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: src/lib/libutil/pidfile.c,v 1.3 2006/06/23 01:42:03 brian Exp $"); 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 50 if (pfh == NULL || pfh->pf_fd == -1) 51 return (EDOOFUS); 52 /* 53 * Check remembered descriptor. 54 */ 55 if (fstat(pfh->pf_fd, &sb) == -1) 56 return (errno); 57 if (sb.st_dev != pfh->pf_dev || sb.st_ino != pfh->pf_ino) 58 return (EDOOFUS); 59 return (0); 60 } 61 62 static int 63 pidfile_read(const char *path, pid_t *pidptr) 64 { 65 char buf[16], *endptr; 66 int error, fd, i; 67 68 fd = open(path, O_RDONLY); 69 if (fd == -1) 70 return (errno); 71 72 i = read(fd, buf, sizeof(buf) - 1); 73 error = errno; /* Remember errno in case close() wants to change it. */ 74 close(fd); 75 if (i == -1) 76 return (error); 77 buf[i] = '\0'; 78 79 *pidptr = strtol(buf, &endptr, 10); 80 if (endptr != &buf[i]) 81 return (EINVAL); 82 83 return (0); 84 } 85 86 struct pidfh * 87 pidfile_open(const char *path, mode_t mode, pid_t *pidptr) 88 { 89 struct pidfh *pfh; 90 struct stat sb; 91 int error, fd; 92 93 pfh = malloc(sizeof(*pfh)); 94 if (pfh == NULL) 95 return (NULL); 96 97 if (path == NULL) { 98 snprintf(pfh->pf_path, sizeof(pfh->pf_path), "/var/run/%s.pid", 99 getprogname()); 100 } else { 101 strlcpy(pfh->pf_path, path, sizeof(pfh->pf_path)); 102 } 103 if (strlen(pfh->pf_path) == sizeof(pfh->pf_path) - 1) { 104 free(pfh); 105 errno = ENAMETOOLONG; 106 return (NULL); 107 } 108 109 /* 110 * Open the PID file and obtain exclusive lock. 111 * We truncate PID file here only to remove old PID immediatelly, 112 * PID file will be truncated again in pidfile_write(), so 113 * pidfile_write() can be called multiple times. 114 */ 115 fd = open(pfh->pf_path, O_WRONLY | O_CREAT | O_NONBLOCK, mode); 116 if (fd >= 0) { 117 struct flock lock; 118 lock.l_type = F_WRLCK; 119 lock.l_whence = SEEK_SET; 120 lock.l_start = 0; 121 lock.l_len = 0; 122 123 if (fcntl(fd, F_SETLK, &lock) == -1) { 124 close(fd); 125 fd = -1; 126 } 127 } 128 129 if (fd == -1) { 130 if (errno == EWOULDBLOCK && pidptr != NULL) { 131 errno = pidfile_read(pfh->pf_path, pidptr); 132 if (errno == 0) 133 errno = EEXIST; 134 } 135 free(pfh); 136 return (NULL); 137 } 138 139 ftruncate(fd, 0); 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), "%lu", 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 (flock(pfh->pf_fd, LOCK_UN) == -1) { 236 if (error == 0) 237 error = errno; 238 } 239 if (close(pfh->pf_fd) == -1) { 240 if (error == 0) 241 error = errno; 242 } 243 if (freeit) 244 free(pfh); 245 else 246 pfh->pf_fd = -1; 247 if (error != 0) { 248 errno = error; 249 return (-1); 250 } 251 return (0); 252 } 253 254 int 255 pidfile_remove(struct pidfh *pfh) 256 { 257 258 return (_pidfile_remove(pfh, 1)); 259 } 260