[gnome-software] When a file exists in multiple cache locations return the newest file

[Joaquim Manuel Pereira Rocha <jrocha src gnome org>]

commit 7012e27011870681e40ec77f2977ec637ba4da88
Author: Richard Hughes <richard hughsie com>
Date:   Wed Nov 9 10:52:21 2016 +0000

    When a file exists in multiple cache locations return the newest file
    
    Inspired by a patch from Joaquim Rocha <jrocha endlessm com>, many thanks.

 src/gs-utils.c |   43 ++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 38 insertions(+), 5 deletions(-)
---
diff --git a/src/gs-utils.c b/src/gs-utils.c
index 4386c34..da868c3 100644
--- a/src/gs-utils.c
+++ b/src/gs-utils.c
@@ -103,6 +103,24 @@ gs_utils_get_file_age (GFile *file)
        return (guint) (now - mtime);
 }
 
+static gchar *
+gs_utils_filename_array_return_newest (GPtrArray *array)
+{
+       const gchar *filename_best = NULL;
+       guint age_lowest = G_MAXUINT;
+       guint i;
+       for (i = 0; i < array->len; i++) {
+               const gchar *fn = g_ptr_array_index (array, i);
+               g_autoptr(GFile) file = file = g_file_new_for_path (fn);
+               guint age_tmp = gs_utils_get_file_age (file);
+               if (age_tmp < age_lowest) {
+                       age_lowest = age_tmp;
+                       filename_best = fn;
+               }
+       }
+       return g_strdup (filename_best);
+}
+
 /**
  * gs_utils_get_cache_filename:
  * @kind: A cache kind, e.g. "firmware" or "screenshots/123x456"
@@ -114,6 +132,9 @@ gs_utils_get_file_age (GFile *file)
  * This may be per-system or per-user, the latter being more likely
  * when %GS_UTILS_CACHE_FLAG_WRITEABLE is specified in @flags.
  *
+ * If there is more than one match, the file that has been modified last is
+ * returned.
+ *
  * Returns: The full path and filename, which may or may not exist, or %NULL
  **/
 gchar *
@@ -126,6 +147,7 @@ gs_utils_get_cache_filename (const gchar *kind,
        g_autofree gchar *vername = NULL;
        g_auto(GStrv) version = g_strsplit (VERSION, ".", 3);
        g_autoptr(GFile) cachedir_file = NULL;
+       g_autoptr(GPtrArray) candidates = g_ptr_array_new_with_free_func (g_free);
 
        /* not writable, so try the system cache first */
        if ((flags & GS_UTILS_CACHE_FLAG_WRITEABLE) == 0) {
@@ -136,8 +158,10 @@ gs_utils_get_cache_filename (const gchar *kind,
                                            kind,
                                            basename,
                                            NULL);
-               if (g_file_test (cachefn, G_FILE_TEST_EXISTS))
-                       return g_steal_pointer (&cachefn);
+               if (g_file_test (cachefn, G_FILE_TEST_EXISTS)) {
+                       g_ptr_array_add (candidates,
+                                        g_steal_pointer (&cachefn));
+               }
        }
 
        /* not writable, so try the system cache first */
@@ -149,8 +173,10 @@ gs_utils_get_cache_filename (const gchar *kind,
                                            kind,
                                            basename,
                                            NULL);
-               if (g_file_test (cachefn, G_FILE_TEST_EXISTS))
-                       return g_steal_pointer (&cachefn);
+               if (g_file_test (cachefn, G_FILE_TEST_EXISTS)) {
+                       g_ptr_array_add (candidates,
+                                        g_steal_pointer (&cachefn));
+               }
        }
 
        /* create the cachedir in a per-release location, creating
@@ -165,7 +191,14 @@ gs_utils_get_cache_filename (const gchar *kind,
        if (!g_file_query_exists (cachedir_file, NULL) &&
            !g_file_make_directory_with_parents (cachedir_file, NULL, error))
                return NULL;
-       return g_build_filename (cachedir, basename, NULL);
+       g_ptr_array_add (candidates, g_build_filename (cachedir, basename, NULL));
+
+       /* common case: we only have one option */
+       if (candidates->len == 1)
+               return g_strdup (g_ptr_array_index (candidates, 0));
+
+       /* return the newest (i.e. one with least age) */
+       return gs_utils_filename_array_return_newest (candidates);
 }
 
 /**