[libsoup] SoupCache: fix setting default value for cache dir

[Cosimo Cecchi <cosimoc src gnome org>]

commit 2f2681fb51a3a02e3df287ead3f2829ae1e876a3
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Mon Oct 2 15:48:24 2017 -0700

    SoupCache: fix setting default value for cache dir
    
    The documentation mentions that a value of NULL can be used to let
    SoupCache use its default, but code currently tries to call
    g_file_test() on NULL in that case, which will cause a critical warning
    to be generated.
    
    Refactor how the cache dir default value is initialized to avoid that
    issue.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=788452

 libsoup/soup-cache.c |   37 ++++++++++++++-----------------------
 1 files changed, 14 insertions(+), 23 deletions(-)
---
diff --git a/libsoup/soup-cache.c b/libsoup/soup-cache.c
index 0963864..dbbc71f 100644
--- a/libsoup/soup-cache.c
+++ b/libsoup/soup-cache.c
@@ -949,8 +949,17 @@ soup_cache_set_property (GObject *object, guint prop_id,
 
        switch (prop_id) {
        case PROP_CACHE_DIR:
+               g_assert (!priv->cache_dir);
+
                priv->cache_dir = g_value_dup_string (value);
-               /* Create directory if it does not exist (FIXME: should we?) */
+
+               if (!priv->cache_dir)
+                       /* Set a default cache dir, different for each user */
+                       priv->cache_dir = g_build_filename (g_get_user_cache_dir (),
+                                                           "httpcache",
+                                                           NULL);
+
+               /* Create directory if it does not exist */
                if (!g_file_test (priv->cache_dir, G_FILE_TEST_EXISTS | G_FILE_TEST_IS_DIR))
                        g_mkdir_with_parents (priv->cache_dir, 0700);
                break;
@@ -984,32 +993,11 @@ soup_cache_get_property (GObject *object, guint prop_id,
 }
 
 static void
-soup_cache_constructed (GObject *object)
-{
-       SoupCachePrivate *priv;
-
-       priv = SOUP_CACHE (object)->priv;
-
-       if (!priv->cache_dir) {
-               /* Set a default cache dir, different for each user */
-               priv->cache_dir = g_build_filename (g_get_user_cache_dir (),
-                                                   "httpcache",
-                                                   NULL);
-               if (!g_file_test (priv->cache_dir, G_FILE_TEST_EXISTS | G_FILE_TEST_IS_DIR))
-                       g_mkdir_with_parents (priv->cache_dir, 0700);
-       }
-
-       if (G_OBJECT_CLASS (soup_cache_parent_class)->constructed)
-               G_OBJECT_CLASS (soup_cache_parent_class)->constructed (object);
-}
-
-static void
 soup_cache_class_init (SoupCacheClass *cache_class)
 {
        GObjectClass *gobject_class = (GObjectClass *)cache_class;
 
        gobject_class->finalize = soup_cache_finalize;
-       gobject_class->constructed = soup_cache_constructed;
        gobject_class->set_property = soup_cache_set_property;
        gobject_class->get_property = soup_cache_get_property;
 
@@ -1044,7 +1032,10 @@ soup_cache_class_init (SoupCacheClass *cache_class)
 
 /**
  * soup_cache_new:
- * @cache_dir: the directory to store the cached data, or %NULL to use the default one
+ * @cache_dir: (allow-none): the directory to store the cached data, or %NULL
+ *   to use the default one. Note that since the cache isn't safe to access for
+ *   multiple processes at once, and the default directory isn't namespaced by
+ *   process, clients are strongly discouraged from passing %NULL.
  * @cache_type: the #SoupCacheType of the cache
  *
  * Creates a new #SoupCache.