[Git][ghc/ghc][master] Fix off by one error in seekBinNoExpand and seekBin

[Marge Bot (@marge-bot)]

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC


Commits:
28009fbc by Matthew Pickering at 2024-04-04T14:48:46-04:00
Fix off by one error in seekBinNoExpand and seekBin

- - - - -


1 changed file:

- compiler/GHC/Utils/Binary.hs


Changes:

=====================================
compiler/GHC/Utils/Binary.hs
=====================================
@@ -243,15 +243,18 @@ tellBin (BinMem _ r _ _) = do ix <- readFastMutInt r; return (BinPtr ix)
 seekBin :: BinHandle -> Bin a -> IO ()
 seekBin h@(BinMem _ ix_r sz_r _) (BinPtr !p) = do
   sz <- readFastMutInt sz_r
-  if (p >= sz)
+  if (p > sz)
         then do expandBin h p; writeFastMutInt ix_r p
         else writeFastMutInt ix_r p
 
--- | SeekBin but without calling expandBin
+-- | 'seekBinNoExpand' moves the index pointer to the location pointed to
+-- by 'Bin a'.
+-- This operation may 'panic', if the pointer location is out of bounds of the
+-- buffer of 'BinHandle'.
 seekBinNoExpand :: BinHandle -> Bin a -> IO ()
 seekBinNoExpand (BinMem _ ix_r sz_r _) (BinPtr !p) = do
   sz <- readFastMutInt sz_r
-  if (p >= sz)
+  if (p > sz)
         then panic "seekBinNoExpand: seek out of range"
         else writeFastMutInt ix_r p
 



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/28009fbc26e4aca7a3b05cedb60c5c9baa31223d

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/28009fbc26e4aca7a3b05cedb60c5c9baa31223d
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