code.delx.au - pulseaudio/blob - src/pulsecore/pid.c

   1 /* $Id$ */
   2
   3 /***
   4   This file is part of PulseAudio.
   5
   6   PulseAudio 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   PulseAudio 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 PulseAudio; 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 #ifdef HAVE_WINDOWS_H
  39 #include <windows.h>
  40 #endif
  41
  42 #include <pulse/xmalloc.h>
  43
  44 #include <pulsecore/core-error.h>
  45 #include <pulsecore/core-util.h>
  46 #include <pulsecore/log.h>
  47
  48 #include "pid.h"
  49
  50 /* Read the PID data from the file descriptor fd, and return it. If no
  51  * pid could be read, return 0, on failure (pid_t) -1 */
  52 static pid_t read_pid(const char *fn, int fd) {
  53     ssize_t r;
  54     char t[20], *e;
  55     uint32_t pid;
  56
  57     assert(fn && fd >= 0);
  58
  59     if ((r = pa_loop_read(fd, t, sizeof(t)-1, NULL)) < 0) {
  60         pa_log_warn("WARNING: failed to read PID file '%s': %s",
  61             fn, pa_cstrerror(errno));
  62         return (pid_t) -1;
  63     }
  64
  65     if (r == 0)
  66         return (pid_t) 0;
  67
  68     t[r] = 0;
  69     if ((e = strchr(t, '\n')))
  70         *e = 0;
  71
  72     if (pa_atou(t, &pid) < 0) {
  73         pa_log("WARNING: failed to parse PID file '%s'", fn);
  74         return (pid_t) -1;
  75     }
  76
  77     return (pid_t) pid;
  78 }
  79
  80 static int open_pid_file(const char *fn, int mode) {
  81     int fd = -1;
  82
  83     for (;;) {
  84         struct stat st;
  85
  86         if ((fd = open(fn, mode, S_IRUSR|S_IWUSR)) < 0) {
  87             if (mode != O_RDONLY || errno != ENOENT)
  88                 pa_log_warn("WARNING: failed to open PID file '%s': %s",
  89                     fn, pa_cstrerror(errno));
  90             goto fail;
  91         }
  92
  93         /* Try to lock the file. If that fails, go without */
  94         if (pa_lock_fd(fd, 1) < 0)
  95             goto fail;
  96
  97         if (fstat(fd, &st) < 0) {
  98             pa_log_warn("WARNING: failed to fstat() PID file '%s': %s",
  99                 fn, pa_cstrerror(errno));
 100             goto fail;
 101         }
 102
 103         /* Does the file still exist in the file system? When ye, w're done, otherwise restart */
 104         if (st.st_nlink >= 1)
 105             break;
 106
 107         if (pa_lock_fd(fd, 0) < 0)
 108             goto fail;
 109
 110         if (close(fd) < 0) {
 111             pa_log_warn("WARNING: failed to close file '%s': %s",
 112                 fn, pa_cstrerror(errno));
 113             goto fail;
 114         }
 115
 116         fd = -1;
 117     }
 118
 119     return fd;
 120
 121 fail:
 122
 123     if (fd >= 0) {
 124         pa_lock_fd(fd, 0);
 125         close(fd);
 126     }
 127
 128     return -1;
 129 }
 130
 131 /* Create a new PID file for the current process. */
 132 int pa_pid_file_create(void) {
 133     int fd = -1;
 134     int ret = -1;
 135     char fn[PATH_MAX];
 136     char t[20];
 137     pid_t pid;
 138     size_t l;
 139
 140 #ifdef OS_IS_WIN32
 141     HANDLE process;
 142 #endif
 143
 144     pa_runtime_path("pid", fn, sizeof(fn));
 145
 146     if ((fd = open_pid_file(fn, O_CREAT|O_RDWR)) < 0)
 147         goto fail;
 148
 149     if ((pid = read_pid(fn, fd)) == (pid_t) -1)
 150         pa_log("corrupt PID file, overwriting.");
 151     else if (pid > 0) {
 152 #ifdef OS_IS_WIN32
 153         if ((process = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, pid)) != NULL) {
 154             CloseHandle(process);
 155 #else
 156         if (kill(pid, 0) >= 0 || errno != ESRCH) {
 157 #endif
 158             pa_log("daemon already running.");
 159             goto fail;
 160         }
 161
 162         pa_log("stale PID file, overwriting.");
 163     }
 164
 165     /* Overwrite the current PID file */
 166     if (lseek(fd, 0, SEEK_SET) == (off_t) -1 || ftruncate(fd, 0) < 0) {
 167         pa_log("failed to truncate PID file '%s': %s",
 168             fn, pa_cstrerror(errno));
 169         goto fail;
 170     }
 171
 172     snprintf(t, sizeof(t), "%lu\n", (unsigned long) getpid());
 173     l = strlen(t);
 174
 175     if (pa_loop_write(fd, t, l, NULL) != (ssize_t) l) {
 176         pa_log("failed to write PID file.");
 177         goto fail;
 178     }
 179
 180     ret = 0;
 181
 182 fail:
 183     if (fd >= 0) {
 184         pa_lock_fd(fd, 0);
 185         close(fd);
 186     }
 187
 188     return ret;
 189 }
 190
 191 /* Remove the PID file, if it is ours */
 192 int pa_pid_file_remove(void) {
 193     int fd = -1;
 194     char fn[PATH_MAX];
 195     int ret = -1;
 196     pid_t pid;
 197
 198     pa_runtime_path("pid", fn, sizeof(fn));
 199
 200     if ((fd = open_pid_file(fn, O_RDWR)) < 0) {
 201         pa_log_warn("WARNING: failed to open PID file '%s': %s",
 202             fn, pa_cstrerror(errno));
 203         goto fail;
 204     }
 205
 206     if ((pid = read_pid(fn, fd)) == (pid_t) -1)
 207         goto fail;
 208
 209     if (pid != getpid()) {
 210         pa_log("WARNING: PID file '%s' not mine!", fn);
 211         goto fail;
 212     }
 213
 214     if (ftruncate(fd, 0) < 0) {
 215         pa_log_warn("WARNING: failed to truncate PID file '%s': %s",
 216             fn, pa_cstrerror(errno));
 217         goto fail;
 218     }
 219
 220 #ifdef OS_IS_WIN32
 221     pa_lock_fd(fd, 0);
 222     close(fd);
 223     fd = -1;
 224 #endif
 225
 226     if (unlink(fn) < 0) {
 227         pa_log_warn("WARNING: failed to remove PID file '%s': %s",
 228             fn, pa_cstrerror(errno));
 229         goto fail;
 230     }
 231
 232     ret = 0;
 233
 234 fail:
 235
 236     if (fd >= 0) {
 237         pa_lock_fd(fd, 0);
 238         close(fd);
 239     }
 240
 241     return ret;
 242 }
 243
 244 /* Check whether the daemon is currently running, i.e. if a PID file
 245  * exists and the PID therein too. Returns 0 on succcess, -1
 246  * otherwise. If pid is non-NULL and a running daemon was found,
 247  * return its PID therein */
 248 int pa_pid_file_check_running(pid_t *pid) {
 249     return pa_pid_file_kill(0, pid);
 250 }
 251
 252 #ifndef OS_IS_WIN32
 253
 254 /* Kill a current running daemon. Return non-zero on success, -1
 255  * otherwise. If successful *pid contains the PID of the daemon
 256  * process. */
 257 int pa_pid_file_kill(int sig, pid_t *pid) {
 258     int fd = -1;
 259     char fn[PATH_MAX];
 260     int ret = -1;
 261     pid_t _pid;
 262
 263     if (!pid)
 264         pid = &_pid;
 265
 266     pa_runtime_path("pid", fn, sizeof(fn));
 267
 268     if ((fd = open_pid_file(fn, O_RDONLY)) < 0)
 269         goto fail;
 270
 271     if ((*pid = read_pid(fn, fd)) == (pid_t) -1)
 272         goto fail;
 273
 274     ret = kill(*pid, sig);
 275
 276 fail:
 277
 278     if (fd >= 0) {
 279         pa_lock_fd(fd, 0);
 280         close(fd);
 281     }
 282
 283     return ret;
 284
 285 }
 286
 287 #else /* OS_IS_WIN32 */
 288
 289 int pa_pid_file_kill(int sig, pid_t *pid) {
 290     return -1;
 291 }
 292
 293 #endif