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Fix poll() if POLLIN == ROLLRDNORM|POLLRDBAND 

It seems like POLLIN is specified as equivalent to POLLRDNORM | POLLRDBAND. Some
systems (e.g. QNX and HP-UX) take this literaly and have POLLIN defined as the
above bit combination. Other systems (e.g. Linux) have POLLIN as just a single
bit.

This means that if no out-of-band data is available (which should never be the
case), the result of poll() will not fulfil (fd.revents & POLLIN) == POLLIN on
QNX, because the POLLRDBAND bit is not set.

In other words, even though poll() signaled that the fd is readable, xcb would
not read from the file descriptor.

Fix this by checking if any bits from POLLIN are set in the result of poll(),
instead of all of them.

(This change was independently done by seanb@qnx.com as well)

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=38001
Acked-by: Julien Cristau <jcristau@debian.org>
Signed-off-by: Uli Schlachter <psychon@znc.in>
This commit is contained in:
Daphne Pfister 2013-09-08 16:25:11 -04:00 committed by Uli Schlachter
parent ac47e0ecdb
commit f1405d9fe4
1 changed files with 2 additions and 2 deletions
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4
src/xcb_conn.c
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@ -443,14 +443,14 @@ int _xcb_conn_wait(xcb_connection_t *c, pthread_cond_t *cond, struct iovec **vec
*/
int may_read = c->in.reading == 1 || !count;
#if USE_POLL
if(may_read && (fd.revents & POLLIN) == POLLIN)
if(may_read && (fd.revents & POLLIN) != 0)
#else
if(may_read && FD_ISSET(c->fd, &rfds))
#endif
ret = ret && _xcb_in_read(c);
#if USE_POLL
if((fd.revents & POLLOUT) == POLLOUT)
if((fd.revents & POLLOUT) != 0)
#else
if(FD_ISSET(c->fd, &wfds))
#endif