mdw@git.distorted.org.uk Git - disorder/blob - server/speaker-command.c

   1 /*
   2  * This file is part of DisOrder
   3  * Copyright (C) 2005, 2006, 2007 Richard Kettlewell
   4  * Portions (C) 2007 Mark Wooding
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  19  * USA
  20  */
  21 /** @file server/speaker-command.c
  22  * @brief Support for @ref BACKEND_COMMAND */
  23
  24 #include <config.h>
  25 #include "types.h"
  26
  27 #include <unistd.h>
  28 #include <poll.h>
  29 #include <errno.h>
  30
  31 #include "configuration.h"
  32 #include "syscalls.h"
  33 #include "log.h"
  34 #include "speaker-protocol.h"
  35 #include "speaker.h"
  36
  37 /** @brief Pipe to subprocess
  38  *
  39  * This is the file descriptor to write to for @ref BACKEND_COMMAND.
  40  */
  41 static int cmdfd = -1;
  42
  43 /** @brief poll array slot for @ref cmdfd
  44  *
  45  * Set by command_beforepoll().
  46  */
  47 static int cmdfd_slot;
  48
  49 /** @brief Start the subprocess for @ref BACKEND_COMMAND */
  50 static void fork_cmd(void) {
  51   pid_t cmdpid;
  52   int pfd[2];
  53   if(cmdfd != -1) close(cmdfd);
  54   xpipe(pfd);
  55   cmdpid = xfork();
  56   if(!cmdpid) {
  57     exitfn = _exit;
  58     signal(SIGPIPE, SIG_DFL);
  59     xdup2(pfd[0], 0);
  60     close(pfd[0]);
  61     close(pfd[1]);
  62     execl("/bin/sh", "sh", "-c", config->speaker_command, (char *)0);
  63     fatal(errno, "error execing /bin/sh");
  64   }
  65   close(pfd[0]);
  66   cmdfd = pfd[1];
  67   D(("forked cmd %d, fd = %d", cmdpid, cmdfd));
  68 }
  69
  70 /** @brief Command backend initialization */
  71 static void command_init(void) {
  72   info("selected command backend");
  73   fork_cmd();
  74 }
  75
  76 /** @brief Play to a subprocess */
  77 static size_t command_play(size_t frames) {
  78   size_t bytes = frames * bpf;
  79   int written_bytes;
  80
  81   written_bytes = write(cmdfd, playing->buffer + playing->start, bytes);
  82   D(("actually play %zu bytes, wrote %d",
  83      bytes, written_bytes));
  84   if(written_bytes < 0) {
  85     switch(errno) {
  86     case EPIPE:
  87       error(0, "hmm, command died; trying another");
  88       fork_cmd();
  89       return 0;
  90     case EAGAIN:
  91       return 0;
  92     default:
  93       fatal(errno, "error writing to subprocess");
  94     }
  95   } else
  96     return written_bytes / bpf;
  97 }
  98
  99 /** @brief Update poll array for writing to subprocess */
 100 static void command_beforepoll(int attribute((unused)) *timeoutp) {
 101   /* We send sample data to the subprocess as fast as it can accept it.
 102    * This isn't ideal as pause latency can be very high as a result. */
 103   if(cmdfd >= 0)
 104     cmdfd_slot = addfd(cmdfd, POLLOUT);
 105 }
 106
 107 /** @brief Process poll() results for subprocess play */
 108 static int command_ready(void) {
 109   if(fds[cmdfd_slot].revents & (POLLOUT | POLLERR))
 110     return 1;
 111   else
 112     return 0;
 113 }
 114
 115 const struct speaker_backend command_backend = {
 116   BACKEND_COMMAND,
 117   0,
 118   command_init,
 119   0,                                    /* activate */
 120   command_play,
 121   0,                                    /* deactivate */
 122   command_beforepoll,
 123   command_ready
 124 };
 125
 126 /*
 127 Local Variables:
 128 c-basic-offset:2
 129 comment-column:40
 130 fill-column:79
 131 indent-tabs-mode:nil
 132 End:
 133 */