[glib/wjt/g_desktop_app_info_get_string_list] gdesktopappinfo: add get_string_list() function

[Will Thompson <wjt src gnome org>]

commit eca1211e9ea687cdb4bc3ce273e736299b285675
Author: Will Thompson <will willthompson co uk>
Date:   Thu Sep 20 16:26:55 2018 +0100

    gdesktopappinfo: add get_string_list() function
    
    The X-Flatpak-RenamedFrom key is used in .desktop files to identify past
    names for the desktop file. It is defined to be a list of strings.
    However, there was previously no correct way to retrieve a list of
    strings from the GKeyFile wrapped by GDesktopAppInfo, short of
    re-parsing the file with GKeyFile.
    
    Note that doing something like:
    
        g_strsplit (g_desktop_app_info_get_string (...), ";", -1)
    
    is not correct: the raw value "a\;b;" represents the one-element list
    ["a;b"], but g_key_file_get_string() rejects the sequence "\;", and so
    g_desktop_app_info_get_string() returns NULL in this case. (Of course, a
    .desktop file with a semicolon in its name is a pathological case.)
    
    Add g_desktop_app_info_get_string_list(), a trivial wrapper around
    g_key_file_get_string_list(), similar to g_desktop_app_info_get_string()
    and co.
    
    The change from g_key_file_free() to g_key_file_unref() in the test is
    needed because g_key_file_free() clears the contents of the keyfile.
    This is fine for all the fields which are eagerly loaded and copied into
    GDesktopAppInfo, but not when we want to access arbitrary stuff from the
    keyfile.

 gio/gdesktopappinfo.c | 27 +++++++++++++++++++++++++++
 gio/gdesktopappinfo.h |  5 +++++
 gio/tests/appinfo.c   | 11 ++++++++++-
 3 files changed, 42 insertions(+), 1 deletion(-)
---
diff --git a/gio/gdesktopappinfo.c b/gio/gdesktopappinfo.c
index d0ffbace3..c55a0abe2 100644
--- a/gio/gdesktopappinfo.c
+++ b/gio/gdesktopappinfo.c
@@ -4534,6 +4534,33 @@ g_desktop_app_info_get_boolean (GDesktopAppInfo *info,
                                  G_KEY_FILE_DESKTOP_GROUP, key, NULL);
 }
 
+/**
+ * g_desktop_app_info_get_string_list:
+ * @info: a #GDesktopAppInfo
+ * @key: the key to look up
+ * @length: (out) (optional): return location for the number of returned strings, or %NULL
+ *
+ * Looks up a string list value in the keyfile backing @info.
+ *
+ * The @key is looked up in the "Desktop Entry" group.
+ *
+ * Returns: (array zero-terminated=1 length=length) (element-type utf8) (transfer full):
+ *  a %NULL-terminated string array or %NULL if the specified
+ *  key cannot be found. The array should be freed with g_strfreev().
+ *
+ * Since: 2.59.0
+ */
+gchar **
+g_desktop_app_info_get_string_list (GDesktopAppInfo *info,
+                                    const char      *key,
+                                    gsize           *length)
+{
+  g_return_val_if_fail (G_IS_DESKTOP_APP_INFO (info), NULL);
+
+  return g_key_file_get_string_list (info->keyfile,
+                                     G_KEY_FILE_DESKTOP_GROUP, key, length, NULL);
+}
+
 /**
  * g_desktop_app_info_has_key:
  * @info: a #GDesktopAppInfo
diff --git a/gio/gdesktopappinfo.h b/gio/gdesktopappinfo.h
index 86a3caa30..1254038a4 100644
--- a/gio/gdesktopappinfo.h
+++ b/gio/gdesktopappinfo.h
@@ -89,6 +89,11 @@ GLIB_AVAILABLE_IN_2_36
 gboolean         g_desktop_app_info_get_boolean       (GDesktopAppInfo *info,
                                                        const char      *key);
 
+GLIB_AVAILABLE_IN_2_60
+gchar **         g_desktop_app_info_get_string_list (GDesktopAppInfo *info,
+                                                     const char      *key,
+                                                     gsize           *length);
+
 GLIB_AVAILABLE_IN_2_38
 const gchar * const *   g_desktop_app_info_list_actions                 (GDesktopAppInfo   *info);
 
diff --git a/gio/tests/appinfo.c b/gio/tests/appinfo.c
index a52bc7094..eef3de9d1 100644
--- a/gio/tests/appinfo.c
+++ b/gio/tests/appinfo.c
@@ -512,6 +512,8 @@ test_from_keyfile (void)
   GKeyFile *kf;
   GError *error = NULL;
   const gchar *categories;
+  gchar **categories_list;
+  gsize categories_count;
   gchar **keywords;
   const gchar *file;
   const gchar *name;
@@ -522,7 +524,7 @@ test_from_keyfile (void)
   g_key_file_load_from_file (kf, path, G_KEY_FILE_NONE, &error);
   g_assert_no_error (error);
   info = g_desktop_app_info_new_from_keyfile (kf);
-  g_key_file_free (kf);
+  g_key_file_unref (kf);
   g_assert (info != NULL);
 
   g_object_get (info, "filename", &file, NULL);
@@ -532,6 +534,12 @@ test_from_keyfile (void)
   g_assert (file == NULL);
   categories = g_desktop_app_info_get_categories (info);
   g_assert_cmpstr (categories, ==, "GNOME;GTK;");
+  categories_list = g_desktop_app_info_get_string_list (info, "Categories", &categories_count);
+  g_assert_cmpint (g_strv_length (categories_list), ==, 2);
+  g_assert_cmpint (categories_count, ==, 2);
+  g_assert_cmpint (g_strv_length (categories_list), ==, 2);
+  g_assert_cmpstr (categories_list[0], ==, "GNOME");
+  g_assert_cmpstr (categories_list[1], ==, "GTK");
   keywords = (gchar **)g_desktop_app_info_get_keywords (info);
   g_assert_cmpint (g_strv_length (keywords), ==, 2);
   g_assert_cmpstr (keywords[0], ==, "keyword1");
@@ -540,6 +548,7 @@ test_from_keyfile (void)
   g_assert_cmpstr (name, ==, "generic-appinfo-test");
   g_assert (!g_desktop_app_info_get_nodisplay (info));
 
+  g_strfreev (categories_list);
   g_object_unref (info);
 }