wp_new_files_iterator: refactor to behave like pipewire

Previously files would be sorted across all configuration dirs
so their filename was all that mattered, not the priority of the directory.

Ex. you could get:

- /etc/wireplumber/10-foo.conf
- /usr/share/wireplumber/20-bar.conf
- $XDG_CONFIG_HOME/wireplumber/30-baz.conf
- /usr/share/wireplumber/40-zzz.conf

This commit changes that so that it follows the hirerachy of the directories
first and then the order of the filenames, starting from the lowest priority
directory. So now for the same files you get:

- /usr/share/wireplumber/20-bar.conf
- /usr/share/wireplumber/40-zzz.conf
- /etc/wireplumber/10-foo.conf
- $XDG_CONFIG_HOME/wireplumber/30-baz.conf

In addition, the hash table is avoided, making things a bit more efficient
and the files are checked for G_FILE_TEST_IS_REGULAR

Shadowing of files still works the same, so in the above example
if /etc/wireplumber/30-baz.conf also exists, it is not returned
in the list, because it's shadowed by $XDG_CONFIG_HOME/wireplumber/30-baz.conf

lib/wp/wp.c

@@ -179,18 +179,30 @@ wp_find_file (WpLookupDirs dirs, const gchar *filename, const gchar *subdir)
   return NULL;
 }
 
+struct conffile_iterator_item
+{
+  gchar *filename;
+  gchar *path;
+};
+
+static void
+conffile_iterator_item_clear (struct conffile_iterator_item *item)
+{
+  g_free (item->filename);
+  g_free (item->path);
+}
+
 struct conffile_iterator_data
 {
-  GList *sorted_keys;
+  GArray *items;
-  GList *ptr;
+  guint idx;
-  GHashTable *ht;
 };
 
 static void
 conffile_iterator_reset (WpIterator *it)
 {
   struct conffile_iterator_data *it_data = wp_iterator_get_user_data (it);
-  it_data->ptr = it_data->sorted_keys;
+  it_data->idx = 0;
 }
 
 static gboolean
@@ -198,9 +210,10 @@ conffile_iterator_next (WpIterator *it, GValue *item)
 {
   struct conffile_iterator_data *it_data = wp_iterator_get_user_data (it);
 
-  if (it_data->ptr) {
+  if (it_data->idx < it_data->items->len) {
-    const gchar *path = g_hash_table_lookup (it_data->ht, it_data->ptr->data);
+    const gchar *path = g_array_index (it_data->items,
-    it_data->ptr = g_list_next (it_data->ptr);
+        struct conffile_iterator_item, it_data->idx).path;
+    it_data->idx++;
     g_value_init (item, G_TYPE_STRING);
     g_value_set_string (item, path);
     return TRUE;
@@ -214,9 +227,10 @@ conffile_iterator_fold (WpIterator *it, WpIteratorFoldFunc func, GValue *ret,
 {
   struct conffile_iterator_data *it_data = wp_iterator_get_user_data (it);
 
-  for (GList *ptr = it_data->sorted_keys; ptr != NULL; ptr = g_list_next (ptr)) {
+  for (guint i = 0; i < it_data->items->len; i++) {
     g_auto (GValue) item = G_VALUE_INIT;
-    const gchar *path = g_hash_table_lookup (it_data->ht, ptr->data);
+    const gchar *path = g_array_index (it_data->items,
+        struct conffile_iterator_item, i).path;
     g_value_init (&item, G_TYPE_STRING);
     g_value_set_string (&item, path);
     if (!func (&item, ret, data))
@@ -229,8 +243,7 @@ static void
 conffile_iterator_finalize (WpIterator *it)
 {
   struct conffile_iterator_data *it_data = wp_iterator_get_user_data (it);
-  g_list_free (it_data->sorted_keys);
+  g_clear_pointer (&it_data->items, g_array_unref);
-  g_hash_table_unref (it_data->ht);
 }
 
 static const WpIteratorMethods conffile_iterator_methods = {
@@ -241,17 +254,31 @@ static const WpIteratorMethods conffile_iterator_methods = {
   .finalize = conffile_iterator_finalize,
 };
 
+static gint
+conffile_iterator_item_compare (const struct conffile_iterator_item *a,
+    const struct conffile_iterator_item *b)
+{
+  return g_strcmp0 (a->filename, b->filename);
+}
+
 /*!
  * \brief Creates an iterator to iterate over configuration files in the
  * \a subdir of the configuration directories
  *
- * Files are sorted across the hierarchy of configuration and data
+ * The configuration directories are determined by the \a dirs parameter.
- * directories with files in higher-priority directories shadowing files in
+ * The \a subdir parameter is the name of the subdirectory to search in,
- * lower-priority directories. Files are only checked for existence, a
+ * inside the configuration directories. If \a subdir is NULL, the base path
- * caller must be able to handle read errors.
+ * of each configuration directory is used.
  *
- * \note the iterator may contain directories too; it is the responsibility
+ * The \a suffix parameter is the filename suffix to match. If \a suffix is
- * of the caller to ignore or recurse into those.
+ * NULL, all files are matched.
+ *
+ * The iterator will iterate over the absolute paths of the configuration
+ * files found, in the order of priority of the directories, starting from
+ * the lowest priority directory (e.g. /usr/share/wireplumber) and ending
+ * with the highest priority directory (e.g. $XDG_CONFIG_HOME/wireplumber).
+ *
+ * Files within each directory are also sorted by filename.
  *
  * \ingroup wp
  * \param dirs the directories to look into
@@ -259,33 +286,38 @@ static const WpIteratorMethods conffile_iterator_methods = {
  *   inside the configuration directories
  * \param suffix (nullable): The filename suffix, NULL matches all entries
  * \returns (transfer full): a new iterator iterating over strings which are
- *   absolute paths to the configuration files found
+ *   absolute paths to the files found
  * \since 0.4.2
  */
 WpIterator *
 wp_new_files_iterator (WpLookupDirs dirs, const gchar *subdir,
     const gchar *suffix)
 {
-  g_autoptr (GHashTable) ht =
+  g_autoptr (GArray) items =
-      g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_free);
+      g_array_new (FALSE, FALSE, sizeof (struct conffile_iterator_item));
   g_autoptr (GPtrArray) dir_paths = NULL;
 
+  g_array_set_clear_func (items, (GDestroyNotify) conffile_iterator_item_clear);
+
   if (subdir == NULL)
     subdir = ".";
 
   /* Note: this list is highest-priority first */
   dir_paths = lookup_dirs (dirs);
 
-  /* Store all filenames with their full path in the hashtable, overriding
+  /* Run backwards through the list to get files in lowest-priority-first order */
-   * previous values. We need to run backwards through the list for that */
   for (guint i = dir_paths->len; i > 0; i--) {
     g_autofree gchar *dirpath =
         g_build_filename (g_ptr_array_index (dir_paths, i - 1), subdir, NULL);
-    g_autoptr(GDir) dir = g_dir_open (dirpath, 0, NULL);
+    g_autoptr (GDir) dir = g_dir_open (dirpath, 0, NULL);
-
-    wp_trace ("searching config dir: %s", dirpath);
 
     if (dir) {
+      g_autoptr (GArray) dir_items = g_array_new (FALSE, FALSE,
+          sizeof (struct conffile_iterator_item));
+
+      wp_trace ("searching dir: %s", dirpath);
+
+      /* Store all filenames with their full path in the local array */
       const gchar *filename;
       while ((filename = g_dir_read_name (dir))) {
         if (filename[0] == '.')
@@ -294,21 +326,42 @@ wp_new_files_iterator (WpLookupDirs dirs, const gchar *subdir,
         if (suffix && !g_str_has_suffix (filename, suffix))
           continue;
 
-        g_hash_table_replace (ht, g_strdup (filename),
+        /* verify the file is regular and canonicalize the path */
-            g_build_filename (dirpath, filename, NULL));
+        g_autofree gchar *path = check_path (dirpath, NULL, filename);
+        if (!path)
+          continue;
+
+        /* remove item with the same filename from the global items array,
+           so that lower priority files can be shadowed */
+        for (guint j = 0; j < items->len; j++) {
+          struct conffile_iterator_item *item = &g_array_index (items,
+              struct conffile_iterator_item, j);
+          if (g_strcmp0 (item->filename, filename) == 0) {
+            g_array_remove_index (items, j);
+            break;
+          }
+        }
+
+        /* append in the local array */
+        g_array_append_val (dir_items, ((struct conffile_iterator_item) {
+          .filename = g_strdup (filename),
+          .path = g_steal_pointer (&path),
+        }));
       }
+
+      /* Sort files of the current dir by filename */
+      g_array_sort (dir_items, (GCompareFunc) conffile_iterator_item_compare);
+
+      /* Append the sorted files to the global array */
+      g_array_append_vals (items, dir_items->data, dir_items->len);
     }
   }
 
-  /* Sort by filename */
-  GList *keys = g_hash_table_get_keys (ht);
-  keys = g_list_sort (keys, (GCompareFunc)g_strcmp0);
-
   /* Construct iterator */
   WpIterator *it = wp_iterator_new (&conffile_iterator_methods,
       sizeof (struct conffile_iterator_data));
   struct conffile_iterator_data *it_data = wp_iterator_get_user_data (it);
-  it_data->sorted_keys = keys;
+  it_data->items = g_steal_pointer (&items);
-  it_data->ht = g_hash_table_ref (ht);
+  it_data->idx = 0;
   return g_steal_pointer (&it);
 }