1*0Sstevel@tonic-gate /* 2*0Sstevel@tonic-gate * CDDL HEADER START 3*0Sstevel@tonic-gate * 4*0Sstevel@tonic-gate * The contents of this file are subject to the terms of the 5*0Sstevel@tonic-gate * Common Development and Distribution License, Version 1.0 only 6*0Sstevel@tonic-gate * (the "License"). You may not use this file except in compliance 7*0Sstevel@tonic-gate * with the License. 8*0Sstevel@tonic-gate * 9*0Sstevel@tonic-gate * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10*0Sstevel@tonic-gate * or http://www.opensolaris.org/os/licensing. 11*0Sstevel@tonic-gate * See the License for the specific language governing permissions 12*0Sstevel@tonic-gate * and limitations under the License. 13*0Sstevel@tonic-gate * 14*0Sstevel@tonic-gate * When distributing Covered Code, include this CDDL HEADER in each 15*0Sstevel@tonic-gate * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16*0Sstevel@tonic-gate * If applicable, add the following below this CDDL HEADER, with the 17*0Sstevel@tonic-gate * fields enclosed by brackets "[]" replaced with your own identifying 18*0Sstevel@tonic-gate * information: Portions Copyright [yyyy] [name of copyright owner] 19*0Sstevel@tonic-gate * 20*0Sstevel@tonic-gate * CDDL HEADER END 21*0Sstevel@tonic-gate */ 22*0Sstevel@tonic-gate /* 23*0Sstevel@tonic-gate * Copyright 2003 Sun Microsystems, Inc. All rights reserved. 24*0Sstevel@tonic-gate * Use is subject to license terms. 25*0Sstevel@tonic-gate */ 26*0Sstevel@tonic-gate 27*0Sstevel@tonic-gate #pragma ident "%Z%%M% %I% %E% SMI" 28*0Sstevel@tonic-gate 29*0Sstevel@tonic-gate #include <unistd.h> 30*0Sstevel@tonic-gate #include <syslog.h> 31*0Sstevel@tonic-gate #include <sys/mman.h> 32*0Sstevel@tonic-gate #include <thread.h> 33*0Sstevel@tonic-gate #include <synch.h> 34*0Sstevel@tonic-gate #include <ndbm.h> 35*0Sstevel@tonic-gate #include "../ypsym.h" 36*0Sstevel@tonic-gate #include "../ypdefs.h" 37*0Sstevel@tonic-gate 38*0Sstevel@tonic-gate /* 39*0Sstevel@tonic-gate * These routines provide mutual exclusion between ypserv and ypxfr. 40*0Sstevel@tonic-gate * Mutual exclusion is needed so that ypxfr doesn't try to rename 41*0Sstevel@tonic-gate * dbm files while ypserv is trying to open them. After ypserv has 42*0Sstevel@tonic-gate * opened a dbm file, it is safe to rename it because ypserv still 43*0Sstevel@tonic-gate * has access to the file through its file descriptor. 44*0Sstevel@tonic-gate */ 45*0Sstevel@tonic-gate 46*0Sstevel@tonic-gate #define LOCKFILE "/var/run/yp_maplock" 47*0Sstevel@tonic-gate struct lockarray { 48*0Sstevel@tonic-gate mutex_t locknode[MAXHASH]; 49*0Sstevel@tonic-gate }; 50*0Sstevel@tonic-gate typedef struct lockarray lockarray; 51*0Sstevel@tonic-gate 52*0Sstevel@tonic-gate /* 53*0Sstevel@tonic-gate * Cross-process robust mutex locks. 54*0Sstevel@tonic-gate * Provide synchronization between YP processes 55*0Sstevel@tonic-gate * by implementing an exclusive locking mechanism 56*0Sstevel@tonic-gate * via a memory-mapped file. 57*0Sstevel@tonic-gate */ 58*0Sstevel@tonic-gate static struct lockarray *shmlockarray; 59*0Sstevel@tonic-gate static int lockfile; 60*0Sstevel@tonic-gate 61*0Sstevel@tonic-gate int 62*0Sstevel@tonic-gate hash(char *s) 63*0Sstevel@tonic-gate { 64*0Sstevel@tonic-gate int n = 0; 65*0Sstevel@tonic-gate int i; 66*0Sstevel@tonic-gate 67*0Sstevel@tonic-gate for (i = 1; *s; i += 10, s++) { 68*0Sstevel@tonic-gate n += i * (*s); 69*0Sstevel@tonic-gate } 70*0Sstevel@tonic-gate n %= MAXHASH; 71*0Sstevel@tonic-gate return (n); 72*0Sstevel@tonic-gate } 73*0Sstevel@tonic-gate 74*0Sstevel@tonic-gate bool 75*0Sstevel@tonic-gate init_locks_mem() 76*0Sstevel@tonic-gate { 77*0Sstevel@tonic-gate int iiter, rc; 78*0Sstevel@tonic-gate int ebusy_cnt = 0; 79*0Sstevel@tonic-gate 80*0Sstevel@tonic-gate /* 81*0Sstevel@tonic-gate * Initialize cross-process locks in memory-mapped file. 82*0Sstevel@tonic-gate */ 83*0Sstevel@tonic-gate for (iiter = 0; iiter < MAXHASH; iiter++) { 84*0Sstevel@tonic-gate if (rc = mutex_init(&(shmlockarray->locknode[iiter]), 85*0Sstevel@tonic-gate USYNC_PROCESS_ROBUST, 0)) { 86*0Sstevel@tonic-gate if (rc == EBUSY) { 87*0Sstevel@tonic-gate ebusy_cnt++; 88*0Sstevel@tonic-gate } else { 89*0Sstevel@tonic-gate syslog(LOG_ERR, 90*0Sstevel@tonic-gate "init_locks_mem():mutex_init():error=%d", 91*0Sstevel@tonic-gate rc); 92*0Sstevel@tonic-gate return (FALSE); 93*0Sstevel@tonic-gate } 94*0Sstevel@tonic-gate } 95*0Sstevel@tonic-gate } 96*0Sstevel@tonic-gate 97*0Sstevel@tonic-gate /* 98*0Sstevel@tonic-gate * EBUSY for all locks OK, it means another process 99*0Sstevel@tonic-gate * has already initialized locks. 100*0Sstevel@tonic-gate */ 101*0Sstevel@tonic-gate if ((ebusy_cnt > 0) && (ebusy_cnt != MAXHASH)) { 102*0Sstevel@tonic-gate syslog(LOG_ERR, 103*0Sstevel@tonic-gate "%s inconsistent. Remove and restart NIS (YP).", LOCKFILE); 104*0Sstevel@tonic-gate return (FALSE); 105*0Sstevel@tonic-gate } 106*0Sstevel@tonic-gate return (TRUE); 107*0Sstevel@tonic-gate } 108*0Sstevel@tonic-gate 109*0Sstevel@tonic-gate bool 110*0Sstevel@tonic-gate init_lock_map() 111*0Sstevel@tonic-gate { 112*0Sstevel@tonic-gate char buff[ sizeof (lockarray) ]; 113*0Sstevel@tonic-gate int write_cnt, lf_size; 114*0Sstevel@tonic-gate struct stat fdata; 115*0Sstevel@tonic-gate 116*0Sstevel@tonic-gate /* 117*0Sstevel@tonic-gate * Locking file initialization algorithm, with recovery mechanism. 118*0Sstevel@tonic-gate * This mechanism has been devised to ensure proper creation 119*0Sstevel@tonic-gate * of a memory-mapped lock file containing mutexes for robust, 120*0Sstevel@tonic-gate * inter-process communication. 121*0Sstevel@tonic-gate * File name is /var/run/yp_maplock (LOCKFILE). It might or might 122*0Sstevel@tonic-gate * not exist. 123*0Sstevel@tonic-gate * 124*0Sstevel@tonic-gate * Algorithm: 125*0Sstevel@tonic-gate * Try to open the file. If file doesn't exist, or size is too small, 126*0Sstevel@tonic-gate * create/rewrite the file, m-map it into memory and initialize the 127*0Sstevel@tonic-gate * mutexes in it. 128*0Sstevel@tonic-gate * If file exists and size is at least large enough, assume it's a 129*0Sstevel@tonic-gate * good file, and m-map the lock structure directly to it. 130*0Sstevel@tonic-gate * 131*0Sstevel@tonic-gate * Recovery from inconsistent state is easy - simply delete the file 132*0Sstevel@tonic-gate * and restart NIS (YP). 133*0Sstevel@tonic-gate */ 134*0Sstevel@tonic-gate 135*0Sstevel@tonic-gate lockfile = open(LOCKFILE, O_RDWR|O_CREAT, 0600); 136*0Sstevel@tonic-gate if (lockfile != -1) { 137*0Sstevel@tonic-gate if (lockf(lockfile, F_LOCK, 0) == 0) { 138*0Sstevel@tonic-gate if (fstat(lockfile, &fdata) == 0) { 139*0Sstevel@tonic-gate lf_size = fdata.st_size; 140*0Sstevel@tonic-gate if (lf_size < sizeof (lockarray)) { 141*0Sstevel@tonic-gate bzero(buff, sizeof (buff)); 142*0Sstevel@tonic-gate if ((write_cnt = write(lockfile, buff, 143*0Sstevel@tonic-gate sizeof (buff)) != sizeof (buff))) { 144*0Sstevel@tonic-gate if (write_cnt < 0) { 145*0Sstevel@tonic-gate syslog(LOG_ERR, 146*0Sstevel@tonic-gate "write(%s) => errno=%d", 147*0Sstevel@tonic-gate LOCKFILE, errno); 148*0Sstevel@tonic-gate } else { 149*0Sstevel@tonic-gate syslog(LOG_ERR, 150*0Sstevel@tonic-gate "write(%s) => %d!=%d: wrong number of bytes written.", 151*0Sstevel@tonic-gate LOCKFILE, 152*0Sstevel@tonic-gate write_cnt, 153*0Sstevel@tonic-gate sizeof (buff)); 154*0Sstevel@tonic-gate } 155*0Sstevel@tonic-gate lockf(lockfile, F_ULOCK, 0); 156*0Sstevel@tonic-gate close(lockfile); 157*0Sstevel@tonic-gate return (FALSE); 158*0Sstevel@tonic-gate } 159*0Sstevel@tonic-gate } 160*0Sstevel@tonic-gate } else { 161*0Sstevel@tonic-gate syslog(LOG_ERR, 162*0Sstevel@tonic-gate "fstat(%s) => errno=%d", LOCKFILE, errno); 163*0Sstevel@tonic-gate lockf(lockfile, F_ULOCK, 0); 164*0Sstevel@tonic-gate close(lockfile); 165*0Sstevel@tonic-gate return (FALSE); 166*0Sstevel@tonic-gate } 167*0Sstevel@tonic-gate } else { 168*0Sstevel@tonic-gate syslog(LOG_ERR, 169*0Sstevel@tonic-gate "lockf(%s,F_LOCK) => errno=%d", LOCKFILE, errno); 170*0Sstevel@tonic-gate close(lockfile); 171*0Sstevel@tonic-gate return (FALSE); 172*0Sstevel@tonic-gate } 173*0Sstevel@tonic-gate } else { 174*0Sstevel@tonic-gate syslog(LOG_ERR, 175*0Sstevel@tonic-gate "open(%s) => errno=%d", LOCKFILE, errno); 176*0Sstevel@tonic-gate return (FALSE); 177*0Sstevel@tonic-gate } 178*0Sstevel@tonic-gate 179*0Sstevel@tonic-gate /* 180*0Sstevel@tonic-gate * File exists with correct size, is open, and we're holding 181*0Sstevel@tonic-gate * the file lock. 182*0Sstevel@tonic-gate */ 183*0Sstevel@tonic-gate shmlockarray = (lockarray *)mmap((caddr_t) 0, sizeof (lockarray), 184*0Sstevel@tonic-gate PROT_READ | PROT_WRITE, MAP_SHARED, lockfile, 0); 185*0Sstevel@tonic-gate if (shmlockarray == MAP_FAILED) { 186*0Sstevel@tonic-gate syslog(LOG_ERR, "mmap(%s) => errno=%d", LOCKFILE, errno); 187*0Sstevel@tonic-gate lockf(lockfile, F_ULOCK, 0); 188*0Sstevel@tonic-gate close(lockfile); 189*0Sstevel@tonic-gate return (FALSE); 190*0Sstevel@tonic-gate } 191*0Sstevel@tonic-gate 192*0Sstevel@tonic-gate /* 193*0Sstevel@tonic-gate * If we wrote zeroes to the file, we also need to initialize 194*0Sstevel@tonic-gate * the mutex locks. 195*0Sstevel@tonic-gate */ 196*0Sstevel@tonic-gate if (lf_size < sizeof (lockarray)) { 197*0Sstevel@tonic-gate if (init_locks_mem() == FALSE) { 198*0Sstevel@tonic-gate lockf(lockfile, F_ULOCK, 0); 199*0Sstevel@tonic-gate close(lockfile); 200*0Sstevel@tonic-gate if (remove(LOCKFILE) != 0) { 201*0Sstevel@tonic-gate syslog(LOG_ERR, 202*0Sstevel@tonic-gate "remove(%s) => errno=%d: Please delete file.", 203*0Sstevel@tonic-gate LOCKFILE, errno); 204*0Sstevel@tonic-gate } 205*0Sstevel@tonic-gate return (FALSE); 206*0Sstevel@tonic-gate } 207*0Sstevel@tonic-gate } 208*0Sstevel@tonic-gate 209*0Sstevel@tonic-gate if (lockf(lockfile, F_ULOCK, 0) != 0) { 210*0Sstevel@tonic-gate syslog(LOG_ERR, 211*0Sstevel@tonic-gate "lockf(%s,F_ULOCK) => errno=%d", 212*0Sstevel@tonic-gate LOCKFILE, errno); 213*0Sstevel@tonic-gate close(lockfile); 214*0Sstevel@tonic-gate return (FALSE); 215*0Sstevel@tonic-gate } 216*0Sstevel@tonic-gate 217*0Sstevel@tonic-gate if (close(lockfile) == 0) { 218*0Sstevel@tonic-gate return (TRUE); 219*0Sstevel@tonic-gate } else { 220*0Sstevel@tonic-gate syslog(LOG_ERR, 221*0Sstevel@tonic-gate "close(%s) => errno=%d", LOCKFILE, errno); 222*0Sstevel@tonic-gate return (FALSE); 223*0Sstevel@tonic-gate } 224*0Sstevel@tonic-gate } 225*0Sstevel@tonic-gate 226*0Sstevel@tonic-gate /* 227*0Sstevel@tonic-gate * FUNCTION : lock_map() 228*0Sstevel@tonic-gate * 229*0Sstevel@tonic-gate * DESCRIPTION: Front end to the lock routine taking map name as argument. 230*0Sstevel@tonic-gate * 231*0Sstevel@tonic-gate * GIVEN : Map name. 232*0Sstevel@tonic-gate * 233*0Sstevel@tonic-gate * RETURNS : Same as lock_core 234*0Sstevel@tonic-gate */ 235*0Sstevel@tonic-gate int 236*0Sstevel@tonic-gate lock_map(char *mapname) 237*0Sstevel@tonic-gate { 238*0Sstevel@tonic-gate int hashval; 239*0Sstevel@tonic-gate 240*0Sstevel@tonic-gate hashval = hash(mapname); 241*0Sstevel@tonic-gate 242*0Sstevel@tonic-gate return( lock_core(hashval)); 243*0Sstevel@tonic-gate } 244*0Sstevel@tonic-gate 245*0Sstevel@tonic-gate /* 246*0Sstevel@tonic-gate * FUNCTION : lock_core() 247*0Sstevel@tonic-gate * 248*0Sstevel@tonic-gate * DESCRIPTION: The core map locking function 249*0Sstevel@tonic-gate * 250*0Sstevel@tonic-gate * GIVEN : Map hash value 251*0Sstevel@tonic-gate * 252*0Sstevel@tonic-gate * RETURNS : 0 = Failure 253*0Sstevel@tonic-gate * 1 = Success 254*0Sstevel@tonic-gate */ 255*0Sstevel@tonic-gate int 256*0Sstevel@tonic-gate lock_core(int hashval) 257*0Sstevel@tonic-gate { 258*0Sstevel@tonic-gate int rc; 259*0Sstevel@tonic-gate 260*0Sstevel@tonic-gate /* 261*0Sstevel@tonic-gate *Robust, cross-process lock implementation 262*0Sstevel@tonic-gate */ 263*0Sstevel@tonic-gate rc = mutex_lock(&(shmlockarray->locknode[hashval])); 264*0Sstevel@tonic-gate while (rc != 0) { 265*0Sstevel@tonic-gate switch (rc) { 266*0Sstevel@tonic-gate case EOWNERDEAD: 267*0Sstevel@tonic-gate /* 268*0Sstevel@tonic-gate * Previows lock owner died, resetting lock 269*0Sstevel@tonic-gate * to recover from error. 270*0Sstevel@tonic-gate */ 271*0Sstevel@tonic-gate rc = mutex_init(&(shmlockarray->locknode[hashval]), 272*0Sstevel@tonic-gate USYNC_PROCESS_ROBUST, 0); 273*0Sstevel@tonic-gate if (rc != 0) { 274*0Sstevel@tonic-gate syslog(LOG_ERR, 275*0Sstevel@tonic-gate "mutex_init(): error=%d", rc); 276*0Sstevel@tonic-gate return (0); 277*0Sstevel@tonic-gate } 278*0Sstevel@tonic-gate rc = mutex_unlock(&(shmlockarray->locknode[hashval])); 279*0Sstevel@tonic-gate if (rc != 0) { 280*0Sstevel@tonic-gate syslog(LOG_ERR, 281*0Sstevel@tonic-gate "mutex_unlock(): error=%d", rc); 282*0Sstevel@tonic-gate return (0); 283*0Sstevel@tonic-gate } 284*0Sstevel@tonic-gate break; 285*0Sstevel@tonic-gate default: 286*0Sstevel@tonic-gate /* 287*0Sstevel@tonic-gate * Unrecoverable problem - nothing to do 288*0Sstevel@tonic-gate * but exit YP and delete lock file. 289*0Sstevel@tonic-gate */ 290*0Sstevel@tonic-gate syslog(LOG_ERR, 291*0Sstevel@tonic-gate "mutex_lock(): error=%d", rc); 292*0Sstevel@tonic-gate syslog(LOG_ERR, 293*0Sstevel@tonic-gate "Please restart NIS (ypstop/ypstart)."); 294*0Sstevel@tonic-gate if (remove(LOCKFILE) != 0) { 295*0Sstevel@tonic-gate syslog(LOG_ERR, 296*0Sstevel@tonic-gate "remove(%s) => errno=%d: Please delete file.", 297*0Sstevel@tonic-gate LOCKFILE, errno); 298*0Sstevel@tonic-gate } 299*0Sstevel@tonic-gate return (0); 300*0Sstevel@tonic-gate } 301*0Sstevel@tonic-gate rc = mutex_lock(&(shmlockarray->locknode[hashval])); 302*0Sstevel@tonic-gate } 303*0Sstevel@tonic-gate 304*0Sstevel@tonic-gate /* Success */ 305*0Sstevel@tonic-gate return (1); 306*0Sstevel@tonic-gate } 307*0Sstevel@tonic-gate 308*0Sstevel@tonic-gate 309*0Sstevel@tonic-gate /* 310*0Sstevel@tonic-gate * FUNCTION : unlock_map() 311*0Sstevel@tonic-gate * 312*0Sstevel@tonic-gate * DESCRIPTION: Front end to the unlock routine taking map name as argument. 313*0Sstevel@tonic-gate * 314*0Sstevel@tonic-gate * GIVEN : Map name. 315*0Sstevel@tonic-gate * 316*0Sstevel@tonic-gate * RETURNS : Same as unlock_core 317*0Sstevel@tonic-gate */ 318*0Sstevel@tonic-gate int 319*0Sstevel@tonic-gate unlock_map(char *mapname) 320*0Sstevel@tonic-gate { 321*0Sstevel@tonic-gate int hashval; 322*0Sstevel@tonic-gate 323*0Sstevel@tonic-gate hashval = hash(mapname); 324*0Sstevel@tonic-gate 325*0Sstevel@tonic-gate return( unlock_core( hashval )); 326*0Sstevel@tonic-gate } 327*0Sstevel@tonic-gate 328*0Sstevel@tonic-gate /* 329*0Sstevel@tonic-gate * FUNCTION : unlock_core() 330*0Sstevel@tonic-gate * 331*0Sstevel@tonic-gate * DESCRIPTION: The core map locking function 332*0Sstevel@tonic-gate * 333*0Sstevel@tonic-gate * GIVEN : Map hash value 334*0Sstevel@tonic-gate * 335*0Sstevel@tonic-gate * RETURNS : 0 = Failure 336*0Sstevel@tonic-gate * 1 = Success 337*0Sstevel@tonic-gate */ 338*0Sstevel@tonic-gate int 339*0Sstevel@tonic-gate unlock_core(int hashval) 340*0Sstevel@tonic-gate { 341*0Sstevel@tonic-gate int rc; 342*0Sstevel@tonic-gate 343*0Sstevel@tonic-gate rc = mutex_unlock(&(shmlockarray->locknode[hashval])); 344*0Sstevel@tonic-gate if (rc != 0) { 345*0Sstevel@tonic-gate syslog(LOG_ERR, 346*0Sstevel@tonic-gate "mutex_unlock(): error=%d", rc); 347*0Sstevel@tonic-gate syslog(LOG_ERR, 348*0Sstevel@tonic-gate "Please restart NIS (ypstop/ypstart)."); 349*0Sstevel@tonic-gate if (remove(LOCKFILE) != 0) { 350*0Sstevel@tonic-gate syslog(LOG_ERR, 351*0Sstevel@tonic-gate "remove(%s) => errno=%d: Please delete file.", 352*0Sstevel@tonic-gate LOCKFILE, errno); 353*0Sstevel@tonic-gate } 354*0Sstevel@tonic-gate return (0); 355*0Sstevel@tonic-gate } 356*0Sstevel@tonic-gate 357*0Sstevel@tonic-gate /* Success */ 358*0Sstevel@tonic-gate return (1); 359*0Sstevel@tonic-gate } 360