shm: Fix compilation of shm on OSX

https://bugzilla.gnome.org/show_bug.cgi?id=689183

configure.ac

@@ -682,15 +682,24 @@ AG_GST_CHECK_FEATURE(QUICKTIME, [QuickTime wrapper], qtwrapper, [
 dnl check for shm_open (for shm plugin)
 translit(dnm, m, l) AM_CONDITIONAL(USE_SHM, true)
 AG_GST_CHECK_FEATURE(SHM, [POSIX shared memory source and sink], shm, [
-  if test "x$HAVE_SYS_SOCKET_H" = "xyes"; then
-    AC_CHECK_LIB([rt], [shm_open],
-       AC_CHECK_DECL([MSG_NOSIGNAL], HAVE_SHM=yes, HAVE_SHM=no, [
-#include <sys/socket.h>
-	 ]),
-	 HAVE_SHM=no)
-  else
-    HAVE_SHM=no
-  fi
+    if test "x$HAVE_SYS_SOCKET_H" = "xyes"; then
+        case $host in
+        *-darwin* | *-macos10*)
+            AM_CONDITIONAL([HAVE_OSX], true)
+            AC_DEFINE(HAVE_OSX,[1],[Apple Mac OS X operating system detected])
+            HAVE_SHM=yes
+            ;;
+        *)
+            AC_CHECK_LIB([rt], [shm_open],
+                AC_CHECK_DECL([MSG_NOSIGNAL], HAVE_SHM=yes, HAVE_SHM=no, [
+                #include <sys/socket.h>
+  	            ]),
+                HAVE_SHM=no)
+            ;;
+        esac
+    else
+        HAVE_SHM=no
+    fi
 ])
 
 dnl check for Video CD

sys/shm/Makefile.am

@@ -2,8 +2,14 @@ plugin_LTLIBRARIES = libgstshm.la
 
 libgstshm_la_SOURCES = shmpipe.c shmalloc.c gstshm.c gstshmsrc.c gstshmsink.c
 libgstshm_la_CFLAGS = $(GST_PLUGINS_BAD_CFLAGS) $(GST_CFLAGS) -DSHM_PIPE_USE_GLIB
-libgstshm_la_LIBADD = -lrt
 libgstshm_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS) $(GST_BASE_LIBS)
+
+if HAVE_OSX
+libgstshm_la_LIBADD =
+else
+libgstshm_la_LIBADD = -lrt
+endif
+
 libgstshm_la_LIBTOOLFLAGS = --tag=disable-static
 
 noinst_HEADERS = gstshmsrc.h gstshmsink.h shmpipe.h  shmalloc.h

sys/shm/shmpipe.c

@@ -27,6 +27,12 @@
 #include "config.h"
 #endif
 
+#ifdef HAVE_OSX
+#ifndef MSG_NOSIGNAL
+#define MSG_NOSIGNAL SO_NOSIGPIPE
+#endif
+#endif
+
 #include "shmpipe.h"
 
 #include <sys/types.h>
@@ -278,7 +284,11 @@ sp_open_shm (char *path, int id, mode_t perms, size_t size)
   if (path)
     flags = O_RDONLY;
   else
+#ifdef HAVE_OSX
+    flags = O_RDWR | O_CREAT | O_EXCL;
+#else
     flags = O_RDWR | O_CREAT | O_TRUNC | O_EXCL;
+#endif
 
   area->shm_fd = -1;