On Feb 29 17:27, Austin Group Bug Tracker via austin-group-l at The Open Group wrote: > ====================================================================== > Summary: Must posix_getdents remember file offsets across > exec? > ====================================================================== > [...] > Likewise, the behavior is unspecified if in between two calls to > <i>posix_getdents</i>() on one file descriptor, the file offset is altered > by a call made on a different file descriptor that refers to the same open > file description and the new offset is not zero.</blockquote>
While the new clarifications look mostly good to me, this snippet still looks like a problem, in particular the restriction "and the new offset is not zero". The reason is that after dup, the process has to create a new DIR for the dup'ed descriptor. The two DIR's are logically distinct. The above paragraph sounds like the behaviour is not supposed to be undefined in the follwoing situation: posix_getdents (fd1, ...); // file pos != 0 after this call fd2 = dup (fd1); lseek (fd2, SEEK_SET, 0); // seeks file to pos 0 via fd2 posix_getdents (fd1, ...); // is now supposed to start at pos 0? If so, I'm not sure how to do this via underlying DIR pointer. The DIR pointer attached to fd1 is either dropped from or duplicated to fd2. It's certainly not the same DIR pointer. The lseek in fd2 can only affect the DIR attached to fd2, not the one from fd1. So, given we don't have a seekable underlying OS file descriptor, how is the second posix_getdents on fd1 supposed to know that it has to restart at pos 0? Thanks, Corinna
