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 (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 /* Copyright (c) 1988 AT&T */ 28 /* All Rights Reserved */ 29 30 #pragma ident "%Z%%M% %I% %E% SMI" 31 32 #include "lint.h" 33 #include <sys/types.h> 34 #include <stdio.h> 35 #include <signal.h> 36 #include <fcntl.h> 37 #include <unistd.h> 38 #include <shadow.h> 39 #include <errno.h> 40 #include <thread.h> 41 #include "mtlib.h" 42 43 #define LOCKFILE "/etc/.pwd.lock" 44 #define S_WAITTIME 15 45 46 static struct flock flock = { 47 0, /* l_type */ 48 0, /* l_whence */ 49 0, /* l_start */ 50 0, /* l_len */ 51 0, /* l_sysid */ 52 0 /* l_pid */ 53 }; 54 55 /* 56 * lckpwdf() returns a 0 for a successful lock within W_WAITTIME 57 * seconds and -1 otherwise. We stand on our head to make it MT-safe. 58 */ 59 60 static pid_t lck_pid = 0; /* process's pid at last lock */ 61 static thread_t lck_tid = 0; /* thread that holds the lock */ 62 static int fildes = -1; 63 static mutex_t lck_lock = DEFAULTMUTEX; 64 65 int 66 lckpwdf(void) 67 { 68 int seconds = 0; 69 70 lmutex_lock(&lck_lock); 71 for (;;) { 72 if (lck_pid != 0 && lck_pid != getpid()) { 73 /* somebody forked */ 74 lck_pid = 0; 75 lck_tid = 0; 76 } 77 if (lck_tid == 0) { 78 if ((fildes = creat(LOCKFILE, 0600)) == -1) 79 break; 80 flock.l_type = F_WRLCK; 81 if (fcntl(fildes, F_SETLK, &flock) != -1) { 82 lck_pid = getpid(); 83 lck_tid = thr_self(); 84 lmutex_unlock(&lck_lock); 85 return (0); 86 } 87 (void) close(fildes); 88 fildes = -1; 89 } 90 if (seconds++ >= S_WAITTIME) { 91 /* 92 * For compatibility with the past, pretend 93 * that we were interrupted by SIGALRM. 94 */ 95 errno = EINTR; 96 break; 97 } 98 lmutex_unlock(&lck_lock); 99 (void) sleep(1); 100 lmutex_lock(&lck_lock); 101 } 102 lmutex_unlock(&lck_lock); 103 return (-1); 104 } 105 106 /* 107 * ulckpwdf() returns 0 for a successful unlock and -1 otherwise 108 */ 109 int 110 ulckpwdf(void) 111 { 112 lmutex_lock(&lck_lock); 113 if (lck_tid == thr_self() && fildes >= 0) { 114 flock.l_type = F_UNLCK; 115 (void) fcntl(fildes, F_SETLK, &flock); 116 (void) close(fildes); 117 fildes = -1; 118 lck_pid = 0; 119 lck_tid = 0; 120 lmutex_unlock(&lck_lock); 121 return (0); 122 } 123 lmutex_unlock(&lck_lock); 124 return (-1); 125 } 126