[PATCH] cygwin_rexec() returns pointer to deallocated memory

Christopher Faylor cgf-use-the-mailinglist-please@cygwin.com
Mon May 26 21:40:00 GMT 2014

On Mon, May 26, 2014 at 10:39:03PM +0200, Peter Rosin wrote:
>On 2014-05-26 18:35, Christopher Faylor wrote:
>> On Mon, May 26, 2014 at 04:27:10PM +0100, David Stacey wrote:
>>> On 26/05/14 14:36, Peter Rosin wrote:
>>>> I believe the comment refers to if "static" is the right answer to the
>>>> problem. Is there a need to handle concurrent calls?
>>> I can't really comment on that. As the code stands, neither of the two 
>>> functions that we are discussing are reentrant. As long as the author 
>>> and the user(s) of the routines are both aware of that then it isn't a 
>>> problem.
>>> I was just trying to fix a coding error that was picked up by Coverity 
>>> Scan; it wasn't my intention to question the design.
>> But that is the usual problem with Coverity.  Making the simple, obvious
>> fix to correct a Coverity warning isn't necessarily the right way to
>> deal with the issue.
>> In this case, the linux man page says:
>>      Multithreading (see pthreads(7))
>> 	 The rexec() and rexec_af() functions are not thread-safe.
>> so static is appropriate.
>"Not thread-safe" doesn't automatically mean that a following call may mess
>with what was returned from a prior call (by the same thread). But since
>it (IMHO) is a poor interface with no description of how to free any
>possibly allocated memory, I agree that static is the only viable option.

The question was about reentrancy.  AFAIK, "reentrant" doesn't mean that
the buffer passed back from a call can't be subsequently modified by the
thread.  I'm not aware of any interface which enforces that behavior.


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