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/util.h>
  45 #include <polypcore/log.h>
  46
  47 #include "pid.h"
  48
  49 /* Read the PID data from the file descriptor fd, and return it. If no
  50  * pid could be read, return 0, on failure (pid_t) -1 */
  51 static pid_t read_pid(const char *fn, int fd) {
  52     ssize_t r;
  53     char t[20], *e;
  54     uint32_t pid;
  55
  56     assert(fn && fd >= 0);
  57
  58     if ((r = pa_loop_read(fd, t, sizeof(t)-1)) < 0) {
  59         pa_log(__FILE__": WARNING: failed to read PID file '%s': %s", fn, strerror(errno));
  60         return (pid_t) -1;
  61     }
  62
  63     if (r == 0)
  64         return (pid_t) 0;
  65
  66     t[r] = 0;
  67     if ((e = strchr(t, '\n')))
  68         *e = 0;
  69
  70     if (pa_atou(t, &pid) < 0) {
  71         pa_log(__FILE__": WARNING: failed to parse PID file '%s'", fn);
  72         return (pid_t) -1;
  73     }
  74
  75     return (pid_t) pid;
  76 }
  77
  78 static int open_pid_file(const char *fn, int mode) {
  79     int fd = -1;
  80     int lock = -1;
  81
  82     for (;;) {
  83         struct stat st;
  84
  85         pa_make_secure_parent_dir(fn);
  86
  87         if ((fd = open(fn, mode, S_IRUSR|S_IWUSR)) < 0) {
  88             if (mode != O_RDONLY || errno != ENOENT)
  89                 pa_log(__FILE__": WARNING: failed to open PID file '%s': %s", fn, strerror(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(__FILE__": Failed to fstat() PID file '%s': %s", fn, strerror(errno));
  99             goto fail;
 100         }
 101
 102         /* Does the file still exist in the file system? When ye, w're done, otherwise restart */
 103         if (st.st_nlink >= 1)
 104             break;
 105
 106         if (pa_lock_fd(fd, 0) < 0)
 107             goto fail;
 108
 109         if (close(fd) < 0) {
 110             pa_log(__FILE__": Failed to close file '%s': %s", fn, strerror(errno));
 111             goto fail;
 112         }
 113
 114         fd = -1;
 115     }
 116
 117     return fd;
 118
 119 fail:
 120
 121     if (fd < 0) {
 122         if (lock >= 0)
 123             pa_lock_fd(fd, 0);
 124
 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(__FILE__": 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(__FILE__": daemon already running.");
 159             goto fail;
 160         }
 161
 162         pa_log(__FILE__": 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(__FILE__": failed to truncate PID fil: %s.", strerror(errno));
 168         goto fail;
 169     }
 170
 171     snprintf(t, sizeof(t), "%lu\n", (unsigned long) getpid());
 172     l = strlen(t);
 173
 174     if (pa_loop_write(fd, t, l) != (ssize_t) l) {
 175         pa_log(__FILE__": failed to write PID file.");
 176         goto fail;
 177     }
 178
 179     ret = 0;
 180
 181 fail:
 182     if (fd >= 0) {
 183         pa_lock_fd(fd, 0);
 184         close(fd);
 185     }
 186
 187     return ret;
 188 }
 189
 190 /* Remove the PID file, if it is ours */
 191 int pa_pid_file_remove(void) {
 192     int fd = -1;
 193     char fn[PATH_MAX];
 194     int ret = -1;
 195     pid_t pid;
 196     char *p;
 197
 198     pa_runtime_path("pid", fn, sizeof(fn));
 199
 200     if ((fd = open_pid_file(fn, O_RDWR)) < 0) {
 201         pa_log(__FILE__": WARNING: failed to open PID file '%s': %s", fn, strerror(errno));
 202         goto fail;
 203     }
 204
 205     if ((pid = read_pid(fn, fd)) == (pid_t) -1)
 206         goto fail;
 207
 208     if (pid != getpid()) {
 209         pa_log(__FILE__": WARNING: PID file '%s' not mine!", fn);
 210         goto fail;
 211     }
 212
 213     if (ftruncate(fd, 0) < 0) {
 214         pa_log(__FILE__": failed to truncate PID file '%s': %s", fn, strerror(errno));
 215         goto fail;
 216     }
 217
 218 #ifdef OS_IS_WIN32
 219     pa_lock_fd(fd, 0);
 220     close(fd);
 221     fd = -1;
 222 #endif
 223
 224     if (unlink(fn) < 0) {
 225         pa_log(__FILE__": failed to remove PID file '%s': %s", fn, strerror(errno));
 226         goto fail;
 227     }
 228
 229     if ((p = pa_parent_dir(fn))) {
 230         rmdir(p);
 231         pa_xfree(p);
 232     }
 233
 234     ret = 0;
 235
 236 fail:
 237
 238     if (fd >= 0) {
 239         pa_lock_fd(fd, 0);
 240         close(fd);
 241     }
 242
 243     return ret;
 244 }
 245
 246 /* Check whether the daemon is currently running, i.e. if a PID file
 247  * exists and the PID therein too. Returns 0 on succcess, -1
 248  * otherwise. If pid is non-NULL and a running daemon was found,
 249  * return its PID therein */
 250 int pa_pid_file_check_running(pid_t *pid) {
 251     return pa_pid_file_kill(0, pid);
 252 }
 253
 254 #ifndef OS_IS_WIN32
 255
 256 /* Kill a current running daemon. Return non-zero on success, -1
 257  * otherwise. If successful *pid contains the PID of the daemon
 258  * process. */
 259 int pa_pid_file_kill(int sig, pid_t *pid) {
 260     int fd = -1;
 261     char fn[PATH_MAX];
 262     int ret = -1;
 263     pid_t _pid;
 264
 265     if (!pid)
 266         pid = &_pid;
 267
 268     pa_runtime_path("pid", fn, sizeof(fn));
 269
 270     if ((fd = open_pid_file(fn, O_RDONLY)) < 0)
 271         goto fail;
 272
 273     if ((*pid = read_pid(fn, fd)) == (pid_t) -1)
 274         goto fail;
 275
 276     ret = kill(*pid, sig);
 277
 278 fail:
 279
 280     if (fd >= 0) {
 281         pa_lock_fd(fd, 0);
 282         close(fd);
 283     }
 284
 285     return ret;
 286
 287 }
 288
 289 #else /* OS_IS_WIN32 */
 290
 291 int pa_pid_file_kill(int sig, pid_t *pid) {
 292     return -1;
 293 }
 294
 295 #endif