1 /* 2 * Copyright (c) 1988, 1993 3 * The Regents of the University of California. 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 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * $FreeBSD: src/lib/libutil/uucplock.c,v 1.12.2.1 2000/10/09 20:20:52 brian Exp $ 34 * $DragonFly: src/lib/libutil/uucplock.c,v 1.2 2003/06/17 04:26:52 dillon Exp $ 35 * 36 * @(#)uucplock.c 8.1 (Berkeley) 6/6/93 37 */ 38 39 #include <sys/types.h> 40 #include <sys/file.h> 41 #include <dirent.h> 42 #include <errno.h> 43 #include <unistd.h> 44 #include <signal.h> 45 #include <stdio.h> 46 #include <stdlib.h> 47 #include <paths.h> 48 #include <string.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 *ttyname) 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 ttyname); 81 if ((tmpfd = creat(lcktmpname, 0664)) < 0) 82 GORET(0, UU_LOCK_CREAT_ERR); 83 84 for (i = 0; i < MAXTRIES; i++) { 85 if (link (lcktmpname, lckname) < 0) { 86 if (errno != EEXIST) 87 GORET(1, UU_LOCK_LINK_ERR); 88 /* 89 * file is already locked 90 * check to see if the process holding the lock 91 * still exists 92 */ 93 if ((fd = open(lckname, O_RDONLY)) < 0) 94 GORET(1, UU_LOCK_OPEN_ERR); 95 96 if ((pid_old = get_pid (fd, &err)) == -1) 97 GORET(2, UU_LOCK_READ_ERR); 98 99 close(fd); 100 101 if (kill(pid_old, 0) == 0 || errno != ESRCH) 102 GORET(1, UU_LOCK_INUSE); 103 /* 104 * The process that locked the file isn't running, so 105 * we'll lock it ourselves 106 */ 107 (void)unlink(lckname); 108 } else { 109 if (!put_pid (tmpfd, pid)) 110 GORET(3, UU_LOCK_WRITE_ERR); 111 break; 112 } 113 } 114 GORET(1, (i >= MAXTRIES) ? UU_LOCK_TRY_ERR : UU_LOCK_OK); 115 116 ret3: 117 (void)unlink(lckname); 118 goto ret1; 119 ret2: 120 (void)close(fd); 121 ret1: 122 (void)close(tmpfd); 123 (void)unlink(lcktmpname); 124 ret0: 125 errno = err; 126 return uuerr; 127 } 128 129 int 130 uu_lock_txfr(const char *ttyname, pid_t pid) 131 { 132 int fd, err; 133 char lckname[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN]; 134 135 snprintf(lckname, sizeof(lckname), _PATH_UUCPLOCK LOCKFMT, ttyname); 136 137 if ((fd = open(lckname, O_RDWR)) < 0) 138 return UU_LOCK_OWNER_ERR; 139 if (get_pid(fd, &err) != getpid()) 140 err = UU_LOCK_OWNER_ERR; 141 else { 142 lseek(fd, 0, SEEK_SET); 143 err = put_pid(fd, pid) ? 0 : UU_LOCK_WRITE_ERR; 144 } 145 close(fd); 146 147 return err; 148 } 149 150 int 151 uu_unlock(const char *ttyname) 152 { 153 char tbuf[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN]; 154 155 (void)snprintf(tbuf, sizeof(tbuf), _PATH_UUCPLOCK LOCKFMT, ttyname); 156 return unlink(tbuf); 157 } 158 159 const char * 160 uu_lockerr(int uu_lockresult) 161 { 162 static char errbuf[128]; 163 char *fmt; 164 165 switch (uu_lockresult) { 166 case UU_LOCK_INUSE: 167 return "device in use"; 168 case UU_LOCK_OK: 169 return ""; 170 case UU_LOCK_OPEN_ERR: 171 fmt = "open error: %s"; 172 break; 173 case UU_LOCK_READ_ERR: 174 fmt = "read error: %s"; 175 break; 176 case UU_LOCK_CREAT_ERR: 177 fmt = "creat error: %s"; 178 break; 179 case UU_LOCK_WRITE_ERR: 180 fmt = "write error: %s"; 181 break; 182 case UU_LOCK_LINK_ERR: 183 fmt = "link error: %s"; 184 break; 185 case UU_LOCK_TRY_ERR: 186 fmt = "too many tries: %s"; 187 break; 188 case UU_LOCK_OWNER_ERR: 189 fmt = "not locking process: %s"; 190 break; 191 default: 192 fmt = "undefined error: %s"; 193 break; 194 } 195 196 (void)snprintf(errbuf, sizeof(errbuf), fmt, strerror(errno)); 197 return errbuf; 198 } 199 200 static int 201 put_pid(int fd, pid_t pid) 202 { 203 char buf[32]; 204 int len; 205 206 len = sprintf (buf, "%10d\n", (int)pid); 207 return write (fd, buf, len) == len; 208 } 209 210 static pid_t 211 get_pid(int fd, int *err) 212 { 213 int bytes_read; 214 char buf[32]; 215 pid_t pid; 216 217 bytes_read = read (fd, buf, sizeof (buf) - 1); 218 if (bytes_read > 0) { 219 buf[bytes_read] = '\0'; 220 pid = strtol (buf, (char **) NULL, 10); 221 } else { 222 pid = -1; 223 *err = bytes_read ? errno : EINVAL; 224 } 225 return pid; 226 } 227 228 /* end of uucplock.c */ 229