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/* Copyright (C) 2016 Andy Wingo <wingo@pobox.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 3 of
* the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301 USA
*/
#define _GNU_SOURCE
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <errno.h>
#include <sys/epoll.h>
#include <libguile.h>
/* {EPoll}
*/
static SCM
scm_primitive_epoll_wake (SCM wakefd)
#define FUNC_NAME "primitive-epoll-wake"
{
int c_fd;
char zero = 0;
c_fd = scm_to_int (wakefd);
if (write (c_fd, &zero, 1) <= 0 && errno != EWOULDBLOCK && errno != EAGAIN)
SCM_SYSERROR;
return SCM_UNSPECIFIED;
}
#undef FUNC_NAME
/* EPoll is a newer Linux interface designed for sets of file
descriptors that are mostly in a dormant state. These primitives
wrap the epoll interface on a very low level.
This is a low-level interface. See the `(fibers epoll)' module for
a more usable wrapper. Note that this low-level interface deals in
file descriptors, not ports, in order to allow higher-level code to
handle the interaction with the garbage collector. */
static SCM
scm_primitive_epoll_create (SCM cloexec_p)
#define FUNC_NAME "epoll-create"
{
int fd;
#ifdef HAVE_EPOLL_CREATE1
fd = epoll_create1 (scm_is_true (cloexec_p) ? EPOLL_CLOEXEC : 0);
if (fd < 0)
SCM_SYSERROR;
#else
fd = epoll_create (16);
if (fd < 0)
SCM_SYSERROR;
if (scm_is_true (cloexec_p))
fcntl (fd, F_SETFD, FD_CLOEXEC, 1);
#endif
return scm_from_int (fd);
}
#undef FUNC_NAME
/* This epoll wrapper always places the fd itself as the "data" of the
events structure. */
static SCM
scm_primitive_epoll_ctl (SCM epfd, SCM op, SCM fd, SCM events)
#define FUNC_NAME "primitive-epoll-ctl"
{
int c_epfd, c_op, c_fd;
struct epoll_event ev = { 0, };
c_epfd = scm_to_int (epfd);
c_op = scm_to_int (op);
c_fd = scm_to_int (fd);
if (SCM_UNBNDP (events))
{
if (c_op == EPOLL_CTL_DEL)
/* Events do not matter in this case. */
ev.events = 0;
else
SCM_MISC_ERROR ("missing events arg", SCM_EOL);
}
else
ev.events = scm_to_uint32 (events);
ev.data.fd = c_fd;
if (epoll_ctl (c_epfd, c_op, c_fd, &ev))
SCM_SYSERROR;
return SCM_UNSPECIFIED;
}
#undef FUNC_NAME
struct epoll_wait_data {
int fd;
struct epoll_event *events;
int maxevents;
int timeout;
int rv;
int err;
};
static void*
do_epoll_wait (void *p)
{
struct epoll_wait_data *data = p;
data->rv = epoll_wait (data->fd, data->events, data->maxevents,
data->timeout);
data->err = errno;
return NULL;
}
/* Wait on the files whose descriptors were registered on EPFD, and
write the resulting events in EVENTSV, a bytevector. Returns the
number of struct epoll_event values that were written to EVENTSV,
which may be zero if no files triggered wakeups within TIMEOUT
milliseconds. */
static SCM
scm_primitive_epoll_wait (SCM epfd, SCM wakefd, SCM wokefd,
SCM eventsv, SCM timeout)
#define FUNC_NAME "primitive-epoll-wait"
{
int c_epfd, c_wakefd, c_wokefd, maxevents, rv, c_timeout;
struct epoll_event *events;
c_epfd = scm_to_int (epfd);
c_wakefd = scm_to_int (wakefd);
c_wokefd = scm_to_int (wokefd);
SCM_VALIDATE_BYTEVECTOR (SCM_ARG2, eventsv);
if (SCM_UNLIKELY (SCM_BYTEVECTOR_LENGTH (eventsv) % sizeof (*events)))
SCM_OUT_OF_RANGE (SCM_ARG2, eventsv);
events = (struct epoll_event *) SCM_BYTEVECTOR_CONTENTS (eventsv);
maxevents = SCM_BYTEVECTOR_LENGTH (eventsv) / sizeof (*events);
c_timeout = scm_to_int (timeout);
if (scm_c_prepare_to_wait_on_fd (c_wakefd))
rv = 0;
else
{
struct epoll_wait_data data = { c_epfd, events, maxevents, c_timeout };
scm_without_guile (do_epoll_wait, &data);
rv = data.rv;
scm_c_wait_finished ();
if (rv < 0)
{
if (data.err == EINTR)
rv = 0;
else
{
errno = data.err;
SCM_SYSERROR;
}
}
else
{
/* Drain woke fd if appropriate. Doing it from Scheme is a
bit gnarly as we don't know if suspendable ports are
enabled or not. */
int i;
for (i = 0; i < rv; i++)
if (events[i].data.fd == c_wokefd)
{
char zeroes[32];
/* Remove wake fd from result set. */
rv--;
memmove (events + i,
events + i + 1,
(rv - i) * sizeof (*events));
/* Drain fd and ignore errors. */
while (read (c_wokefd, zeroes, sizeof zeroes) == sizeof zeroes)
;
break;
}
}
}
return scm_from_int (rv);
}
#undef FUNC_NAME
/* Low-level helpers for (fibers poll). */
void
init_fibers_epoll (void)
{
scm_c_define_gsubr ("primitive-epoll-wake", 1, 0, 0,
scm_primitive_epoll_wake);
scm_c_define_gsubr ("primitive-epoll-create", 1, 0, 0,
scm_primitive_epoll_create);
scm_c_define_gsubr ("primitive-epoll-ctl", 3, 1, 0,
scm_primitive_epoll_ctl);
scm_c_define_gsubr ("primitive-epoll-wait", 5, 0, 0,
scm_primitive_epoll_wait);
scm_c_define ("%sizeof-struct-epoll-event",
scm_from_size_t (sizeof (struct epoll_event)));
scm_c_define ("%offsetof-struct-epoll-event-fd",
scm_from_size_t (offsetof (struct epoll_event, data.fd)));
scm_c_define ("EPOLLIN", scm_from_int (EPOLLIN));
scm_c_define ("EPOLLOUT", scm_from_int (EPOLLOUT));
#ifdef EPOLLRDHUP
scm_c_define ("EPOLLRDHUP", scm_from_int (EPOLLRDHUP));
#endif
scm_c_define ("EPOLLPRI", scm_from_int (EPOLLPRI));
scm_c_define ("EPOLLERR", scm_from_int (EPOLLERR));
scm_c_define ("EPOLLHUP", scm_from_int (EPOLLHUP));
scm_c_define ("EPOLLET", scm_from_int (EPOLLET));
#ifdef EPOLLONESHOT
scm_c_define ("EPOLLONESHOT", scm_from_int (EPOLLONESHOT));
#endif
scm_c_define ("EPOLL_CTL_ADD", scm_from_int (EPOLL_CTL_ADD));
scm_c_define ("EPOLL_CTL_MOD", scm_from_int (EPOLL_CTL_MOD));
scm_c_define ("EPOLL_CTL_DEL", scm_from_int (EPOLL_CTL_DEL));
}
/*
Local Variables:
c-file-style: "gnu"
End:
*/
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