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 <err.h> 40 #include <errno.h> 41 #include <libutil.h> 42 43 static int _pidfile_remove(struct pidfh *pfh, int freeit); 44 45 static int 46 pidfile_verify(struct pidfh *pfh) 47 { 48 struct stat sb; 49 int fd; 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 buf[i] = '\0'; 79 80 *pidptr = strtol(buf, &endptr, 10); 81 if (endptr != &buf[i]) 82 return (EINVAL); 83 84 return (0); 85 } 86 87 struct pidfh * 88 pidfile_open(const char *path, mode_t mode, pid_t *pidptr) 89 { 90 struct pidfh *pfh; 91 struct stat sb; 92 int error, fd; 93 94 pfh = malloc(sizeof(*pfh)); 95 if (pfh == NULL) 96 return (NULL); 97 98 if (path == NULL) { 99 snprintf(pfh->pf_path, sizeof(pfh->pf_path), "/var/run/%s.pid", 100 getprogname()); 101 } else { 102 strlcpy(pfh->pf_path, path, sizeof(pfh->pf_path)); 103 } 104 if (strlen(pfh->pf_path) == sizeof(pfh->pf_path) - 1) { 105 free(pfh); 106 errno = ENAMETOOLONG; 107 return (NULL); 108 } 109 110 /* 111 * Open the PID file and obtain exclusive lock. 112 * We truncate PID file here only to remove old PID immediatelly, 113 * PID file will be truncated again in pidfile_write(), so 114 * pidfile_write() can be called multiple times. 115 */ 116 fd = open(pfh->pf_path, 117 O_WRONLY | O_CREAT | O_EXLOCK | O_TRUNC | O_NONBLOCK, mode); 118 if (fd == -1) { 119 if (errno == EWOULDBLOCK && pidptr != NULL) { 120 errno = pidfile_read(pfh->pf_path, pidptr); 121 if (errno == 0) 122 errno = EEXIST; 123 } 124 free(pfh); 125 return (NULL); 126 } 127 /* 128 * Remember file information, so in pidfile_write() we are sure we write 129 * to the proper descriptor. 130 */ 131 if (fstat(fd, &sb) == -1) { 132 error = errno; 133 unlink(pfh->pf_path); 134 close(fd); 135 free(pfh); 136 errno = error; 137 return (NULL); 138 } 139 140 pfh->pf_fd = fd; 141 pfh->pf_dev = sb.st_dev; 142 pfh->pf_ino = sb.st_ino; 143 144 return (pfh); 145 } 146 147 int 148 pidfile_write(struct pidfh *pfh) 149 { 150 struct stat sb; 151 char pidstr[16]; 152 int error, fd; 153 154 /* 155 * Check remembered descriptor, so we don't overwrite some other 156 * file if pidfile was closed and descriptor reused. 157 */ 158 errno = pidfile_verify(pfh); 159 if (errno != 0) { 160 /* 161 * Don't close descriptor, because we are not sure if it's ours. 162 */ 163 return (-1); 164 } 165 fd = pfh->pf_fd; 166 167 /* 168 * Truncate PID file, so multiple calls of pidfile_write() are allowed. 169 */ 170 if (ftruncate(fd, 0) == -1) { 171 error = errno; 172 _pidfile_remove(pfh, 0); 173 errno = error; 174 return (-1); 175 } 176 177 snprintf(pidstr, sizeof(pidstr), "%u", getpid()); 178 if (write(fd, pidstr, strlen(pidstr)) != (ssize_t)strlen(pidstr)) { 179 error = errno; 180 _pidfile_remove(pfh, 0); 181 errno = error; 182 return (-1); 183 } 184 185 return (0); 186 } 187 188 int 189 pidfile_close(struct pidfh *pfh) 190 { 191 int error; 192 193 error = pidfile_verify(pfh); 194 if (error != 0) { 195 errno = error; 196 return (-1); 197 } 198 199 if (close(pfh->pf_fd) == -1) 200 error = errno; 201 free(pfh); 202 if (error != 0) { 203 errno = error; 204 return (-1); 205 } 206 return (0); 207 } 208 209 static int 210 _pidfile_remove(struct pidfh *pfh, int freeit) 211 { 212 int error; 213 214 error = pidfile_verify(pfh); 215 if (error != 0) { 216 errno = error; 217 return (-1); 218 } 219 220 if (unlink(pfh->pf_path) == -1) 221 error = errno; 222 if (flock(pfh->pf_fd, LOCK_UN) == -1) { 223 if (error == 0) 224 error = errno; 225 } 226 if (close(pfh->pf_fd) == -1) { 227 if (error == 0) 228 error = errno; 229 } 230 if (freeit) 231 free(pfh); 232 else 233 pfh->pf_fd = -1; 234 if (error != 0) { 235 errno = error; 236 return (-1); 237 } 238 return (0); 239 } 240 241 int 242 pidfile_remove(struct pidfh *pfh) 243 { 244 245 return (_pidfile_remove(pfh, 1)); 246 } 247