newlib-cygwin/winsup/cygwin/poll.cc

162 lines
4.5 KiB
C++

/* poll.cc. Implements poll(2) via usage of select(2) call.
This file is part of Cygwin.
This software is a copyrighted work licensed under the terms of the
Cygwin license. Please consult the file "CYGWIN_LICENSE" for
details. */
#define FD_SETSIZE 16384 // lots of fds
#include "winsup.h"
#include <sys/poll.h>
#include <sys/param.h>
#include <stdlib.h>
#define USE_SYS_TYPES_FD_SET
#include "cygerrno.h"
#include "path.h"
#include "fhandler.h"
#include "dtable.h"
#include "cygheap.h"
#include "pinfo.h"
#include "sigproc.h"
#include "select.h"
extern "C" int
poll (struct pollfd *fds, nfds_t nfds, int timeout)
{
int max_fd = 0;
int invalid_fds = 0;
fd_set *read_fds, *write_fds, *except_fds;
struct timeval tv = { timeout / 1000, (timeout % 1000) * 1000 };
for (unsigned int i = 0; i < nfds; ++i)
if (fds[i].fd > max_fd)
max_fd = fds[i].fd;
size_t fds_size = howmany (max_fd + 1, NFDBITS) * sizeof (fd_mask);
read_fds = (fd_set *) alloca (fds_size);
write_fds = (fd_set *) alloca (fds_size);
except_fds = (fd_set *) alloca (fds_size);
if (!read_fds || !write_fds || !except_fds)
{
set_errno (EINVAL); /* According to SUSv3. */
return -1;
}
memset (read_fds, 0, fds_size);
memset (write_fds, 0, fds_size);
memset (except_fds, 0, fds_size);
for (unsigned int i = 0; i < nfds; ++i)
{
fds[i].revents = 0;
if (!cygheap->fdtab.not_open (fds[i].fd))
{
if (fds[i].events & POLLIN)
FD_SET(fds[i].fd, read_fds);
if (fds[i].events & POLLOUT)
FD_SET(fds[i].fd, write_fds);
if (fds[i].events & POLLPRI)
FD_SET(fds[i].fd, except_fds);
}
else if (fds[i].fd >= 0)
{
++invalid_fds;
fds[i].revents = POLLNVAL;
}
}
/* Invalid fds? */
if (invalid_fds > 0)
{
/* Only invalid fds? Return. */
if ((nfds_t) invalid_fds == nfds)
return invalid_fds;
/* POSIX doesn't explicitely define this behaviour, but on Linux,
the timeout is set to 0 if an error occurs, and POLLNVAL is one
of these errors. So, for Linux-compatibility's sake... */
tv.tv_sec = tv.tv_usec = 0;
}
int ret = cygwin_select (max_fd + 1, read_fds, write_fds, except_fds,
timeout < 0 ? NULL : &tv);
/* timeout, signal, whatever? Return. If invalid fds exist, return with
their number. */
if (ret <= 0)
return invalid_fds ?: ret;
/* Set revents fields and count fds with non-zero revents fields for
return value. */
ret = 0;
for (unsigned int i = 0; i < nfds; ++i)
{
if (fds[i].fd >= 0 && fds[i].revents != POLLNVAL)
{
fhandler_socket *sock;
/* Check if the descriptor has been closed, or if shutdown for the
read side has been called on a socket. */
if (cygheap->fdtab.not_open (fds[i].fd)
|| ((sock = cygheap->fdtab[fds[i].fd]->is_socket ())
&& sock->saw_shutdown_read ()))
fds[i].revents = POLLHUP;
else
{
if (FD_ISSET(fds[i].fd, read_fds))
/* This should be sufficient for sockets, too. Using
MSG_PEEK, as before, can be considered dangerous at
best. Quote from W. Richard Stevens: "The presence
of an error can be considered either normal data or
an error (POLLERR). In either case, a subsequent read
will return -1 with errno set to the appropriate value."
So it looks like there's actually no good reason to
return POLLERR. */
fds[i].revents |= POLLIN;
/* Handle failed connect. A failed connect implicitly sets
POLLOUT, if requested, but it doesn't set POLLIN. */
if ((fds[i].events & POLLIN)
&& (sock = cygheap->fdtab[fds[i].fd]->is_socket ())
&& sock->connect_state () == connect_failed)
fds[i].revents |= (POLLIN | POLLERR);
else
{
if (FD_ISSET(fds[i].fd, write_fds))
fds[i].revents |= POLLOUT;
if (FD_ISSET(fds[i].fd, except_fds))
fds[i].revents |= POLLPRI;
}
}
if (fds[i].revents)
++ret;
}
}
/* Number of fds with event includes the invalid fds. */
return ret + invalid_fds;
}
extern "C" int
ppoll (struct pollfd *fds, nfds_t nfds, const struct timespec *timeout_ts,
const sigset_t *sigmask)
{
int timeout;
sigset_t oldset = _my_tls.sigmask;
__try
{
timeout = (timeout_ts == NULL)
? -1
: (timeout_ts->tv_sec * 1000 + timeout_ts->tv_nsec / 1000000);
if (sigmask)
set_signal_mask (_my_tls.sigmask, *sigmask);
int ret = poll (fds, nfds, timeout);
if (sigmask)
set_signal_mask (_my_tls.sigmask, oldset);
return ret;
}
__except (EFAULT) {}
__endtry
return -1;
}