Made decoding array lookup safe

Ignore-this: 346535974ae363daf4ade7e22ed48ad7 darcs-hash:20090226144653-a4fee-42808f15a3bab3fa1712ab12d8b0cfb54ff96aad
2009-02-26 06:46:53 -08:00 · 2009-02-26 06:46:53 -08:00 · 3270e03da1
commit 3270e03da1
parent 6eb2d51ee2
1 changed files with 8 additions and 4 deletions
--- a/Data/Encoding/Base.hs
+++ b/Data/Encoding/Base.hs
@ -76,7 +76,11 @@ decodeWithArray2 :: ByteSource m => UArray (Word8,Word8) Int -> m Char
 decodeWithArray2 arr = do
  w1 <- fetchWord8
  w2 <- fetchWord8
-  let res = arr!(w1,w2)
-  if res < 0
-    then throwException $ IllegalCharacter w1
-    else return $ chr res
+  if inRange (bounds arr) (w1,w2)
+    then (do
+           let res = arr!(w1,w2)
+           if res < 0
+             then throwException $ IllegalCharacter w1
+             else return $ chr res
+         )
+    else throwException $ IllegalCharacter w1