gst/gst.c: If the fork()'ed child process can't write the updated registry cache...

Original commit message from CVS:
* gst/gst.c: (scan_and_update_registry), (init_post):
If the fork()'ed child process can't write the updated registry cache
file to disk for some reason, make it exit with a failure exit code,
so that the parent can then re-scan the plugins itself and update the
registry structures in memory and work with that (rather than failing
when creating elements because seemingly no plugins are available).
Refactor registry scanning code into separate function for this and
also separate fork() and non-fork() code paths. Fixes #344748.

diff --git a/ChangeLog b/ChangeLog
index c8edef5..0bb4d21 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2006-06-13  Tim-Philipp Müller  <tim at centricular dot net>
+
+       * gst/gst.c: (scan_and_update_registry), (init_post):
+         If the fork()'ed child process can't write the updated registry cache
+         file to disk for some reason, make it exit with a failure exit code,
+         so that the parent can then re-scan the plugins itself and update the
+         registry structures in memory and work with that (rather than failing
+         when creating elements because seemingly no plugins are available).
+         Refactor registry scanning code into separate function for this and
+         also separate fork() and non-fork() code paths. Fixes #344748.
+
 2006-06-13  Wim Taymans  <wim@fluendo.com>
 
        * docs/manual/advanced-dataaccess.xml:

diff --git a/gst/gst.c b/gst/gst.c
index c327f77..81d0c10 100644 (file)
--- a/gst/gst.c
+++ b/gst/gst.c
@@ -543,6 +543,100 @@ static GstPluginDesc plugin_desc = {
   GST_PADDING_INIT
 };
 
+#ifndef GST_DISABLE_REGISTRY
+
+static gboolean
+scan_and_update_registry (GstRegistry * default_registry,
+    const gchar * registry_file, gboolean write_changes)
+{
+  const gchar *plugin_path;
+  gboolean changed = FALSE;
+  GList *l;
+
+  GST_DEBUG ("reading registry cache: %s", registry_file);
+  gst_registry_xml_read_cache (default_registry, registry_file);
+
+  /* scan paths specified via --gst-plugin-path */
+  GST_DEBUG ("scanning paths added via --gst-plugin-path");
+  for (l = plugin_paths; l != NULL; l = l->next) {
+    GST_INFO ("Scanning plugin path: \"%s\"", (gchar *) l->data);
+    /* CHECKME: add changed |= here as well? */
+    gst_registry_scan_path (default_registry, (gchar *) l->data);
+    g_free (l->data);
+  }
+  g_list_free (plugin_paths);
+  plugin_paths = NULL;
+
+  /* GST_PLUGIN_PATH specifies a list of directories to scan for
+   * additional plugins.  These take precedence over the system plugins */
+  plugin_path = g_getenv ("GST_PLUGIN_PATH");
+  if (plugin_path) {
+    char **list;
+    int i;
+
+    GST_DEBUG ("GST_PLUGIN_PATH set to %s", plugin_path);
+    list = g_strsplit (plugin_path, G_SEARCHPATH_SEPARATOR_S, 0);
+    for (i = 0; list[i]; i++) {
+      changed |= gst_registry_scan_path (default_registry, list[i]);
+    }
+    g_strfreev (list);
+  } else {
+    GST_DEBUG ("GST_PLUGIN_PATH not set");
+  }
+
+  /* GST_PLUGIN_SYSTEM_PATH specifies a list of plugins that are always
+   * loaded by default.  If not set, this defaults to the system-installed
+   * path, and the plugins installed in the user's home directory */
+  plugin_path = g_getenv ("GST_PLUGIN_SYSTEM_PATH");
+  if (plugin_path == NULL) {
+    char *home_plugins;
+
+    GST_DEBUG ("GST_PLUGIN_SYSTEM_PATH not set");
+
+    /* plugins in the user's home directory take precedence over
+     * system-installed ones */
+    home_plugins = g_build_filename (g_get_home_dir (),
+        ".gstreamer-" GST_MAJORMINOR, "plugins", NULL);
+    changed |= gst_registry_scan_path (default_registry, home_plugins);
+    g_free (home_plugins);
+
+    /* add the main (installed) library path */
+    changed |= gst_registry_scan_path (default_registry, PLUGINDIR);
+  } else {
+    gchar **list;
+    gint i;
+
+    GST_DEBUG ("GST_PLUGIN_SYSTEM_PATH set to %s", plugin_path);
+    list = g_strsplit (plugin_path, G_SEARCHPATH_SEPARATOR_S, 0);
+    for (i = 0; list[i]; i++) {
+      changed |= gst_registry_scan_path (default_registry, list[i]);
+    }
+    g_strfreev (list);
+  }
+
+  if (!changed) {
+    GST_DEBUG ("registry cache has not changed");
+    return TRUE;
+  }
+
+  if (!write_changes) {
+    GST_DEBUG ("not trying to write registry cache changes to file");
+    return TRUE;
+  }
+
+  GST_DEBUG ("writing registry cache");
+  if (!gst_registry_xml_write_cache (default_registry, registry_file)) {
+    g_warning ("Problem writing registry cache to %s: %s", registry_file,
+        g_strerror (errno));
+    return FALSE;
+  }
+
+  GST_DEBUG ("registry cache written successfully");
+  return TRUE;
+}
+
+#endif /* GST_DISABLE_REGISTRY */
+
 /*
  * this bit handles:
  * - initalization of threads if we use them
@@ -598,24 +692,12 @@ init_post (void)
 #ifndef GST_DISABLE_REGISTRY
   {
     char *registry_file;
-    const char *plugin_path;
     GstRegistry *default_registry;
-    gboolean changed = FALSE;
-    GList *l;
 
 #ifdef HAVE_FORK
     pid_t pid;
 #endif
 
-    for (l = plugin_paths; l != NULL; l = l->next) {
-      GST_INFO ("Scanning plugin path: \"%s\"", (gchar *) l->data);
-      /* CHECKME: add changed |= here as well? */
-      gst_registry_scan_path (gst_registry_get_default (), (gchar *) l->data);
-      g_free (l->data);
-    }
-    g_list_free (plugin_paths);
-    plugin_paths = NULL;
-
     default_registry = gst_registry_get_default ();
     registry_file = g_strdup (g_getenv ("GST_REGISTRY"));
     if (registry_file == NULL) {
@@ -635,71 +717,18 @@ init_post (void)
     }
 
     if (pid == 0) {
-      /* this is the child */
-#endif /* HAVE_FORK */
+      gboolean res;
 
+      /* this is the child */
       GST_DEBUG ("child reading registry cache");
-      gst_registry_xml_read_cache (default_registry, registry_file);
-
-      /* GST_PLUGIN_PATH specifies a list of directories to scan for
-       * additional plugins.  These take precedence over the system plugins */
-      plugin_path = g_getenv ("GST_PLUGIN_PATH");
-      if (plugin_path) {
-        char **list;
-        int i;
-
-        GST_DEBUG ("GST_PLUGIN_PATH set to %s", plugin_path);
-        list = g_strsplit (plugin_path, G_SEARCHPATH_SEPARATOR_S, 0);
-        for (i = 0; list[i]; i++) {
-          changed |= gst_registry_scan_path (default_registry, list[i]);
-        }
-        g_strfreev (list);
-      } else {
-        GST_DEBUG ("GST_PLUGIN_PATH not set");
-      }
-
-      /* GST_PLUGIN_SYSTEM_PATH specifies a list of plugins that are always
-       * loaded by default.  If not set, this defaults to the system-installed
-       * path, and the plugins installed in the user's home directory */
-      plugin_path = g_getenv ("GST_PLUGIN_SYSTEM_PATH");
-      if (plugin_path == NULL) {
-        char *home_plugins;
-
-        GST_DEBUG ("GST_PLUGIN_SYSTEM_PATH not set");
-
-        /* plugins in the user's home directory take precedence over
-         * system-installed ones */
-        home_plugins = g_build_filename (g_get_home_dir (),
-            ".gstreamer-" GST_MAJORMINOR, "plugins", NULL);
-        changed |= gst_registry_scan_path (default_registry, home_plugins);
-        g_free (home_plugins);
-
-        /* add the main (installed) library path */
-        changed |= gst_registry_scan_path (default_registry, PLUGINDIR);
-      } else {
-        char **list;
-        int i;
-
-        GST_DEBUG ("GST_PLUGIN_SYSTEM_PATH set to %s", plugin_path);
-        list = g_strsplit (plugin_path, G_SEARCHPATH_SEPARATOR_S, 0);
-        for (i = 0; list[i]; i++) {
-          changed |= gst_registry_scan_path (default_registry, list[i]);
-        }
-        g_strfreev (list);
-      }
-
-      if (changed) {
-        GST_DEBUG ("writing registry cache");
-        gst_registry_xml_write_cache (default_registry, registry_file);
-      }
-
+      res = scan_and_update_registry (default_registry, registry_file, TRUE);
       _gst_registry_remove_cache_plugins (default_registry);
-
-#ifdef HAVE_FORK
       g_free (registry_file);
+
       /* need to use _exit, so that any exit handlers registered don't
        * bring down the main program */
-      _exit (0);
+      GST_DEBUG ("child exiting: %s", (res) ? "SUCCESS" : "FAILURE");
+      _exit ((res) ? EXIT_SUCCESS : EXIT_FAILURE);
     } else {
       /* parent */
       int status;
@@ -720,9 +749,22 @@ init_post (void)
 
       GST_DEBUG ("child exited normally with return value %d",
           WEXITSTATUS (status));
-      GST_DEBUG ("parent reading registry cache");
-      gst_registry_xml_read_cache (default_registry, registry_file);
+
+      if (WEXITSTATUS (status) == EXIT_SUCCESS) {
+        GST_DEBUG ("parent reading registry cache");
+        gst_registry_xml_read_cache (default_registry, registry_file);
+      } else {
+        GST_DEBUG ("parent re-scanning registry");
+        scan_and_update_registry (default_registry, registry_file, FALSE);
+      }
     }
+
+#else /* HAVE_FORK */
+
+    /* fork() not available */
+    GST_DEBUG ("updating registry cache");
+    scan_and_update_registry (default_registry, registry_file, TRUE);
+
 #endif /* HAVE_FORK */
 
     g_free (registry_file);