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Improve weak locking by using flock()

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This commit is contained in:
Andrey A. Chernov 1997-08-05 12:58:02 +00:00
parent 4c26232f70
commit e1a10354cb
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=27920
1 changed files with 8 additions and 4 deletions
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12
lib/libutil/uucplock.c
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@ -30,7 +30,7 @@
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $Id: uucplock.c,v 1.5 1997/04/02 04:24:39 ache Exp $
* $Id: uucplock.c,v 1.6 1997/05/12 10:36:14 brian Exp $
*
*/
@ -70,13 +70,13 @@ int uu_lock (const char *ttyname)
int err;
(void)snprintf(tbuf, sizeof(tbuf), _PATH_UUCPLOCK LOCKFMT, ttyname);
fd = open(tbuf, O_RDWR|O_CREAT|O_EXCL, 0660);
fd = open(tbuf, O_RDWR|O_CREAT|O_EXCL|O_EXLOCK, 0660);
if (fd < 0) {
/*
* file is already locked
* check to see if the process holding the lock still exists
*/
fd = open(tbuf, O_RDWR, 0);
fd = open(tbuf, O_RDWR|O_SHLOCK);
if (fd < 0)
return UU_LOCK_OPEN_ERR;
@ -100,13 +100,17 @@ int uu_lock (const char *ttyname)
errno = err;
return UU_LOCK_SEEK_ERR;
}
if (flock(fd, LOCK_EX|LOCK_NB) < 0) {
(void)close(fd);
return UU_LOCK_INUSE;
}
/* fall out and finish the locking process */
}
pid = getpid();
if (!put_pid (fd, pid)) {
err = errno;
(void)close(fd);
(void)unlink(tbuf);
(void)close(fd);
errno = err;
return UU_LOCK_WRITE_ERR;
}