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 static int _pidfile_remove(struct pidfh *pfh, int freeit); 45 46 static int 47 pidfile_verify(const struct pidfh *pfh) 48 { 49 struct stat sb; 50 51 if (pfh == NULL || pfh->pf_fd == -1) 52 return (EDOOFUS); 53 /* 54 * Check remembered descriptor. 55 */ 56 if (fstat(pfh->pf_fd, &sb) == -1) 57 return (errno); 58 if (sb.st_dev != pfh->pf_dev || sb.st_ino != pfh->pf_ino) 59 return (EDOOFUS); 60 return (0); 61 } 62 63 static int 64 pidfile_read(const char *path, pid_t *pidptr) 65 { 66 char buf[16], *endptr; 67 int error, fd, i; 68 69 fd = open(path, O_RDONLY); 70 if (fd == -1) 71 return (errno); 72 73 i = read(fd, buf, sizeof(buf) - 1); 74 error = errno; /* Remember errno in case close() wants to change it. */ 75 close(fd); 76 if (i == -1) 77 return (error); 78 else if (i == 0) 79 return (EAGAIN); 80 buf[i] = '\0'; 81 82 *pidptr = strtol(buf, &endptr, 10); 83 if (endptr != &buf[i]) 84 return (EINVAL); 85 86 return (0); 87 } 88 89 struct pidfh * 90 pidfile_open(const char *path, mode_t mode, pid_t *pidptr) 91 { 92 struct pidfh *pfh; 93 struct stat sb; 94 int error, fd, len, count; 95 struct timespec rqtp; 96 97 pfh = malloc(sizeof(*pfh)); 98 if (pfh == NULL) 99 return (NULL); 100 101 if (path == NULL) 102 len = snprintf(pfh->pf_path, sizeof(pfh->pf_path), 103 "/var/run/%s.pid", getprogname()); 104 else 105 len = snprintf(pfh->pf_path, sizeof(pfh->pf_path), 106 "%s", path); 107 if (len >= (int)sizeof(pfh->pf_path)) { 108 free(pfh); 109 errno = ENAMETOOLONG; 110 return (NULL); 111 } 112 113 /* 114 * Open the PID file and obtain exclusive lock. 115 * We truncate PID file here only to remove old PID immediatelly, 116 * PID file will be truncated again in pidfile_write(), so 117 * pidfile_write() can be called multiple times. 118 */ 119 fd = flopen(pfh->pf_path, 120 O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NONBLOCK, mode); 121 if (fd == -1) { 122 if (errno == EWOULDBLOCK && pidptr != NULL) { 123 count = 20; 124 rqtp.tv_sec = 0; 125 rqtp.tv_nsec = 5000000; 126 for (;;) { 127 errno = pidfile_read(pfh->pf_path, pidptr); 128 if (errno != EAGAIN || --count == 0) 129 break; 130 nanosleep(&rqtp, 0); 131 } 132 if (errno == EAGAIN) 133 *pidptr = -1; 134 if (errno == 0 || errno == EAGAIN) 135 errno = EEXIST; 136 } 137 free(pfh); 138 return (NULL); 139 } 140 141 /* 142 * Remember file information, so in pidfile_write() we are sure we write 143 * to the proper descriptor. 144 */ 145 if (fstat(fd, &sb) == -1) { 146 error = errno; 147 unlink(pfh->pf_path); 148 close(fd); 149 free(pfh); 150 errno = error; 151 return (NULL); 152 } 153 154 pfh->pf_fd = fd; 155 pfh->pf_dev = sb.st_dev; 156 pfh->pf_ino = sb.st_ino; 157 158 return (pfh); 159 } 160 161 int 162 pidfile_write(struct pidfh *pfh) 163 { 164 char pidstr[16]; 165 int error, fd; 166 167 /* 168 * Check remembered descriptor, so we don't overwrite some other 169 * file if pidfile was closed and descriptor reused. 170 */ 171 errno = pidfile_verify(pfh); 172 if (errno != 0) { 173 /* 174 * Don't close descriptor, because we are not sure if it's ours. 175 */ 176 return (-1); 177 } 178 fd = pfh->pf_fd; 179 180 /* 181 * Truncate PID file, so multiple calls of pidfile_write() are allowed. 182 */ 183 if (ftruncate(fd, 0) == -1) { 184 error = errno; 185 _pidfile_remove(pfh, 0); 186 errno = error; 187 return (-1); 188 } 189 190 snprintf(pidstr, sizeof(pidstr), "%u", getpid()); 191 if (pwrite(fd, pidstr, strlen(pidstr), 0) != (ssize_t)strlen(pidstr)) { 192 error = errno; 193 _pidfile_remove(pfh, 0); 194 errno = error; 195 return (-1); 196 } 197 198 return (0); 199 } 200 201 int 202 pidfile_close(struct pidfh *pfh) 203 { 204 int error; 205 206 error = pidfile_verify(pfh); 207 if (error != 0) { 208 errno = error; 209 return (-1); 210 } 211 212 if (close(pfh->pf_fd) == -1) 213 error = errno; 214 free(pfh); 215 if (error != 0) { 216 errno = error; 217 return (-1); 218 } 219 return (0); 220 } 221 222 static int 223 _pidfile_remove(struct pidfh *pfh, int freeit) 224 { 225 int error; 226 227 error = pidfile_verify(pfh); 228 if (error != 0) { 229 errno = error; 230 return (-1); 231 } 232 233 if (unlink(pfh->pf_path) == -1) 234 error = errno; 235 if (close(pfh->pf_fd) == -1) { 236 if (error == 0) 237 error = errno; 238 } 239 if (freeit) 240 free(pfh); 241 else 242 pfh->pf_fd = -1; 243 if (error != 0) { 244 errno = error; 245 return (-1); 246 } 247 return (0); 248 } 249 250 int 251 pidfile_remove(struct pidfh *pfh) 252 { 253 254 return (_pidfile_remove(pfh, 1)); 255 } 256 257 int 258 pidfile_fileno(const struct pidfh *pfh) 259 { 260 261 if (pfh == NULL || pfh->pf_fd == -1) { 262 errno = EDOOFUS; 263 return (-1); 264 } 265 return (pfh->pf_fd); 266 } 267