code.delx.au - pulseaudio/blob - polyp/pid.c

   1 /* $Id$ */
   2
   3 /***
   4   This file is part of polypaudio.
   5
   6   polypaudio is free software; you can redistribute it and/or modify
   7   it under the terms of the GNU Lesser General Public License as
   8   published by the Free Software Foundation; either version 2 of the
   9   License, or (at your option) any later version.
  10
  11   polypaudio 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 Lesser General Public
  17   License along with polypaudio; if not, write to the Free Software
  18   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  19   USA.
  20 ***/
  21
  22 #ifdef HAVE_CONFIG_H
  23 #include <config.h>
  24 #endif
  25
  26 #include <fcntl.h>
  27 #include <unistd.h>
  28 #include <errno.h>
  29 #include <sys/types.h>
  30 #include <sys/stat.h>
  31 #include <string.h>
  32 #include <stdio.h>
  33 #include <assert.h>
  34 #include <stdlib.h>
  35 #include <limits.h>
  36 #include <signal.h>
  37
  38 #include "pid.h"
  39 #include "util.h"
  40 #include "log.h"
  41
  42 /* Read the PID data from the file descriptor fd, and return it. If no
  43  * pid could be read, return 0, on failure (pid_t) -1 */
  44 static pid_t read_pid(const char *fn, int fd) {
  45     ssize_t r;
  46     char t[20], *e;
  47     uint32_t pid;
  48
  49     assert(fn && fd >= 0);
  50
  51     if ((r = pa_loop_read(fd, t, sizeof(t)-1)) < 0) {
  52         pa_log(__FILE__": WARNING: failed to read PID file '%s': %s\n", fn, strerror(errno));
  53         return (pid_t) -1;
  54     }
  55
  56     if (r == 0)
  57         return (pid_t) 0;
  58
  59     t[r] = 0;
  60     if ((e = strchr(t, '\n')))
  61         *e = 0;
  62
  63     if (pa_atou(t, &pid) < 0) {
  64         pa_log(__FILE__": WARNING: failed to parse PID file '%s'\n", fn);
  65         return (pid_t) -1;
  66     }
  67
  68     return (pid_t) pid;
  69 }
  70
  71 static int open_pid_file(const char *fn, int mode) {
  72     int fd = -1;
  73     int lock = -1;
  74
  75     for (;;) {
  76         struct stat st;
  77
  78         pa_make_secure_parent_dir(fn);
  79
  80         if ((fd = open(fn, mode, S_IRUSR|S_IWUSR)) < 0) {
  81             if (mode != O_RDONLY || errno != ENOENT)
  82                 pa_log(__FILE__": WARNING: failed to open PID file '%s': %s\n", fn, strerror(errno));
  83             goto fail;
  84         }
  85
  86         /* Try to lock the file. If that fails, go without */
  87         if (pa_lock_fd(fd, 1) < 0)
  88             goto fail;
  89
  90         if (fstat(fd, &st) < 0) {
  91             pa_log(__FILE__": Failed to fstat() PID file '%s': %s\n", fn, strerror(errno));
  92             goto fail;
  93         }
  94
  95         /* Does the file still exist in the file system? When ye, w're done, otherwise restart */
  96         if (st.st_nlink >= 1)
  97             break;
  98
  99         if (pa_lock_fd(fd, 0) < 0)
 100             goto fail;
 101
 102         if (close(fd) < 0) {
 103             pa_log(__FILE__": Failed to close file '%s': %s\n", fn, strerror(errno));
 104             goto fail;
 105         }
 106
 107         fd = -1;
 108     }
 109
 110     return fd;
 111
 112 fail:
 113
 114     if (fd < 0) {
 115         if (lock >= 0)
 116             pa_lock_fd(fd, 0);
 117
 118         close(fd);
 119     }
 120
 121     return -1;
 122 }
 123
 124 /* Create a new PID file for the current process. */
 125 int pa_pid_file_create(void) {
 126     int fd = -1;
 127     int ret = -1;
 128     char fn[PATH_MAX];
 129     char t[20];
 130     pid_t pid;
 131     size_t l;
 132
 133     pa_runtime_path("pid", fn, sizeof(fn));
 134
 135     if ((fd = open_pid_file(fn, O_CREAT|O_RDWR)) < 0)
 136         goto fail;
 137
 138     if ((pid = read_pid(fn, fd)) == (pid_t) -1)
 139         pa_log(__FILE__": corrupt PID file, overwriting.\n");
 140     else if (pid > 0) {
 141         if (kill(pid, 0) >= 0 || errno != ESRCH) {
 142             pa_log(__FILE__": daemon already running.\n");
 143             goto fail;
 144         }
 145
 146         pa_log(__FILE__": stale PID file, overwriting.\n");
 147     }
 148
 149     /* Overwrite the current PID file */
 150     if (lseek(fd, 0, SEEK_SET) == (off_t) -1 || ftruncate(fd, 0) < 0) {
 151         pa_log(__FILE__": failed to truncate PID fil: %s.\n", strerror(errno));
 152         goto fail;
 153     }
 154
 155     snprintf(t, sizeof(t), "%lu\n", (unsigned long) getpid());
 156     l = strlen(t);
 157
 158     if (pa_loop_write(fd, t, l) != (ssize_t) l) {
 159         pa_log(__FILE__": failed to write PID file.\n");
 160         goto fail;
 161     }
 162
 163     ret = 0;
 164
 165 fail:
 166     if (fd >= 0) {
 167         pa_lock_fd(fd, 0);
 168         close(fd);
 169     }
 170
 171     return ret;
 172 }
 173
 174 /* Remove the PID file, if it is ours */
 175 int pa_pid_file_remove(void) {
 176     int fd = -1;
 177     char fn[PATH_MAX];
 178     int ret = -1;
 179     pid_t pid;
 180
 181     pa_runtime_path("pid", fn, sizeof(fn));
 182
 183     if ((fd = open_pid_file(fn, O_RDWR)) < 0) {
 184         pa_log(__FILE__": WARNING: failed to open PID file '%s': %s\n", fn, strerror(errno));
 185         goto fail;
 186     }
 187
 188     if ((pid = read_pid(fn, fd)) == (pid_t) -1)
 189         goto fail;
 190
 191     if (pid != getpid()) {
 192         pa_log(__FILE__": WARNING: PID file '%s' not mine!\n", fn);
 193         goto fail;
 194     }
 195
 196     if (ftruncate(fd, 0) < 0) {
 197         pa_log(__FILE__": failed to truncate PID file '%s': %s\n", fn, strerror(errno));
 198         goto fail;
 199     }
 200
 201     if (unlink(fn) < 0) {
 202         pa_log(__FILE__": failed to remove PID file '%s': %s\n", fn, strerror(errno));
 203         goto fail;
 204     }
 205
 206     ret = 0;
 207
 208 fail:
 209
 210     if (fd >= 0) {
 211         pa_lock_fd(fd, 0);
 212         close(fd);
 213     }
 214
 215     return ret;
 216 }
 217
 218 /* Check whether the daemon is currently running, i.e. if a PID file
 219  * exists and the PID therein too. Returns 0 on succcess, -1
 220  * otherwise. If pid is non-NULL and a running daemon was found,
 221  * return its PID therein */
 222 int pa_pid_file_check_running(pid_t *pid) {
 223     return pa_pid_file_kill(0, pid);
 224 }
 225
 226 /* Kill a current running daemon. Return non-zero on success, -1
 227  * otherwise. If successful *pid contains the PID of the daemon
 228  * process. */
 229 int pa_pid_file_kill(int sig, pid_t *pid) {
 230     int fd = -1;
 231     char fn[PATH_MAX];
 232     int ret = -1;
 233     pid_t _pid;
 234
 235     if (!pid)
 236         pid = &_pid;
 237
 238     pa_runtime_path("pid", fn, sizeof(fn));
 239
 240     if ((fd = open_pid_file(fn, O_RDONLY)) < 0)
 241         goto fail;
 242
 243     if ((*pid = read_pid(fn, fd)) == (pid_t) -1)
 244         goto fail;
 245
 246     ret = kill(*pid, sig);
 247
 248 fail:
 249
 250     if (fd >= 0) {
 251         pa_lock_fd(fd, 0);
 252         close(fd);
 253     }
 254
 255     return ret;
 256
 257 }