[gnome-photos] Add photos_utils_take_string

[Debarshi Ray <debarshir src gnome org>]

commit 04eeb1afd68f8c47e434f8de9e3f39f00c9f6f39
Author: Debarshi Ray <debarshir gnome org>
Date:   Sat Jul 9 15:10:52 2016 +0200

    Add photos_utils_take_string
    
    This is a variant of photos_utils_set_string where string_ptr takes
    ownership of new_string.
    
    Based on an implementation by Emmanuele Bassi.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=768548

 src/photos-utils.c |   28 ++++++++++++++++++++++++++++
 src/photos-utils.h |    2 ++
 2 files changed, 30 insertions(+), 0 deletions(-)
---
diff --git a/src/photos-utils.c b/src/photos-utils.c
index 1fc46d9..cb21e92 100644
--- a/src/photos-utils.c
+++ b/src/photos-utils.c
@@ -1473,3 +1473,31 @@ photos_utils_set_string (gchar **string_ptr, const gchar *new_string)
  out:
   return ret_val;
 }
+
+
+gboolean
+photos_utils_take_string (gchar **string_ptr, gchar *new_string)
+{
+  gboolean ret_val = FALSE;
+
+  g_return_val_if_fail (string_ptr != NULL, FALSE);
+
+  if (*string_ptr == new_string)
+    {
+      new_string = NULL;
+      goto out;
+    }
+
+  if (g_strcmp0 (*string_ptr, new_string) == 0)
+    goto out;
+
+  g_free (*string_ptr);
+  *string_ptr = new_string;
+  new_string = NULL;
+
+  ret_val = TRUE;
+
+ out:
+  g_free (new_string);
+  return ret_val;
+}
diff --git a/src/photos-utils.h b/src/photos-utils.h
index 184ecff..1821811 100644
--- a/src/photos-utils.h
+++ b/src/photos-utils.h
@@ -178,6 +178,8 @@ void             photos_utils_set_favorite                (const gchar *urn, gbo
 
 gboolean         photos_utils_set_string                  (gchar **string_ptr, const gchar *new_string);
 
+gboolean         photos_utils_take_string                 (gchar **string_ptr, gchar *new_string);
+
 G_END_DECLS
 
 #endif /* PHOTOS_UTILS_H */