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 <assert.h>
  37 #include <stdlib.h>
  38 #include <limits.h>
  39 #include <signal.h>
  40
  41 #ifdef HAVE_WINDOWS_H
  42 #include <windows.h>
  43 #endif
  44
  45 #include <pulse/xmalloc.h>
  46
  47 #include <pulsecore/core-error.h>
  48 #include <pulsecore/core-util.h>
  49 #include <pulsecore/log.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     assert(fn && fd >= 0);
  61
  62     if ((r = pa_loop_read(fd, t, sizeof(t)-1, NULL)) < 0) {
  63         pa_log_warn("WARNING: failed to read PID file '%s': %s",
  64             fn, pa_cstrerror(errno));
  65         return (pid_t) -1;
  66     }
  67
  68     if (r == 0)
  69         return (pid_t) 0;
  70
  71     t[r] = 0;
  72     if ((e = strchr(t, '\n')))
  73         *e = 0;
  74
  75     if (pa_atou(t, &pid) < 0) {
  76         pa_log("WARNING: failed to parse PID file '%s'", fn);
  77         return (pid_t) -1;
  78     }
  79
  80     return (pid_t) pid;
  81 }
  82
  83 static int open_pid_file(const char *fn, int mode) {
  84     int fd = -1;
  85
  86     for (;;) {
  87         struct stat st;
  88
  89         if ((fd = open(fn, mode, S_IRUSR|S_IWUSR)) < 0) {
  90             if (mode != O_RDONLY || errno != ENOENT)
  91                 pa_log_warn("WARNING: failed to open PID file '%s': %s",
  92                     fn, pa_cstrerror(errno));
  93             goto fail;
  94         }
  95
  96         /* Try to lock the file. If that fails, go without */
  97         if (pa_lock_fd(fd, 1) < 0)
  98             goto fail;
  99
 100         if (fstat(fd, &st) < 0) {
 101             pa_log_warn("WARNING: failed to fstat() PID file '%s': %s",
 102                 fn, pa_cstrerror(errno));
 103             goto fail;
 104         }
 105
 106         /* Does the file still exist in the file system? When ye, w're done, otherwise restart */
 107         if (st.st_nlink >= 1)
 108             break;
 109
 110         if (pa_lock_fd(fd, 0) < 0)
 111             goto fail;
 112
 113         if (close(fd) < 0) {
 114             pa_log_warn("WARNING: failed to close file '%s': %s",
 115                 fn, pa_cstrerror(errno));
 116             goto fail;
 117         }
 118
 119         fd = -1;
 120     }
 121
 122     return fd;
 123
 124 fail:
 125
 126     if (fd >= 0) {
 127         pa_lock_fd(fd, 0);
 128         close(fd);
 129     }
 130
 131     return -1;
 132 }
 133
 134 /* Create a new PID file for the current process. */
 135 int pa_pid_file_create(void) {
 136     int fd = -1;
 137     int ret = -1;
 138     char fn[PATH_MAX];
 139     char t[20];
 140     pid_t pid;
 141     size_t l;
 142
 143 #ifdef OS_IS_WIN32
 144     HANDLE process;
 145 #endif
 146
 147     pa_runtime_path("pid", fn, sizeof(fn));
 148
 149     if ((fd = open_pid_file(fn, O_CREAT|O_RDWR)) < 0)
 150         goto fail;
 151
 152     if ((pid = read_pid(fn, fd)) == (pid_t) -1)
 153         pa_log("corrupt PID file, overwriting.");
 154     else if (pid > 0) {
 155 #ifdef OS_IS_WIN32
 156         if ((process = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, pid)) != NULL) {
 157             CloseHandle(process);
 158 #else
 159         if (kill(pid, 0) >= 0 || errno != ESRCH) {
 160 #endif
 161             pa_log("daemon already running.");
 162             goto fail;
 163         }
 164
 165         pa_log("stale PID file, overwriting.");
 166     }
 167
 168     /* Overwrite the current PID file */
 169     if (lseek(fd, 0, SEEK_SET) == (off_t) -1 || ftruncate(fd, 0) < 0) {
 170         pa_log("failed to truncate PID file '%s': %s",
 171             fn, pa_cstrerror(errno));
 172         goto fail;
 173     }
 174
 175     snprintf(t, sizeof(t), "%lu\n", (unsigned long) getpid());
 176     l = strlen(t);
 177
 178     if (pa_loop_write(fd, t, l, NULL) != (ssize_t) l) {
 179         pa_log("failed to write PID file.");
 180         goto fail;
 181     }
 182
 183     ret = 0;
 184
 185 fail:
 186     if (fd >= 0) {
 187         pa_lock_fd(fd, 0);
 188         close(fd);
 189     }
 190
 191     return ret;
 192 }
 193
 194 /* Remove the PID file, if it is ours */
 195 int pa_pid_file_remove(void) {
 196     int fd = -1;
 197     char fn[PATH_MAX];
 198     int ret = -1;
 199     pid_t pid;
 200
 201     pa_runtime_path("pid", fn, sizeof(fn));
 202
 203     if ((fd = open_pid_file(fn, O_RDWR)) < 0) {
 204         pa_log_warn("WARNING: failed to open PID file '%s': %s",
 205             fn, pa_cstrerror(errno));
 206         goto fail;
 207     }
 208
 209     if ((pid = read_pid(fn, fd)) == (pid_t) -1)
 210         goto fail;
 211
 212     if (pid != getpid()) {
 213         pa_log("WARNING: PID file '%s' not mine!", fn);
 214         goto fail;
 215     }
 216
 217     if (ftruncate(fd, 0) < 0) {
 218         pa_log_warn("WARNING: failed to truncate PID file '%s': %s",
 219             fn, pa_cstrerror(errno));
 220         goto fail;
 221     }
 222
 223 #ifdef OS_IS_WIN32
 224     pa_lock_fd(fd, 0);
 225     close(fd);
 226     fd = -1;
 227 #endif
 228
 229     if (unlink(fn) < 0) {
 230         pa_log_warn("WARNING: failed to remove PID file '%s': %s",
 231             fn, pa_cstrerror(errno));
 232         goto fail;
 233     }
 234
 235     ret = 0;
 236
 237 fail:
 238
 239     if (fd >= 0) {
 240         pa_lock_fd(fd, 0);
 241         close(fd);
 242     }
 243
 244     return ret;
 245 }
 246
 247 /* Check whether the daemon is currently running, i.e. if a PID file
 248  * exists and the PID therein too. Returns 0 on succcess, -1
 249  * otherwise. If pid is non-NULL and a running daemon was found,
 250  * return its PID therein */
 251 int pa_pid_file_check_running(pid_t *pid) {
 252     return pa_pid_file_kill(0, pid);
 253 }
 254
 255 #ifndef OS_IS_WIN32
 256
 257 /* Kill a current running daemon. Return non-zero on success, -1
 258  * otherwise. If successful *pid contains the PID of the daemon
 259  * process. */
 260 int pa_pid_file_kill(int sig, pid_t *pid) {
 261     int fd = -1;
 262     char fn[PATH_MAX];
 263     int ret = -1;
 264     pid_t _pid;
 265
 266     if (!pid)
 267         pid = &_pid;
 268
 269     pa_runtime_path("pid", fn, sizeof(fn));
 270
 271     if ((fd = open_pid_file(fn, O_RDONLY)) < 0)
 272         goto fail;
 273
 274     if ((*pid = read_pid(fn, fd)) == (pid_t) -1)
 275         goto fail;
 276
 277     ret = kill(*pid, sig);
 278
 279 fail:
 280
 281     if (fd >= 0) {
 282         pa_lock_fd(fd, 0);
 283         close(fd);
 284     }
 285
 286     return ret;
 287
 288 }
 289
 290 #else /* OS_IS_WIN32 */
 291
 292 int pa_pid_file_kill(int sig, pid_t *pid) {
 293     return -1;
 294 }
 295
 296 #endif