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(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_NONBLOCK, mode); 121 if (fd == -1) { 122 count = 0; 123 rqtp.tv_sec = 0; 124 rqtp.tv_nsec = 5000000; 125 if (errno == EWOULDBLOCK && pidptr != NULL) { 126 again: 127 errno = pidfile_read(pfh->pf_path, pidptr); 128 if (errno == 0) 129 errno = EEXIST; 130 else if (errno == EAGAIN) { 131 if (++count <= 3) { 132 nanosleep(&rqtp, 0); 133 goto again; 134 } 135 } 136 } 137 free(pfh); 138 return (NULL); 139 } 140 /* 141 * Remember file information, so in pidfile_write() we are sure we write 142 * to the proper descriptor. 143 */ 144 if (fstat(fd, &sb) == -1) { 145 error = errno; 146 unlink(pfh->pf_path); 147 close(fd); 148 free(pfh); 149 errno = error; 150 return (NULL); 151 } 152 153 pfh->pf_fd = fd; 154 pfh->pf_dev = sb.st_dev; 155 pfh->pf_ino = sb.st_ino; 156 157 return (pfh); 158 } 159 160 int 161 pidfile_write(struct pidfh *pfh) 162 { 163 char pidstr[16]; 164 int error, fd; 165 166 /* 167 * Check remembered descriptor, so we don't overwrite some other 168 * file if pidfile was closed and descriptor reused. 169 */ 170 errno = pidfile_verify(pfh); 171 if (errno != 0) { 172 /* 173 * Don't close descriptor, because we are not sure if it's ours. 174 */ 175 return (-1); 176 } 177 fd = pfh->pf_fd; 178 179 /* 180 * Truncate PID file, so multiple calls of pidfile_write() are allowed. 181 */ 182 if (ftruncate(fd, 0) == -1) { 183 error = errno; 184 _pidfile_remove(pfh, 0); 185 errno = error; 186 return (-1); 187 } 188 189 snprintf(pidstr, sizeof(pidstr), "%u", getpid()); 190 if (pwrite(fd, pidstr, strlen(pidstr), 0) != (ssize_t)strlen(pidstr)) { 191 error = errno; 192 _pidfile_remove(pfh, 0); 193 errno = error; 194 return (-1); 195 } 196 197 return (0); 198 } 199 200 int 201 pidfile_close(struct pidfh *pfh) 202 { 203 int error; 204 205 error = pidfile_verify(pfh); 206 if (error != 0) { 207 errno = error; 208 return (-1); 209 } 210 211 if (close(pfh->pf_fd) == -1) 212 error = errno; 213 free(pfh); 214 if (error != 0) { 215 errno = error; 216 return (-1); 217 } 218 return (0); 219 } 220 221 static int 222 _pidfile_remove(struct pidfh *pfh, int freeit) 223 { 224 int error; 225 226 error = pidfile_verify(pfh); 227 if (error != 0) { 228 errno = error; 229 return (-1); 230 } 231 232 if (unlink(pfh->pf_path) == -1) 233 error = errno; 234 if (close(pfh->pf_fd) == -1) { 235 if (error == 0) 236 error = errno; 237 } 238 if (freeit) 239 free(pfh); 240 else 241 pfh->pf_fd = -1; 242 if (error != 0) { 243 errno = error; 244 return (-1); 245 } 246 return (0); 247 } 248 249 int 250 pidfile_remove(struct pidfh *pfh) 251 { 252 253 return (_pidfile_remove(pfh, 1)); 254 } 255