parser.rl: check before use

* ext/json/parser/parser.rl (unescape_unicode): check if valid
  before bit-or assignments.
  reported by Denis Denisov <denji0k AT gmail.com>.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49027 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 4 insertions, 4 deletions

diff --git a/ext/json/parser/parser.c b/ext/json/parser/parser.c
index 560aa8977f..f9d0d193b6 100644
--- a/ext/json/parser/parser.c
+++ b/ext/json/parser/parser.c
@@ -28,16 +28,16 @@ static UTF32 unescape_unicode(const unsigned char *p)
     UTF32 result = 0;
     b = digit_values[p[0]];
     if (b < 0) return UNI_REPLACEMENT_CHAR;
-    result = (result << 4) | b;
+    result = (result << 4) | (unsigned char)b;
     b = digit_values[p[1]];
-    result = (result << 4) | b;
     if (b < 0) return UNI_REPLACEMENT_CHAR;
+    result = (result << 4) | (unsigned char)b;
     b = digit_values[p[2]];
-    result = (result << 4) | b;
     if (b < 0) return UNI_REPLACEMENT_CHAR;
+    result = (result << 4) | (unsigned char)b;
     b = digit_values[p[3]];
-    result = (result << 4) | b;
     if (b < 0) return UNI_REPLACEMENT_CHAR;
+    result = (result << 4) | (unsigned char)b;
     return result;
 }