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

   1 /* $Id$ */
   2
   3 /***
   4   This file is part of PulseAudio.
   5
   6   Copyright 2004-2006 Lennart Poettering
   7   Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
   8
   9   PulseAudio is free software; you can redistribute it and/or modify
  10   it under the terms of the GNU Lesser General Public License as
  11   published by the Free Software Foundation; either version 2 of the
  12   License, or (at your option) any later version.
  13
  14   PulseAudio is distributed in the hope that it will be useful, but
  15   WITHOUT ANY WARRANTY; without even the implied warranty of
  16   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  17   General Public License for more details.
  18
  19   You should have received a copy of the GNU Lesser General Public
  20   License along with PulseAudio; if not, write to the Free Software
  21   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  22   USA.
  23 ***/
  24
  25 #ifdef HAVE_CONFIG_H
  26 #include <config.h>
  27 #endif
  28
  29 #include <fcntl.h>
  30 #include <unistd.h>
  31 #include <errno.h>
  32 #include <sys/types.h>
  33 #include <sys/stat.h>
  34 #include <string.h>
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <limits.h>
  38 #include <signal.h>
  39
  40 #ifdef HAVE_WINDOWS_H
  41 #include <windows.h>
  42 #endif
  43
  44 #include <pulse/xmalloc.h>
  45
  46 #include <pulsecore/core-error.h>
  47 #include <pulsecore/core-util.h>
  48 #include <pulsecore/log.h>
  49 #include <pulsecore/macro.h>
  50
  51 #include "pid.h"
  52
  53 /* Read the PID data from the file descriptor fd, and return it. If no
  54  * pid could be read, return 0, on failure (pid_t) -1 */
  55 static pid_t read_pid(const char *fn, int fd) {
  56     ssize_t r;
  57     char t[20], *e;
  58     uint32_t pid;
  59
  60     pa_assert(fn);
  61     pa_assert(fd >= 0);
  62
  63     if ((r = pa_loop_read(fd, t, sizeof(t)-1, NULL)) < 0) {
  64         pa_log_warn("WARNING: failed to read PID file '%s': %s",
  65             fn, pa_cstrerror(errno));
  66         return (pid_t) -1;
  67     }
  68
  69     if (r == 0)
  70         return (pid_t) 0;
  71
  72     t[r] = 0;
  73     if ((e = strchr(t, '\n')))
  74         *e = 0;
  75
  76     if (pa_atou(t, &pid) < 0) {
  77         pa_log_warn("WARNING: failed to parse PID file '%s'", fn);
  78         return (pid_t) -1;
  79     }
  80
  81     return (pid_t) pid;
  82 }
  83
  84 static int open_pid_file(const char *fn, int mode) {
  85     int fd = -1;
  86
  87     pa_assert(fn);
  88
  89     for (;;) {
  90         struct stat st;
  91
  92         if ((fd = open(fn, mode, S_IRUSR|S_IWUSR)) < 0) {
  93             if (mode != O_RDONLY || errno != ENOENT)
  94                 pa_log_warn("WARNING: failed to open PID file '%s': %s",
  95                     fn, pa_cstrerror(errno));
  96             goto fail;
  97         }
  98
  99         /* Try to lock the file. If that fails, go without */
 100         if (pa_lock_fd(fd, 1) < 0)
 101             goto fail;
 102
 103         if (fstat(fd, &st) < 0) {
 104             pa_log_warn("WARNING: failed to fstat() PID file '%s': %s",
 105                 fn, pa_cstrerror(errno));
 106             goto fail;
 107         }
 108
 109         /* Does the file still exist in the file system? When ye, w're done, otherwise restart */
 110         if (st.st_nlink >= 1)
 111             break;
 112
 113         if (pa_lock_fd(fd, 0) < 0)
 114             goto fail;
 115
 116         if (close(fd) < 0) {
 117             pa_log_warn("WARNING: failed to close file '%s': %s",
 118                 fn, pa_cstrerror(errno));
 119             goto fail;
 120         }
 121
 122         fd = -1;
 123     }
 124
 125     return fd;
 126
 127 fail:
 128
 129     if (fd >= 0) {
 130         pa_lock_fd(fd, 0);
 131         close(fd);
 132     }
 133
 134     return -1;
 135 }
 136
 137 /* Create a new PID file for the current process. */
 138 int pa_pid_file_create(void) {
 139     int fd = -1;
 140     int ret = -1;
 141     char fn[PATH_MAX];
 142     char t[20];
 143     pid_t pid;
 144     size_t l;
 145
 146 #ifdef OS_IS_WIN32
 147     HANDLE process;
 148 #endif
 149
 150     pa_runtime_path("pid", fn, sizeof(fn));
 151
 152     if ((fd = open_pid_file(fn, O_CREAT|O_RDWR)) < 0)
 153         goto fail;
 154
 155     if ((pid = read_pid(fn, fd)) == (pid_t) -1)
 156         pa_log("corrupt PID file, overwriting.");
 157     else if (pid > 0) {
 158 #ifdef OS_IS_WIN32
 159         if ((process = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, pid)) != NULL) {
 160             CloseHandle(process);
 161 #else
 162         if (kill(pid, 0) >= 0 || errno != ESRCH) {
 163 #endif
 164             pa_log("daemon already running.");
 165             goto fail;
 166         }
 167
 168         pa_log("stale PID file, overwriting.");
 169     }
 170
 171     /* Overwrite the current PID file */
 172     if (lseek(fd, 0, SEEK_SET) == (off_t) -1 || ftruncate(fd, 0) < 0) {
 173         pa_log("failed to truncate PID file '%s': %s",
 174             fn, pa_cstrerror(errno));
 175         goto fail;
 176     }
 177
 178     pa_snprintf(t, sizeof(t), "%lu\n", (unsigned long) getpid());
 179     l = strlen(t);
 180
 181     if (pa_loop_write(fd, t, l, NULL) != (ssize_t) l) {
 182         pa_log("failed to write PID file.");
 183         goto fail;
 184     }
 185
 186     ret = 0;
 187
 188 fail:
 189     if (fd >= 0) {
 190         pa_lock_fd(fd, 0);
 191         close(fd);
 192     }
 193
 194     return ret;
 195 }
 196
 197 /* Remove the PID file, if it is ours */
 198 int pa_pid_file_remove(void) {
 199     int fd = -1;
 200     char fn[PATH_MAX];
 201     int ret = -1;
 202     pid_t pid;
 203
 204     pa_runtime_path("pid", fn, sizeof(fn));
 205
 206     if ((fd = open_pid_file(fn, O_RDWR)) < 0) {
 207         pa_log_warn("WARNING: failed to open PID file '%s': %s",
 208             fn, pa_cstrerror(errno));
 209         goto fail;
 210     }
 211
 212     if ((pid = read_pid(fn, fd)) == (pid_t) -1)
 213         goto fail;
 214
 215     if (pid != getpid()) {
 216         pa_log("WARNING: PID file '%s' not mine!", fn);
 217         goto fail;
 218     }
 219
 220     if (ftruncate(fd, 0) < 0) {
 221         pa_log_warn("WARNING: failed to truncate PID file '%s': %s",
 222             fn, pa_cstrerror(errno));
 223         goto fail;
 224     }
 225
 226 #ifdef OS_IS_WIN32
 227     pa_lock_fd(fd, 0);
 228     close(fd);
 229     fd = -1;
 230 #endif
 231
 232     if (unlink(fn) < 0) {
 233         pa_log_warn("WARNING: failed to remove PID file '%s': %s",
 234             fn, pa_cstrerror(errno));
 235         goto fail;
 236     }
 237
 238     ret = 0;
 239
 240 fail:
 241
 242     if (fd >= 0) {
 243         pa_lock_fd(fd, 0);
 244         pa_assert_se(close(fd) == 0);
 245     }
 246
 247     return ret;
 248 }
 249
 250 /* Check whether the daemon is currently running, i.e. if a PID file
 251  * exists and the PID therein too. Returns 0 on succcess, -1
 252  * otherwise. If pid is non-NULL and a running daemon was found,
 253  * return its PID therein */
 254 int pa_pid_file_check_running(pid_t *pid) {
 255     return pa_pid_file_kill(0, pid);
 256 }
 257
 258 #ifndef OS_IS_WIN32
 259
 260 /* Kill a current running daemon. Return non-zero on success, -1
 261  * otherwise. If successful *pid contains the PID of the daemon
 262  * process. */
 263 int pa_pid_file_kill(int sig, pid_t *pid) {
 264     int fd = -1;
 265     char fn[PATH_MAX];
 266     int ret = -1;
 267     pid_t _pid;
 268
 269     if (!pid)
 270         pid = &_pid;
 271
 272     pa_runtime_path("pid", fn, sizeof(fn));
 273
 274     if ((fd = open_pid_file(fn, O_RDONLY)) < 0)
 275         goto fail;
 276
 277     if ((*pid = read_pid(fn, fd)) == (pid_t) -1)
 278         goto fail;
 279
 280     ret = kill(*pid, sig);
 281
 282 fail:
 283
 284     if (fd >= 0) {
 285         pa_lock_fd(fd, 0);
 286         pa_assert_se(close(fd) == 0);
 287     }
 288
 289     return ret;
 290
 291 }
 292
 293 #else /* OS_IS_WIN32 */
 294
 295 int pa_pid_file_kill(int sig, pid_t *pid) {
 296     return -1;
 297 }
 298
 299 #endif