Ghosts of Unix past, part 2: Conflated designs

Posted Nov 11, 2010 1:10 UTC (Thu) by jonabbey (guest, #2736)
In reply to: Ghosts of Unix past, part 2: Conflated designs by Yorick
Parent article: Ghosts of Unix past, part 2: Conflated designs

Reading from /proc/self/fd and closing descriptors based on that is still subject to race conditions in threaded programs.

Ghosts of Unix past, part 2: Conflated designs

Posted Nov 11, 2010 2:38 UTC (Thu) by foom (subscriber, #14868) [Link]

Nope, it's not, because you do the closing of fds after forking (but before exec). You are guaranteed that there will be no other threads running at that point.

Ghosts of Unix past, part 2: Conflated designs

Posted Nov 11, 2010 3:30 UTC (Thu) by quotemstr (subscriber, #45331) [Link]

After fork(), a program has one thread.

Ghosts of Unix past, part 2: Conflated designs

Posted Nov 17, 2010 0:23 UTC (Wed) by mhelsley (guest, #11324) [Link]

And if your process links with libraries that internally use fds then you could easily trample the "internal" workings of those libraries by closing the fds. So a naive process can't assume it knows how to handle each fd in /proc/self/fd* without blurring the lines between library and application.