Random number chosen by openTempFile is always 1804289383846930886

import System.Directory
import System.IO
main = do
  (p, _) <- openTempFile "/tmp" ""
  print p
  removeFile p

$ runghc temp.hs
"/tmp/1804289383846930886"
$ runghc temp.hs
"/tmp/1804289383846930886"
$ runghc temp.hs
"/tmp/1804289383846930886"
$ runghc temp.hs
"/tmp/1804289383846930886"

This “random” number is the concatenation of the first two numbers 1804289383, 846930886 returned by glibc’s rand() when not seeded (or seeded with 1).

This is not immediately a library security bug, I think: the file is created with O_EXCL, and if it already exists, openTempFile will move onto the next value 16816927771714636915, and so on. However, the predictable filenames make a potential application security bug that much more likely.

(For your amusement, Google 1804289383846930886.)

Trac metadata

Trac field	Value
Version	7.10.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	libraries/base
Test case
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