code.delx.au - pulseaudio/blob - src/polypcore/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 #ifdef HAVE_WINDOWS_H
  39 #include <windows.h>
  40 #endif
  41
  42 #include <polyp/xmalloc.h>
  43
  44 #include <polypcore/core-error.h>
  45 #include <polypcore/core-util.h>
  46 #include <polypcore/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)) < 0) {
  60         pa_log_warn(__FILE__": 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(__FILE__": 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     int lock = -1;
  83
  84     for (;;) {
  85         struct stat st;
  86
  87         pa_make_secure_parent_dir(fn);
  88
  89         if ((fd = open(fn, mode, S_IRUSR|S_IWUSR)) < 0) {
  90             if (mode != O_RDONLY || errno != ENOENT)
  91                 pa_log_warn(__FILE__": 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(__FILE__": 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(__FILE__": 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         if (lock >= 0)
 128             pa_lock_fd(fd, 0);
 129
 130         close(fd);
 131     }
 132
 133     return -1;
 134 }
 135
 136 /* Create a new PID file for the current process. */
 137 int pa_pid_file_create(void) {
 138     int fd = -1;
 139     int ret = -1;
 140     char fn[PATH_MAX];
 141     char t[20];
 142     pid_t pid;
 143     size_t l;
 144
 145 #ifdef OS_IS_WIN32
 146     HANDLE process;
 147 #endif
 148
 149     pa_runtime_path("pid", fn, sizeof(fn));
 150
 151     if ((fd = open_pid_file(fn, O_CREAT|O_RDWR)) < 0)
 152         goto fail;
 153
 154     if ((pid = read_pid(fn, fd)) == (pid_t) -1)
 155         pa_log(__FILE__": corrupt PID file, overwriting.");
 156     else if (pid > 0) {
 157 #ifdef OS_IS_WIN32
 158         if ((process = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, pid)) != NULL) {
 159             CloseHandle(process);
 160 #else
 161         if (kill(pid, 0) >= 0 || errno != ESRCH) {
 162 #endif
 163             pa_log(__FILE__": daemon already running.");
 164             goto fail;
 165         }
 166
 167         pa_log(__FILE__": stale PID file, overwriting.");
 168     }
 169
 170     /* Overwrite the current PID file */
 171     if (lseek(fd, 0, SEEK_SET) == (off_t) -1 || ftruncate(fd, 0) < 0) {
 172         pa_log(__FILE__": failed to truncate PID file '%s': %s",
 173             fn, pa_cstrerror(errno));
 174         goto fail;
 175     }
 176
 177     snprintf(t, sizeof(t), "%lu\n", (unsigned long) getpid());
 178     l = strlen(t);
 179
 180     if (pa_loop_write(fd, t, l) != (ssize_t) l) {
 181         pa_log(__FILE__": failed to write PID file.");
 182         goto fail;
 183     }
 184
 185     ret = 0;
 186
 187 fail:
 188     if (fd >= 0) {
 189         pa_lock_fd(fd, 0);
 190         close(fd);
 191     }
 192
 193     return ret;
 194 }
 195
 196 /* Remove the PID file, if it is ours */
 197 int pa_pid_file_remove(void) {
 198     int fd = -1;
 199     char fn[PATH_MAX];
 200     int ret = -1;
 201     pid_t pid;
 202     char *p;
 203
 204     pa_runtime_path("pid", fn, sizeof(fn));
 205
 206     if ((fd = open_pid_file(fn, O_RDWR)) < 0) {
 207         pa_log_warn(__FILE__": 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(__FILE__": WARNING: PID file '%s' not mine!", fn);
 217         goto fail;
 218     }
 219
 220     if (ftruncate(fd, 0) < 0) {
 221         pa_log_warn(__FILE__": 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(__FILE__": WARNING: failed to remove PID file '%s': %s",
 234             fn, pa_cstrerror(errno));
 235         goto fail;
 236     }
 237
 238     if ((p = pa_parent_dir(fn))) {
 239         rmdir(p);
 240         pa_xfree(p);
 241     }
 242
 243     ret = 0;
 244
 245 fail:
 246
 247     if (fd >= 0) {
 248         pa_lock_fd(fd, 0);
 249         close(fd);
 250     }
 251
 252     return ret;
 253 }
 254
 255 /* Check whether the daemon is currently running, i.e. if a PID file
 256  * exists and the PID therein too. Returns 0 on succcess, -1
 257  * otherwise. If pid is non-NULL and a running daemon was found,
 258  * return its PID therein */
 259 int pa_pid_file_check_running(pid_t *pid) {
 260     return pa_pid_file_kill(0, pid);
 261 }
 262
 263 #ifndef OS_IS_WIN32
 264
 265 /* Kill a current running daemon. Return non-zero on success, -1
 266  * otherwise. If successful *pid contains the PID of the daemon
 267  * process. */
 268 int pa_pid_file_kill(int sig, pid_t *pid) {
 269     int fd = -1;
 270     char fn[PATH_MAX];
 271     int ret = -1;
 272     pid_t _pid;
 273
 274     if (!pid)
 275         pid = &_pid;
 276
 277     pa_runtime_path("pid", fn, sizeof(fn));
 278
 279     if ((fd = open_pid_file(fn, O_RDONLY)) < 0)
 280         goto fail;
 281
 282     if ((*pid = read_pid(fn, fd)) == (pid_t) -1)
 283         goto fail;
 284
 285     ret = kill(*pid, sig);
 286
 287 fail:
 288
 289     if (fd >= 0) {
 290         pa_lock_fd(fd, 0);
 291         close(fd);
 292     }
 293
 294     return ret;
 295
 296 }
 297
 298 #else /* OS_IS_WIN32 */
 299
 300 int pa_pid_file_kill(int sig, pid_t *pid) {
 301     return -1;
 302 }
 303
 304 #endif