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From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Subject: Fix poll and select POSIX compliancy details about errors
This fixes the following:
- On error, poll must not return without polling, including EBADF, and instead
report POLLHUP/POLLERR/POLLNVAL
- Select must report EBADF if some set contains an invalid FD.
The idea is to move error management to after all select calls, in the
poll/select final treatment. The error is instead recorded in a new `error'
field, and a new SELECT_ERROR bit set.
Thanks Svante Signell for the initial version of the patch.
* hurd/hurdselect.c (SELECT_ERROR): New macro.
(_hurd_select):
- Add `error' field to `d' structures array.
- If a poll descriptor is bogus, set EBADF, but continue with a zero timeout.
- Go through the whole fd_set, not only until _hurd_dtablesize. Return EBADF
there is any bit set above _hurd_dtablesize.
- Do not request io_select on bogus descriptors (SELECT_ERROR).
- On io_select request error, record the error.
- On io_select bogus reply, use EIO error code.
- On io_select bogus or error reply, record the error.
- Do not destroy reply port for bogus FDs.
- On error, make poll set POLLHUP in the EPIPE case, POLLNVAL in the EBADF
case, or else POLLERR.
- On error, make select simulated readiness.
---
hurd/hurdselect.c | 149 +++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 108 insertions(+), 41 deletions(-)
diff --git a/hurd/hurdselect.c b/hurd/hurdselect.c
index 70780dd..dcda71b 100644
--- a/hurd/hurdselect.c
+++ b/hurd/hurdselect.c
@@ -34,6 +34,7 @@
/* Used to record that a particular select rpc returned. Must be distinct
from SELECT_ALL (which better not have the high bit set). */
#define SELECT_RETURNED ((SELECT_ALL << 1) & ~SELECT_ALL)
+#define SELECT_ERROR (SELECT_RETURNED << 1)
/* Check the first NFDS descriptors either in POLLFDS (if nonnnull) or in
each of READFDS, WRITEFDS, EXCEPTFDS that is nonnull. If TIMEOUT is not
@@ -61,6 +62,7 @@ _hurd_select (int nfds,
mach_port_t io_port;
int type;
mach_port_t reply_port;
+ int error;
} d[nfds];
sigset_t oset;
@@ -118,6 +120,7 @@ _hurd_select (int nfds,
if (pollfds)
{
+ int error = 0;
/* Collect interesting descriptors from the user's `pollfd' array.
We do a first pass that reads the user's array before taking
any locks. The second pass then only touches our own stack,
@@ -151,28 +154,47 @@ _hurd_select (int nfds,
if (fd < _hurd_dtablesize)
{
d[i].cell = _hurd_dtable[fd];
- d[i].io_port = _hurd_port_get (&d[i].cell->port, &d[i].ulink);
- if (d[i].io_port != MACH_PORT_NULL)
- continue;
+ if (d[i].cell != NULL)
+ {
+ d[i].io_port = _hurd_port_get (&d[i].cell->port,
+ &d[i].ulink);
+ if (d[i].io_port != MACH_PORT_NULL)
+ continue;
+ }
}
- /* If one descriptor is bogus, we fail completely. */
- while (i-- > 0)
- if (d[i].type != 0)
- _hurd_port_free (&d[i].cell->port,
- &d[i].ulink, d[i].io_port);
- break;
+ /* Bogus descriptor, make it EBADF already. */
+ d[i].error = EBADF;
+ d[i].type = SELECT_ERROR;
+ error = 1;
}
__mutex_unlock (&_hurd_dtable_lock);
HURD_CRITICAL_END;
- if (i < nfds)
+ if (error)
{
- if (sigmask)
- __sigprocmask (SIG_SETMASK, &oset, NULL);
- errno = EBADF;
- return -1;
+ /* Set timeout to 0. */
+ struct timeval now;
+ err = __gettimeofday(&now, NULL);
+ if (err)
+ {
+ /* Really bad luck. */
+ err = errno;
+ HURD_CRITICAL_BEGIN;
+ __mutex_lock (&_hurd_dtable_lock);
+ while (i-- > 0)
+ if (d[i].type & ~SELECT_ERROR != 0)
+ _hurd_port_free (&d[i].cell->port, &d[i].ulink,
+ d[i].io_port);
+ __mutex_unlock (&_hurd_dtable_lock);
+ HURD_CRITICAL_END;
+ errno = err;
+ return -1;
+ }
+ ts.tv_sec = now.tv_sec;
+ ts.tv_nsec = now.tv_usec * 1000;
+ reply_msgid = IO_SELECT_TIMEOUT_REPLY_MSGID;
}
lastfd = i - 1;
@@ -199,9 +221,6 @@ _hurd_select (int nfds,
HURD_CRITICAL_BEGIN;
__mutex_lock (&_hurd_dtable_lock);
- if (nfds > _hurd_dtablesize)
- nfds = _hurd_dtablesize;
-
/* Collect the ports for interesting FDs. */
firstfd = lastfd = -1;
for (i = 0; i < nfds; ++i)
@@ -216,9 +235,15 @@ _hurd_select (int nfds,
d[i].type = type;
if (type)
{
- d[i].cell = _hurd_dtable[i];
- d[i].io_port = _hurd_port_get (&d[i].cell->port, &d[i].ulink);
- if (d[i].io_port == MACH_PORT_NULL)
+ if (i < _hurd_dtablesize)
+ {
+ d[i].cell = _hurd_dtable[i];
+ if (d[i].cell != NULL)
+ d[i].io_port = _hurd_port_get (&d[i].cell->port,
+ &d[i].ulink);
+ }
+ if (i >= _hurd_dtablesize || d[i].cell == NULL ||
+ d[i].io_port == MACH_PORT_NULL)
{
/* If one descriptor is bogus, we fail completely. */
while (i-- > 0)
@@ -243,6 +268,9 @@ _hurd_select (int nfds,
errno = EBADF;
return -1;
}
+
+ if (nfds > _hurd_dtablesize)
+ nfds = _hurd_dtablesize;
}
@@ -260,7 +288,9 @@ _hurd_select (int nfds,
portset = MACH_PORT_NULL;
for (i = firstfd; i <= lastfd; ++i)
- if (d[i].type)
+ if (!(d[i].type & ~SELECT_ERROR))
+ d[i].reply_port = MACH_PORT_NULL;
+ else
{
int type = d[i].type;
d[i].reply_port = __mach_reply_port ();
@@ -294,11 +324,10 @@ _hurd_select (int nfds,
}
else
{
- /* No error should happen. Callers of select
- don't expect to see errors, so we simulate
- readiness of the erring object and the next call
- hopefully will get the error again. */
- d[i].type |= SELECT_RETURNED;
+ /* No error should happen, but record it for later
+ processing. */
+ d[i].error = err;
+ d[i].type |= SELECT_ERROR;
++got;
}
_hurd_port_free (&d[i].cell->port, &d[i].ulink, d[i].io_port);
@@ -404,9 +433,10 @@ _hurd_select (int nfds,
#endif
msg.head.msgh_size != sizeof msg.success)
{
- /* Error or bogus reply. Simulate readiness. */
+ /* Error or bogus reply. */
+ if (!msg.error.err)
+ msg.error.err = EIO;
__mach_msg_destroy (&msg.head);
- msg.success.result = SELECT_ALL;
}
/* Look up the respondent's reply port and record its
@@ -418,9 +448,18 @@ _hurd_select (int nfds,
if (d[i].type
&& d[i].reply_port == msg.head.msgh_local_port)
{
- d[i].type &= msg.success.result;
- if (d[i].type)
- ++ready;
+ if (msg.error.err)
+ {
+ d[i].error = msg.error.err;
+ d[i].type = SELECT_ERROR;
+ ++ready;
+ }
+ else
+ {
+ d[i].type &= msg.success.result;
+ if (d[i].type)
+ ++ready;
+ }
d[i].type |= SELECT_RETURNED;
++got;
@@ -454,7 +493,7 @@ _hurd_select (int nfds,
if (firstfd != -1)
for (i = firstfd; i <= lastfd; ++i)
- if (d[i].type)
+ if (d[i].reply_port != MACH_PORT_NULL)
__mach_port_destroy (__mach_task_self (), d[i].reply_port);
if (firstfd == -1 || (firstfd != lastfd && portset != MACH_PORT_NULL))
/* Destroy PORTSET, but only if it's not actually the reply port for a
@@ -476,15 +515,29 @@ _hurd_select (int nfds,
int type = d[i].type;
int_fast16_t revents = 0;
- if (type & SELECT_RETURNED)
- {
- if (type & SELECT_READ)
- revents |= POLLIN;
- if (type & SELECT_WRITE)
- revents |= POLLOUT;
- if (type & SELECT_URG)
- revents |= POLLPRI;
- }
+ if (type & SELECT_ERROR)
+ switch (d[i].error)
+ {
+ case EPIPE:
+ revents = POLLHUP;
+ break;
+ case EBADF:
+ revents = POLLNVAL;
+ break;
+ default:
+ revents = POLLERR;
+ break;
+ }
+ else
+ if (type & SELECT_RETURNED)
+ {
+ if (type & SELECT_READ)
+ revents |= POLLIN;
+ if (type & SELECT_WRITE)
+ revents |= POLLOUT;
+ if (type & SELECT_URG)
+ revents |= POLLPRI;
+ }
pollfds[i].revents = revents;
}
@@ -504,6 +557,20 @@ _hurd_select (int nfds,
if ((type & SELECT_RETURNED) == 0)
type = 0;
+ /* Callers of select don't expect to see errors, so we simulate
+ readiness of the erring object and the next call hopefully
+ will get the error again. */
+ if (type & SELECT_ERROR)
+ {
+ type = 0;
+ if (readfds != NULL && FD_ISSET (i, readfds))
+ type |= SELECT_READ;
+ if (writefds != NULL && FD_ISSET (i, writefds))
+ type |= SELECT_WRITE;
+ if (exceptfds != NULL && FD_ISSET (i, exceptfds))
+ type |= SELECT_URG;
+ }
+
if (type & SELECT_READ)
ready++;
else if (readfds)
--
tg: (de946c7..) t/poll_errors_fixes (depends on: t/io_select_timeout)
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