alsapid/helper.c

   1 /* -*- Mode: C ; c-basic-offset: 2 -*- */
   2 /*
   3  * LADI Session Handler (ladish)
   4  *
   5  * Copyright (C) 2010 Nedko Arnaudov <nedko@arnaudov.name>
   6  *
   7  **************************************************************************
   8  * This file contains alsapid helper functionality
   9  **************************************************************************
  10  *
  11  * LADI Session Handler is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * LADI Session Handler is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with LADI Session Handler. If not, see <http://www.gnu.org/licenses/>
  23  * or write to the Free Software Foundation, Inc.,
  24  * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  25  */
  26
  27 #define _GNU_SOURCE
  28 #include <string.h>             /* GNU basename() */
  29
  30 #include <stdio.h>
  31 #include <stdlib.h>             /* atoll */
  32 #include <unistd.h>
  33 #include <sys/types.h>
  34 #include <linux/limits.h>
  35
  36 #include "alsapid.h"
  37
  38 void alsapid_compose_src_link(int alsa_client_id, char * buffer)
  39 {
  40   sprintf(buffer, "/tmp/alsapid-%lld-%d", (long long)getuid(), alsa_client_id);
  41 }
  42
  43 void alsapid_compose_dst_link(char * buffer)
  44 {
  45   sprintf(buffer, "/proc/%lld", (long long)getpid());
  46 }
  47
  48 bool alsapid_get_pid(int alsa_client_id, pid_t * pid_ptr)
  49 {
  50   char src[PATH_MAX];
  51   char dst[PATH_MAX + 1];
  52   ssize_t ret;
  53   pid_t pid;
  54
  55   alsapid_compose_src_link(alsa_client_id, src);
  56
  57   ret = readlink(src, dst, PATH_MAX);
  58   if (ret == -1)
  59   {
  60     return false;
  61   }
  62
  63   dst[ret] = 0;
  64
  65   pid = (pid_t)atoll(basename(dst));
  66   if (pid <= 1)
  67   {
  68     return false;
  69   }
  70
  71   *pid_ptr = pid;
  72   return true;
  73 }