On Thu, Aug 13, 2009 at 07:52:01PM +0000, Eric Blake wrote:
>cygwin <karl <at> sipxx.com> writes:
>
>>
>> - if (dup2(to_child_pipe[0], STDIN_FILENO) < 0 ||
>> - close(to_child_pipe[1]) < 0 ||
>> - close(from_child_pipe[0]) < 0 ||
>> - dup2(from_child_pipe[1], STDOUT_FILENO) < 0) {
>> - rsyserr(FERROR, errno, "Failed to dup/close");
>> + if (dup2(to_child_pipe[0], STDIN_FILENO) < 0) {
>> + rsyserr(FERROR, errno, "Failed to dup2(to-0)");
>> exit_cleanup(RERR_IPC);
>> }
>> - if (to_child_pipe[0] != STDIN_FILENO)
>> - close(to_child_pipe[0]);
>> - if (from_child_pipe[1] != STDOUT_FILENO)
>> - close(from_child_pipe[1]);
>
>Ouch. rsync has a bug even without your patch: if you run rsync with
>stdout closed (as opposed to redirected), then to_child_pipe[0] can be
>1, and you end up closing the just-duplicated from_child_pipe[1] that
>was copied to the new stdout. To be correct, rsync must compare
>to_child_pipe[0] against both 0 and 1, not just 0 (likewise for
>from_child_pipe[1] against both 0 and 1, not just 1). Amazing how
>often this type of bug reappears, too - historical cygwin has had it in
>the past with newlib's popen implementation (I fixed it 2006-08-22), as
>well as m4 1.4.13-1 having it due to code from gnulib (I fixed it
>2009-07- 17).
Just a point of order: Cygwin doesn't use the newlib version of
popen.
cgf
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