GitLab

The elemIndices for strict ByteString causes SEGV in some situation.

import Data.Int
import qualified Data.ByteString as S

main = do
 cs <- S.getContents
 let ps = S.elemIndices 10 cs
 putStrLn $ "S.length cs = " ++ show (S.length cs)
 putStrLn $ "length ps = " ++ show (length ps)

If above program gets some large input, it crashes.

$ ghc --make ei
[1 of 1] Compiling Main             ( ei.hs, ei.o )
Linking ei ...
$ yes | head -10000 | ./ei
S.length cs = 20000
Segmentation fault

By the way, there might be a border of SEGV or not.

$ yes | head -4096 | ./ei
S.length cs = 8192
Segmentation fault
$ yes | head -4095 | ./ei
S.length cs = 8190
length ps = 4095

And this script works fine.

import qualified Data.ByteString as S
import qualified Data.ByteString.Lazy as L

main = do
 let cs = S.pack . take 8192 . cycle $ [48,10]
     ps = S.elemIndices 10 cs
 putStrLn $ "length cs = " ++ show (S.length cs)
 putStrLn $ "length ps = " ++ show (length ps)

I think there is causes about the bug in S.getContents or S.elemIndices or both. But I cannot figure out it.

Trac metadata

Trac field	Value
Version	6.10.4
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	libraries/base
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture