sys/: it's not legal to ask the

Original commit message from CVS:
* sys/ximage/ximagesink.c: (gst_ximagesink_check_xshm_calls),
(gst_ximagesink_ximage_new):
* sys/xvimage/xvimagesink.c: (gst_xvimagesink_check_xshm_calls),
(gst_xvimagesink_xvimage_new):
Apparently on Solaris and OS/X (at least), it's not legal to ask the
X server to attach to a shared memory segment after we've deleted it,
with the result that MIT-SHM is disabled. Instead, remove it only after
X succeeds in attaching too.

ChangeLog

@@ -1,3 +1,15 @@
+2008-07-17  Jan Schmidt  <Jan.Schmidt@sun.com>
+
+	* sys/ximage/ximagesink.c: (gst_ximagesink_check_xshm_calls),
+	(gst_ximagesink_ximage_new):
+	* sys/xvimage/xvimagesink.c: (gst_xvimagesink_check_xshm_calls),
+	(gst_xvimagesink_xvimage_new):
+
+	Apparently on Solaris and OS/X (at least), it's not legal to ask the
+	X server to attach to a shared memory segment after we've deleted it,
+	with the result that MIT-SHM is disabled. Instead, remove it only after 
+	X succeeds in attaching too.
+
 2008-07-16  David Schleef  <ds@schleef.org>
 
 	* gst/audiotestsrc/gstaudiotestsrc.c:

sys/ximage/ximagesink.c

@@ -361,22 +361,24 @@ gst_ximagesink_check_xshm_calls (GstXImageSink * ximagesink,
     goto beach;
   }
 
-  /* Delete the shared memory segment as soon as we manage to attach. 
-   * This way, it will be deleted as soon as we detach later, and not
-   * leaked if we crash. */
-  shmctl (SHMInfo.shmid, IPC_RMID, NULL);
-
   ximage->data = SHMInfo.shmaddr;
   SHMInfo.readOnly = FALSE;
 
   if (XShmAttach (xcontext->disp, &SHMInfo) == 0) {
     GST_WARNING ("Failed to XShmAttach");
+    /* Clean up shm seg */
+    shmctl (SHMInfo.shmid, IPC_RMID, NULL);
     goto beach;
   }
 
   /* Sync to ensure we see any errors we caused */
   XSync (xcontext->disp, FALSE);
 
+  /* Delete the shared memory segment as soon as everyone is attached. 
+   * This way, it will be deleted as soon as we detach later, and not
+   * leaked if we crash. */
+  shmctl (SHMInfo.shmid, IPC_RMID, NULL);
+
   if (!error_caught) {
     did_attach = TRUE;
     /* store whether we succeeded in result */
@@ -480,15 +482,13 @@ gst_ximagesink_ximage_new (GstXImageSink * ximagesink, GstCaps * caps)
       goto beach;
     }
 
-    /* Now that we've attached, we can delete the shared memory segment.
-     * This way, it will be deleted as soon as we detach later, and not
-     * leaked if we crash. */
-    shmctl (ximage->SHMInfo.shmid, IPC_RMID, NULL);
-
     ximage->ximage->data = ximage->SHMInfo.shmaddr;
     ximage->SHMInfo.readOnly = FALSE;
 
     if (XShmAttach (ximagesink->xcontext->disp, &ximage->SHMInfo) == 0) {
+      /* Clean up shm seg */
+      shmctl (ximage->SHMInfo.shmid, IPC_RMID, NULL);
+
       g_mutex_unlock (ximagesink->x_lock);
       GST_ELEMENT_ERROR (ximagesink, RESOURCE, WRITE,
           ("Failed to create output image buffer of %dx%d pixels",
@@ -497,6 +497,12 @@ gst_ximagesink_ximage_new (GstXImageSink * ximagesink, GstCaps * caps)
     }
 
     XSync (ximagesink->xcontext->disp, FALSE);
+
+    /* Now that everyone has attached, we can delete the shared memory segment.
+     * This way, it will be deleted as soon as we detach later, and not
+     * leaked if we crash. */
+    shmctl (ximage->SHMInfo.shmid, IPC_RMID, NULL);
+
   } else
 #endif /* HAVE_XSHM */
   {

sys/xvimage/xvimagesink.c

@@ -426,9 +426,9 @@ gst_xvimagesink_check_xshm_calls (GstXContext * xcontext)
   handler = XSetErrorHandler (gst_xvimagesink_handle_xerror);
 
   /* Trying to create a 1x1 picture */
-  GST_DEBUG ("XvShmCreateImage of 1x1");
+  GST_DEBUG ("XvShmCreateImage of 100x100");
   xvimage = XvShmCreateImage (xcontext->disp, xcontext->xv_port_id,
-      xcontext->im_format, NULL, 1, 1, &SHMInfo);
+      xcontext->im_format, NULL, 100, 100, &SHMInfo);
 
   /* Might cause an error, sync to ensure it is noticed */
   XSync (xcontext->disp, FALSE);
@@ -452,29 +452,34 @@ gst_xvimagesink_check_xshm_calls (GstXContext * xcontext)
     goto beach;
   }
 
-  /* Delete the shared memory segment as soon as we manage to attach.
-   * This way, it will be deleted as soon as we detach later, and not
-   * leaked if we crash. */
-  shmctl (SHMInfo.shmid, IPC_RMID, NULL);
-
   xvimage->data = SHMInfo.shmaddr;
   SHMInfo.readOnly = FALSE;
 
   if (XShmAttach (xcontext->disp, &SHMInfo) == 0) {
     GST_WARNING ("Failed to XShmAttach");
+    /* Clean up the shared memory segment */
+    shmctl (SHMInfo.shmid, IPC_RMID, NULL);
     goto beach;
   }
 
   /* Sync to ensure we see any errors we caused */
   XSync (xcontext->disp, FALSE);
 
-  GST_DEBUG ("XServer ShmAttached to 0x%x, id 0x%lx", SHMInfo.shmid,
+  /* Delete the shared memory segment as soon as everyone is attached.
-      SHMInfo.shmseg);
+   * This way, it will be deleted as soon as we detach later, and not
+   * leaked if we crash. */
+  shmctl (SHMInfo.shmid, IPC_RMID, NULL);
 
   if (!error_caught) {
+    GST_DEBUG ("XServer ShmAttached to 0x%x, id 0x%lx", SHMInfo.shmid,
+        SHMInfo.shmseg);
+
     did_attach = TRUE;
     /* store whether we succeeded in result */
     result = TRUE;
+  } else {
+    GST_WARNING ("MIT-SHM extension check failed at XShmAttach. "
+        "Not using shared memory.");
   }
 
 beach:
@@ -626,15 +631,13 @@ gst_xvimagesink_xvimage_new (GstXvImageSink * xvimagesink, GstCaps * caps)
       goto beach_unlocked;
     }
 
-    /* Delete the shared memory segment as soon as we manage to attach.
-     * This way, it will be deleted as soon as we detach later, and not
-     * leaked if we crash. */
-    shmctl (xvimage->SHMInfo.shmid, IPC_RMID, NULL);
-
     xvimage->xvimage->data = xvimage->SHMInfo.shmaddr;
     xvimage->SHMInfo.readOnly = FALSE;
 
     if (XShmAttach (xvimagesink->xcontext->disp, &xvimage->SHMInfo) == 0) {
+      /* Clean up the shared memory segment */
+      shmctl (xvimage->SHMInfo.shmid, IPC_RMID, NULL);
+
       g_mutex_unlock (xvimagesink->x_lock);
       GST_ELEMENT_ERROR (xvimagesink, RESOURCE, WRITE,
           ("Failed to create output image buffer of %dx%d pixels",
@@ -643,6 +646,12 @@ gst_xvimagesink_xvimage_new (GstXvImageSink * xvimagesink, GstCaps * caps)
     }
 
     XSync (xvimagesink->xcontext->disp, FALSE);
+
+    /* Delete the shared memory segment as soon as we everyone is attached.
+     * This way, it will be deleted as soon as we detach later, and not
+     * leaked if we crash. */
+    shmctl (xvimage->SHMInfo.shmid, IPC_RMID, NULL);
+
     GST_DEBUG_OBJECT (xvimagesink, "XServer ShmAttached to 0x%x, id 0x%lx",
         xvimage->SHMInfo.shmid, xvimage->SHMInfo.shmseg);
   } else