[tracker] libtracker-data: Limit error message length

[Martyn James Russell <mr src gnome org>]

commit 4297d86544c5a8f7ec2ae621fddadd725e63beb7
Author: Martin Kampas <martin kampas tieto com>
Date:   Mon Jul 7 14:18:56 2014 +0200

    libtracker-data: Limit error message length
    
    When a very long error message is eventually sent over D-Bus and the
    original method call involves file descriptor passing, it hits Gnome bug
    732615 and the sending process gets aborted.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=732839

 src/libtracker-common/tracker-utils.c     |   26 ++++++++++++++++++++++++++
 src/libtracker-common/tracker-utils.h     |    2 ++
 src/libtracker-data/tracker-data-update.c |   10 ++++++----
 3 files changed, 34 insertions(+), 4 deletions(-)
---
diff --git a/src/libtracker-common/tracker-utils.c b/src/libtracker-common/tracker-utils.c
index fe1b5cb..a9cb706 100644
--- a/src/libtracker-common/tracker-utils.c
+++ b/src/libtracker-common/tracker-utils.c
@@ -210,3 +210,29 @@ tracker_strhex (const guint8 *data,
        return new_str;
 }
 
+/**
+ * tracker_utf8_truncate:
+ * @str: Nul-terminated input string
+ * @max_size: Maximum length of the output string
+ *
+ * Returns up to @max_size characters long substring of @str, followed
+ * with "[…]" when actually truncated.
+ *
+ * Returns: A newly allocated string which should be disposed with g_free()
+ */
+gchar *
+tracker_utf8_truncate (const gchar  *str,
+                       gsize         max_size)
+{
+       gchar *retv = NULL;
+
+       if (g_utf8_strlen (str, -1) > max_size) {
+               gchar *substring = g_utf8_substring (str, 0, max_size - 3);
+               retv = g_strdup_printf ("%s[…]", substring);
+               g_free (substring);
+       } else {
+               retv = g_strdup (str);
+       }
+
+       return retv;
+}
diff --git a/src/libtracker-common/tracker-utils.h b/src/libtracker-common/tracker-utils.h
index 035be96..87ca7b3 100644
--- a/src/libtracker-common/tracker-utils.h
+++ b/src/libtracker-common/tracker-utils.h
@@ -43,6 +43,8 @@ gchar *  tracker_seconds_to_string          (gdouble       seconds,
 gchar *  tracker_strhex                     (const guint8 *data,
                                              gsize         size,
                                              gchar         delimiter);
+gchar *  tracker_utf8_truncate              (const gchar  *str,
+                                             gsize         max_size);
 
 G_END_DECLS
 
diff --git a/src/libtracker-data/tracker-data-update.c b/src/libtracker-data/tracker-data-update.c
index a01d197..31f840f 100644
--- a/src/libtracker-data/tracker-data-update.c
+++ b/src/libtracker-data/tracker-data-update.c
@@ -1699,8 +1699,8 @@ cache_insert_metadata_decomposed (TrackerProperty  *property,
                GValue old_value = { 0 };
                GValue new_value = { 0 };
                GValue *v;
-               const gchar *old_value_str = NULL;
-               const gchar *new_value_str = NULL;
+               gchar *old_value_str = NULL;
+               gchar *new_value_str = NULL;
 
                g_value_init (&old_value, G_TYPE_STRING);
                g_value_init (&new_value, G_TYPE_STRING);
@@ -1709,12 +1709,12 @@ cache_insert_metadata_decomposed (TrackerProperty  *property,
                 * whatever transformation needed */
                v = &g_array_index (old_values, GValue, 0);
                if (g_value_transform (v, &old_value)) {
-                       old_value_str = g_value_get_string (&old_value);
+                       old_value_str = tracker_utf8_truncate (g_value_get_string (&old_value), 255);
                }
 
                v = &g_array_index (old_values, GValue, 1);
                if (g_value_transform (v, &new_value)) {
-                       new_value_str = g_value_get_string (&new_value);
+                       new_value_str = tracker_utf8_truncate (g_value_get_string (&new_value), 255);
                }
 
                g_set_error (error, TRACKER_SPARQL_ERROR, TRACKER_SPARQL_ERROR_CONSTRAINT,
@@ -1725,6 +1725,8 @@ cache_insert_metadata_decomposed (TrackerProperty  *property,
                             old_value_str ? old_value_str : "<untransformable>",
                             new_value_str ? new_value_str : "<untransformable>");
 
+               g_free (old_value_str);
+               g_free (new_value_str);
                g_value_unset (&old_value);
                g_value_unset (&new_value);
                g_value_unset (&gvalue);