Almost completely rewritten gstreamer-register.

Original commit message from CVS:
Almost completely rewritten gstreamer-register.
Now checks most errors that can happen, and displays a useful message.

tools/gstreamer-register.c

@@ -1,21 +1,127 @@
+/* GStreamer
+ * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
+ *                    2000 Wim Taymans <wtay@chello.be>
+ *
+ * gstreamer-register.c: Plugin subsystem for loading elements, types, and libs
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
 #include <stdlib.h>
 #include <gst/gst.h>
 
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <string.h>
+#include <errno.h>
+
+#define GST_CONFIG_DIR           "/etc/gstreamer"
+#define GLOBAL_REGISTRY_FILE     GST_CONFIG_DIR"/reg.xml"
+#define GLOBAL_REGISTRY_FILE_TMP GST_CONFIG_DIR"/.reg.xml.tmp"
+
 extern gboolean _gst_plugin_spew;
 
+static void error_perm() {
+    g_print("\n(%s)\n"
+	    "Do you have the appropriate permissions?\n"
+	    "You may need to be root to run this command.\n\n",
+	    strerror(errno));
+    exit(1);
+}
+
+static void usage(const char *progname) {
+    g_print("usage: %s\n", progname);
+    g_print("Builds the plugin registry for gstreamer.\n");
+    g_print("This command will usually require superuser privileges.\n\n");
+    exit(0);
+}
+
+static int is_file(const char * filename) {
+  struct stat statbuf;
+  if(stat(filename, &statbuf)) return 0;
+  return S_ISREG(statbuf.st_mode);
+}
+
+static int is_dir(const char * filename) {
+  struct stat statbuf;
+  if(stat(filename, &statbuf)) return 0;
+  return S_ISDIR(statbuf.st_mode);
+}
+
+static void move_file(const char * nameold, const char * namenew) {
+    if (!is_file(nameold)) {
+	g_print("Temporary `%s' is not a file", nameold);
+	error_perm();
+    }
+    if (is_dir(namenew)) {
+	g_print("Destination path `%s' is a directory\n", namenew);
+	g_print("Please remove, or reconfigure GStreamer\n\n");
+	exit(1);
+    }
+    if (rename(nameold, namenew)) {
+	g_print("Cannot move `%s' to `%s'", nameold, namenew);
+	error_perm();
+    }
+}
+
+static int make_dir(const char * dirname) {
+    mode_t mode = 0766;
+    return !mkdir(dirname, mode);
+}
+
+void check_dir(const char * dirname) {
+    if (!is_dir(dirname)) {
+	if (!make_dir(dirname)) {
+	    g_print("Cannot create GStreamer registry directory `%s'",
+		    dirname);
+	    error_perm();
+	}
+    }
+}
+
 int main(int argc,char *argv[]) 
 {
-  xmlDocPtr doc;
+    xmlDocPtr doc;
 
-  unlink("/etc/gstreamer/reg.xml");
+    if (argc != 1) usage(argv[0]);
 
-  _gst_plugin_spew = TRUE;
-  gst_init(&argc,&argv);
+    // Check that directory for config exists
+    check_dir(GST_CONFIG_DIR);
+    
+    // Read the plugins
+    _gst_plugin_spew = TRUE;
+    gst_init(&argc,&argv);
+    doc = xmlNewDoc("1.0");
+    doc->root = xmlNewDocNode(doc, NULL, "GST-PluginRegistry", NULL);
+    gst_plugin_save_thyself(doc->root);
 
-  doc = xmlNewDoc("1.0");
-  doc->root = xmlNewDocNode(doc, NULL, "GST-PluginRegistry", NULL);
-  gst_plugin_save_thyself(doc->root);
-  xmlSaveFile("/etc/gstreamer/reg.xml", doc);
-  exit(0);
+    // Save the registry to a tmp file.
+    // FIXME; check for failure.
+    if (xmlSaveFile(GLOBAL_REGISTRY_FILE_TMP, doc)) {
+	g_print("Cannot save new registry `%s'",
+		GLOBAL_REGISTRY_FILE_TMP);
+	error_perm();
+    }
+
+    // Make the tmp file live.
+    move_file(GLOBAL_REGISTRY_FILE_TMP, GLOBAL_REGISTRY_FILE);
+
+    return(0);
 }