AC_HELP_STRING([--disable-threads], [build without multithread safety])]),
+    [gl_use_threads=$enableval],
+    [if test -n "$gl_use_threads_default"; then
+       gl_use_threads="$gl_use_threads_default"
+     else
+changequote(,)dnl
+       case "$host_os" in
+         dnl Disable multithreading by default on OSF/1, because it interferes
+         dnl with fork()/exec(): When msgexec is linked with -lpthread, its
+         dnl child process gets an endless segmentation fault inside execvp().
+         dnl Disable multithreading by default on Cygwin 1.5.x, because it has
+         dnl bugs that lead to endless loops or crashes. See
+         dnl <http://cygwin.com/ml/cygwin/2009-08/msg00283.html>.
+         osf*) gl_use_threads=no ;;
+         cygwin*)
+               case `uname -r` in
+                 1.[0-5].*) gl_use_threads=no ;;
+                 *)         gl_use_threads=yes ;;
+               esac
+               ;;
+         *)    gl_use_threads=yes ;;
+       esac
+changequote([,])dnl
+     fi
+    ])
+  if test "$gl_use_threads" = yes || test "$gl_use_threads" = posix; then
+    # For using <pthread.h>:
+    case "$host_os" in
+      osf*)
+        # On OSF/1, the compiler needs the flag -D_REENTRANT so that it
+        # groks <pthread.h>. cc also understands the flag -pthread, but
+        # we don't use it because 1. gcc-2.95 doesn't understand -pthread,
+        # 2. putting a flag into CPPFLAGS that has an effect on the linker
+        # causes the AC_LINK_IFELSE test below to succeed unexpectedly,
+        # leading to wrong values of LIBTHREAD and LTLIBTHREAD.
+        CPPFLAGS="$CPPFLAGS -D_REENTRANT"
+        ;;
+    esac
+    # Some systems optimize for single-threaded programs by default, and
+    # need special flags to disable these optimizations. For example, the
+    # definition of 'errno' in <errno.h>.
+    case "$host_os" in
+      aix* | freebsd*) CPPFLAGS="$CPPFLAGS -D_THREAD_SAFE" ;;
+      solaris*) CPPFLAGS="$CPPFLAGS -D_REENTRANT" ;;
+    esac
+  fi
+])
+
+dnl The guts of gl_THREADLIB. Needs to be expanded only once.
+
+AC_DEFUN([gl_THREADLIB_BODY],
+[
+  AC_REQUIRE([gl_THREADLIB_EARLY_BODY])
+  gl_threads_api=none
+  LIBTHREAD=
+  LTLIBTHREAD=
+  LIBMULTITHREAD=
+  LTLIBMULTITHREAD=
+  if test "$gl_use_threads" != no; then
+    dnl Check whether the compiler and linker support weak declarations.
+    AC_CACHE_CHECK([whether imported symbols can be declared weak],
+      [gl_cv_have_weak],
+      [gl_cv_have_weak=no
+       dnl First, test whether the compiler accepts it syntactically.
+       AC_LINK_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[extern void xyzzy ();
+#pragma weak xyzzy]],
+            [[xyzzy();]])],
+         [gl_cv_have_weak=maybe])
+       if test $gl_cv_have_weak = maybe; then
+         dnl Second, test whether it actually works. On Cygwin 1.7.2, with
+         dnl gcc 4.3, symbols declared weak always evaluate to the address 0.
+         AC_RUN_IFELSE(
+           [AC_LANG_SOURCE([[
+#include <stdio.h>
+#pragma weak fputs
+int main ()
+{
+  return (fputs == NULL);
+}]])],
+           [gl_cv_have_weak=yes],
+           [gl_cv_have_weak=no],
+           [dnl When cross-compiling, assume that only ELF platforms support
+            dnl weak symbols.
+            AC_EGREP_CPP([Extensible Linking Format],
+              [#ifdef __ELF__
+               Extensible Linking Format
+               #endif
+              ],
+              [gl_cv_have_weak="guessing yes"],
+              [gl_cv_have_weak="guessing no"])
+           ])
+       fi
+      ])
+    if test "$gl_use_threads" = yes || test "$gl_use_threads" = posix; then
+      # On OSF/1, the compiler needs the flag -pthread or -D_REENTRANT so that
+      # it groks <pthread.h>. It's added above, in gl_THREADLIB_EARLY_BODY.
+      AC_CHECK_HEADER([pthread.h],
+        [gl_have_pthread_h=yes], [gl_have_pthread_h=no])
+      if test "$gl_have_pthread_h" = yes; then
+        # Other possible tests:
+        #   -lpthreads (FSU threads, PCthreads)
+        #   -lgthreads
+        gl_have_pthread=
+        # Test whether both pthread_mutex_lock and pthread_mutexattr_init exist
+        # in libc. IRIX 6.5 has the first one in both libc and libpthread, but
+        # the second one only in libpthread, and lock.c needs it.
+        AC_LINK_IFELSE(
+          [AC_LANG_PROGRAM(
+             [[#include <pthread.h>]],
+             [[pthread_mutex_lock((pthread_mutex_t*)0);
+               pthread_mutexattr_init((pthread_mutexattr_t*)0);]])],
+          [gl_have_pthread=yes])
+        # Test for libpthread by looking for pthread_kill. (Not pthread_self,
+        # since it is defined as a macro on OSF/1.)
+        if test -n "$gl_have_pthread"; then
+          # The program links fine without libpthread. But it may actually
+          # need to link with libpthread in order to create multiple threads.
+          AC_CHECK_LIB([pthread], [pthread_kill],
+            [LIBMULTITHREAD=-lpthread LTLIBMULTITHREAD=-lpthread
+             # On Solaris and HP-UX, most pthread functions exist also in libc.
+             # Therefore pthread_in_use() needs to actually try to create a
+             # thread: pthread_create from libc will fail, whereas
+             # pthread_create will actually create a thread.
+             case "$host_os" in
+               solaris* | hpux*)
+                 AC_DEFINE([PTHREAD_IN_USE_DETECTION_HARD], [1],
+                   [Define if the pthread_in_use() detection is hard.])
+             esac
+            ])
+        else
+          # Some library is needed. Try libpthread and libc_r.
+          AC_CHECK_LIB([pthread], [pthread_kill],
+            [gl_have_pthread=yes
+             LIBTHREAD=-lpthread LTLIBTHREAD=-lpthread
+             LIBMULTITHREAD=-lpthread LTLIBMULTITHREAD=-lpthread])
+          if test -z "$gl_have_pthread"; then
+            # For FreeBSD 4.
+            AC_CHECK_LIB([c_r], [pthread_kill],
+              [gl_have_pthread=yes
+               LIBTHREAD=-lc_r LTLIBTHREAD=-lc_r
+               LIBMULTITHREAD=-lc_r LTLIBMULTITHREAD=-lc_r])
+          fi
+        fi
+        if test -n "$gl_have_pthread"; then
+          gl_threads_api=posix
+          AC_DEFINE([USE_POSIX_THREADS], [1],
+            [Define if the POSIX multithreading library can be used.])
+          if test -n "$LIBMULTITHREAD" || test -n "$LTLIBMULTITHREAD"; then
+            if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
+              AC_DEFINE([USE_POSIX_THREADS_WEAK], [1],
+                [Define if references to the POSIX multithreading library should be made weak.])
+              LIBTHREAD=
+              LTLIBTHREAD=
+            fi
+          fi
+        fi
+      fi
+    fi
+    if test -z "$gl_have_pthread"; then
+      if test "$gl_use_threads" = yes || test "$gl_use_threads" = solaris; then
+        gl_have_solaristhread=
+        gl_save_LIBS="$LIBS"
+        LIBS="$LIBS -lthread"
+        AC_LINK_IFELSE(
+          [AC_LANG_PROGRAM(
+             [[
+#include <thread.h>
+#include <synch.h>
+             ]],
+             [[thr_self();]])],
+          [gl_have_solaristhread=yes])
+        LIBS="$gl_save_LIBS"
+        if test -n "$gl_have_solaristhread"; then
+          gl_threads_api=solaris
+          LIBTHREAD=-lthread
+          LTLIBTHREAD=-lthread
+          LIBMULTITHREAD="$LIBTHREAD"
+          LTLIBMULTITHREAD="$LTLIBTHREAD"
+          AC_DEFINE([USE_SOLARIS_THREADS], [1],
+            [Define if the old Solaris multithreading library can be used.])
+          if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
+            AC_DEFINE([USE_SOLARIS_THREADS_WEAK], [1],
+              [Define if references to the old Solaris multithreading library should be made weak.])
+            LIBTHREAD=
+            LTLIBTHREAD=
+          fi
+        fi
+      fi
+    fi
+    if test -z "$gl_have_pthread"; then
+      case "$gl_use_threads" in
+        yes | windows | win32) # The 'win32' is for backward compatibility.
+          if { case "$host_os" in
+                 mingw*) true;;
+                 *) false;;
+               esac
+             }; then
+            gl_threads_api=windows
+            AC_DEFINE([USE_WINDOWS_THREADS], [1],
+              [Define if the native Windows multithreading API can be used.])
+          fi
+          ;;
+      esac
+    fi
+  fi
+  AC_MSG_CHECKING([for multithread API to use])
+  AC_MSG_RESULT([$gl_threads_api])
+  AC_SUBST([LIBTHREAD])
+  AC_SUBST([LTLIBTHREAD])
+  AC_SUBST([LIBMULTITHREAD])
+  AC_SUBST([LTLIBMULTITHREAD])
+])
+
+AC_DEFUN([gl_THREADLIB],
+[
+  AC_REQUIRE([gl_THREADLIB_EARLY])
+  AC_REQUIRE([gl_THREADLIB_BODY])
+])
+
+
+dnl gl_DISABLE_THREADS
+dnl ------------------
+dnl Sets the gl_THREADLIB default so that threads are not used by default.
+dnl The user can still override it at installation time, by using the
+dnl configure option '--enable-threads'.
+
+AC_DEFUN([gl_DISABLE_THREADS], [
+  m4_divert_text([INIT_PREPARE], [gl_use_threads_default=no])
+])
+
+
+dnl Survey of platforms:
+dnl
+dnl Platform           Available  Compiler    Supports   test-lock
+dnl                    flavours   option      weak       result
+dnl ---------------    ---------  ---------   --------   ---------
+dnl Linux 2.4/glibc    posix      -lpthread       Y      OK
+dnl
+dnl GNU Hurd/glibc     posix
+dnl
+dnl FreeBSD 5.3        posix      -lc_r           Y
+dnl                    posix      -lkse ?         Y
+dnl                    posix      -lpthread ?     Y
+dnl                    posix      -lthr           Y
+dnl
+dnl FreeBSD 5.2        posix      -lc_r           Y
+dnl                    posix      -lkse           Y
+dnl                    posix      -lthr           Y
+dnl
+dnl FreeBSD 4.0,4.10   posix      -lc_r           Y      OK
+dnl
+dnl NetBSD 1.6         --
+dnl
+dnl OpenBSD 3.4        posix      -lpthread       Y      OK
+dnl
+dnl Mac OS X 10.[123]  posix      -lpthread       Y      OK
+dnl
+dnl Solaris 7,8,9      posix      -lpthread       Y      Sol 7,8: 0.0; Sol 9: OK
+dnl                    solaris    -lthread        Y      Sol 7,8: 0.0; Sol 9: OK
+dnl
+dnl HP-UX 11           posix      -lpthread       N (cc) OK
+dnl                                               Y (gcc)
+dnl
+dnl IRIX 6.5           posix      -lpthread       Y      0.5
+dnl
+dnl AIX 4.3,5.1        posix      -lpthread       N      AIX 4: 0.5; AIX 5: OK
+dnl
+dnl OSF/1 4.0,5.1      posix      -pthread (cc)   N      OK
+dnl                               -lpthread (gcc) Y
+dnl
+dnl Cygwin             posix      -lpthread       Y      OK
+dnl
+dnl Any of the above   pth        -lpth                  0.0
+dnl
+dnl Mingw              windows                    N      OK
+dnl
+dnl BeOS 5             --
+dnl
+dnl The test-lock result shows what happens if in test-lock.c EXPLICIT_YIELD is
+dnl turned off:
+dnl   OK if all three tests terminate OK,
+dnl   0.5 if the first test terminates OK but the second one loops endlessly,
+dnl   0.0 if the first test already loops endlessly.
diff --git a/src/Makefile.am b/src/Makefile.am
index 74d89be..51b2ea9 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -30,7 +30,15 @@ extra_cppflags =
 endif
 
 localedir = $(datadir)/locale
+
 bin_PROGRAMS = gpg-error
+
+if HAVE_W32_SYSTEM
+noinst_PROGRAMS = gen-w32-lock-obj
+else
+noinst_PROGRAMS = gen-posix-lock-obj
+endif
+
 lib_LTLIBRARIES = libgpg-error.la
 include_HEADERS = gpg-error.h
 bin_SCRIPTS = gpg-error-config
@@ -42,7 +50,8 @@ EXTRA_DIST = mkstrtable.awk err-sources.h.in err-codes.h.in \
 	mkerrcodes.awk mkerrcodes1.awk mkerrcodes2.awk mkerrcodes.c \
 	mkheader.c gpg-error.h.in mkw32errmap.c w32-add.h w32ce-add.h \
 	err-sources.h err-codes.h gpg-error-config.in gpg-error.m4 \
-	gpg-error.def.in versioninfo.rc.in
+	gpg-error.def.in versioninfo.rc.in \
+	w32-lock-obj-pub.in
 
 BUILT_SOURCES = err-sources.h err-codes.h code-to-errno.h code-from-errno.h \
 	err-sources-sym.h err-codes-sym.h errnos-sym.h gpg-error.h \
@@ -53,11 +62,10 @@ tmp_files = _mkerrcodes.h _gpg-error.def.h mkw32errmap.tab.h mkw32errmap.map.c
 CLEANFILES = err-sources.h err-codes.h code-to-errno.h code-from-errno.h \
 	gpg-error.h mkerrcodes mkerrcodes.h gpg-error.def mkw32errmap.tab.h \
 	mkw32errmap.map.c err-sources-sym.h err-codes-sym.h errnos-sym.h \
-	gpg-extra/errno.h mkheader $(tmp_files)
+	gpg-extra/errno.h mkheader $(tmp_files) posix-lock-obj-pub.in
 
 if HAVE_W32_SYSTEM
-arch_sources = w32-gettext.c
-
+arch_sources = w32-gettext.c w32-lock.c w32-lock-obj.h w32-thread.c
 RCCOMPILE = $(RC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) \
             -DLOCALEDIR=\"$(localedir)\" $(AM_CPPFLAGS) $(CPPFLAGS)
 LTRCCOMPILE = $(LIBTOOL) --mode=compile --tag=RC $(RCCOMPILE)
@@ -82,7 +90,7 @@ libgpg_error_la_DEPENDENCIES = $(gpg_error_res) gpg-error.def
 intllibs =
 
 else
-arch_sources =
+arch_sources = posix-lock.c posix-lock-obj.h posix-thread.c
 gpg_error_res =
 no_undefined =
 export_symbols =
@@ -98,17 +106,22 @@ libgpg_error_la_LDFLAGS = -version-info \
   @LIBGPG_ERROR_LT_CURRENT@:@LIBGPG_ERROR_LT_REVISION@:@LIBGPG_ERROR_LT_AGE@ \
   $(no_undefined) $(export_symbols)
 
-parts_of_gpg_error_h = 	 \
-	gpg-error.h.in   \
-	err-sources.h.in \
-	err-codes.h.in 	 \
-	errnos.in 	 \
-	w32-add.h	 \
-	w32ce-add.h
+parts_of_gpg_error_h = 	 	\
+	gpg-error.h.in  	\
+	err-sources.h.in 	\
+	err-codes.h.in 	 	\
+	errnos.in 	 	\
+	w32-add.h	 	\
+	w32ce-add.h      	\
+	w32-lock-obj-pub.in
+
+if ! HAVE_W32_SYSTEM
+parts_of_gpg_error_h += posix-lock-obj-pub.in
+endif
 
 
 libgpg_error_la_SOURCES = gpg-error.h gettext.h $(arch_sources) \
-	init.c init.h version.c \
+	init.c init.h version.c lock.h thread.h \
 	strsource.c strerror.c code-to-errno.c code-from-errno.c
 
 # Note that RCCOMPILE needs the same defines as ..._la_CPPFLAGS but
@@ -195,9 +208,14 @@ errnos-sym.h: Makefile mkstrtable.awk errnos.in
 		-v prefix=GPG_ERR_ -v namespace=errnos_ \
 		$(srcdir)/errnos.in >$@
 
+
 mkheader: mkheader.c Makefile
 	$(CC_FOR_BUILD) -g -O0 -I. -I$(srcdir) -o $@ $(srcdir)/mkheader.c
 
+
+posix-lock-obj-pub.in: Makefile gen-posix-lock-obj posix-lock-obj.h
+	./gen-posix-lock-obj >$@
+
 # We also depend on versioninfo.rc because that is build by
 # config.status and thus has up-to-date version numbers.
 gpg-error.h: Makefile mkheader $(parts_of_gpg_error_h) versioninfo.rc
diff --git a/src/err-codes.h.in b/src/err-codes.h.in
index 4ecc24e..c912bcd 100644
--- a/src/err-codes.h.in
+++ b/src/err-codes.h.in
@@ -247,7 +247,11 @@
 212	GPG_ERR_SEXP_ODD_HEX_NUMBERS	Odd hexadecimal numbers in S-expression
 213	GPG_ERR_SEXP_BAD_OCT_CHAR	Bad octal character in S-expression
 
-# 214 to 254 are free to be used. 255 and 256 are RFU.
+# 214 to 253 are free to be used.
+
+254	GPG_ERR_INV_LOCK_OBJ		Invalid lock object
+
+# 255 and 256 are RFU.
 
 # Error codes pertaining to the Assuan IPC interface
 257	GPG_ERR_ASS_GENERAL		General IPC error
diff --git a/src/gen-posix-lock-obj.c b/src/gen-posix-lock-obj.c
new file mode 100644
index 0000000..b641fd0
--- /dev/null
+++ b/src/gen-posix-lock-obj.c
@@ -0,0 +1,95 @@
+/* gen-posix-lock-obj.c - Build tool to construct the lock object.
+   Copyright (C) 2014 g10 Code GmbH
+
+   This file is part of libgpg-error.
+
+   libgpg-error is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public License
+   as published by the Free Software Foundation; either version 2.1 of
+   the License, or (at your option) any later version.
+
+   libgpg-error is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#if HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#ifdef HAVE_W32_SYSTEM
+# error This module may not be build for Windows.
+#endif
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <pthread.h>
+
+#include "posix-lock-obj.h"
+
+#define PGM "gen-posix-lock-obj"
+
+/* Check that configure did its job.  */
+#if SIZEOF_PTHREAD_MUTEX_T < 4
+# error sizeof pthread_mutex_t is not known.
+#endif
+
+static pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;
+
+
+int
+main (void)
+{
+  unsigned char *p;
+  int i;
+  struct {
+    pthread_mutex_t mtx;
+    long vers;
+  } dummyobj;
+
+  if (sizeof mtx != SIZEOF_PTHREAD_MUTEX_T)
+    {
+      fprintf (stderr, PGM ": pthread_mutex_t mismatch\n");
+      exit (1);
+    }
+
+  if (sizeof (dummyobj) != sizeof (_gpgrt_lock_t))
+    {
+      fprintf (stderr, PGM ": internal and external lock object mismatch\n");
+      exit (1);
+    }
+
+  /* To force a probably suitable alignment of the structure we use a
+     union and include a long and a pointer to a long.  */
+  printf ("## File created by " PGM " - DO NOT EDIT\n"
+          "## To be included by mkheader into gpg-error.h\n"
+          "\n"
+          "typedef union\n"
+          "{\n"
+          "  struct {\n"
+          "    volatile char _priv[%d];\n"
+          "    long _vers;\n"
+          "  } d;\n"
+          "  long _x_align;\n"
+          "  long *_xp_align;\n"
+          "} gpgrt_lock_t;\n"
+          "\n"
+          "#define GPGRT_LOCK_INITIALIZER {{{",
+          SIZEOF_PTHREAD_MUTEX_T);
+  p = (unsigned char *)&mtx;
+  for (i=0; i < sizeof mtx; i++)
+    {
+      if (i && !(i % 8))
+        printf (" \\\n%*s", 34, "");
+      printf ("%u", p[i]);
+      if (i < sizeof mtx - 1)
+        putchar (',');
+    }
+  printf ("},%d}}\n", LOCK_ABI_VERSION);
+
+  return 0;
+}
diff --git a/src/gen-w32-lock-obj.c b/src/gen-w32-lock-obj.c
new file mode 100644
index 0000000..9e49d1e
--- /dev/null
+++ b/src/gen-w32-lock-obj.c
@@ -0,0 +1,55 @@
+/* gen-w32-lock-obj.c - Build tool to get the size of the lock object.
+   Copyright (C) 2014 g10 Code GmbH
+
+   This file is part of libgpg-error.
+
+   libgpg-error is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public License
+   as published by the Free Software Foundation; either version 2.1 of
+   the License, or (at your option) any later version.
+
+   libgpg-error is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#if HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#ifndef HAVE_W32_SYSTEM
+# error This module may only be build for Windows.
+#endif
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <windows.h>
+
+#include "w32-lock-obj.h"
+
+
+int
+main (void)
+{
+  _gpgrt_lock_t lk;
+  unsigned char *p;
+  int i;
+
+  printf ("sizeof CRITICAL_SECTION = %u\n", (int)sizeof (CRITICAL_SECTION));
+  printf ("sizeof    _gpgrt_lock_t = %u\n", (int)sizeof lk);
+
+  memset (&lk, 0, sizeof lk);
+  lk.vers = LOCK_ABI_VERSION;
+  lk.started = -1;
+  printf ("#define GPGRT_LOCK_INITIALIZER {");
+  p = (unsigned char *)&lk;
+  for (i=0; i < sizeof lk - 1; i++)
+    printf ("%u,", p[i]);
+  printf ("%u}\n", p[sizeof(lk)-1]);
+
+  return 0;
+}
diff --git a/src/gpg-error.def.in b/src/gpg-error.def.in
index 62e0681..2ea482a 100644
--- a/src/gpg-error.def.in
+++ b/src/gpg-error.def.in
@@ -28,3 +28,9 @@ EXPORTS
 #endif
  gpg_err_deinit		      @18
  gpg_error_check_version      @19
+
+ gpgrt_lock_init              @20
+ gpgrt_lock_lock              @21
+ gpgrt_lock_unlock            @22
+ gpgrt_lock_destroy           @23
+ gpgrt_yield                  @24
diff --git a/src/gpg-error.h.in b/src/gpg-error.h.in
index a2fb044..adb796b 100644
--- a/src/gpg-error.h.in
+++ b/src/gpg-error.h.in
@@ -66,7 +66,10 @@ extern "C" {
 
    GPG_ERR_ENABLE_GETTEXT_MACROS: Define to provide macros to map the
    internal gettext API to standard names.  This has only an effect on
-   Windows platforms.  */
+   Windows platforms.
+
+   In addition to the error codes, Libgpg-error also provides a set of
+   functions used by most GnuPG components.  */
 
 
 /* The error source type gpg_err_source_t.
@@ -279,9 +282,35 @@ gpg_error_from_syserror (void)
   return gpg_error (gpg_err_code_from_syserror ());
 }
 
+
+
+/* Lock functions.  */
+
+@include:lock-obj@
+
+#define GPGRT_LOCK_DEFINE(name) \
+  static gpgrt_lock_t name  = GPGRT_LOCK_INITIALIZER
+
+
+gpg_err_code_t gpgrt_lock_init (gpgrt_lock_t *lockhd);
+gpg_err_code_t gpgrt_lock_lock (gpgrt_lock_t *lockhd);
+gpg_err_code_t gpgrt_lock_unlock (gpgrt_lock_t *lockhd);
+gpg_err_code_t gpgrt_lock_destroy (gpgrt_lock_t *lockhd);
+
+
+
+/* Thread functions.  */
+
+gpg_err_code_t gpgrt_yield (void);
+
+
+
+
+/* Estream */
+
+
+
 #ifdef __cplusplus
 }
 #endif
-
-
 #endif	/* GPG_ERROR_H */
diff --git a/src/lock.h b/src/lock.h
new file mode 100644
index 0000000..b60f2c2
--- /dev/null
+++ b/src/lock.h
@@ -0,0 +1,24 @@
+/* lock.h - Declarations for *-lock.c
+   Copyright (C) 2014 g10 Code GmbH
+
+   This file is part of libgpg-error.
+
+   libgpg-error is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public License
+   as published by the Free Software Foundation; either version 2.1 of
+   the License, or (at your option) any later version.
+
+   libgpg-error is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LOCK_H
+#define LOCK_H
+
+
+#endif /*LOCK_H*/
diff --git a/src/mkheader.c b/src/mkheader.c
index eea7914..e7db729 100644
--- a/src/mkheader.c
+++ b/src/mkheader.c
@@ -132,7 +132,8 @@ write_errnos_in (char *line)
    is not further expanded.  It may have comments indicated by a
    double hash mark at the begin of a line.  OUTF is called for each
    read line and passed a buffer with the content of line sans line
-   line endings. */
+   line endings.  If NAME is prefixed with "./" it is included from
+   the current directory and not from the source directory. */
 static void
 include_file (const char *fname, int lnr, const char *name, void (*outf)(char*))
 {
@@ -147,7 +148,11 @@ include_file (const char *fname, int lnr, const char *name, void (*outf)(char*))
       fputs (PGM ": out of core\n", stderr);
       exit (1);
     }
-  strcpy (incfname, srcdir);
+
+  if (*name == '.' && name[1] == '/')
+    *incfname = 0;
+  else
+    strcpy (incfname, srcdir);
   strcat (incfname, name);
 
   fp = fopen (incfname, "r");
@@ -242,6 +247,15 @@ write_special (const char *fname, int lnr, const char *tag)
           include_file (fname, lnr, "w32ce-add.h", write_line);
         }
     }
+  else if (!strcmp (tag, "include:lock-obj"))
+    {
+      if (!strcmp (host_os, "mingw32"))
+        {
+          include_file (fname, lnr, "w32-lock-obj-pub.in", write_line);
+        }
+      else
+        include_file (fname, lnr, "./posix-lock-obj-pub.in", write_line);
+    }
   else
     return 0; /* Unknown tag.  */
 
diff --git a/src/posix-lock-obj.h b/src/posix-lock-obj.h
new file mode 100644
index 0000000..a5a9ee7
--- /dev/null
+++ b/src/posix-lock-obj.h
@@ -0,0 +1,32 @@
+/* posic-lock-obj.h - Declaration of the POSIX lock object
+   Copyright (C) 2014 g10 Code GmbH
+
+   This file is part of libgpg-error.
+
+   libgpg-error is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public License
+   as published by the Free Software Foundation; either version 2.1 of
+   the License, or (at your option) any later version.
+
+   libgpg-error is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef POSIX_LOCK_OBJ_H
+#define POSIX_LOCK_OBJ_H
+
+#define LOCK_ABI_VERSION 1
+
+typedef struct
+{
+  pthread_mutex_t mtx;
+  long vers;
+} _gpgrt_lock_t;
+
+
+#endif /*POSIX_LOCK_OBJ_H*/
diff --git a/src/posix-lock.c b/src/posix-lock.c
new file mode 100644
index 0000000..46e3a84
--- /dev/null
+++ b/src/posix-lock.c
@@ -0,0 +1,213 @@
+/* posix-lock.c - GPGRT lock functions for POSIX systems
+   Copyright (C) 2005-2009 Free Software Foundation, Inc.
+   Copyright (C) 2014 g10 Code GmbH
+
+   This file is part of libgpg-error.
+
+   libgpg-error is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public License
+   as published by the Free Software Foundation; either version 2.1 of
+   the License, or (at your option) any later version.
+
+   libgpg-error is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+   Parts of the code, in particular use_pthreads_p, are based on code
+   from gettext, written by Bruno Haible <[email protected]>, 2005.
+ */
+
+#if HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#ifdef HAVE_W32_SYSTEM
+# error This module may not be build for Windows.
+#endif
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+
+#if USE_POSIX_THREADS
+# include <pthread.h>
+#endif
+
+#include "gpg-error.h"
+#include "lock.h"
+#include "posix-lock-obj.h"
+
+
+#if USE_POSIX_THREADS
+# if USE_POSIX_THREADS_WEAK
+   /* On ELF systems it is easy to use pthreads using weak
+      references.  Take care not to test the address of a weak
+      referenced function we actually use; some GCC versions have a
+      bug were &foo != NULL is always evaluated to true in PIC mode.  */
+#  pragma weak pthread_cancel
+#  pragma weak pthread_mutex_init
+#  pragma weak pthread_mutex_lock
+#  pragma weak pthread_mutex_unlock
+#  pragma weak pthread_mutex_destroy
+#  if ! PTHREAD_IN_USE_DETECTION_HARD
+#   define use_pthread_p() (!!pthread_cancel)
+#  endif
+# else /*!USE_POSIX_THREADS_WEAK*/
+#  if ! PTHREAD_IN_USE_DETECTION_HARD
+#   define use_pthread_p() (1)
+#  endif
+# endif /*!USE_POSIX_THREADS_WEAK*/
+# if PTHREAD_IN_USE_DETECTION_HARD
+/* The function to be executed by a dummy thread.  */
+static void *
+dummy_thread_func (void *arg)
+{
+  return arg;
+}
+
+static int
+use_pthread_p (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))
+        result = 0; /* Thread creation failed.  */
+      else
+        {
+          /* Thread creation works.  */
+          void *retval;
+          if (pthread_join (thread, &retval) != 0)
+            abort ();
+          result = 1;
+        }
+      tested = 1;
+    }
+  return result;
+}
+#endif /*PTHREAD_IN_USE_DETECTION_HARD*/
+#endif /*USE_POSIX_THREADS*/
+
+
+
+static _gpgrt_lock_t *
+get_lock_object (gpgrt_lock_t *lockhd)
+{
+  _gpgrt_lock_t *lock = (_gpgrt_lock_t*)lockhd;
+
+  if (lock->vers != LOCK_ABI_VERSION)
+    abort ();
+  if (sizeof (gpgrt_lock_t) < sizeof (_gpgrt_lock_t))
+    abort ();
+
+  return lock;
+}
+
+
+gpg_err_code_t
+gpgrt_lock_init (gpgrt_lock_t *lockhd)
+{
+  _gpgrt_lock_t *lock = get_lock_object (lockhd);
+  int rc;
+
+#if USE_POSIX_THREADS
+  if (use_pthread_p())
+    {
+      rc = pthread_mutex_init (&lock->mtx, NULL);
+      if (rc)
+        rc = gpg_err_code_from_errno (rc);
+    }
+  else
+    rc = 0; /* Threads are not used.  */
+#else /* Unknown thread system.  */
+  rc = GPG_ERR_NOT_IMPLEMENTED;
+#endif /* Unknown thread system.  */
+
+  return rc;
+}
+
+
+gpg_err_code_t
+gpgrt_lock_lock (gpgrt_lock_t *lockhd)
+{
+  _gpgrt_lock_t *lock = get_lock_object (lockhd);
+  int rc;
+
+#if USE_POSIX_THREADS
+  if (use_pthread_p())
+    {
+      rc = pthread_mutex_lock (&lock->mtx);
+      if (rc)
+        rc = gpg_err_code_from_errno (rc);
+    }
+  else
+    rc = 0; /* Threads are not used.  */
+#else /* Unknown thread system.  */
+  rc = GPG_ERR_NOT_IMPLEMENTED;
+#endif /* Unknown thread system.  */
+
+  return rc;
+}
+
+
+gpg_err_code_t
+gpgrt_lock_unlock (gpgrt_lock_t *lockhd)
+{
+  _gpgrt_lock_t *lock = get_lock_object (lockhd);
+  int rc;
+
+#if USE_POSIX_THREADS
+  if (use_pthread_p())
+    {
+      rc = pthread_mutex_unlock (&lock->mtx);
+      if (rc)
+        rc = gpg_err_code_from_errno (rc);
+    }
+  else
+    rc = 0; /* Threads are not used.  */
+#else /* Unknown thread system.  */
+  rc = GPG_ERR_NOT_IMPLEMENTED;
+#endif /* Unknown thread system.  */
+
+  return rc;
+}
+
+
+/* Note: Use this function only if no other thread holds or waits for
+   this lock.  */
+gpg_err_code_t
+gpgrt_lock_destroy (gpgrt_lock_t *lockhd)
+{
+  _gpgrt_lock_t *lock = get_lock_object (lockhd);
+  int rc;
+
+#if USE_POSIX_THREADS
+  if (use_pthread_p())
+    {
+      rc = pthread_mutex_destroy (&lock->mtx);
+      if (rc)
+        rc = gpg_err_code_from_errno (rc);
+      else
+        {
+          /* Re-init the the mutex so that it can be re-used.  */
+          gpgrt_lock_t tmp = GPGRT_LOCK_INITIALIZER;
+          memcpy (lockhd, &tmp, sizeof tmp);
+        }
+    }
+  else
+    rc = 0; /* Threads are not used.  */
+#else /* Unknown thread system.  */
+  rc = GPG_ERR_NOT_IMPLEMENTED;
+#endif /* Unknown thread system.  */
+
+  return rc;
+}
diff --git a/src/posix-thread.c b/src/posix-thread.c
new file mode 100644
index 0000000..a739e40
--- /dev/null
+++ b/src/posix-thread.c
@@ -0,0 +1,63 @@
+/* posix-thread.c - GPGRT thread functions for POSIX systems
+   Copyright (C) 2014 g10 Code GmbH
+
+   This file is part of libgpg-error.
+
+   libgpg-error is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public License
+   as published by the Free Software Foundation; either version 2.1 of
+   the License, or (at your option) any later version.
+
+   libgpg-error is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#if HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#ifdef HAVE_W32_SYSTEM
+# error This module may not be build for Windows.
+#endif
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>  /* Get posix option macros.  */
+
+#if USE_POSIX_THREADS
+# ifdef _POSIX_PRIORITY_SCHEDULING
+#  include <sched.h>
+# endif
+#elif USE_SOLARIS_THREADS
+# include <thread.h>
+#endif
+
+#include "gpg-error.h"
+
+#include "thread.h"
+
+
+gpg_err_code_t
+gpgrt_yield (void)
+{
+#if USE_POSIX_THREADS
+# ifdef _POSIX_PRIORITY_SCHEDULING
+   sched_yield ();
+# else
+   return GPG_ERR_NOT_SUPPORTED;
+# endif
+#elif USE_SOLARIS_THREADS
+  thr_yield ();
+#else
+  return GPG_ERR_NOT_SUPPORTED;
+#endif
+
+  return 0;
+}
diff --git a/src/thread.h b/src/thread.h
new file mode 100644
index 0000000..0b2cf04
--- /dev/null
+++ b/src/thread.h
@@ -0,0 +1,24 @@
+/* thread.h - Declarations for *-thread.c
+   Copyright (C) 2014 g10 Code GmbH
+
+   This file is part of libgpg-error.
+
+   libgpg-error is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public License
+   as published by the Free Software Foundation; either version 2.1 of
+   the License, or (at your option) any later version.
+
+   libgpg-error is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef THREAD_H
+#define THREAD_H
+
+
+#endif /*THREAD_H*/
diff --git a/src/version.c b/src/version.c
index 36e2d58..5b40537 100644
--- a/src/version.c
+++ b/src/version.c
@@ -1,5 +1,5 @@
 /* version.c - Version checking
- * Copyright (C) 2001, 2002, 2012, 2013 g10 Code GmbH
+ * Copyright (C) 2001, 2002, 2012, 2013, 2014 g10 Code GmbH
  *
  * This file is part of libgpg-error.
  *
@@ -39,7 +39,7 @@ cright_blurb (void)
   static const char blurb[] =
     "\n\n"
     "This is Libgpg-error " PACKAGE_VERSION " - An error code library\n"
-    "Copyright 2003, 2004, 2010, 2013 g10 Code GmbH\n"
+    "Copyright 2003, 2004, 2010, 2013, 2014 g10 Code GmbH\n"
     "\n"
     "(" BUILD_REVISION " " BUILD_TIMESTAMP ")\n"
     "\n\n";
diff --git a/src/w32-lock-obj-pub.in b/src/w32-lock-obj-pub.in
new file mode 100644
index 0000000..2f3f911
--- /dev/null
+++ b/src/w32-lock-obj-pub.in
@@ -0,0 +1,44 @@
+## w32-lock-obj-pub.in - Include fragment for gpg-error.h       -*- c-*-
+## Copyright (C) 2014 g10 Code GmbH
+##
+## This file is free software; as a special exception the author gives
+## unlimited permission to copy and/or distribute it, with or without
+## modifications, as long as this notice is preserved.
+##
+## This file is distributed in the hope that it will be useful, but
+## WITHOUT ANY WARRANTY, to the extent permitted by law; without even the
+## implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+##
+##
+## This file defines the public version of the lock object for 32 bit
+## Windows.  The actual used version is in w32-lock-obj.h.  This file
+## is inserted into gpg-error.h by mkheader.c.  The tool
+## gen-w32-lock-obj.c has been used to construct it.
+
+#ifdef _WIN64
+
+#pragma pack(push, 8)
+typedef struct
+{
+  volatile char priv[56];
+} gpgrt_lock_t;
+#pragma pack(pop)
+
+#define GPGRT_LOCK_INITIALIZER {1,0,0,0,0,0,0,0,255,255,255,255, \
+                                0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, \
+                                0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, \
+                                0,0,0,0,0,0,0,0,0,0,0,0}
+
+#else
+
+#pragma pack(push, 8)
+typedef struct
+{
+  volatile char priv[36];
+} gpgrt_lock_t;
+#pragma pack(pop)
+
+#define GPGRT_LOCK_INITIALIZER {1,0,0,0,0,0,0,0,255,255,255,255, \
+                                0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, \
+                                0,0,0,0,0,0,0,0}
+#endif
diff --git a/src/w32-lock-obj.h b/src/w32-lock-obj.h
new file mode 100644
index 0000000..ef53546
--- /dev/null
+++ b/src/w32-lock-obj.h
@@ -0,0 +1,38 @@
+/* w32-lock-obj.h - Declaration of the Windows lock object
+   Copyright (C) 2014 g10 Code GmbH
+
+   This file is part of libgpg-error.
+
+   libgpg-error is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public License
+   as published by the Free Software Foundation; either version 2.1 of
+   the License, or (at your option) any later version.
+
+   libgpg-error is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef W32_LOCK_OBJ_H
+#define W32_LOCK_OBJ_H
+
+#define LOCK_ABI_VERSION 1
+
+/* The real definition of our lock object.  The public definition is
+   named gpgrt_lock_t and hides this internal structure.  */
+#pragma pack(push, 8)
+typedef struct
+{
+  long vers;
+  volatile long initdone;
+  volatile long started;
+  CRITICAL_SECTION csec;
+} _gpgrt_lock_t;
+#pragma pack(pop)
+
+
+#endif /*W32_LOCK_OBJ_H*/
diff --git a/src/w32-lock.c b/src/w32-lock.c
new file mode 100644
index 0000000..0ad9409
--- /dev/null
+++ b/src/w32-lock.c
@@ -0,0 +1,119 @@
+/* w32-lock.c - GPGRT lock functions for Windows
+   Copyright (C) 2014 g10 Code GmbH
+
+   This file is part of libgpg-error.
+
+   libgpg-error is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public License
+   as published by the Free Software Foundation; either version 2.1 of
+   the License, or (at your option) any later version.
+
+   libgpg-error is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#if HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#ifndef HAVE_W32_SYSTEM
+# error This module may only be build for Windows.
+#endif
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <gpg-error.h>
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+#include "lock.h"
+#include "w32-lock-obj.h"
+
+
+static _gpgrt_lock_t *
+get_lock_object (gpgrt_lock_t *lockhd)
+{
+  _gpgrt_lock_t *lock = (_gpgrt_lock_t*)lockhd;
+
+  if (lock->vers != LOCK_ABI_VERSION)
+    abort ();
+
+  return lock;
+}
+
+
+gpg_err_code_t
+gpgrt_lock_init (gpgrt_lock_t *lockhd)
+{
+  _gpgrt_lock_t *lock = get_lock_object (lockhd);
+
+  if (sizeof (gpgrt_lock_t) < sizeof (_gpgrt_lock_t))
+    abort ();
+  InitializeCriticalSection (&lock->csec);
+  lock->initdone = 1;
+}
+
+
+gpg_err_code_t
+gpgrt_lock_lock (gpgrt_lock_t *lockhd)
+{
+  _gpgrt_lock_t *lock = get_lock_object (lockhd);
+
+  if (!lock->initdone)
+    {
+      if (!InterlockedIncrement (&lock->started))
+        {
+          /* The new value of started is 0.  Because the initial value
+             if the variable was -1 we known that this thread is the
+             first who needs this lock.  Thus we initialize now.  All
+             other threads won't get 0 back from InterlockedIncrement
+             and thus fall into the wait loop below.  We ignore that
+             STARTED may in theory overflow if this thread starves for
+             too long.  */
+          gpgrt_lock_init (lockhd);
+        }
+      else
+        {
+          while (!lock->initdone)
+            Sleep (0);
+        }
+    }
+
+  EnterCriticalSection (&lock->csec);
+  return 0;
+}
+
+
+gpg_err_code_t
+gpgrt_lock_unlock (gpgrt_lock_t *lockhd)
+{
+  _gpgrt_lock_t *lock = get_lock_object (lockhd);
+
+  if (!lock->initdone)
+    return GPG_ERR_INV_LOCK_OBJ;
+  LeaveCriticalSection (&lock->csec);
+  return 0;
+}
+
+
+/* Note: Use this function only if no other thread holds or waits for
+   this lock.  */
+gpg_err_code_t
+gpgrt_lock_destroy (gpgrt_lock_t *lockhd)
+{
+  _gpgrt_lock_t *lock = get_lock_object (lockhd);
+
+  if (!lock->initdone)
+    return GPG_ERR_INV_LOCK_OBJ;
+  DeleteCriticalSection (&lock->csec);
+  lock->initdone = 0;
+  lock->started = -1;
+  return 0;
+}
diff --git a/src/w32-thread.c b/src/w32-thread.c
new file mode 100644
index 0000000..f86be35
--- /dev/null
+++ b/src/w32-thread.c
@@ -0,0 +1,44 @@
+/* w32-thread.c - GPGRT thread functions for Windows
+   Copyright (C) 2014 g10 Code GmbH
+
+   This file is part of libgpg-error.
+
+   libgpg-error is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public License
+   as published by the Free Software Foundation; either version 2.1 of
+   the License, or (at your option) any later version.
+
+   libgpg-error is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#if HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#ifndef HAVE_W32_SYSTEM
+# error This module may only be build for Windows.
+#endif
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <gpg-error.h>
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+#include "thread.h"
+
+
+gpg_err_code_t
+gpgrt_yield (void)
+{
+  Sleep (0);
+  return 0;
+}
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 1a27f81..277a78b 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -25,11 +25,16 @@ else
 extra_includes =
 endif
 
+gpg_error_lib = ../src/libgpg-error.la
 
-TESTS = t-version t-strerror t-syserror
+TESTS = t-version t-strerror t-syserror t-lock
 
 INCLUDES = -I$(top_builddir)/src $(extra_includes)
 
-LDADD = ../src/libgpg-error.la
+
+LDADD = $(gpg_error_lib)
 
 noinst_PROGRAMS = $(TESTS)
+noinst_HEADERS = t-common.h
+
+t_lock_LDADD = $(gpg_error_lib) $(LIBMULTITHREAD)
diff --git a/tests/t-common.h b/tests/t-common.h
new file mode 100644
index 0000000..85bcd51
--- /dev/null
+++ b/tests/t-common.h
@@ -0,0 +1,99 @@
+/* t-common.h - Common code for the tests.
+ * Copyright (C) 2013 g10 Code GmbH
+ *
+ * This file is part of libgpg-error.
+ *
+ * libgpg-error is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * libgpg-error is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdarg.h>
+
+#include "../src/gpg-error.h"
+
+#ifndef PGM
+# error Macro PGM not defined.
+#endif
+
+
+static int verbose;
+static int debug;
+static int errorcount;
+
+
+static void
+die (const char *format, ...)
+{
+  va_list arg_ptr ;
+
+  fflush (stdout);
+#ifdef HAVE_FLOCKFILE
+  flockfile (stderr);
+#endif
+  fprintf (stderr, "%s: ", PGM);
+  va_start (arg_ptr, format) ;
+  vfprintf (stderr, format, arg_ptr);
+  va_end (arg_ptr);
+  if (*format && format[strlen(format)-1] != '\n')
+    putc ('\n', stderr);
+#ifdef HAVE_FLOCKFILE
+  funlockfile (stderr);
+#endif
+  exit (1);
+}
+
+
+static void
+fail (const char *format, ...)
+{
+  va_list arg_ptr;
+
+  fflush (stdout);
+#ifdef HAVE_FLOCKFILE
+  flockfile (stderr);
+#endif
+  fprintf (stderr, "%s: ", PGM);
+  va_start (arg_ptr, format);
+  vfprintf (stderr, format, arg_ptr);
+  va_end (arg_ptr);
+  if (*format && format[strlen(format)-1] != '\n')
+    putc ('\n', stderr);
+#ifdef HAVE_FLOCKFILE
+  funlockfile (stderr);
+#endif
+  errorcount++;
+  if (errorcount >= 50)
+    die ("stopped after 50 errors.");
+}
+
+
+static void
+show (const char *format, ...)
+{
+  va_list arg_ptr;
+
+  if (!verbose)
+    return;
+#ifdef HAVE_FLOCKFILE
+  flockfile (stderr);
+#endif
+  fprintf (stderr, "%s: ", PGM);
+  va_start (arg_ptr, format);
+  vfprintf (stderr, format, arg_ptr);
+  if (*format && format[strlen(format)-1] != '\n')
+    putc ('\n', stderr);
+  va_end (arg_ptr);
+#ifdef HAVE_FLOCKFILE
+  funlockfile (stderr);
+#endif
+}
diff --git a/tests/t-lock.c b/tests/t-lock.c
new file mode 100644
index 0000000..91923fb
--- /dev/null
+++ b/tests/t-lock.c
@@ -0,0 +1,318 @@
+/* t-lock.c - Check the lock functions
+ * Copyright (C) 2013 g10 Code GmbH
+ *
+ * This file is part of libgpg-error.
+ *
+ * libgpg-error is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * libgpg-error is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#if HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#ifdef _WIN32
+# include <windows.h>
+#else
+# include <pthread.h>
+#endif
+
+#define PGM "t-lock"
+
+#include "t-common.h"
+
+#ifdef _WIN32
+# define THREAD_RET_TYPE  DWORD WINAPI
+# define THREAD_RET_VALUE 0
+#else
+# define THREAD_RET_TYPE  void *
+# define THREAD_RET_VALUE NULL
+#endif
+
+
+/* Our tests works by having a a couple of accountant threads which do
+   random transactions between accounts and a revision threads which
+   checks that the balance of all accounts is invariant.  The idea for
+   this check is due to Bruno Haible.  */
+#define N_ACCOUNT 8
+#define ACCOUNT_VALUE 42
+static int account[N_ACCOUNT];
+GPGRT_LOCK_DEFINE (accounts_lock);
+
+/* Number of transactions done by each accountant.  */
+#define N_TRANSACTIONS 1000
+
+/* Number of accountants to run.  */
+#define N_ACCOUNTANTS 5
+
+/* Maximum transaction value.  A quite low value is used so that we
+   would get an integer overflow.  */
+#define MAX_TRANSACTION_VALUE 50
+
+/* Flag to tell the revision thread to finish.  */
+static volatile int stop_revision_thread;
+
+
+/* Initialze all accounts.  */
+static void
+init_accounts (void)
+{
+  int i;
+
+  for (i=0; i < N_ACCOUNT; i++)
+    account[i] = ACCOUNT_VALUE;
+}
+
+
+/* Check that the sum of all accounts matches the intial sum.  */
+static void
+check_accounts (void)
+{
+  int i, sum;
+
+  sum = 0;
+  for (i = 0; i < N_ACCOUNT; i++)
+    sum += account[i];
+  if (sum != N_ACCOUNT * ACCOUNT_VALUE)
+    die ("accounts out of balance");
+}
+
+
+static void
+print_accounts (void)
+{
+  int i;
+
+  for (i=0; i < N_ACCOUNT; i++)
+    printf ("account %d: %6d\n", i, account[i]);
+}
+
+
+/* Get a a random integer value in the range 0 to HIGH.  */
+static unsigned int
+get_rand (int high)
+{
+  return (unsigned int)(1+(int)((double)(high+1)*rand ()/(RAND_MAX+1.0))) - 1;
+}
+
+
+/* Pick a random account.  Note that this fucntion is not
+   thread-safe. */
+static int
+pick_account (void)
+{
+  return get_rand (N_ACCOUNT - 1);
+}
+
+
+/* Pick a random value for a transaction.  This is not thread-safe.  */
+static int
+pick_value (void)
+{
+  return get_rand (MAX_TRANSACTION_VALUE);
+}
+
+
+/* This is the revision department.  */
+static THREAD_RET_TYPE
+revision_thread (void *arg)
+{
+  gpg_err_code_t rc;
+  int i;
+
+  (void)arg;
+
+  while (!stop_revision_thread)
+    {
+      rc = gpgrt_lock_lock (&accounts_lock);
+      if (rc)
+        fail ("gpgrt_lock_lock failed at %d: %s", __LINE__, gpg_strerror (rc));
+
+      check_accounts ();
+      rc = gpgrt_lock_unlock (&accounts_lock);
+      if (rc)
+        fail ("gpgrt_lock_unlock failed at %d: %s", __LINE__,gpg_strerror (rc));
+      if (!(++i%7))
+        gpgrt_yield ();
+    }
+  return THREAD_RET_VALUE;
+}
+
+
+/* This is one of our accountants.  */
+static THREAD_RET_TYPE
+accountant_thread (void *arg)
+{
+  gpg_err_code_t rc;
+  int i;
+  int acc1, acc2;
+  int value;
+
+  (void)arg;
+
+  for (i = 0; i < N_TRANSACTIONS; i++)
+    {
+      rc = gpgrt_lock_lock (&accounts_lock);
+      if (rc)
+        fail ("gpgrt_lock_lock failed at %d: %s", __LINE__, gpg_strerror (rc));
+
+      acc1 = pick_account ();
+      acc2 = pick_account ();
+      value = pick_value ();
+      account[acc1] += value;
+      account[acc2] -= value;
+
+      rc = gpgrt_lock_unlock (&accounts_lock);
+      if (rc)
+        fail ("gpgrt_lock_unlock failed at %d: %s", __LINE__,gpg_strerror (rc));
+      if (i && !(i%8))
+        gpgrt_yield ();
+    }
+  return THREAD_RET_VALUE;
+}
+
+
+static void
+run_test (void)
+{
+#ifdef _WIN32
+  HANDLE rthread;
+  HANDLE athreads[N_ACCOUNTANTS];
+  int i;
+  int rc;
+
+  stop_revision_thread = 0;
+  rthread = CreateThread (NULL, 0, revision_thread, NULL, 0, NULL);
+  if (!rthread)
+    die ("error creating revision thread: rc=%d", (int)GetLastError ());
+
+  for (i=0; i < N_ACCOUNTANTS; i++)
+    {
+      athreads[i] = CreateThread (NULL, 0, accountant_thread, NULL, 0, NULL);
+      if (!athreads[i])
+        die ("error creating accountant thread %d: rc=%d",
+             i, (int)GetLastError ());
+    }
+
+  for (i=0; i < N_ACCOUNTANTS; i++)
+    {
+      rc = WaitForSingleObject (athreads[i], INFINITE);
+      if (rc == WAIT_OBJECT_0)
+        show ("accountant thread %d has terminated", i);
+      else
+        fail ("waiting for accountant thread %d failed: %d",
+              i, (int)GetLastError ());
+      CloseHandle (athreads[i]);
+    }
+  stop_revision_thread = 1;
+
+  rc = WaitForSingleObject (rthread, INFINITE);
+  if (rc == WAIT_OBJECT_0)
+    show ("revision thread has terminated");
+  else
+    fail ("waiting for revision thread failed: %d", (int)GetLastError ());
+  CloseHandle (rthread);
+
+#else /*!_WIN32*/
+  pthread_t rthread;
+  pthread_t athreads[N_ACCOUNTANTS];
+  int i;
+
+  stop_revision_thread = 0;
+  pthread_create (&rthread, NULL, revision_thread, NULL);
+
+  for (i=0; i < N_ACCOUNTANTS; i++)
+    pthread_create (&athreads[i], NULL, accountant_thread, NULL);
+
+  for (i=0; i < N_ACCOUNTANTS; i++)
+    {
+      pthread_join (athreads[i], NULL);
+      show ("accountant thread %d has terminated", i);
+    }
+
+  stop_revision_thread = 1;
+  pthread_join (rthread, NULL);
+  show ("revision thread has terminated");
+
+#endif /*!_WIN32*/
+
+  gpgrt_lock_destroy (&accounts_lock);
+}
+
+
+int
+main (int argc, char **argv)
+{
+  int last_argc = -1;
+  int rc;
+
+  if (argc)
+    {
+      argc--; argv++;
+    }
+  while (argc && last_argc != argc )
+    {
+      last_argc = argc;
+      if (!strcmp (*argv, "--help"))
+        {
+          puts (
+"usage: ./t-lock [options]\n"
+"\n"
+"Options:\n"
+"  --verbose      Show what is going on\n"
+"  --debug        Flyswatter\n"
+);
+          exit (0);
+        }
+      if (!strcmp (*argv, "--verbose"))
+        {
+          verbose = 1;
+          argc--; argv++;
+        }
+      else if (!strcmp (*argv, "--debug"))
+        {
+          verbose = debug = 1;
+          argc--; argv++;
+        }
+    }
+
+  srand (time(NULL)*getpid());
+
+  if (!gpg_error_check_version (GPG_ERROR_VERSION))
+    {
+      die ("gpg_error_check_version returned an error");
+      errorcount++;
+    }
+
+  init_accounts ();
+  check_accounts ();
+  run_test ();
+  check_accounts ();
+  /* Run a second time to check deinit code.  */
+  run_test ();
+  check_accounts ();
+  /* And a third time to test an explicit init.  */
+  rc = gpgrt_lock_init (&accounts_lock);
+  if (rc)
+    fail ("gpgrt_lock_init failed at %d: %s", __LINE__, gpg_strerror (rc));
+  run_test ();
+  check_accounts ();
+  if (verbose)
+    print_accounts ();
+
+  return errorcount ? 1 : 0;
+}