1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1988, 1993 5 * The Regents of the University of California. 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 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #ifndef lint 36 static const char sccsid[] = "@(#)uucplock.c 8.1 (Berkeley) 6/6/93"; 37 #endif /* not lint */ 38 39 #include <sys/types.h> 40 #include <sys/file.h> 41 #include <dirent.h> 42 #include <errno.h> 43 #include <paths.h> 44 #include <signal.h> 45 #include <stdio.h> 46 #include <stdlib.h> 47 #include <string.h> 48 #include <unistd.h> 49 #include "libutil.h" 50 51 #define MAXTRIES 5 52 53 #define LOCKTMP "LCKTMP..%d" 54 #define LOCKFMT "LCK..%s" 55 56 #define GORET(level, val) { err = errno; uuerr = (val); \ 57 goto __CONCAT(ret, level); } 58 59 /* Forward declarations */ 60 static int put_pid (int fd, pid_t pid); 61 static pid_t get_pid (int fd,int *err); 62 63 /* 64 * uucp style locking routines 65 */ 66 67 int 68 uu_lock(const char *tty_name) 69 { 70 int fd, tmpfd, i; 71 pid_t pid, pid_old; 72 char lckname[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN], 73 lcktmpname[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN]; 74 int err, uuerr; 75 76 pid = getpid(); 77 (void)snprintf(lcktmpname, sizeof(lcktmpname), _PATH_UUCPLOCK LOCKTMP, 78 pid); 79 (void)snprintf(lckname, sizeof(lckname), _PATH_UUCPLOCK LOCKFMT, 80 tty_name); 81 if ((tmpfd = open(lcktmpname, O_CREAT | O_TRUNC | O_WRONLY | O_CLOEXEC, 82 0664)) < 0) 83 GORET(0, UU_LOCK_CREAT_ERR); 84 85 for (i = 0; i < MAXTRIES; i++) { 86 if (link (lcktmpname, lckname) < 0) { 87 if (errno != EEXIST) 88 GORET(1, UU_LOCK_LINK_ERR); 89 /* 90 * file is already locked 91 * check to see if the process holding the lock 92 * still exists 93 */ 94 if ((fd = open(lckname, O_RDONLY | O_CLOEXEC)) < 0) 95 GORET(1, UU_LOCK_OPEN_ERR); 96 97 if ((pid_old = get_pid (fd, &err)) == -1) 98 GORET(2, UU_LOCK_READ_ERR); 99 100 close(fd); 101 102 if (kill(pid_old, 0) == 0 || errno != ESRCH) 103 GORET(1, UU_LOCK_INUSE); 104 /* 105 * The process that locked the file isn't running, so 106 * we'll lock it ourselves 107 */ 108 (void)unlink(lckname); 109 } else { 110 if (!put_pid (tmpfd, pid)) 111 GORET(3, UU_LOCK_WRITE_ERR); 112 break; 113 } 114 } 115 GORET(1, (i >= MAXTRIES) ? UU_LOCK_TRY_ERR : UU_LOCK_OK); 116 117 ret3: 118 (void)unlink(lckname); 119 goto ret1; 120 ret2: 121 (void)close(fd); 122 ret1: 123 (void)close(tmpfd); 124 (void)unlink(lcktmpname); 125 ret0: 126 errno = err; 127 return uuerr; 128 } 129 130 int 131 uu_lock_txfr(const char *tty_name, pid_t pid) 132 { 133 int fd, err; 134 char lckname[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN]; 135 136 snprintf(lckname, sizeof(lckname), _PATH_UUCPLOCK LOCKFMT, tty_name); 137 138 if ((fd = open(lckname, O_RDWR | O_CLOEXEC)) < 0) 139 return UU_LOCK_OWNER_ERR; 140 if (get_pid(fd, &err) != getpid()) 141 err = UU_LOCK_OWNER_ERR; 142 else { 143 lseek(fd, (off_t)0, SEEK_SET); 144 err = put_pid(fd, pid) ? 0 : UU_LOCK_WRITE_ERR; 145 } 146 close(fd); 147 148 return err; 149 } 150 151 int 152 uu_unlock(const char *tty_name) 153 { 154 char tbuf[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN]; 155 156 (void)snprintf(tbuf, sizeof(tbuf), _PATH_UUCPLOCK LOCKFMT, tty_name); 157 return unlink(tbuf); 158 } 159 160 const char * 161 uu_lockerr(int uu_lockresult) 162 { 163 static char errbuf[128]; 164 const char *fmt; 165 166 switch (uu_lockresult) { 167 case UU_LOCK_INUSE: 168 return "device in use"; 169 case UU_LOCK_OK: 170 return ""; 171 case UU_LOCK_OPEN_ERR: 172 fmt = "open error: %s"; 173 break; 174 case UU_LOCK_READ_ERR: 175 fmt = "read error: %s"; 176 break; 177 case UU_LOCK_CREAT_ERR: 178 fmt = "creat error: %s"; 179 break; 180 case UU_LOCK_WRITE_ERR: 181 fmt = "write error: %s"; 182 break; 183 case UU_LOCK_LINK_ERR: 184 fmt = "link error: %s"; 185 break; 186 case UU_LOCK_TRY_ERR: 187 fmt = "too many tries: %s"; 188 break; 189 case UU_LOCK_OWNER_ERR: 190 fmt = "not locking process: %s"; 191 break; 192 default: 193 fmt = "undefined error: %s"; 194 break; 195 } 196 197 (void)snprintf(errbuf, sizeof(errbuf), fmt, strerror(errno)); 198 return errbuf; 199 } 200 201 static int 202 put_pid(int fd, pid_t pid) 203 { 204 char buf[32]; 205 int len; 206 207 len = sprintf (buf, "%10d\n", (int)pid); 208 return write (fd, buf, (size_t)len) == len; 209 } 210 211 static pid_t 212 get_pid(int fd, int *err) 213 { 214 int bytes_read; 215 char buf[32]; 216 pid_t pid; 217 218 bytes_read = read (fd, buf, sizeof (buf) - 1); 219 if (bytes_read > 0) { 220 buf[bytes_read] = '\0'; 221 pid = (pid_t)strtol (buf, (char **) NULL, 10); 222 } else { 223 pid = -1; 224 *err = bytes_read ? errno : EINVAL; 225 } 226 return pid; 227 } 228 229 /* end of uucplock.c */ 230