parser: Ignore UTF-8 BOM if necessaryhandle-utf8-bom

According to JSON spec BOM shouldn't be part of the JSON data, but
also recommends to tolerate files with a BOM marker. As this is common
in several Windows JSON generators, handle it graceful in json-glib and
skip it for UTF-8 BOM.

Fixes: https://gitlab.gnome.org/GNOME/json-glib/-/issues/56

1 files changed, 15 insertions, 1 deletions

diff --git a/json-glib/json-parser.c b/json-glib/json-parser.c
index 4e08848..4a560d8 100644
--- a/json-glib/json-parser.c
+++ b/json-glib/json-parser.c
@@ -970,7 +970,7 @@ json_parser_new_immutable (void)
 
 static gboolean
 json_parser_load (JsonParser   *parser,
-                  const gchar  *data,
+                  const gchar  *input_data,
                   gsize         length,
                   GError      **error)
 {
@@ -979,6 +979,7 @@ json_parser_load (JsonParser   *parser,
   gboolean done;
   gboolean retval = TRUE;
   gint i;
+  gchar *data = input_data;
 
   json_parser_clear (parser);
 
@@ -991,6 +992,19 @@ json_parser_load (JsonParser   *parser,
       return FALSE;
     }
 
+  if (length >= 3)
+    {
+      /* Check for UTF-8 signature and skip it if necessary */
+       if (((data[0] & 0xFF) == 0xEF) &&
+           ((data[1] & 0xFF) == 0xBB) &&
+           ((data[2] & 0xFF) == 0xBF))
+         {
+           JSON_NOTE (PARSER, "Skipping BOM");
+           data += 3;
+           length -= 3;
+         }
+    }
+
   scanner = json_scanner_create (parser);
   json_scanner_input_text (scanner, data, length);