[epiphany] gsb-utils: Handle missing firstValue in RiceDeltaEncoding object

[Gabriel Ivașcu <gabrielivascu src gnome org>]

commit eccbca238a41115e01845534add6db5f27da63b1
Author: Gabriel Ivascu <gabrielivascu gnome org>
Date:   Sat Jan 27 01:09:20 2018 +0200

    gsb-utils: Handle missing firstValue in RiceDeltaEncoding object
    
    https://bugzilla.gnome.org/show_bug.cgi?id=792930

 lib/safe-browsing/ephy-gsb-utils.c |    9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)
---
diff --git a/lib/safe-browsing/ephy-gsb-utils.c b/lib/safe-browsing/ephy-gsb-utils.c
index 62823a5..e448c7b 100644
--- a/lib/safe-browsing/ephy-gsb-utils.c
+++ b/lib/safe-browsing/ephy-gsb-utils.c
@@ -467,7 +467,7 @@ ephy_gsb_utils_rice_delta_decode (JsonObject *rde,
 {
   EphyGSBRiceDecoder *decoder;
   const char *data_b64 = NULL;
-  const char *first_value_str;
+  const char *first_value_str = NULL;
   guint32 *items;
   guint8 *data;
   gsize data_len;
@@ -477,9 +477,8 @@ ephy_gsb_utils_rice_delta_decode (JsonObject *rde,
   g_assert (rde);
   g_assert (num_items);
 
-  /* This field is never missing. */
-  first_value_str = json_object_get_string_member (rde, "firstValue");
-
+  if (json_object_has_member (rde, "firstValue"))
+    first_value_str = json_object_get_string_member (rde, "firstValue");
   if (json_object_has_member (rde, "riceParameter"))
     parameter = json_object_get_int_member (rde, "riceParameter");
   if (json_object_has_member (rde, "numEntries"))
@@ -489,7 +488,7 @@ ephy_gsb_utils_rice_delta_decode (JsonObject *rde,
 
   *num_items = 1 + num_entries;
   items = g_malloc (*num_items * sizeof (guint32));
-  items[0] = g_ascii_strtoull (first_value_str, NULL, 10);
+  items[0] = first_value_str ? g_ascii_strtoull (first_value_str, NULL, 10) : 0;
 
   if (num_entries == 0)
     return items;