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audio_pipe.c
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audio_pipe.c
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/*
* pipe output driver. This file is part of Shairport.
* Copyright (c) James Laird 2013
* All rights reserved.
*
* Modifications for audio synchronisation
* and related work, copyright (c) Mike Brady 2014
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include "audio.h"
#include "common.h"
#include <errno.h>
#include <fcntl.h>
#include <memory.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
static int fd = -1;
char *pipename = NULL;
int warned = 0;
static void start(int sample_rate, int sample_format) {
// this will leave fd as -1 if a reader hasn't been attached
fd = open(pipename, O_WRONLY | O_NONBLOCK);
if ((fd < -1) && (warned == 0)) {
warn("Error %d opening the pipe named \"%s\".", errno, pipename);
warned = 1;
}
}
static void play(short buf[], int samples) {
// if the file is not open, try to open it.
char errorstring[1024];
if (fd == -1) {
fd = open(pipename, O_WRONLY | O_NONBLOCK);
}
// if it's got a reader, write to it.
if (fd > 0) {
int rc = non_blocking_write(fd, buf, samples * 4);
if ((rc < 0) && (warned == 0)) {
strerror_r(errno, (char *)errorstring, 1024);
warn("Error %d writing to the pipe named \"%s\": \"%s\".", errno, pipename, errorstring);
warned = 1;
}
} else if ((fd == -1) && (warned == 0)) {
strerror_r(errno, (char *)errorstring, 1024);
warn("Error %d opening the pipe named \"%s\": \"%s\".", errno, pipename, errorstring);
warned = 1;
}
}
static void stop(void) {
// Don't close the pipe just because a play session has stopped.
// if (fd > 0)
// close(fd);
}
static int init(int argc, char **argv) {
debug(1, "pipe init");
const char *str;
int value;
double dvalue;
// set up default values first
config.audio_backend_buffer_desired_length = 1.0;
config.audio_backend_latency_offset = 0;
// do the "general" audio options. Note, these options are in the "general" stanza!
parse_general_audio_options();
if (config.cfg != NULL) {
/* Get the Output Pipename. */
const char *str;
if (config_lookup_string(config.cfg, "pipe.name", &str)) {
pipename = (char *)str;
}
if ((pipename) && (strcasecmp(pipename, "STDOUT") == 0))
die("Can't use \"pipe\" backend for STDOUT. Use the \"stdout\" backend instead.");
}
if ((pipename == NULL) && (argc != 1))
die("bad or missing argument(s) to pipe");
if (argc == 1)
pipename = strdup(argv[0]);
// here, create the pipe
if (mkfifo(pipename, 0644) && errno != EEXIST)
die("Could not create output pipe \"%s\"", pipename);
debug(1, "Pipename is \"%s\"", pipename);
return 0;
}
static void deinit(void) {
if (fd > 0)
close(fd);
}
static void help(void) { printf(" pipe takes 1 argument: the name of the FIFO to write to.\n"); }
audio_output audio_pipe = {.name = "pipe",
.help = &help,
.init = &init,
.deinit = &deinit,
.start = &start,
.stop = &stop,
.flush = NULL,
.delay = NULL,
.play = &play,
.volume = NULL,
.parameters = NULL,
.mute = NULL};