[glib] Emit meaningful error messages

[Matthias Clasen <matthiasc src gnome org>]

commit de0d7a335c76cd158f69d83788985ed05db5756b
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Jan 30 17:53:48 2012 -0500

    Emit meaningful error messages
    
    That is useful, even if this is only an internal tool.
    I have been scratching my head why this tool would
    break distcheck...

 gio/data-to-c.c |   13 ++++++++++---
 1 files changed, 10 insertions(+), 3 deletions(-)
---
diff --git a/gio/data-to-c.c b/gio/data-to-c.c
index b20369f..9dcf286 100644
--- a/gio/data-to-c.c
+++ b/gio/data-to-c.c
@@ -26,12 +26,19 @@ main (int argc, char **argv)
 {
   char *content;
   int i;
+  GError *error = NULL;
 
   if (argc != 3)
-    return 1;
+    {
+      g_printerr ("Usage: data-to-c <filename> <variable>");
+      return 1;
+    }
 
-  if (!g_file_get_contents (argv[1], &content, NULL, NULL))
-    return 1;
+  if (!g_file_get_contents (argv[1], &content, NULL, &error))
+    {
+      g_printerr ("%s", error->message);
+      return 1;
+    }
 
   g_print ("const char %s[] = \"", argv[2]);