[GHC] #8802: createProcess implictlitly escapes and quotes command line parameters

[GHC]

#8802: createProcess implictlitly escapes and quotes command line parameters
--------------------------------------+------------------------------------
        Reporter:  jstolarek          |            Owner:
            Type:  bug                |           Status:  closed
        Priority:  high               |        Milestone:  7.8.1
       Component:  libraries/process  |          Version:  7.9
      Resolution:  invalid            |         Keywords:
Operating System:  Linux              |     Architecture:  Unknown/Multiple
 Type of failure:  Runtime crash      |       Difficulty:  Unknown
       Test Case:                     |       Blocked By:
        Blocking:                     |  Related Tickets:
--------------------------------------+------------------------------------

Comment (by jstolarek):

 Replying to [comment:6 nomeata]:
 > Well, if you check where `translate` is being used: It is only used on
 Windows
 Hm... looks like you're right. In that case which part of the code quotes
 parameters to `proc`? Because this clearly is performed at some point.

 > you are using `proc`, where the main feature is precisely that it is
 ''not'' being passed through the shell.
 Ah, now I see. This is poorly documented. Documentation for `proc` says:

   Construct a `CreateProcess` record for passing to `createProcess`,
 representing '''a raw command with arguments'''. [highlight by me]

 My understanding was that "raw command" is supposed to be a shell command.
 Now I see that `proc` is intended to create a raw process, not a shell
 command (which is implied by the function's name but certainly not by its
 documentation).

 > With proc it is safe to call proc "echo" [possibly_malicous_string]
 I don't understand this. Could you give example of how
 possibly_malicous_string could be dangerous (assuming characters are not
 escaped)?

 > Any security-aware code should only use proc
 Please explain why. If I write a Haskell program that runs external
 command I can do a lot of bad things even when parameters to `proc` are
 escaped.

 > If you want shell features, use shell instead of proc
 Problem with `shell` is that it runs `sh` shell, not `bash`. Replacing
 `proc` with `shell` in my example code gives:

 {{{
 /bin/sh: -c: line 0: syntax error near unexpected token `('
 /bin/sh: -c: line 0: `diff <(echo $FOO) <(echo $BAR)'
 }}}

 I don't think this ticket should be closed - this is at least a
 documentation bug.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8802#comment:7>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler