17c478bd9Sstevel@tonic-gate /* 27c478bd9Sstevel@tonic-gate * CDDL HEADER START 37c478bd9Sstevel@tonic-gate * 47c478bd9Sstevel@tonic-gate * The contents of this file are subject to the terms of the 57c478bd9Sstevel@tonic-gate * Common Development and Distribution License, Version 1.0 only 67c478bd9Sstevel@tonic-gate * (the "License"). You may not use this file except in compliance 77c478bd9Sstevel@tonic-gate * with the License. 87c478bd9Sstevel@tonic-gate * 97c478bd9Sstevel@tonic-gate * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 107c478bd9Sstevel@tonic-gate * or http://www.opensolaris.org/os/licensing. 117c478bd9Sstevel@tonic-gate * See the License for the specific language governing permissions 127c478bd9Sstevel@tonic-gate * and limitations under the License. 137c478bd9Sstevel@tonic-gate * 147c478bd9Sstevel@tonic-gate * When distributing Covered Code, include this CDDL HEADER in each 157c478bd9Sstevel@tonic-gate * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 167c478bd9Sstevel@tonic-gate * If applicable, add the following below this CDDL HEADER, with the 177c478bd9Sstevel@tonic-gate * fields enclosed by brackets "[]" replaced with your own identifying 187c478bd9Sstevel@tonic-gate * information: Portions Copyright [yyyy] [name of copyright owner] 197c478bd9Sstevel@tonic-gate * 207c478bd9Sstevel@tonic-gate * CDDL HEADER END 217c478bd9Sstevel@tonic-gate */ 22*e8031f0aSraf 237c478bd9Sstevel@tonic-gate /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */ 247c478bd9Sstevel@tonic-gate /* All Rights Reserved */ 257c478bd9Sstevel@tonic-gate 267c478bd9Sstevel@tonic-gate /* 27*e8031f0aSraf * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 28*e8031f0aSraf * Use is subject to license terms. 297c478bd9Sstevel@tonic-gate */ 307c478bd9Sstevel@tonic-gate 317c478bd9Sstevel@tonic-gate #pragma ident "%Z%%M% %I% %E% SMI" 327c478bd9Sstevel@tonic-gate /*LINTLIBRARY*/ 337c478bd9Sstevel@tonic-gate 34*e8031f0aSraf #include "c_synonyms.h" 357c478bd9Sstevel@tonic-gate #include "maillock.h" 367c478bd9Sstevel@tonic-gate #include <sys/types.h> 377c478bd9Sstevel@tonic-gate #include <fcntl.h> 387c478bd9Sstevel@tonic-gate #include <stdio.h> 397c478bd9Sstevel@tonic-gate #include <string.h> 407c478bd9Sstevel@tonic-gate #include <unistd.h> 417c478bd9Sstevel@tonic-gate #include <stdlib.h> 427c478bd9Sstevel@tonic-gate #include <utime.h> 437c478bd9Sstevel@tonic-gate 447c478bd9Sstevel@tonic-gate #include <sys/stat.h> 457c478bd9Sstevel@tonic-gate 467c478bd9Sstevel@tonic-gate static char *lockext = ".lock"; /* Lock suffix for mailname */ 477c478bd9Sstevel@tonic-gate static char curlock[PATHSIZE]; /* Last used name of lock */ 487c478bd9Sstevel@tonic-gate static int locked; /* To note that we locked it */ 497c478bd9Sstevel@tonic-gate static time_t locktime; /* time lock file was touched */ 507c478bd9Sstevel@tonic-gate static time_t lock1(char *, char *); 517c478bd9Sstevel@tonic-gate 527c478bd9Sstevel@tonic-gate /* 537c478bd9Sstevel@tonic-gate * Lock the specified mail file by setting the file mailfile.lock. 547c478bd9Sstevel@tonic-gate * We must, of course, be careful to remove the lock file by a call 557c478bd9Sstevel@tonic-gate * to unlock before we stop. The algorithm used here is to see if 567c478bd9Sstevel@tonic-gate * the lock exists, and if it does, to check its modify time. If it 577c478bd9Sstevel@tonic-gate * is older than 5 minutes, we assume error and set our own file. 587c478bd9Sstevel@tonic-gate * Otherwise, we wait for 5 seconds and try again. 597c478bd9Sstevel@tonic-gate */ 607c478bd9Sstevel@tonic-gate 617c478bd9Sstevel@tonic-gate /*ARGSUSED*/ 627c478bd9Sstevel@tonic-gate int 637c478bd9Sstevel@tonic-gate maillock(char *user, int retrycnt) 647c478bd9Sstevel@tonic-gate { 657c478bd9Sstevel@tonic-gate time_t t; 667c478bd9Sstevel@tonic-gate struct stat sbuf; 677c478bd9Sstevel@tonic-gate int statfailed; 687c478bd9Sstevel@tonic-gate char locktmp[PATHSIZE]; /* Usable lock temporary */ 697c478bd9Sstevel@tonic-gate char file[PATHSIZE]; 707c478bd9Sstevel@tonic-gate 717c478bd9Sstevel@tonic-gate if (locked) 727c478bd9Sstevel@tonic-gate return (0); 737c478bd9Sstevel@tonic-gate (void) strcpy(file, MAILDIR); 747c478bd9Sstevel@tonic-gate (void) strcat(file, user); 757c478bd9Sstevel@tonic-gate (void) strcpy(curlock, file); 767c478bd9Sstevel@tonic-gate (void) strcat(curlock, lockext); 777c478bd9Sstevel@tonic-gate (void) strcpy(locktmp, file); 787c478bd9Sstevel@tonic-gate (void) strcat(locktmp, "XXXXXX"); 797c478bd9Sstevel@tonic-gate (void) mktemp(locktmp); 807c478bd9Sstevel@tonic-gate (void) remove(locktmp); 817c478bd9Sstevel@tonic-gate statfailed = 0; 827c478bd9Sstevel@tonic-gate for (;;) { 837c478bd9Sstevel@tonic-gate t = lock1(locktmp, curlock); 847c478bd9Sstevel@tonic-gate if (t == (time_t)0) { 857c478bd9Sstevel@tonic-gate locked = 1; 867c478bd9Sstevel@tonic-gate locktime = time(0); 877c478bd9Sstevel@tonic-gate return (0); 887c478bd9Sstevel@tonic-gate } 897c478bd9Sstevel@tonic-gate if (stat(curlock, &sbuf) < 0) { 907c478bd9Sstevel@tonic-gate if (statfailed++ > 5) 917c478bd9Sstevel@tonic-gate return (-1); 927c478bd9Sstevel@tonic-gate (void) sleep(5); 937c478bd9Sstevel@tonic-gate continue; 947c478bd9Sstevel@tonic-gate } 957c478bd9Sstevel@tonic-gate statfailed = 0; 967c478bd9Sstevel@tonic-gate 977c478bd9Sstevel@tonic-gate /* 987c478bd9Sstevel@tonic-gate * Compare the time of the temp file with the time 997c478bd9Sstevel@tonic-gate * of the lock file, rather than with the current 1007c478bd9Sstevel@tonic-gate * time of day, since the files may reside on 1017c478bd9Sstevel@tonic-gate * another machine whose time of day differs from 1027c478bd9Sstevel@tonic-gate * ours. If the lock file is less than 5 minutes 1037c478bd9Sstevel@tonic-gate * old, keep trying. 1047c478bd9Sstevel@tonic-gate */ 1057c478bd9Sstevel@tonic-gate if (t < sbuf.st_ctime + 300) { 1067c478bd9Sstevel@tonic-gate (void) sleep(5); 1077c478bd9Sstevel@tonic-gate continue; 1087c478bd9Sstevel@tonic-gate } 1097c478bd9Sstevel@tonic-gate (void) remove(curlock); 1107c478bd9Sstevel@tonic-gate } 1117c478bd9Sstevel@tonic-gate } 1127c478bd9Sstevel@tonic-gate 1137c478bd9Sstevel@tonic-gate /* 1147c478bd9Sstevel@tonic-gate * Remove the mail lock, and note that we no longer 1157c478bd9Sstevel@tonic-gate * have it locked. 1167c478bd9Sstevel@tonic-gate */ 1177c478bd9Sstevel@tonic-gate void 1187c478bd9Sstevel@tonic-gate mailunlock(void) 1197c478bd9Sstevel@tonic-gate { 1207c478bd9Sstevel@tonic-gate (void) remove(curlock); 1217c478bd9Sstevel@tonic-gate locked = 0; 1227c478bd9Sstevel@tonic-gate } 1237c478bd9Sstevel@tonic-gate 1247c478bd9Sstevel@tonic-gate /* 1257c478bd9Sstevel@tonic-gate * Attempt to set the lock by creating the temporary file, 1267c478bd9Sstevel@tonic-gate * then doing a link/unlink. If it succeeds, return 0, 1277c478bd9Sstevel@tonic-gate * else return a guess of the current time on the machine 1287c478bd9Sstevel@tonic-gate * holding the file. 1297c478bd9Sstevel@tonic-gate */ 1307c478bd9Sstevel@tonic-gate static time_t 1317c478bd9Sstevel@tonic-gate lock1(char tempfile[], char name[]) 1327c478bd9Sstevel@tonic-gate { 1337c478bd9Sstevel@tonic-gate int fd; 1347c478bd9Sstevel@tonic-gate struct stat sbuf; 1357c478bd9Sstevel@tonic-gate 1367c478bd9Sstevel@tonic-gate fd = open(tempfile, O_RDWR|O_CREAT|O_EXCL, 0600); 1377c478bd9Sstevel@tonic-gate if (fd < 0) 1387c478bd9Sstevel@tonic-gate return (time(0)); 1397c478bd9Sstevel@tonic-gate (void) fstat(fd, &sbuf); 1407c478bd9Sstevel@tonic-gate /* 1417c478bd9Sstevel@tonic-gate * Write the string "0" into the lock file to give us some 1427c478bd9Sstevel@tonic-gate * interoperability with SVR4 mailers. SVR4 mailers expect 1437c478bd9Sstevel@tonic-gate * a process ID to be written into the lock file and then 1447c478bd9Sstevel@tonic-gate * use kill() to see if the process is alive or not. We write 1457c478bd9Sstevel@tonic-gate * 0 into it so that SVR4 mailers will always think our lock file 1467c478bd9Sstevel@tonic-gate * is valid. 1477c478bd9Sstevel@tonic-gate */ 1487c478bd9Sstevel@tonic-gate (void) write(fd, "0", 2); 1497c478bd9Sstevel@tonic-gate (void) close(fd); 1507c478bd9Sstevel@tonic-gate if (link(tempfile, name) < 0) { 1517c478bd9Sstevel@tonic-gate (void) remove(tempfile); 1527c478bd9Sstevel@tonic-gate return (sbuf.st_ctime); 1537c478bd9Sstevel@tonic-gate } 1547c478bd9Sstevel@tonic-gate (void) remove(tempfile); 1557c478bd9Sstevel@tonic-gate return ((time_t)0); 1567c478bd9Sstevel@tonic-gate } 1577c478bd9Sstevel@tonic-gate 1587c478bd9Sstevel@tonic-gate /* 1597c478bd9Sstevel@tonic-gate * Update the change time on the lock file so 1607c478bd9Sstevel@tonic-gate * others will know we're still using it. 1617c478bd9Sstevel@tonic-gate */ 1627c478bd9Sstevel@tonic-gate void 1637c478bd9Sstevel@tonic-gate touchlock(void) 1647c478bd9Sstevel@tonic-gate { 1657c478bd9Sstevel@tonic-gate struct stat sbuf; 1667c478bd9Sstevel@tonic-gate time_t t; 1677c478bd9Sstevel@tonic-gate struct utimbuf tp; 1687c478bd9Sstevel@tonic-gate 1697c478bd9Sstevel@tonic-gate if (!locked) 1707c478bd9Sstevel@tonic-gate return; 1717c478bd9Sstevel@tonic-gate 1727c478bd9Sstevel@tonic-gate /* if it hasn't been at least 3 minutes, don't bother */ 1737c478bd9Sstevel@tonic-gate if (time(&t) < locktime + 180) 1747c478bd9Sstevel@tonic-gate return; 1757c478bd9Sstevel@tonic-gate locktime = t; 1767c478bd9Sstevel@tonic-gate 1777c478bd9Sstevel@tonic-gate if (stat(curlock, &sbuf) < 0) 1787c478bd9Sstevel@tonic-gate return; 1797c478bd9Sstevel@tonic-gate /* 1807c478bd9Sstevel@tonic-gate * Don't actually change the times, we just want the 1817c478bd9Sstevel@tonic-gate * side effect that utime causes st_ctime to be set 1827c478bd9Sstevel@tonic-gate * to the current time. 1837c478bd9Sstevel@tonic-gate */ 1847c478bd9Sstevel@tonic-gate tp.actime = sbuf.st_atime; 1857c478bd9Sstevel@tonic-gate tp.modtime = sbuf.st_mtime; 1867c478bd9Sstevel@tonic-gate (void) utime(curlock, &tp); 1877c478bd9Sstevel@tonic-gate } 188