1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2005 Pawel Jakub Dawidek <pjd@FreeBSD.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include <sys/param.h> 33 #include <sys/capsicum.h> 34 #include <sys/file.h> 35 #include <sys/stat.h> 36 37 #include <err.h> 38 #include <errno.h> 39 #include <fcntl.h> 40 #include <libgen.h> 41 #include <libutil.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <string.h> 45 #include <time.h> 46 #include <unistd.h> 47 48 struct pidfh { 49 int pf_dirfd; 50 int pf_fd; 51 char pf_dir[MAXPATHLEN + 1]; 52 char pf_filename[MAXPATHLEN + 1]; 53 dev_t pf_dev; 54 ino_t pf_ino; 55 }; 56 57 static int _pidfile_remove(struct pidfh *pfh, int freeit); 58 59 static int 60 pidfile_verify(const struct pidfh *pfh) 61 { 62 struct stat sb; 63 64 if (pfh == NULL || pfh->pf_fd == -1) 65 return (EDOOFUS); 66 /* 67 * Check remembered descriptor. 68 */ 69 if (fstat(pfh->pf_fd, &sb) == -1) 70 return (errno); 71 if (sb.st_dev != pfh->pf_dev || sb.st_ino != pfh->pf_ino) 72 return (EDOOFUS); 73 return (0); 74 } 75 76 static int 77 pidfile_read(int dirfd, const char *filename, pid_t *pidptr) 78 { 79 char buf[16], *endptr; 80 int error, fd, i; 81 82 fd = openat(dirfd, filename, O_RDONLY | O_CLOEXEC); 83 if (fd == -1) 84 return (errno); 85 86 i = read(fd, buf, sizeof(buf) - 1); 87 error = errno; /* Remember errno in case close() wants to change it. */ 88 close(fd); 89 if (i == -1) 90 return (error); 91 else if (i == 0) 92 return (EAGAIN); 93 buf[i] = '\0'; 94 95 *pidptr = strtol(buf, &endptr, 10); 96 if (endptr != &buf[i]) 97 return (EINVAL); 98 99 return (0); 100 } 101 102 struct pidfh * 103 pidfile_open(const char *pathp, mode_t mode, pid_t *pidptr) 104 { 105 char path[MAXPATHLEN]; 106 struct pidfh *pfh; 107 struct stat sb; 108 int error, fd, dirfd, dirlen, filenamelen, count; 109 struct timespec rqtp; 110 cap_rights_t caprights; 111 112 pfh = malloc(sizeof(*pfh)); 113 if (pfh == NULL) 114 return (NULL); 115 116 if (pathp == NULL) { 117 dirlen = snprintf(pfh->pf_dir, sizeof(pfh->pf_dir), 118 "/var/run/"); 119 filenamelen = snprintf(pfh->pf_filename, 120 sizeof(pfh->pf_filename), "%s.pid", getprogname()); 121 } else { 122 if (strlcpy(path, pathp, sizeof(path)) >= sizeof(path)) { 123 free(pfh); 124 errno = ENAMETOOLONG; 125 return (NULL); 126 } 127 dirlen = strlcpy(pfh->pf_dir, dirname(path), 128 sizeof(pfh->pf_dir)); 129 (void)strlcpy(path, pathp, sizeof(path)); 130 filenamelen = strlcpy(pfh->pf_filename, basename(path), 131 sizeof(pfh->pf_filename)); 132 } 133 134 if (dirlen >= (int)sizeof(pfh->pf_dir) || 135 filenamelen >= (int)sizeof(pfh->pf_filename)) { 136 free(pfh); 137 errno = ENAMETOOLONG; 138 return (NULL); 139 } 140 141 dirfd = open(pfh->pf_dir, O_CLOEXEC | O_DIRECTORY | O_NONBLOCK); 142 if (dirfd == -1) { 143 error = errno; 144 free(pfh); 145 errno = error; 146 return (NULL); 147 } 148 149 /* 150 * Open the PID file and obtain exclusive lock. 151 * We truncate PID file here only to remove old PID immediately, 152 * PID file will be truncated again in pidfile_write(), so 153 * pidfile_write() can be called multiple times. 154 */ 155 fd = flopenat(dirfd, pfh->pf_filename, 156 O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NONBLOCK, mode); 157 if (fd == -1) { 158 if (errno == EWOULDBLOCK) { 159 if (pidptr == NULL) { 160 errno = EEXIST; 161 } else { 162 count = 20; 163 rqtp.tv_sec = 0; 164 rqtp.tv_nsec = 5000000; 165 for (;;) { 166 errno = pidfile_read(dirfd, 167 pfh->pf_filename, pidptr); 168 if (errno != EAGAIN || --count == 0) 169 break; 170 nanosleep(&rqtp, 0); 171 } 172 if (errno == EAGAIN) 173 *pidptr = -1; 174 if (errno == 0 || errno == EAGAIN) 175 errno = EEXIST; 176 } 177 } 178 error = errno; 179 close(dirfd); 180 free(pfh); 181 errno = error; 182 return (NULL); 183 } 184 185 /* 186 * Remember file information, so in pidfile_write() we are sure we write 187 * to the proper descriptor. 188 */ 189 if (fstat(fd, &sb) == -1) { 190 goto failed; 191 } 192 193 if (cap_rights_limit(dirfd, 194 cap_rights_init(&caprights, CAP_UNLINKAT)) < 0 && errno != ENOSYS) { 195 goto failed; 196 } 197 198 if (cap_rights_limit(fd, cap_rights_init(&caprights, CAP_PWRITE, 199 CAP_FSTAT, CAP_FTRUNCATE)) < 0 && 200 errno != ENOSYS) { 201 goto failed; 202 } 203 204 pfh->pf_dirfd = dirfd; 205 pfh->pf_fd = fd; 206 pfh->pf_dev = sb.st_dev; 207 pfh->pf_ino = sb.st_ino; 208 209 return (pfh); 210 211 failed: 212 error = errno; 213 unlinkat(dirfd, pfh->pf_filename, 0); 214 close(dirfd); 215 close(fd); 216 free(pfh); 217 errno = error; 218 return (NULL); 219 } 220 221 int 222 pidfile_write(struct pidfh *pfh) 223 { 224 char pidstr[16]; 225 int error, fd; 226 227 /* 228 * Check remembered descriptor, so we don't overwrite some other 229 * file if pidfile was closed and descriptor reused. 230 */ 231 errno = pidfile_verify(pfh); 232 if (errno != 0) { 233 /* 234 * Don't close descriptor, because we are not sure if it's ours. 235 */ 236 return (-1); 237 } 238 fd = pfh->pf_fd; 239 240 /* 241 * Truncate PID file, so multiple calls of pidfile_write() are allowed. 242 */ 243 if (ftruncate(fd, 0) == -1) { 244 error = errno; 245 _pidfile_remove(pfh, 0); 246 errno = error; 247 return (-1); 248 } 249 250 snprintf(pidstr, sizeof(pidstr), "%u", getpid()); 251 if (pwrite(fd, pidstr, strlen(pidstr), 0) != (ssize_t)strlen(pidstr)) { 252 error = errno; 253 _pidfile_remove(pfh, 0); 254 errno = error; 255 return (-1); 256 } 257 258 return (0); 259 } 260 261 int 262 pidfile_close(struct pidfh *pfh) 263 { 264 int error; 265 266 error = pidfile_verify(pfh); 267 if (error != 0) { 268 errno = error; 269 return (-1); 270 } 271 272 if (close(pfh->pf_fd) == -1) 273 error = errno; 274 if (close(pfh->pf_dirfd) == -1 && error == 0) 275 error = errno; 276 277 free(pfh); 278 if (error != 0) { 279 errno = error; 280 return (-1); 281 } 282 return (0); 283 } 284 285 static int 286 _pidfile_remove(struct pidfh *pfh, int freeit) 287 { 288 int error; 289 290 error = pidfile_verify(pfh); 291 if (error != 0) { 292 errno = error; 293 return (-1); 294 } 295 296 if (funlinkat(pfh->pf_dirfd, pfh->pf_filename, pfh->pf_fd, 0) == -1) { 297 if (errno == EDEADLK) 298 return (-1); 299 error = errno; 300 } 301 if (close(pfh->pf_fd) == -1 && error == 0) 302 error = errno; 303 if (close(pfh->pf_dirfd) == -1 && error == 0) 304 error = errno; 305 if (freeit) 306 free(pfh); 307 else 308 pfh->pf_fd = -1; 309 if (error != 0) { 310 errno = error; 311 return (-1); 312 } 313 return (0); 314 } 315 316 int 317 pidfile_remove(struct pidfh *pfh) 318 { 319 320 return (_pidfile_remove(pfh, 1)); 321 } 322 323 int 324 pidfile_fileno(const struct pidfh *pfh) 325 { 326 327 if (pfh == NULL || pfh->pf_fd == -1) { 328 errno = EDOOFUS; 329 return (-1); 330 } 331 return (pfh->pf_fd); 332 } 333