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 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 #include <signal.h> 27 #include <sys/types.h> 28 #include <sys/time.h> 29 #include <sys/stat.h> 30 #include <fcntl.h> 31 #include <stdio.h> 32 #include <unistd.h> 33 #include <strings.h> 34 #include <errno.h> 35 #include <assert.h> 36 37 #include "cfg_impl.h" 38 #include "cfg_lockd.h" 39 40 41 #define segment_off(s) ((off_t)(s) * sizeof (pid_t)) 42 43 static int local_lockfd; 44 static int local_lockfda; 45 46 void 47 cfg_lfinit() 48 { 49 local_lockfd = open(CFG_RDEV_LOCKFILE, O_RDWR|O_CREAT, 0644); 50 local_lockfda = open(CFG_RDEV_LOCKFILE, O_RDWR|O_APPEND, 0644); 51 } 52 53 int 54 cfg_filelock(int segment, int flag) 55 { 56 struct flock lk; 57 struct stat sb; 58 pid_t pid = 0; 59 off_t off = segment_off(segment); 60 int rc; 61 62 while (fstat(local_lockfd, &sb) == -1 && errno == EINTR) 63 ; 64 if (sb.st_size < off + sizeof (pid_t)) { 65 if ((flag&O_CREAT) == 0) 66 return (CFG_LF_EOF); 67 write(local_lockfda, &pid, sizeof (pid_t)); 68 } 69 bzero(&lk, sizeof (lk)); 70 lk.l_type = F_WRLCK; 71 lk.l_whence = SEEK_SET; 72 lk.l_start = off; 73 lk.l_len = (off_t)sizeof (pid_t); 74 75 while ((rc = fcntl(local_lockfd, F_SETLK, &lk)) < 0 && errno == EINTR) 76 ; 77 if (rc == -1 && errno == EAGAIN) 78 return (CFG_LF_AGAIN); 79 80 return (CFG_LF_OKAY); 81 } 82 83 84 int 85 cfg_fileunlock(int segment) 86 { 87 struct flock lk; 88 off_t off = segment_off(segment); 89 90 bzero(&lk, sizeof (lk)); 91 lk.l_type = F_UNLCK; 92 lk.l_whence = SEEK_SET; 93 lk.l_start = off; 94 lk.l_len = (off_t)sizeof (pid_t); 95 96 while (fcntl(local_lockfd, F_SETLK, &lk) < 0 && errno == EINTR) 97 ; 98 return (1); 99 } 100 101 void 102 cfg_readpid(int segment, pid_t *pidp) 103 { 104 off_t off = segment_off(segment); 105 lseek(local_lockfd, off, SEEK_SET); 106 read(local_lockfd, pidp, sizeof (pid_t)); 107 } 108 109 void 110 cfg_writepid(int segment, pid_t pid) 111 { 112 off_t off = segment_off(segment); 113 lseek(local_lockfd, off, SEEK_SET); 114 write(local_lockfd, &pid, sizeof (pid_t)); 115 } 116 117 void 118 cfg_enterpid() 119 { 120 int i; 121 pid_t pid; 122 123 for (i = 0; ; i++) { 124 if (cfg_filelock(i, O_CREAT) == CFG_LF_OKAY) { 125 cfg_readpid(i, &pid); 126 if (pid != (pid_t)0) { 127 cfg_fileunlock(i); 128 continue; 129 } 130 pid = getpid(); 131 cfg_writepid(i, pid); 132 break; 133 } 134 } 135 } 136