1 /*
2 * pipe output driver. This file is part of Shairport.
3 * Copyright (c) James Laird 2013
4 * All rights reserved.
5 *
6 * Modifications for audio synchronisation
7 * and related work, copyright (c) Mike Brady 2014
8 * All rights reserved.
9 *
10 * Permission is hereby granted, free of charge, to any person
11 * obtaining a copy of this software and associated documentation
12 * files (the "Software"), to deal in the Software without
13 * restriction, including without limitation the rights to use,
14 * copy, modify, merge, publish, distribute, sublicense, and/or
15 * sell copies of the Software, and to permit persons to whom the
16 * Software is furnished to do so, subject to the following conditions:
17 *
18 * The above copyright notice and this permission notice shall be
19 * included in all copies or substantial portions of the Software.
20 *
21 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
22 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
23 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
24 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
25 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
26 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
27 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
28 * OTHER DEALINGS IN THE SOFTWARE.
29 */
30
31 #include "audio.h"
32 #include "common.h"
33 #include <errno.h>
34 #include <fcntl.h>
35 #include <memory.h>
36 #include <stdio.h>
37 #include <stdlib.h>
38 #include <sys/stat.h>
39 #include <sys/types.h>
40 #include <unistd.h>
41
42 static int fd = -1;
43
44 char *pipename = NULL;
45 char *default_pipe_name = "/tmp/shairport-sync-audio";
46
start(int sample_rate,int sample_format)47 static void start(__attribute__((unused)) int sample_rate,
48 __attribute__((unused)) int sample_format) {
49
50 // this will leave fd as -1 if a reader hasn't been attached to the pipe
51 // we check that it's not a "real" error though. From the "man 2 open" page:
52 // "ENXIO O_NONBLOCK | O_WRONLY is set, the named file is a FIFO, and no process has the FIFO
53 // open for reading."
54
55 fd = try_to_open_pipe_for_writing(pipename);
56 // we check that it's not a "real" error. From the "man 2 open" page:
57 // "ENXIO O_NONBLOCK | O_WRONLY is set, the named file is a FIFO, and no process has the FIFO
58 // open for reading." Which is okay.
59 if ((fd == -1) && (errno != ENXIO)) {
60 char errorstring[1024];
61 strerror_r(errno, (char *)errorstring, sizeof(errorstring));
62 debug(1, "audio_pipe start -- error %d (\"%s\") opening pipe: \"%s\".", errno,
63 (char *)errorstring, pipename);
64 warn("can not open audio pipe -- error %d (\"%s\") opening pipe: \"%s\".", errno,
65 (char *)errorstring, pipename);
66 }
67 }
68
play(void * buf,int samples)69 static int play(void *buf, int samples) {
70 // if the file is not open, try to open it.
71 char errorstring[1024];
72 if (fd == -1) {
73 fd = try_to_open_pipe_for_writing(pipename);
74 }
75 // if it's got a reader, write to it.
76 if (fd > 0) {
77 // int rc = non_blocking_write(fd, buf, samples * 4);
78 int rc = write(fd, buf, samples * 4);
79 if ((rc < 0) && (errno != EPIPE)) {
80 strerror_r(errno, (char *)errorstring, 1024);
81 debug(1, "audio_pip play: error %d writing to the pipe named \"%s\": \"%s\".", errno,
82 pipename, errorstring);
83 }
84 }
85 return 0;
86 }
87
stop(void)88 static void stop(void) {
89 // Don't close the pipe just because a play session has stopped.
90 }
91
init(int argc,char ** argv)92 static int init(int argc, char **argv) {
93 // debug(1, "pipe init");
94 // const char *str;
95 // int value;
96 // double dvalue;
97
98 // set up default values first
99
100 config.audio_backend_buffer_desired_length = 1.0;
101 config.audio_backend_latency_offset = 0;
102
103 // do the "general" audio options. Note, these options are in the "general" stanza!
104 parse_general_audio_options();
105
106 if (config.cfg != NULL) {
107 /* Get the Output Pipename. */
108 const char *str;
109 if (config_lookup_string(config.cfg, "pipe.name", &str)) {
110 pipename = (char *)str;
111 }
112 }
113
114 if (argc > 1)
115 die("too many command-line arguments to pipe");
116
117 if (argc == 1)
118 pipename = argv[0]; // command line argument has priority
119
120 if ((pipename) && (strcasecmp(pipename, "STDOUT") == 0))
121 die("Can't use \"pipe\" backend for STDOUT. Use the \"stdout\" backend instead.");
122
123 if (pipename == NULL)
124 pipename = default_pipe_name; // if none specified
125
126 // here, create the pipe
127 mode_t oldumask = umask(000);
128 if (mkfifo(pipename, 0666) && errno != EEXIST)
129 die("Could not create audio pipe \"%s\"", pipename);
130 umask(oldumask);
131
132 debug(1, "audio pipe name is \"%s\"", pipename);
133
134 return 0;
135 }
136
deinit(void)137 static void deinit(void) {
138 if (fd > 0)
139 close(fd);
140 }
141
help(void)142 static void help(void) { printf(" specify the pathname of the pipe to write to.\n"); }
143
144 audio_output audio_pipe = {.name = "pipe",
145 .help = &help,
146 .init = &init,
147 .deinit = &deinit,
148 .prepare = NULL,
149 .start = &start,
150 .stop = &stop,
151 .is_running = NULL,
152 .flush = NULL,
153 .delay = NULL,
154 .play = &play,
155 .volume = NULL,
156 .parameters = NULL,
157 .mute = NULL};
158