1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 #pragma ident "%Z%%M% %I% %E% SMI" 28 29 /* Copyright (c) 1988 AT&T */ 30 /* All Rights Reserved */ 31 32 33 #pragma weak lckpwdf = _lckpwdf 34 #pragma weak ulckpwdf = _ulckpwdf 35 36 #include "synonyms.h" 37 #include <sys/types.h> 38 #include <stdio.h> 39 #include <signal.h> 40 #include <fcntl.h> 41 #include <unistd.h> 42 #include <shadow.h> 43 #include <errno.h> 44 #include <thread.h> 45 #include "mtlib.h" 46 47 #define LOCKFILE "/etc/.pwd.lock" 48 #define S_WAITTIME 15 49 50 static struct flock flock = { 51 0, /* l_type */ 52 0, /* l_whence */ 53 0, /* l_start */ 54 0, /* l_len */ 55 0, /* l_sysid */ 56 0 /* l_pid */ 57 }; 58 59 /* 60 * lckpwdf() returns a 0 for a successful lock within W_WAITTIME 61 * seconds and -1 otherwise. We stand on our head to make it MT-safe. 62 */ 63 64 static pid_t lck_pid = 0; /* process's pid at last lock */ 65 static thread_t lck_tid = 0; /* thread that holds the lock */ 66 static int fildes = -1; 67 static mutex_t lck_lock = DEFAULTMUTEX; 68 69 int 70 lckpwdf(void) 71 { 72 int seconds = 0; 73 74 lmutex_lock(&lck_lock); 75 for (;;) { 76 if (lck_pid != 0 && lck_pid != getpid()) { 77 /* somebody forked */ 78 lck_pid = 0; 79 lck_tid = 0; 80 } 81 if (lck_tid == 0) { 82 if ((fildes = creat(LOCKFILE, 0600)) == -1) 83 break; 84 flock.l_type = F_WRLCK; 85 if (fcntl(fildes, F_SETLK, &flock) != -1) { 86 lck_pid = getpid(); 87 lck_tid = thr_self(); 88 lmutex_unlock(&lck_lock); 89 return (0); 90 } 91 (void) close(fildes); 92 fildes = -1; 93 } 94 if (seconds++ >= S_WAITTIME) { 95 /* 96 * For compatibility with the past, pretend 97 * that we were interrupted by SIGALRM. 98 */ 99 errno = EINTR; 100 break; 101 } 102 lmutex_unlock(&lck_lock); 103 (void) sleep(1); 104 lmutex_lock(&lck_lock); 105 } 106 lmutex_unlock(&lck_lock); 107 return (-1); 108 } 109 110 /* 111 * ulckpwdf() returns 0 for a successful unlock and -1 otherwise 112 */ 113 int 114 ulckpwdf(void) 115 { 116 lmutex_lock(&lck_lock); 117 if (lck_tid == thr_self() && fildes >= 0) { 118 flock.l_type = F_UNLCK; 119 (void) fcntl(fildes, F_SETLK, &flock); 120 (void) close(fildes); 121 fildes = -1; 122 lck_pid = 0; 123 lck_tid = 0; 124 lmutex_unlock(&lck_lock); 125 return (0); 126 } 127 lmutex_unlock(&lck_lock); 128 return (-1); 129 } 130