jackspa-cli.c

   1 /* jackspa-cli.c - simple CLI LADSPA host for the Jack Audio Connection Kit
   2  * Copyright © 2013 Géraud Meyer <graud@gmx.com>
   3  *
   4  * This file is part of ng-jackspa.
   5  *
   6  * ng-jackspa is free software; you can redistribute it and/or modify it under
   7  * the terms of the GNU General Public License version 2 as published by the
   8  * Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with ng-jackspa.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include <stdlib.h>
  20 #include <stdio.h>
  21 #include <unistd.h>
  22 #include <signal.h>
  23 #include <fcntl.h>
  24 #include "jackspa.h"
  25 #include "control.h"
  26
  27 #define PROGRAM_NAME "jackspa-cli"
  28
  29 #define NOTIF_BACKGROUND "continuing to run in the background"
  30
  31 volatile sig_atomic_t stop_signaled = 0;
  32
  33 static void stop_handler(int s)
  34 {
  35         stop_signaled = 1;
  36 }
  37
  38 static int tty = -1; /* controlling terminal or -1 */
  39
  40 static void background_handler(int s)
  41 {
  42         int i;
  43
  44         /* setup a child that will stop us then wake us up */
  45         i = fork();
  46         if (i < 0) {
  47                 /* error, use the default handler */
  48                 signal(SIGTSTP, SIG_DFL);
  49                 kill(0, SIGTSTP);
  50         }
  51         else if (i == 0) {
  52                 if (tty >= 0)
  53                         write( STDOUT_FILENO, PROGRAM_NAME ": " NOTIF_BACKGROUND "\n",
  54                           sizeof(PROGRAM_NAME)-1 + 2 + sizeof(NOTIF_BACKGROUND)-1 + 1 );
  55                 /* make sure the parent is not in the foreground (or has no ctty) */
  56                 for (i = 1; tcgetpgrp(tty) == getpgid(getppid()); i <<= 1) {
  57                         kill(getppid(), SIGSTOP); /* let the shell regain control of the tty */
  58                         usleep(i), kill(getppid(), SIGCONT);
  59                 }
  60                 _exit(0);
  61     }
  62 }
  63
  64 int main(int argc, char *argv[])
  65 {
  66         int rc = 0;
  67
  68         tty = open("/dev/tty", O_NOCTTY);
  69
  70         /* Signals */
  71         struct sigaction act;
  72         act.sa_flags = 0;
  73         rc = !sigemptyset(&act.sa_mask);
  74         if (rc) {
  75                 /* SIGINT handler to exit gracefully */
  76                 act.sa_handler = stop_handler;
  77                 rc = !sigaction(SIGINT, &act, NULL) && rc;
  78                 /* SIGTTIN handler to avoid being stopped */
  79                 act.sa_handler = SIG_IGN;
  80                 rc = !sigaction(SIGTTIN, &act, NULL) && rc;
  81                 /* SIGTSTP handler to go into the background */
  82                 act.sa_handler = background_handler;
  83                 rc = !sigaction(SIGTSTP, &act, NULL) && rc;
  84                 /* SIGCHLD handler to avoid a child to become defunct */
  85                 act.sa_handler = SIG_IGN;
  86                 rc = !sigaction(SIGCHLD, &act, NULL) && rc;
  87         }
  88         if (!rc)
  89                 fputs(PROGRAM_NAME ": error while setting up the signal handlers\n", stderr);
  90
  91         /* Initialize jackspa */
  92         state_t state;
  93         if (!jackspa_init(&state, argc, argv))
  94                 return 1;
  95
  96         /* Set the default values */
  97         unsigned long c;
  98         controls_t controls;
  99         if (control_buildall(&c, &controls, &state))
 100                 return 2;
 101
 102         /* Wait */
 103         if (!isatty(fileno(stdin)))
 104                 while (!stop_signaled) sleep(-1);
 105         else
 106                 while (!stop_signaled && !feof(stdin))
 107                         if (getpgrp() == tcgetpgrp(STDIN_FILENO))
 108                                 /* we are in the foreground process group */
 109                                 getchar();
 110                         else usleep(100000);
 111
 112         control_cleanupall(c, &controls);
 113
 114         return 0;
 115 }