mirror of
https://github.com/alsa-project/alsa-utils
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109 lines
2.4 KiB
C
109 lines
2.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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//
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// waiter-select.c - Waiter for event notification by select(2).
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//
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// Copyright (c) 2018 Takashi Sakamoto <o-takashi@sakamocchi.jp>
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//
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// Licensed under the terms of the GNU General Public License, version 2.
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#include "waiter.h"
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <errno.h>
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#include <sys/select.h>
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// Except for POLLERR.
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#ifdef POLLRDNORM
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// This program is for userspace compliant to POSIX 2008 (IEEE 1003.1:2008).
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// This is the default compliance level since glibc-2.12 or later.
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# define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP)
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# define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT)
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#else
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// However it's allowed to be for old compliance levels.
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# define POLLIN_SET (POLLIN | POLLHUP)
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# define POLLOUT_SET (POLLOUT)
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#endif
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#define POLLEX_SET (POLLPRI)
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struct select_state {
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fd_set rfds_rd;
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fd_set rfds_wr;
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fd_set rfds_ex;
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};
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static int select_prepare(struct waiter_context *)
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{
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return 0;
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}
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static int select_wait_event(struct waiter_context *waiter, int timeout_msec)
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{
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struct select_state *state = waiter->private_data;
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struct pollfd *pfd;
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int fd_max;
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struct timeval tv, *tv_ptr;
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int i;
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int err;
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FD_ZERO(&state->rfds_rd);
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FD_ZERO(&state->rfds_wr);
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FD_ZERO(&state->rfds_ex);
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fd_max = 0;
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for (i = 0; i < (int)waiter->pfd_count; ++i) {
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pfd = &waiter->pfds[i];
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if (pfd->events & POLLIN_SET)
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FD_SET(pfd->fd, &state->rfds_rd);
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if (pfd->events & POLLOUT_SET)
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FD_SET(pfd->fd, &state->rfds_wr);
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if (pfd->events & POLLEX_SET)
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FD_SET(pfd->fd, &state->rfds_ex);
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if (pfd->fd > fd_max)
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fd_max = pfd->fd;
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}
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if (timeout_msec < 0) {
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tv_ptr = NULL;
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} else {
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tv.tv_sec = 0;
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tv.tv_usec = timeout_msec * 1000;
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tv_ptr = &tv;
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}
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err = select(fd_max + 1, &state->rfds_rd, &state->rfds_wr,
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&state->rfds_ex, tv_ptr);
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if (err < 0)
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return -errno;
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for (i = 0; i < (int)waiter->pfd_count; ++i) {
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pfd = &waiter->pfds[i];
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pfd->revents = 0;
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if (FD_ISSET(pfd->fd, &state->rfds_rd))
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pfd->revents |= POLLIN;
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if (FD_ISSET(pfd->fd, &state->rfds_wr))
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pfd->revents |= POLLOUT;
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if (FD_ISSET(pfd->fd, &state->rfds_ex))
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pfd->revents |= POLLHUP;
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}
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return err;
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}
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static void select_release(struct waiter_context *)
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{
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return;
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}
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const struct waiter_data waiter_select = {
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.ops = {
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.prepare = select_prepare,
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.wait_event = select_wait_event,
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.release = select_release,
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},
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.private_size = sizeof(struct select_state),
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};
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