querymodules: Add --system argument

When run as a system trigger, we really don't want to be consulting
e.g. /root/.pangorc.  Also, the OSTree build system can run as
non-root, but we don't in this case want to look at /home/user since
the user may not even exist in the password database inside the
chroot.

https://bugzilla.gnome.org/show_bug.cgi?id=667960

2 files changed, 61 insertions, 15 deletions

diff --git a/pango/pango-utils.c b/pango/pango-utils.c
index 44ec353d..8177dab2 100644
--- a/pango/pango-utils.c
+++ b/pango/pango-utils.c
@@ -532,6 +532,7 @@ pango_scan_int (const char **pos, int *out)
 }
 
 static GHashTable *config_hash = NULL;
+static gboolean did_read_user_config = FALSE;
 
 static void
 read_config_file (const char *filename, gboolean enoent_error)
@@ -604,23 +605,41 @@ read_config_file (const char *filename, gboolean enoent_error)
 }
 
 static void
-read_config (void)
+ensure_config_hash (void)
 {
   if (!config_hash)
-    {
-      char *filename;
-      const char *home;
-      const char *envvar;
-
-      config_hash = g_hash_table_new_full (g_str_hash, g_str_equal,
-					   (GDestroyNotify)g_free,
-					   (GDestroyNotify)g_free);
-      filename = g_build_filename (pango_get_sysconf_subdirectory (),
-				   "pangorc",
-				   NULL);
-      read_config_file (filename, FALSE);
-      g_free (filename);
+    config_hash = g_hash_table_new_full (g_str_hash, g_str_equal,
+					 (GDestroyNotify)g_free,
+					 (GDestroyNotify)g_free);
+}
+
+static void
+read_config_system (void)
+{
+  char *filename;
+
+  ensure_config_hash ();
+
+  filename = g_build_filename (pango_get_sysconf_subdirectory (),
+			       "pangorc",
+			       NULL);
+  read_config_file (filename, FALSE);
+  g_free (filename);
+}
+
+static void
+read_config (void)
+{
+  char *filename;
+  const char *home;
+  const char *envvar;
 
+  read_config_system ();
+
+  if (!did_read_user_config)
+    {
+      did_read_user_config = TRUE;
+  
       home = g_get_home_dir ();
       if (home && *home)
 	{
@@ -636,6 +655,26 @@ read_config (void)
 }
 
 /**
+ * pango_config_key_get_system:
+ * @key: Key to look up, in the form "SECTION/KEY".
+ *
+ * Looks up a key, consulting only the Pango system config database
+ * in $sysconfdir/pango/pangorc.
+ *
+ * Return value: the value, if found, otherwise %NULL. The value is a
+ * newly-allocated string and must be freed with g_free().
+ **/
+char *
+pango_config_key_get_system (const char *key)
+{
+  g_return_val_if_fail (key != NULL, NULL);
+
+  read_config_system ();
+
+  return g_strdup (g_hash_table_lookup (config_hash, key));
+}
+
+/**
  * pango_config_key_get:
  * @key: Key to look up, in the form "SECTION/KEY".
  *
diff --git a/pango/querymodules.c b/pango/querymodules.c
index ef2d09a3..a1eec703 100644
--- a/pango/querymodules.c
+++ b/pango/querymodules.c
@@ -44,6 +44,8 @@
 #endif
 #define SOEXT_LEN ((int) strlen (SOEXT))
 
+static gboolean system_mode;
+
 static gboolean
 string_needs_escape (const char *str)
 {
@@ -205,6 +207,8 @@ main (int argc, char **argv)
     {
       {"version",	0, G_OPTION_FLAG_NO_ARG, G_OPTION_ARG_CALLBACK, &show_version,
        "Show version numbers",                                             NULL},
+      {"system",	0, 0, G_OPTION_ARG_NONE, &system_mode,
+       "Do not load configuration from home directory", NULL},
       {NULL}
     };
 
@@ -237,7 +241,10 @@ main (int argc, char **argv)
       char **dirs;
       int i;
 
-      path = pango_config_key_get ("Pango/ModulesPath");
+      if (system_mode)
+	path = pango_config_key_get_system ("Pango/ModulesPath");
+      else
+	path = pango_config_key_get ("Pango/ModulesPath");
       if (!path)
 	path = g_build_filename (pango_get_lib_subdirectory (),
 				 MODULE_VERSION,