110d63b7dSRichard Lowe /*
210d63b7dSRichard Lowe * CDDL HEADER START
310d63b7dSRichard Lowe *
410d63b7dSRichard Lowe * The contents of this file are subject to the terms of the
510d63b7dSRichard Lowe * Common Development and Distribution License (the "License").
610d63b7dSRichard Lowe * You may not use this file except in compliance with the License.
710d63b7dSRichard Lowe *
810d63b7dSRichard Lowe * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
910d63b7dSRichard Lowe * or http://www.opensolaris.org/os/licensing.
1010d63b7dSRichard Lowe * See the License for the specific language governing permissions
1110d63b7dSRichard Lowe * and limitations under the License.
1210d63b7dSRichard Lowe *
1310d63b7dSRichard Lowe * When distributing Covered Code, include this CDDL HEADER in each
1410d63b7dSRichard Lowe * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
1510d63b7dSRichard Lowe * If applicable, add the following below this CDDL HEADER, with the
1610d63b7dSRichard Lowe * fields enclosed by brackets "[]" replaced with your own identifying
1710d63b7dSRichard Lowe * information: Portions Copyright [yyyy] [name of copyright owner]
1810d63b7dSRichard Lowe *
1910d63b7dSRichard Lowe * CDDL HEADER END
2010d63b7dSRichard Lowe */
2110d63b7dSRichard Lowe /*
2210d63b7dSRichard Lowe * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
2310d63b7dSRichard Lowe * Use is subject to license terms.
2410d63b7dSRichard Lowe */
2510d63b7dSRichard Lowe
2610d63b7dSRichard Lowe #include <stdio.h>
2710d63b7dSRichard Lowe #include <stdlib.h>
2810d63b7dSRichard Lowe #include <string.h>
2910d63b7dSRichard Lowe #include <sys/errno.h>
3010d63b7dSRichard Lowe #include <sys/param.h>
3110d63b7dSRichard Lowe #include <sys/stat.h>
3210d63b7dSRichard Lowe #include <sys/types.h>
3310d63b7dSRichard Lowe #include <unistd.h>
3410d63b7dSRichard Lowe #include <vroot/vroot.h>
3510d63b7dSRichard Lowe #include <signal.h>
3610d63b7dSRichard Lowe #include <errno.h> /* errno */
3710d63b7dSRichard Lowe #include <libintl.h>
3810d63b7dSRichard Lowe
39*356ba08cSToomas Soome static void file_lock_error(char *msg, char *file, const char *str,
40*356ba08cSToomas Soome char *arg1, char * arg2);
4110d63b7dSRichard Lowe
4210d63b7dSRichard Lowe #define BLOCK_INTERUPTS sigfillset(&newset) ; \
4310d63b7dSRichard Lowe sigprocmask(SIG_SETMASK, &newset, &oldset)
4410d63b7dSRichard Lowe
4510d63b7dSRichard Lowe #define UNBLOCK_INTERUPTS \
4610d63b7dSRichard Lowe sigprocmask(SIG_SETMASK, &oldset, &newset)
4710d63b7dSRichard Lowe
4810d63b7dSRichard Lowe /*
4910d63b7dSRichard Lowe * This code stolen from the NSE library and changed to not depend
5010d63b7dSRichard Lowe * upon any NSE routines or header files.
5110d63b7dSRichard Lowe *
5210d63b7dSRichard Lowe * Simple file locking.
5310d63b7dSRichard Lowe * Create a symlink to a file. The "test and set" will be
5410d63b7dSRichard Lowe * atomic as creating the symlink provides both functions.
5510d63b7dSRichard Lowe *
5610d63b7dSRichard Lowe * The timeout value specifies how long to wait for stale locks
5710d63b7dSRichard Lowe * to disappear. If the lock is more than 'timeout' seconds old
5810d63b7dSRichard Lowe * then it is ok to blow it away. This part has a small window
5910d63b7dSRichard Lowe * of vunerability as the operations of testing the time,
6010d63b7dSRichard Lowe * removing the lock and creating a new one are not atomic.
6110d63b7dSRichard Lowe * It would be possible for two processes to both decide to blow
6210d63b7dSRichard Lowe * away the lock and then have process A remove the lock and establish
6310d63b7dSRichard Lowe * its own, and then then have process B remove the lock which accidentily
6410d63b7dSRichard Lowe * removes A's lock rather than the stale one.
6510d63b7dSRichard Lowe *
6610d63b7dSRichard Lowe * A further complication is with the NFS. If the file in question is
6710d63b7dSRichard Lowe * being served by an NFS server, then its time is set by that server.
6810d63b7dSRichard Lowe * We can not use the time on the client machine to check for a stale
6910d63b7dSRichard Lowe * lock. Therefore, a temp file on the server is created to get
7010d63b7dSRichard Lowe * the servers current time.
7110d63b7dSRichard Lowe *
7210d63b7dSRichard Lowe * Returns an error message. NULL return means the lock was obtained.
7310d63b7dSRichard Lowe *
7410d63b7dSRichard Lowe * 12/6/91 Added the parameter "file_locked". Before this parameter
7510d63b7dSRichard Lowe * was added, the calling procedure would have to wait for file_lock()
7610d63b7dSRichard Lowe * to return before it sets the flag. If the user interrupted "make"
7710d63b7dSRichard Lowe * between the time the lock was acquired and the time file_lock()
7810d63b7dSRichard Lowe * returns, make wouldn't know that the file has been locked, and therefore
7910d63b7dSRichard Lowe * it wouldn' remove the lock. Setting the flag right after locking the file
8010d63b7dSRichard Lowe * makes this window much smaller.
8110d63b7dSRichard Lowe */
8210d63b7dSRichard Lowe
8310d63b7dSRichard Lowe int
file_lock(char * name,char * lockname,int * file_locked,int timeout)8410d63b7dSRichard Lowe file_lock(char *name, char *lockname, int *file_locked, int timeout)
8510d63b7dSRichard Lowe {
8610d63b7dSRichard Lowe int counter = 0;
8710d63b7dSRichard Lowe static char msg[MAXPATHLEN+1];
8810d63b7dSRichard Lowe int printed_warning = 0;
8910d63b7dSRichard Lowe int r;
9010d63b7dSRichard Lowe struct stat statb;
9110d63b7dSRichard Lowe sigset_t newset;
9210d63b7dSRichard Lowe sigset_t oldset;
9310d63b7dSRichard Lowe
9410d63b7dSRichard Lowe *file_locked = 0;
9510d63b7dSRichard Lowe if (timeout <= 0) {
9610d63b7dSRichard Lowe timeout = 120;
9710d63b7dSRichard Lowe }
9810d63b7dSRichard Lowe for (;;) {
9910d63b7dSRichard Lowe BLOCK_INTERUPTS;
10010d63b7dSRichard Lowe r = symlink(name, lockname);
10110d63b7dSRichard Lowe if (r == 0) {
10210d63b7dSRichard Lowe *file_locked = 1;
10310d63b7dSRichard Lowe UNBLOCK_INTERUPTS;
10410d63b7dSRichard Lowe return 0; /* success */
10510d63b7dSRichard Lowe }
10610d63b7dSRichard Lowe UNBLOCK_INTERUPTS;
10710d63b7dSRichard Lowe
10810d63b7dSRichard Lowe if (errno != EEXIST) {
109*356ba08cSToomas Soome file_lock_error(msg, name, "symlink(%s, %s)",
110*356ba08cSToomas Soome name, lockname);
11110d63b7dSRichard Lowe fprintf(stderr, "%s", msg);
11210d63b7dSRichard Lowe return errno;
11310d63b7dSRichard Lowe }
11410d63b7dSRichard Lowe
11510d63b7dSRichard Lowe counter = 0;
11610d63b7dSRichard Lowe for (;;) {
11710d63b7dSRichard Lowe sleep(1);
11810d63b7dSRichard Lowe r = lstat(lockname, &statb);
11910d63b7dSRichard Lowe if (r == -1) {
12010d63b7dSRichard Lowe /*
12110d63b7dSRichard Lowe * The lock must have just gone away - try
12210d63b7dSRichard Lowe * again.
12310d63b7dSRichard Lowe */
12410d63b7dSRichard Lowe break;
12510d63b7dSRichard Lowe }
12610d63b7dSRichard Lowe
12710d63b7dSRichard Lowe if ((counter > 5) && (!printed_warning)) {
12810d63b7dSRichard Lowe /* Print waiting message after 5 secs */
12910d63b7dSRichard Lowe (void) getcwd(msg, MAXPATHLEN);
130*356ba08cSToomas Soome fprintf(stderr, gettext(
131*356ba08cSToomas Soome "file_lock: file %s is already locked.\n"),
13210d63b7dSRichard Lowe name);
133*356ba08cSToomas Soome fprintf(stderr, gettext(
134*356ba08cSToomas Soome "file_lock: will periodically check the "
135*356ba08cSToomas Soome "lockfile %s for two minutes.\n"),
13610d63b7dSRichard Lowe lockname);
137*356ba08cSToomas Soome fprintf(stderr, gettext(
138*356ba08cSToomas Soome "Current working directory %s\n"), msg);
13910d63b7dSRichard Lowe
14010d63b7dSRichard Lowe printed_warning = 1;
14110d63b7dSRichard Lowe }
14210d63b7dSRichard Lowe
14310d63b7dSRichard Lowe if (++counter > timeout ) {
14410d63b7dSRichard Lowe /*
14510d63b7dSRichard Lowe * Waited enough - return an error..
14610d63b7dSRichard Lowe */
14710d63b7dSRichard Lowe return EEXIST;
14810d63b7dSRichard Lowe }
14910d63b7dSRichard Lowe }
15010d63b7dSRichard Lowe }
15110d63b7dSRichard Lowe /* NOTREACHED */
15210d63b7dSRichard Lowe }
15310d63b7dSRichard Lowe
15410d63b7dSRichard Lowe /*
15510d63b7dSRichard Lowe * Format a message telling why the lock could not be created.
15610d63b7dSRichard Lowe */
15710d63b7dSRichard Lowe static void
file_lock_error(char * msg,char * file,const char * str,char * arg1,char * arg2)158*356ba08cSToomas Soome file_lock_error(char *msg, char *file, const char *str, char *arg1, char *arg2)
15910d63b7dSRichard Lowe {
160*356ba08cSToomas Soome int len, err;
161*356ba08cSToomas Soome char *ptr;
16210d63b7dSRichard Lowe
16310d63b7dSRichard Lowe sprintf(msg, gettext("Could not lock file `%s'; "), file);
16410d63b7dSRichard Lowe len = strlen(msg);
16510d63b7dSRichard Lowe sprintf(&msg[len], str, arg1, arg2);
16610d63b7dSRichard Lowe strcat(msg, gettext(" failed - "));
167*356ba08cSToomas Soome
168*356ba08cSToomas Soome err = errno;
169*356ba08cSToomas Soome errno = 0;
170*356ba08cSToomas Soome ptr = strerror(err);
171*356ba08cSToomas Soome if (errno != EINVAL) {
172*356ba08cSToomas Soome strcat(msg, ptr);
17310d63b7dSRichard Lowe } else {
17410d63b7dSRichard Lowe len = strlen(msg);
175*356ba08cSToomas Soome sprintf(&msg[len], "errno %d", err);
17610d63b7dSRichard Lowe }
17710d63b7dSRichard Lowe }
178