[project @ 2004-10-08 10:28:37 by simonmar]

- make sure we don't overflow the table
- use a checked array index just in case we *do* try to overflow
- fix a harmless off-by-one

diff --git a/Data/HashTable.hs b/Data/HashTable.hs
index b392ce2..39fc93c 100644 (file)
--- a/Data/HashTable.hs
+++ b/Data/HashTable.hs
@@ -187,7 +187,7 @@ new
 
 new cmp hash_fn = do
   -- make a new hash table with a single, empty, segment
-  dir     <- newIOArray (0,dIR_SIZE) undefined
+  dir     <- newIOArray (0,dIR_SIZE-1) undefined
   segment <- newIOArray (0,sEGMENT_SIZE-1) []
   myWriteArray dir 0 segment
 
@@ -271,9 +271,15 @@ expandHashTable
       newsegment = newbucket `shiftR` sEGMENT_SHIFT
       newindex   = newbucket .&. sEGMENT_MASK
   --
+  if newsegment >= dIR_SIZE    -- make sure we don't overflow the table.
+       then return table
+       else do
+  --
   when (newindex == 0) $
        do segment <- newIOArray (0,sEGMENT_SIZE-1) []
-          myWriteArray dir newsegment segment
+          writeIOArray dir newsegment segment
+          -- doesn't happen very often, so we might as well use a safe
+          -- array index here.
   --
   let table' =
        if (split+1) < max