Mercurial > hg > octave-jordi > gnulib-hg
changeset 17924:68876b89b3ad
poll: fixes for large fds
* lib/poll.c (poll): Don't check directly for NFD too large.
Don't rely on undefined behavior in FD_SET when an arg exceeds
FD_SETSIZE. Always set revents afterwards, even if to zero.
* tests/test-poll.c (poll1): Set revents to -1 instead of 0,
as that makes the test a bit stricter.
author | Paul Eggert <eggert@cs.ucla.edu> |
---|---|
date | Fri, 20 Feb 2015 10:37:49 -0800 |
parents | 2b5c3699ac6f |
children | b76a3e3d3926 |
files | ChangeLog lib/poll.c tests/test-poll.c |
diffstat | 3 files changed, 31 insertions(+), 43 deletions(-) [+] |
line wrap: on
line diff
--- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,12 @@ +2015-02-20 Paul Eggert <eggert@cs.ucla.edu> + + poll: fixes for large fds + * lib/poll.c (poll): Don't check directly for NFD too large. + Don't rely on undefined behavior in FD_SET when an arg exceeds + FD_SETSIZE. Always set revents afterwards, even if to zero. + * tests/test-poll.c (poll1): Set revents to -1 instead of 0, + as that makes the test a bit stricter. + 2015-02-19 Kevin Cernekee <cernekee@google.com> fcntl: Fix cross compiling
--- a/lib/poll.c +++ b/lib/poll.c @@ -334,26 +334,15 @@ int maxfd, rc; nfds_t i; -# ifdef _SC_OPEN_MAX - static int sc_open_max = -1; - - if (nfd < 0 - || (nfd > sc_open_max - && (sc_open_max != -1 - || nfd > (sc_open_max = sysconf (_SC_OPEN_MAX))))) + if (nfd < 0) { errno = EINVAL; return -1; } -# else /* !_SC_OPEN_MAX */ -# ifdef OPEN_MAX - if (nfd < 0 || nfd > OPEN_MAX) - { - errno = EINVAL; - return -1; - } -# endif /* OPEN_MAX -- else, no check is needed */ -# endif /* !_SC_OPEN_MAX */ + /* Don't check directly for NFD too large. Any practical use of a + too-large NFD is caught by one of the other checks below, and + checking directly for getdtablesize is too much of a portability + and/or performance and/or correctness hassle. */ /* EFAULT is not necessary to implement, but let's do it in the simplest case. */ @@ -394,10 +383,17 @@ { if (pfd[i].fd < 0) continue; - + if (maxfd < pfd[i].fd) + { + maxfd = pfd[i].fd; + if (FD_SETSIZE <= maxfd) + { + errno = EINVAL; + return -1; + } + } if (pfd[i].events & (POLLIN | POLLRDNORM)) FD_SET (pfd[i].fd, &rfds); - /* see select(2): "the only exceptional condition detectable is out-of-band data received on a socket", hence we push POLLWRBAND events onto wfds instead of efds. */ @@ -405,18 +401,6 @@ FD_SET (pfd[i].fd, &wfds); if (pfd[i].events & (POLLPRI | POLLRDBAND)) FD_SET (pfd[i].fd, &efds); - if (pfd[i].fd >= maxfd - && (pfd[i].events & (POLLIN | POLLOUT | POLLPRI - | POLLRDNORM | POLLRDBAND - | POLLWRNORM | POLLWRBAND))) - { - maxfd = pfd[i].fd; - if (maxfd > FD_SETSIZE) - { - errno = EOVERFLOW; - return -1; - } - } } /* examine fd sets */ @@ -427,18 +411,13 @@ /* establish results */ rc = 0; for (i = 0; i < nfd; i++) - if (pfd[i].fd < 0) - pfd[i].revents = 0; - else - { - int happened = compute_revents (pfd[i].fd, pfd[i].events, - &rfds, &wfds, &efds); - if (happened) - { - pfd[i].revents = happened; - rc++; - } - } + { + pfd[i].revents = (pfd[i].fd < 0 + ? 0 + : compute_revents (pfd[i].fd, pfd[i].events, + &rfds, &wfds, &efds)); + rc += pfd[i].revents != 0; + } return rc; #else