1 /*- 2 * Copyright (c) 2005 Pawel Jakub Dawidek <pjd@FreeBSD.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 #include <sys/param.h> 31 #include <sys/file.h> 32 #include <sys/stat.h> 33 34 #include <stdio.h> 35 #include <stdlib.h> 36 #include <unistd.h> 37 #include <fcntl.h> 38 #include <string.h> 39 #include <time.h> 40 #include <err.h> 41 #include <errno.h> 42 #include <libutil.h> 43 44 struct pidfh { 45 int pf_fd; 46 char pf_path[MAXPATHLEN + 1]; 47 dev_t pf_dev; 48 ino_t pf_ino; 49 }; 50 51 static int _pidfile_remove(struct pidfh *pfh, int freeit); 52 53 static int 54 pidfile_verify(const struct pidfh *pfh) 55 { 56 struct stat sb; 57 58 if (pfh == NULL || pfh->pf_fd == -1) 59 return (EDOOFUS); 60 /* 61 * Check remembered descriptor. 62 */ 63 if (fstat(pfh->pf_fd, &sb) == -1) 64 return (errno); 65 if (sb.st_dev != pfh->pf_dev || sb.st_ino != pfh->pf_ino) 66 return (EDOOFUS); 67 return (0); 68 } 69 70 static int 71 pidfile_read(const char *path, pid_t *pidptr) 72 { 73 char buf[16], *endptr; 74 int error, fd, i; 75 76 fd = open(path, O_RDONLY | O_CLOEXEC); 77 if (fd == -1) 78 return (errno); 79 80 i = read(fd, buf, sizeof(buf) - 1); 81 error = errno; /* Remember errno in case close() wants to change it. */ 82 close(fd); 83 if (i == -1) 84 return (error); 85 else if (i == 0) 86 return (EAGAIN); 87 buf[i] = '\0'; 88 89 *pidptr = strtol(buf, &endptr, 10); 90 if (endptr != &buf[i]) 91 return (EINVAL); 92 93 return (0); 94 } 95 96 struct pidfh * 97 pidfile_open(const char *path, mode_t mode, pid_t *pidptr) 98 { 99 struct pidfh *pfh; 100 struct stat sb; 101 int error, fd, len, count; 102 struct timespec rqtp; 103 104 pfh = malloc(sizeof(*pfh)); 105 if (pfh == NULL) 106 return (NULL); 107 108 if (path == NULL) 109 len = snprintf(pfh->pf_path, sizeof(pfh->pf_path), 110 "/var/run/%s.pid", getprogname()); 111 else 112 len = snprintf(pfh->pf_path, sizeof(pfh->pf_path), 113 "%s", path); 114 if (len >= (int)sizeof(pfh->pf_path)) { 115 free(pfh); 116 errno = ENAMETOOLONG; 117 return (NULL); 118 } 119 120 /* 121 * Open the PID file and obtain exclusive lock. 122 * We truncate PID file here only to remove old PID immediately, 123 * PID file will be truncated again in pidfile_write(), so 124 * pidfile_write() can be called multiple times. 125 */ 126 fd = flopen(pfh->pf_path, 127 O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NONBLOCK, mode); 128 if (fd == -1) { 129 if (errno == EWOULDBLOCK) { 130 if (pidptr == NULL) { 131 errno = EEXIST; 132 } else { 133 count = 20; 134 rqtp.tv_sec = 0; 135 rqtp.tv_nsec = 5000000; 136 for (;;) { 137 errno = pidfile_read(pfh->pf_path, 138 pidptr); 139 if (errno != EAGAIN || --count == 0) 140 break; 141 nanosleep(&rqtp, 0); 142 } 143 if (errno == EAGAIN) 144 *pidptr = -1; 145 if (errno == 0 || errno == EAGAIN) 146 errno = EEXIST; 147 } 148 } 149 free(pfh); 150 return (NULL); 151 } 152 153 /* 154 * Remember file information, so in pidfile_write() we are sure we write 155 * to the proper descriptor. 156 */ 157 if (fstat(fd, &sb) == -1) { 158 error = errno; 159 unlink(pfh->pf_path); 160 close(fd); 161 free(pfh); 162 errno = error; 163 return (NULL); 164 } 165 166 pfh->pf_fd = fd; 167 pfh->pf_dev = sb.st_dev; 168 pfh->pf_ino = sb.st_ino; 169 170 return (pfh); 171 } 172 173 int 174 pidfile_write(struct pidfh *pfh) 175 { 176 char pidstr[16]; 177 int error, fd; 178 179 /* 180 * Check remembered descriptor, so we don't overwrite some other 181 * file if pidfile was closed and descriptor reused. 182 */ 183 errno = pidfile_verify(pfh); 184 if (errno != 0) { 185 /* 186 * Don't close descriptor, because we are not sure if it's ours. 187 */ 188 return (-1); 189 } 190 fd = pfh->pf_fd; 191 192 /* 193 * Truncate PID file, so multiple calls of pidfile_write() are allowed. 194 */ 195 if (ftruncate(fd, 0) == -1) { 196 error = errno; 197 _pidfile_remove(pfh, 0); 198 errno = error; 199 return (-1); 200 } 201 202 snprintf(pidstr, sizeof(pidstr), "%u", getpid()); 203 if (pwrite(fd, pidstr, strlen(pidstr), 0) != (ssize_t)strlen(pidstr)) { 204 error = errno; 205 _pidfile_remove(pfh, 0); 206 errno = error; 207 return (-1); 208 } 209 210 return (0); 211 } 212 213 int 214 pidfile_close(struct pidfh *pfh) 215 { 216 int error; 217 218 error = pidfile_verify(pfh); 219 if (error != 0) { 220 errno = error; 221 return (-1); 222 } 223 224 if (close(pfh->pf_fd) == -1) 225 error = errno; 226 free(pfh); 227 if (error != 0) { 228 errno = error; 229 return (-1); 230 } 231 return (0); 232 } 233 234 static int 235 _pidfile_remove(struct pidfh *pfh, int freeit) 236 { 237 int error; 238 239 error = pidfile_verify(pfh); 240 if (error != 0) { 241 errno = error; 242 return (-1); 243 } 244 245 if (unlink(pfh->pf_path) == -1) 246 error = errno; 247 if (close(pfh->pf_fd) == -1) { 248 if (error == 0) 249 error = errno; 250 } 251 if (freeit) 252 free(pfh); 253 else 254 pfh->pf_fd = -1; 255 if (error != 0) { 256 errno = error; 257 return (-1); 258 } 259 return (0); 260 } 261 262 int 263 pidfile_remove(struct pidfh *pfh) 264 { 265 266 return (_pidfile_remove(pfh, 1)); 267 } 268 269 int 270 pidfile_fileno(const struct pidfh *pfh) 271 { 272 273 if (pfh == NULL || pfh->pf_fd == -1) { 274 errno = EDOOFUS; 275 return (-1); 276 } 277 return (pfh->pf_fd); 278 } 279