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fdwatch.c
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fdwatch.c
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/* fdwatch.c - fd watcher routines, either select() or poll()
**
** Copyright © 1999,2000 by Jef Poskanzer <jef@acme.com>.
** All rights reserved.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
** 1. Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** 2. Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in the
** documentation and/or other materials provided with the distribution.
**
** THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
** ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
** OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
** SUCH DAMAGE.
*/
#include <sys/types.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <syslog.h>
#ifndef MIN
#define MIN(a,b) ((a) < (b) ? (a) : (b))
#endif
#ifdef HAVE_POLL_H
#include <poll.h>
#else /* HAVE_POLL_H */
#ifdef HAVE_SYS_POLL_H
#include <sys/poll.h>
#endif /* HAVE_SYS_POLL_H */
#endif /* HAVE_POLL_H */
#ifdef HAVE_SYS_EVENT_H
#include <sys/event.h>
#endif /* HAVE_SYS_EVENT_H */
#include "fdwatch.h"
#ifdef HAVE_SELECT
#ifndef FD_SET
#define NFDBITS 32
#define FD_SETSIZE 32
#define FD_SET(n, p) ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS)))
#define FD_CLR(n, p) ((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS)))
#define FD_ISSET(n, p) ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS)))
#define FD_ZERO(p) bzero((char*)(p), sizeof(*(p)))
#endif /* !FD_SET */
#endif /* HAVE_SELECT */
static int nfiles;
static long nwatches;
static int* fd_rw;
static void** fd_data;
#ifdef HAVE_KQUEUE
static int kqueue_init( int nfiles );
static void kqueue_add_fd( int fd, int rw );
static void kqueue_del_fd( int fd );
static int kqueue_watch( long timeout_msecs );
static int kqueue_check_fd( int fd );
static int kqueue_get_fd( int ridx );
#else /* HAVE_KQUEUE */
# ifdef HAVE_POLL
static int poll_init( int nfiles );
static void poll_add_fd( int fd, int rw );
static void poll_del_fd( int fd );
static int poll_watch( long timeout_msecs );
static int poll_check_fd( int fd );
static int poll_get_fd( int ridx );
# else /* HAVE_POLL */
# ifdef HAVE_SELECT
static int select_init( int nfiles );
static void select_add_fd( int fd, int rw );
static void select_del_fd( int fd );
static int select_watch( long timeout_msecs );
static int select_check_fd( int fd );
static int select_get_fd( int ridx );
static int select_get_maxfd( void );
# endif /* HAVE_SELECT */
# endif /* HAVE_POLL */
#endif /* HAVE_KQUEUE */
/* Routines. */
/* Figure out how many file descriptors the system allows, and
** initialize the fdwatch data structures. Returns -1 on failure.
*/
int
fdwatch_get_nfiles( void )
{
#ifdef RLIMIT_NOFILE
struct rlimit rl;
#endif /* RLIMIT_NOFILE */
/* Figure out how many fd's we can have. */
nfiles = getdtablesize();
#ifdef RLIMIT_NOFILE
/* If we have getrlimit(), use that, and attempt to raise the limit. */
if ( getrlimit( RLIMIT_NOFILE, &rl ) == 0 )
{
nfiles = rl.rlim_cur;
if ( rl.rlim_max == RLIM_INFINITY )
rl.rlim_cur = 8192; /* arbitrary */
else if ( rl.rlim_max > rl.rlim_cur )
rl.rlim_cur = rl.rlim_max;
if ( setrlimit( RLIMIT_NOFILE, &rl ) == 0 )
nfiles = rl.rlim_cur;
}
#endif /* RLIMIT_NOFILE */
#if defined(HAVE_SELECT) && ! ( defined(HAVE_POLL) || defined(HAVE_KQUEUE) )
/* If we use select(), then we must limit ourselves to FD_SETSIZE. */
nfiles = MIN( nfiles, FD_SETSIZE );
#endif /* HAVE_SELECT && ! ( HAVE_POLL || HAVE_KQUEUE ) */
/* Initialize the fdwatch data structures. */
nwatches = 0;
fd_rw = (int*) malloc( sizeof(int) * nfiles );
fd_data = (void**) malloc( sizeof(void*) * nfiles );
if ( fd_rw == (int*) 0 || fd_data == (void**) 0 )
return -1;
#ifdef HAVE_KQUEUE
if ( kqueue_init( nfiles ) == -1 )
return -1;
#else /* HAVE_KQUEUE */
# ifdef HAVE_POLL
if ( poll_init( nfiles ) == -1 )
return -1;
# else /* HAVE_POLL */
# ifdef HAVE_SELECT
if ( select_init( nfiles ) == -1 )
return -1;
# endif /* HAVE_SELECT */
# endif /* HAVE_POLL */
#endif /* HAVE_KQUEUE */
return nfiles;
}
/* Add a descriptor to the watch list. rw is either FDW_READ or FDW_WRITE. */
void
fdwatch_add_fd( int fd, void* client_data, int rw )
{
#ifdef HAVE_KQUEUE
kqueue_add_fd( fd, rw );
#else /* HAVE_KQUEUE */
# ifdef HAVE_POLL
poll_add_fd( fd, rw );
# else /* HAVE_POLL */
# ifdef HAVE_SELECT
select_add_fd( fd, rw );
# endif /* HAVE_SELECT */
# endif /* HAVE_POLL */
#endif /* HAVE_KQUEUE */
fd_rw[fd] = rw;
fd_data[fd] = client_data;
}
/* Remove a descriptor from the watch list. */
void
fdwatch_del_fd( int fd )
{
#ifdef HAVE_KQUEUE
kqueue_del_fd( fd );
#else /* HAVE_KQUEUE */
# ifdef HAVE_POLL
poll_del_fd( fd );
# else /* HAVE_POLL */
# ifdef HAVE_SELECT
select_del_fd( fd );
# endif /* HAVE_SELECT */
# endif /* HAVE_POLL */
#endif /* HAVE_KQUEUE */
fd_data[fd] = (void*) 0;
}
/* Do the watch. Return value is the number of descriptors that are ready,
** or 0 if the timeout expired, or -1 on errors. A timeout of INFTIM means
** wait indefinitely.
*/
int
fdwatch( long timeout_msecs )
{
++nwatches;
#ifdef HAVE_KQUEUE
return kqueue_watch( timeout_msecs );
#else /* HAVE_KQUEUE */
# ifdef HAVE_POLL
return poll_watch( timeout_msecs );
# else /* HAVE_POLL */
# ifdef HAVE_SELECT
return select_watch( timeout_msecs );
# else /* HAVE_SELECT */
return -1;
# endif /* HAVE_SELECT */
# endif /* HAVE_POLL */
#endif /* HAVE_KQUEUE */
}
/* Check if a descriptor was ready. */
int
fdwatch_check_fd( int fd )
{
#ifdef HAVE_KQUEUE
return kqueue_check_fd( fd );
#else
# ifdef HAVE_POLL
return poll_check_fd( fd );
# else /* HAVE_POLL */
# ifdef HAVE_SELECT
return select_check_fd( fd );
# else /* HAVE_SELECT */
return 0;
# endif /* HAVE_SELECT */
# endif /* HAVE_POLL */
#endif /* HAVE_KQUEUE */
}
void*
fdwatch_get_client_data( int ridx )
{
int fd;
#ifdef HAVE_KQUEUE
fd = kqueue_get_fd( ridx );
#else /* HAVE_KQUEUE */
# ifdef HAVE_POLL
fd = poll_get_fd( ridx );
# else /* HAVE_POLL */
# ifdef HAVE_SELECT
fd = select_get_fd( ridx );
# else /* HAVE_SELECT */
fd = -1;
# endif /* HAVE_SELECT */
# endif /* HAVE_POLL */
#endif /* HAVE_KQUEUE */
if ( fd < 0 || fd >= nfiles )
return (void*) 0;
return fd_data[fd];
}
/* Generate debugging statistics syslog message. */
void
fdwatch_logstats( long secs )
{
char* which;
#ifdef HAVE_KQUEUE
which = "kevent";
#else /* HAVE_KQUEUE */
# ifdef HAVE_POLL
which = "poll";
# else /* HAVE_POLL */
# ifdef HAVE_SELECT
which = "select";
# else /* HAVE_SELECT */
which = "UNKNOWN";
# endif /* HAVE_SELECT */
# endif /* HAVE_POLL */
#endif /* HAVE_KQUEUE */
syslog(
LOG_NOTICE, " fdwatch - %ld %ss (%g/sec)",
nwatches, which, (float) nwatches / secs );
nwatches = 0;
}
#ifdef HAVE_KQUEUE
static struct kevent* kqchanges;
static int nkqchanges;
static struct kevent* kqevents;
static int* kqrfdidx;
static int kq;
static int
kqueue_init( int nfiles )
{
kq = kqueue();
if ( kq == -1 )
return -1;
kqchanges = (struct kevent*) malloc( sizeof(struct kevent) * 2 * nfiles );
kqevents = (struct kevent*) malloc( sizeof(struct kevent) * nfiles );
kqrfdidx = (int*) malloc( sizeof(int) * nfiles );
if ( kqchanges == (struct kevent*) 0 || kqevents == (struct kevent*) 0 ||
kqrfdidx == (int*) 0 )
return -1;
return 0;
}
static void
kqueue_add_fd( int fd, int rw )
{
kqchanges[nkqchanges].ident = fd;
kqchanges[nkqchanges].flags = EV_ADD;
switch ( rw )
{
case FDW_READ: kqchanges[nkqchanges].filter = EVFILT_READ; break;
case FDW_WRITE: kqchanges[nkqchanges].filter = EVFILT_WRITE; break;
default: break;
}
++nkqchanges;
}
static void
kqueue_del_fd( int fd )
{
kqchanges[nkqchanges].ident = fd;
kqchanges[nkqchanges].flags = EV_DELETE;
switch ( fd_rw[fd] )
{
case FDW_READ: kqchanges[nkqchanges].filter = EVFILT_READ; break;
case FDW_WRITE: kqchanges[nkqchanges].filter = EVFILT_WRITE; break;
}
++nkqchanges;
}
static int
kqueue_watch( long timeout_msecs )
{
int i, r;
if ( timeout_msecs == INFTIM )
r = kevent(
kq, kqchanges, nkqchanges, kqevents, nfiles, (struct timespec*) 0 );
else
{
struct timespec ts;
ts.tv_sec = timeout_msecs / 1000L;
ts.tv_nsec = ( timeout_msecs % 1000L ) * 1000000L;
r = kevent( kq, kqchanges, nkqchanges, kqevents, nfiles, &ts );
}
nkqchanges = 0;
if ( r == -1 )
return -1;
for ( i = 0; i < r; ++i )
if ( ! ( kqevents[i].flags & EV_ERROR ) )
kqrfdidx[kqevents[i].ident] = i;
return r;
}
static int
kqueue_check_fd( int fd )
{
int ridx = kqrfdidx[fd];
if ( kqevents[ridx].ident != fd )
return 0;
switch ( fd_rw[fd] )
{
case FDW_READ: return kqevents[ridx].filter == EVFILT_READ;
case FDW_WRITE: return kqevents[ridx].filter == EVFILT_WRITE;
default: return 0;
}
}
static int
kqueue_get_fd( int ridx )
{
int fd;
if ( kqevents[ridx].flags & EV_ERROR )
return -1;
fd = kqevents[ridx].ident;
if ( kqueue_check_fd( fd ) )
return fd;
return -1;
}
#else /* HAVE_KQUEUE */
# ifdef HAVE_POLL
static struct pollfd* pollfds;
static int npollfds;
static int* poll_fdidx;
static int* poll_rfdidx;
static int
poll_init( int nfiles )
{
pollfds = (struct pollfd*) malloc( sizeof(struct pollfd) * nfiles );
poll_fdidx = (int*) malloc( sizeof(int) * nfiles );
poll_rfdidx = (int*) malloc( sizeof(int) * nfiles );
if ( pollfds == (struct pollfd*) 0 || poll_fdidx == (int*) 0 ||
poll_rfdidx == (int*) 0 )
return -1;
return 0;
}
static void
poll_add_fd( int fd, int rw )
{
pollfds[npollfds].fd = fd;
switch ( rw )
{
case FDW_READ: pollfds[npollfds].events = POLLIN; break;
case FDW_WRITE: pollfds[npollfds].events = POLLOUT; break;
default: break;
}
poll_fdidx[fd] = npollfds;
++npollfds;
}
static void
poll_del_fd( int fd )
{
int idx = poll_fdidx[fd];
--npollfds;
pollfds[idx] = pollfds[npollfds];
poll_fdidx[pollfds[idx].fd] = idx;
}
static int
poll_watch( long timeout_msecs )
{
int r, ridx, i;
r = poll( pollfds, npollfds, (int) timeout_msecs );
if ( r == -1 )
return -1;
ridx = 0;
for ( i = 0; i < npollfds; ++i )
if ( pollfds[i].revents & ( POLLIN | POLLOUT ) )
poll_rfdidx[ridx++] = pollfds[i].fd;
return r;
}
static int
poll_check_fd( int fd )
{
switch ( fd_rw[fd] )
{
case FDW_READ: return pollfds[poll_fdidx[fd]].revents & POLLIN;
case FDW_WRITE: return pollfds[poll_fdidx[fd]].revents & POLLOUT;
default: return 0;
}
}
static int
poll_get_fd( int ridx )
{
int fd = poll_rfdidx[ridx];
if ( poll_check_fd( fd ) )
return fd;
return -1;
}
# else /* HAVE_POLL */
# ifdef HAVE_SELECT
static fd_set master_rfdset;
static fd_set master_wfdset;
static fd_set working_rfdset;
static fd_set working_wfdset;
static int* select_fds;
static int* select_fdidx;
static int* select_rfdidx;
static int nselect_fds;
static int maxfd;
static int maxfd_changed;
static int
select_init( int nfiles )
{
FD_ZERO( &master_rfdset );
FD_ZERO( &master_wfdset );
select_fds = (int*) malloc( sizeof(int) * nfiles );
select_fdidx = (int*) malloc( sizeof(int) * nfiles );
select_rfdidx = (int*) malloc( sizeof(int) * nfiles );
if ( select_fds == (int*) 0 || select_fdidx == (int*) 0 ||
select_rfdidx == (int*) 0 )
return -1;
maxfd = -1;
maxfd_changed = 0;
return 0;
}
static void
select_add_fd( int fd, int rw )
{
select_fds[nselect_fds] = fd;
switch ( rw )
{
case FDW_READ: FD_SET( fd, &master_rfdset ); break;
case FDW_WRITE: FD_SET( fd, &master_wfdset ); break;
default: break;
}
if ( fd > maxfd )
maxfd = fd;
select_fdidx[fd] = nselect_fds;
++nselect_fds;
}
static void
select_del_fd( int fd )
{
int idx = select_fdidx[fd];
--nselect_fds;
select_fds[idx] = select_fds[nselect_fds];
select_fdidx[select_fds[idx]] = idx;
FD_CLR( fd, &master_rfdset );
FD_CLR( fd, &master_wfdset );
if ( fd >= maxfd )
maxfd_changed = 1;
}
static int
select_watch( long timeout_msecs )
{
int mfd;
int r, fd, ridx;
working_rfdset = master_rfdset;
working_wfdset = master_wfdset;
mfd = select_get_maxfd();
if ( timeout_msecs == INFTIM )
r = select(
mfd + 1, &working_rfdset, &working_wfdset, (fd_set*) 0,
(struct timeval*) 0 );
else
{
struct timeval timeout;
timeout.tv_sec = timeout_msecs / 1000L;
timeout.tv_usec = ( timeout_msecs % 1000L ) * 1000L;
r = select(
mfd + 1, &working_rfdset, &working_wfdset, (fd_set*) 0, &timeout );
}
if ( r == -1 )
return -1;
ridx = 0;
for ( fd = 0; fd <= mfd; ++fd )
if ( select_check_fd( fd ) )
select_rfdidx[ridx++] = fd;
return r;
}
static int
select_check_fd( int fd )
{
switch ( fd_rw[fd] )
{
case FDW_READ: return FD_ISSET( fd, &working_rfdset );
case FDW_WRITE: return FD_ISSET( fd, &working_wfdset );
default: return 0;
}
}
static int
select_get_fd( int ridx )
{
int fd = select_rfdidx[ridx];
if ( select_check_fd( fd ) )
return fd;
return -1;
}
static int
select_get_maxfd( void )
{
if ( maxfd_changed )
{
int i;
maxfd = -1;
for ( i = 0; i < nselect_fds; ++i )
if ( select_fds[i] > maxfd )
maxfd = select_fds[i];
maxfd_changed = 0;
}
return maxfd;
}
# endif /* HAVE_SELECT */
# endif /* HAVE_POLL */
#endif /* HAVE_KQUEUE */