mirror of https://gerrit.osmocom.org/libosmocore
602 lines
15 KiB
C
602 lines
15 KiB
C
/*! \file select.c
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* select filedescriptor handling.
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* Taken from:
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* userspace logging daemon for the iptables ULOG target
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* of the linux 2.4 netfilter subsystem. */
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/*
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* (C) 2000-2020 by Harald Welte <laforge@gnumonks.org>
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* All Rights Reserverd.
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*
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* SPDX-License-Identifier: GPL-2.0+
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301, USA.
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*/
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#include <fcntl.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <string.h>
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#include <stdbool.h>
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#include <errno.h>
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#include <osmocom/core/select.h>
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#include <osmocom/core/linuxlist.h>
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#include <osmocom/core/timer.h>
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#include <osmocom/core/logging.h>
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#include <osmocom/core/talloc.h>
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#include <osmocom/core/utils.h>
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#include "../config.h"
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#if defined(HAVE_SYS_SELECT_H) && defined(HAVE_POLL_H)
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#include <sys/select.h>
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#include <poll.h>
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/*! \addtogroup select
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* @{
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* select() loop abstraction
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*
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* \file select.c */
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/* keep a set of file descriptors per-thread, so that each thread can have its own
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* distinct set of file descriptors to interact with */
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static __thread int maxfd = 0;
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static __thread struct llist_head osmo_fds; /* TLS cannot use LLIST_HEAD() */
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static __thread int unregistered_count;
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#ifndef FORCE_IO_SELECT
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struct poll_state {
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/* array of pollfd */
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struct pollfd *poll;
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/* number of entries in pollfd allocated */
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unsigned int poll_size;
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/* number of osmo_fd registered */
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unsigned int num_registered;
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};
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static __thread struct poll_state g_poll;
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#endif /* FORCE_IO_SELECT */
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/*! Set up an osmo-fd. Will not register it.
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* \param[inout] ofd Osmo FD to be set-up
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* \param[in] fd OS-level file descriptor number
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* \param[in] when bit-mask of OSMO_FD_{READ,WRITE,EXECEPT}
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* \param[in] cb Call-back function to be called
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* \param[in] data Private context pointer
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* \param[in] priv_nr Private number
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*/
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void osmo_fd_setup(struct osmo_fd *ofd, int fd, unsigned int when,
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int (*cb)(struct osmo_fd *fd, unsigned int what),
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void *data, unsigned int priv_nr)
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{
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ofd->fd = fd;
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ofd->when = when;
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ofd->cb = cb;
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ofd->data = data;
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ofd->priv_nr = priv_nr;
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}
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/*! Update the 'when' field of osmo_fd. "ofd->when = (ofd->when & when_mask) | when".
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* Use this function instead of directly modifying ofd->when, as the latter will be
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* removed soon. */
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void osmo_fd_update_when(struct osmo_fd *ofd, unsigned int when_mask, unsigned int when)
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{
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ofd->when &= when_mask;
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ofd->when |= when;
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}
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/*! Check if a file descriptor is already registered
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* \param[in] fd osmocom file descriptor to be checked
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* \returns true if registered; otherwise false
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*/
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bool osmo_fd_is_registered(struct osmo_fd *fd)
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{
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struct osmo_fd *entry;
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llist_for_each_entry(entry, &osmo_fds, list) {
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if (entry == fd) {
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return true;
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}
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}
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return false;
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}
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/*! Register a new file descriptor with select loop abstraction
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* \param[in] fd osmocom file descriptor to be registered
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* \returns 0 on success; negative in case of error
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*/
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int osmo_fd_register(struct osmo_fd *fd)
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{
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int flags;
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/* make FD nonblocking */
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flags = fcntl(fd->fd, F_GETFL);
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if (flags < 0)
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return flags;
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flags |= O_NONBLOCK;
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flags = fcntl(fd->fd, F_SETFL, flags);
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if (flags < 0)
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return flags;
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/* set close-on-exec flag */
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flags = fcntl(fd->fd, F_GETFD);
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if (flags < 0)
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return flags;
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flags |= FD_CLOEXEC;
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flags = fcntl(fd->fd, F_SETFD, flags);
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if (flags < 0)
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return flags;
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/* Register FD */
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if (fd->fd > maxfd)
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maxfd = fd->fd;
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#ifdef OSMO_FD_CHECK
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if (osmo_fd_is_registered(fd)) {
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fprintf(stderr, "Adding a osmo_fd that is already in the list.\n");
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return 0;
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}
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#endif
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#ifndef FORCE_IO_SELECT
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if (g_poll.num_registered + 1 > g_poll.poll_size) {
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struct pollfd *p;
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unsigned int new_size = g_poll.poll_size ? g_poll.poll_size * 2 : 1024;
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p = talloc_realloc(OTC_GLOBAL, g_poll.poll, struct pollfd, new_size);
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if (!p)
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return -ENOMEM;
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memset(p + g_poll.poll_size, 0, new_size - g_poll.poll_size);
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g_poll.poll = p;
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g_poll.poll_size = new_size;
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}
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g_poll.num_registered++;
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#endif /* FORCE_IO_SELECT */
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llist_add_tail(&fd->list, &osmo_fds);
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return 0;
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}
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/*! Unregister a file descriptor from select loop abstraction
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* \param[in] fd osmocom file descriptor to be unregistered
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*/
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void osmo_fd_unregister(struct osmo_fd *fd)
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{
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/* Note: when fd is inside the osmo_fds list (not registered before)
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* this function will crash! If in doubt, check file descriptor with
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* osmo_fd_is_registered() */
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unregistered_count++;
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llist_del(&fd->list);
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#ifndef FORCE_IO_SELECT
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g_poll.num_registered--;
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#endif /* FORCE_IO_SELECT */
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}
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/*! Close a file descriptor, mark it as closed + unregister from select loop abstraction
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* \param[in] fd osmocom file descriptor to be unregistered + closed
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*
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* If \a fd is registered, we unregister it from the select() loop
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* abstraction. We then close the fd and set it to -1, as well as
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* unsetting any 'when' flags */
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void osmo_fd_close(struct osmo_fd *fd)
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{
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if (osmo_fd_is_registered(fd))
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osmo_fd_unregister(fd);
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if (fd->fd != -1)
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close(fd->fd);
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fd->fd = -1;
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fd->when = 0;
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}
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/*! Populate the fd_sets and return the highest fd number
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* \param[in] _rset The readfds to populate
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* \param[in] _wset The wrtiefds to populate
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* \param[in] _eset The errorfds to populate
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*
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* \returns The highest file descriptor seen or 0 on an empty list
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*/
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inline int osmo_fd_fill_fds(void *_rset, void *_wset, void *_eset)
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{
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fd_set *readset = _rset, *writeset = _wset, *exceptset = _eset;
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struct osmo_fd *ufd;
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int highfd = 0;
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llist_for_each_entry(ufd, &osmo_fds, list) {
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if (ufd->when & OSMO_FD_READ)
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FD_SET(ufd->fd, readset);
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if (ufd->when & OSMO_FD_WRITE)
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FD_SET(ufd->fd, writeset);
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if (ufd->when & OSMO_FD_EXCEPT)
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FD_SET(ufd->fd, exceptset);
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if (ufd->fd > highfd)
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highfd = ufd->fd;
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}
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return highfd;
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}
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inline int osmo_fd_disp_fds(void *_rset, void *_wset, void *_eset)
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{
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struct osmo_fd *ufd, *tmp;
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int work = 0;
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fd_set *readset = _rset, *writeset = _wset, *exceptset = _eset;
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restart:
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unregistered_count = 0;
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llist_for_each_entry_safe(ufd, tmp, &osmo_fds, list) {
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int flags = 0;
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if (FD_ISSET(ufd->fd, readset)) {
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flags |= OSMO_FD_READ;
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FD_CLR(ufd->fd, readset);
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}
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if (FD_ISSET(ufd->fd, writeset)) {
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flags |= OSMO_FD_WRITE;
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FD_CLR(ufd->fd, writeset);
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}
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if (FD_ISSET(ufd->fd, exceptset)) {
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flags |= OSMO_FD_EXCEPT;
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FD_CLR(ufd->fd, exceptset);
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}
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if (flags) {
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work = 1;
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/* make sure to clear any log context before processing the next incoming message
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* as part of some file descriptor callback. This effectively prevents "context
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* leaking" from processing of one message into processing of the next message as part
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* of one iteration through the list of file descriptors here. See OS#3813 */
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log_reset_context();
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ufd->cb(ufd, flags);
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}
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/* ugly, ugly hack. If more than one filedescriptor was
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* unregistered, they might have been consecutive and
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* llist_for_each_entry_safe() is no longer safe */
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/* this seems to happen with the last element of the list as well */
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if (unregistered_count >= 1)
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goto restart;
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}
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return work;
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}
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#ifndef FORCE_IO_SELECT
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/* fill g_poll.poll and return the number of entries filled */
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static unsigned int poll_fill_fds(void)
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{
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struct osmo_fd *ufd;
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unsigned int i = 0;
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llist_for_each_entry(ufd, &osmo_fds, list) {
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struct pollfd *p;
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if (!ufd->when)
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continue;
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p = &g_poll.poll[i++];
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p->fd = ufd->fd;
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p->events = 0;
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p->revents = 0;
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/* use the same mapping as the Linux kernel does in fs/select.c */
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if (ufd->when & OSMO_FD_READ)
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p->events |= POLLIN | POLLHUP | POLLERR;
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if (ufd->when & OSMO_FD_WRITE)
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p->events |= POLLOUT | POLLERR;
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if (ufd->when & OSMO_FD_EXCEPT)
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p->events |= POLLPRI;
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}
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return i;
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}
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/* iterate over first n_fd entries of g_poll.poll + dispatch */
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static int poll_disp_fds(int n_fd)
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{
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struct osmo_fd *ufd;
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unsigned int i;
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int work = 0;
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for (i = 0; i < n_fd; i++) {
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struct pollfd *p = &g_poll.poll[i];
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int flags = 0;
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if (!p->revents)
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continue;
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ufd = osmo_fd_get_by_fd(p->fd);
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if (!ufd) {
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/* FD might have been unregistered meanwhile */
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continue;
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}
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/* use the same mapping as the Linux kernel does in fs/select.c */
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if (p->revents & (POLLIN | POLLHUP | POLLERR))
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flags |= OSMO_FD_READ;
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if (p->revents & (POLLOUT | POLLERR))
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flags |= OSMO_FD_WRITE;
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if (p->revents & POLLPRI)
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flags |= OSMO_FD_EXCEPT;
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/* make sure we never report more than the user requested */
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flags &= ufd->when;
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if (flags) {
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work = 1;
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/* make sure to clear any log context before processing the next incoming message
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* as part of some file descriptor callback. This effectively prevents "context
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* leaking" from processing of one message into processing of the next message as part
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* of one iteration through the list of file descriptors here. See OS#3813 */
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log_reset_context();
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ufd->cb(ufd, flags);
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}
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}
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return work;
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}
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static int _osmo_select_main(int polling)
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{
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unsigned int n_poll;
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int rc;
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/* prepare read and write fdsets */
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n_poll = poll_fill_fds();
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if (!polling)
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osmo_timers_prepare();
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rc = poll(g_poll.poll, n_poll, polling ? 0 : osmo_timers_nearest_ms());
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if (rc < 0)
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return 0;
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/* fire timers */
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osmo_timers_update();
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OSMO_ASSERT(osmo_ctx->select);
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/* call registered callback functions */
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return poll_disp_fds(n_poll);
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}
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#else /* FORCE_IO_SELECT */
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/* the old implementation based on select, used 2008-2020 */
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static int _osmo_select_main(int polling)
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{
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fd_set readset, writeset, exceptset;
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int rc;
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struct timeval no_time = {0, 0};
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FD_ZERO(&readset);
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FD_ZERO(&writeset);
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FD_ZERO(&exceptset);
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/* prepare read and write fdsets */
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osmo_fd_fill_fds(&readset, &writeset, &exceptset);
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if (!polling)
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osmo_timers_prepare();
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rc = select(maxfd+1, &readset, &writeset, &exceptset, polling ? &no_time : osmo_timers_nearest());
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if (rc < 0)
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return 0;
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/* fire timers */
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osmo_timers_update();
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OSMO_ASSERT(osmo_ctx->select);
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/* call registered callback functions */
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return osmo_fd_disp_fds(&readset, &writeset, &exceptset);
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}
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#endif /* FORCE_IO_SELECT */
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/*! select main loop integration
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* \param[in] polling should we pollonly (1) or block on select (0)
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* \returns 0 if no fd handled; 1 if fd handled; negative in case of error
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*/
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int osmo_select_main(int polling)
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{
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int rc = _osmo_select_main(polling);
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#ifndef EMBEDDED
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if (talloc_total_size(osmo_ctx->select) != 0) {
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osmo_panic("You cannot use the 'select' volatile "
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"context if you don't use osmo_select_main_ctx()!\n");
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}
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#endif
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return rc;
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}
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#ifndef EMBEDDED
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/*! select main loop integration with temporary select-dispatch talloc context
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* \param[in] polling should we pollonly (1) or block on select (0)
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* \returns 0 if no fd handled; 1 if fd handled; negative in case of error
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*/
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int osmo_select_main_ctx(int polling)
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{
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int rc = _osmo_select_main(polling);
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/* free all the children of the volatile 'select' scope context */
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talloc_free_children(osmo_ctx->select);
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return rc;
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}
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#endif
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/*! find an osmo_fd based on the integer fd
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* \param[in] fd file descriptor to use as search key
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* \returns \ref osmo_fd for \ref fd; NULL in case it doesn't exist */
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struct osmo_fd *osmo_fd_get_by_fd(int fd)
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{
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struct osmo_fd *ofd;
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llist_for_each_entry(ofd, &osmo_fds, list) {
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if (ofd->fd == fd)
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return ofd;
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}
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return NULL;
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}
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/*! initialize the osmocom select abstraction for the current thread */
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void osmo_select_init(void)
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{
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INIT_LLIST_HEAD(&osmo_fds);
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}
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/* ensure main thread always has pre-initialized osmo_fds */
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static __attribute__((constructor)) void on_dso_load_select(void)
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{
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osmo_select_init();
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}
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#ifdef HAVE_SYS_TIMERFD_H
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#include <sys/timerfd.h>
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/*! disable the osmocom-wrapped timerfd */
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int osmo_timerfd_disable(struct osmo_fd *ofd)
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{
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const struct itimerspec its_null = {
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.it_value = { 0, 0 },
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.it_interval = { 0, 0 },
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};
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return timerfd_settime(ofd->fd, 0, &its_null, NULL);
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}
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/*! schedule the osmocom-wrapped timerfd to occur first at \a first, then periodically at \a interval
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* \param[in] ofd Osmocom wrapped timerfd
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* \param[in] first Relative time at which the timer should first execute (NULL = \a interval)
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* \param[in] interval Time interval at which subsequent timer shall fire
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* \returns 0 on success; negative on error */
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int osmo_timerfd_schedule(struct osmo_fd *ofd, const struct timespec *first,
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const struct timespec *interval)
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{
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struct itimerspec its;
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if (ofd->fd < 0)
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return -EINVAL;
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/* first expiration */
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if (first)
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its.it_value = *first;
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else
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its.it_value = *interval;
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/* repeating interval */
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its.it_interval = *interval;
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return timerfd_settime(ofd->fd, 0, &its, NULL);
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}
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/*! setup osmocom-wrapped timerfd
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* \param[inout] ofd Osmocom-wrapped timerfd on which to operate
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* \param[in] cb Call-back function called when timerfd becomes readable
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* \param[in] data Opaque data to be passed on to call-back
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* \returns 0 on success; negative on error
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*
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* We simply initialize the data structures here, but do not yet
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* schedule the timer.
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*/
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int osmo_timerfd_setup(struct osmo_fd *ofd, int (*cb)(struct osmo_fd *, unsigned int), void *data)
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{
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|
ofd->cb = cb;
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ofd->data = data;
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ofd->when = OSMO_FD_READ;
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|
|
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if (ofd->fd < 0) {
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|
int rc;
|
|
|
|
ofd->fd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK);
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|
if (ofd->fd < 0)
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return ofd->fd;
|
|
|
|
rc = osmo_fd_register(ofd);
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|
if (rc < 0) {
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|
osmo_fd_unregister(ofd);
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|
close(ofd->fd);
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|
ofd->fd = -1;
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return rc;
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}
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}
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return 0;
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}
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|
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#endif /* HAVE_SYS_TIMERFD_H */
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|
|
|
#ifdef HAVE_SYS_SIGNALFD_H
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#include <sys/signalfd.h>
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|
|
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static int signalfd_callback(struct osmo_fd *ofd, unsigned int what)
|
|
{
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|
struct osmo_signalfd *osfd = ofd->data;
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|
struct signalfd_siginfo fdsi;
|
|
int rc;
|
|
|
|
rc = read(ofd->fd, &fdsi, sizeof(fdsi));
|
|
if (rc < 0) {
|
|
osmo_fd_unregister(ofd);
|
|
close(ofd->fd);
|
|
ofd->fd = -1;
|
|
return rc;
|
|
}
|
|
|
|
osfd->cb(osfd, &fdsi);
|
|
|
|
return 0;
|
|
};
|
|
|
|
/*! create a signalfd and register it with osmocom select loop.
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|
* \param[in] ctx talloc context from which osmo_signalfd is to be allocated
|
|
* \param[in] set of signals to be accept via this file descriptor
|
|
* \param[in] cb call-back function to be called for each arriving signal
|
|
* \param[in] data opaque user-provided data to pass to callback
|
|
* \returns pointer to newly-allocated + registered osmo_signalfd; NULL on error */
|
|
struct osmo_signalfd *
|
|
osmo_signalfd_setup(void *ctx, sigset_t set, osmo_signalfd_cb *cb, void *data)
|
|
{
|
|
struct osmo_signalfd *osfd = talloc_size(ctx, sizeof(*osfd));
|
|
int fd, rc;
|
|
|
|
if (!osfd)
|
|
return NULL;
|
|
|
|
osfd->data = data;
|
|
osfd->sigset = set;
|
|
osfd->cb = cb;
|
|
|
|
fd = signalfd(-1, &osfd->sigset, SFD_NONBLOCK);
|
|
if (fd < 0) {
|
|
talloc_free(osfd);
|
|
return NULL;
|
|
}
|
|
|
|
osmo_fd_setup(&osfd->ofd, fd, OSMO_FD_READ, signalfd_callback, osfd, 0);
|
|
rc = osmo_fd_register(&osfd->ofd);
|
|
if (rc < 0) {
|
|
close(fd);
|
|
talloc_free(osfd);
|
|
return NULL;
|
|
}
|
|
|
|
return osfd;
|
|
}
|
|
|
|
#endif /* HAVE_SYS_SIGNALFD_H */
|
|
|
|
/*! @} */
|
|
|
|
#endif /* _HAVE_SYS_SELECT_H */
|