1 files changed, 47 insertions, 0 deletions
diff --git a/gl/m4/lock.m4 b/gl/m4/lock.m4
new file mode 100644
index 0000000..88cf557
--- /dev/null
+++ b/gl/m4/lock.m4
@@ -0,0 +1,47 @@
+# lock.m4 serial 14
+dnl Copyright (C) 2005-2023 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.
+
+AC_DEFUN([gl_LOCK],
+[
+  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.
+    has_rwlock=false
+    AC_CHECK_TYPE([pthread_rwlock_t],
+      [has_rwlock=true
+       AC_DEFINE([HAVE_PTHREAD_RWLOCK], [1],
+         [Define if the POSIX multithreading library has read/write locks.])],
+      [],
+      [#include <pthread.h>])
+    if $has_rwlock; then
+      gl_PTHREAD_RWLOCK_RDLOCK_PREFER_WRITER
+    fi
+    # 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;
+return !x;
+#endif
+        ]])],
+      [AC_DEFINE([HAVE_PTHREAD_MUTEX_RECURSIVE], [1],
+         [Define if the <pthread.h> defines PTHREAD_MUTEX_RECURSIVE.])])
+  fi
+  gl_PREREQ_LOCK
+])
+
+# Prerequisites of lib/glthread/lock.c.
+AC_DEFUN([gl_PREREQ_LOCK], [:])