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/* select filedescriptor handling, taken from:
* userspace logging daemon for the iptables ULOG target
* of the linux 2.4 netfilter subsystem.
*
* (C) 2000-2009 by Harald Welte <laforge@gnumonks.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <sys/select.h>
#include <osmocom/core/select.h>
#include <osmocom/core/linuxlist.h>
#include <osmocom/core/timer.h>
#include "../config.h"
#ifdef HAVE_SYS_SELECT_H
/*! \addtogroup select
* @{
*/
/*! \file select.c
* \brief select loop abstraction
*/
static int maxfd = 0;
static LLIST_HEAD(osmo_fds);
static int unregistered_count;
/*! \brief Check if a file descriptor is already registered
* \param[in] fd osmocom file descriptor to be checked
* \returns true if registered; otherwise false
*/
bool osmo_fd_is_registered(struct osmo_fd *fd)
{
struct osmo_fd *entry;
llist_for_each_entry(entry, &osmo_fds, list) {
if (entry == fd) {
return true;
}
}
return false;
}
/*! \brief Register a new file descriptor with select loop abstraction
* \param[in] fd osmocom file descriptor to be registered
* \returns 0 on success; negative in case of error
*/
int osmo_fd_register(struct osmo_fd *fd)
{
int flags;
/* make FD nonblocking */
flags = fcntl(fd->fd, F_GETFL);
if (flags < 0)
return flags;
flags |= O_NONBLOCK;
flags = fcntl(fd->fd, F_SETFL, flags);
if (flags < 0)
return flags;
/* set close-on-exec flag */
flags = fcntl(fd->fd, F_GETFD);
if (flags < 0)
return flags;
flags |= FD_CLOEXEC;
flags = fcntl(fd->fd, F_SETFD, flags);
if (flags < 0)
return flags;
/* Register FD */
if (fd->fd > maxfd)
maxfd = fd->fd;
#ifdef BSC_FD_CHECK
if (osmo_fd_is_registered(fd)) {
fprintf(stderr, "Adding a osmo_fd that is already in the list.\n");
return 0;
}
#endif
llist_add_tail(&fd->list, &osmo_fds);
return 0;
}
/*! \brief Unregister a file descriptor from select loop abstraction
* \param[in] fd osmocom file descriptor to be unregistered
*/
void osmo_fd_unregister(struct osmo_fd *fd)
{
/* Note: when fd is inside the osmo_fds list (not registered before)
* this function will crash! If in doubt, check file descriptor with
* osmo_fd_is_registered() */
unregistered_count++;
llist_del(&fd->list);
}
/*! \brief Populate the fd_sets and return the highest fd number
* \param[in] _rset The readfds to populate
* \param[in] _wset The wrtiefds to populate
* \param[in] _eset The errorfds to populate
*
* \returns The highest file descriptor seen or 0 on an empty list
*/
inline int osmo_fd_fill_fds(void *_rset, void *_wset, void *_eset)
{
fd_set *readset = _rset, *writeset = _wset, *exceptset = _eset;
struct osmo_fd *ufd;
int highfd = 0;
llist_for_each_entry(ufd, &osmo_fds, list) {
if (ufd->when & BSC_FD_READ)
FD_SET(ufd->fd, readset);
if (ufd->when & BSC_FD_WRITE)
FD_SET(ufd->fd, writeset);
if (ufd->when & BSC_FD_EXCEPT)
FD_SET(ufd->fd, exceptset);
if (ufd->fd > highfd)
highfd = ufd->fd;
}
return highfd;
}
inline int osmo_fd_disp_fds(void *_rset, void *_wset, void *_eset)
{
struct osmo_fd *ufd, *tmp;
int work = 0;
fd_set *readset = _rset, *writeset = _wset, *exceptset = _eset;
restart:
unregistered_count = 0;
llist_for_each_entry_safe(ufd, tmp, &osmo_fds, list) {
int flags = 0;
if (FD_ISSET(ufd->fd, readset)) {
flags |= BSC_FD_READ;
FD_CLR(ufd->fd, readset);
}
if (FD_ISSET(ufd->fd, writeset)) {
flags |= BSC_FD_WRITE;
FD_CLR(ufd->fd, writeset);
}
if (FD_ISSET(ufd->fd, exceptset)) {
flags |= BSC_FD_EXCEPT;
FD_CLR(ufd->fd, exceptset);
}
if (flags) {
work = 1;
ufd->cb(ufd, flags);
}
/* ugly, ugly hack. If more than one filedescriptor was
* unregistered, they might have been consecutive and
* llist_for_each_entry_safe() is no longer safe */
/* this seems to happen with the last element of the list as well */
if (unregistered_count >= 1)
goto restart;
}
return work;
}
/*! \brief select main loop integration
* \param[in] polling should we pollonly (1) or block on select (0)
* \returns 0 if no fd handled; 1 if fd handled; negative in case of error
*/
int osmo_select_main(int polling)
{
fd_set readset, writeset, exceptset;
int rc;
struct timeval no_time = {0, 0};
FD_ZERO(&readset);
FD_ZERO(&writeset);
FD_ZERO(&exceptset);
/* prepare read and write fdsets */
osmo_fd_fill_fds(&readset, &writeset, &exceptset);
if (!polling)
osmo_timers_prepare();
rc = select(maxfd+1, &readset, &writeset, &exceptset, polling ? &no_time : osmo_timers_nearest());
if (rc < 0)
return 0;
/* fire timers */
osmo_timers_update();
/* call registered callback functions */
return osmo_fd_disp_fds(&readset, &writeset, &exceptset);
}
/*! \brief find an osmo_fd based on the integer fd
* \param[in] fd file descriptor to use as search key
* \returns \ref osmo_fd for \ref fd; NULL in case it doesn't exist */
struct osmo_fd *osmo_fd_get_by_fd(int fd)
{
struct osmo_fd *ofd;
llist_for_each_entry(ofd, &osmo_fds, list) {
if (ofd->fd == fd)
return ofd;
}
return NULL;
}
/*! @} */
#endif /* _HAVE_SYS_SELECT_H */
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