[GHC] #7654: Cannot specify argv[0] with createProcess

[GHC]

#7654: Cannot specify argv[0] with createProcess
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Reporter:  MtnViewMark       |          Owner:                   
    Type:  feature request   |         Status:  new              
Priority:  normal            |      Component:  libraries/process
 Version:  7.6.2             |       Keywords:  process          
      Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple 
 Failure:  None/Unknown      |      Blockedby:                   
Blocking:                    |        Related:                   
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 There are conditions where it is important to specify the value of argv[0]
 as distinct from the FilePath of the file to execute.

 When createProcess is called with CmdSpec (inside the CreateProcess
 argument) of RawCommand, the code in
 System.Process.Internals.runGenProcess_ builds the argv list by
 concatenating the FilePath of the command to run on to the supplied args,
 then passing that array to the c code runInteractiveProcess.
 runInteractiveProcess in turn uses argv[0] as the initial argument to
 either execvp() or execvpe(). Thus, argv[0], and the command to execute
 must be the same.

 The fix is simple, but long.... runInteractiveProcess should take an
 adiditional parameter that is the command to exec, distinct from the args
 array (which continues to hold the now distinct argv[0]). runGenProcess_
 should keep cmd and args distinct, and build cstrs from args, not
 cmd:args. commandToProcess needs to then take on the work of prepending
 the cmd to the args array, in the case of RawCommand or ShellCommand. NOW,
 we can introduce a new constructore RawCommandWithArg0 FilePath String
 [String] where argv[0] is specified, and commandToProcess for that can
 easily build the args from that parameter.

 I should probably prepare a patch for this....  But I wanted to get the
 ticket in as the issue was fresh in my mind.

 This is a feature request, but realize that without a change, an important
 part of POSIX support is missing.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7654>
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