-/*
- * Lock the specified mail file by setting the file mailfile.lock.
- * We must, of course, be careful to unlink the lock file by a call
- * to unlock before we stop. The algorithm used here is to see if
- * the lock exists, and if it does, to check its modify time. If it
- * is older than 30 seconds, we assume error and set our own file.
- * Otherwise, we wait for 5 seconds and try again.
- */
-
-char *maillock = ".lock"; /* Lock suffix for mailname */
-char *lockname = "/usr/spool/mail/tmXXXXXX";
-char locktmp[30]; /* Usable lock temporary */
-char curlock[50]; /* Last used name of lock */
-int locked; /* To note that we locked it */
-
-lock(file)
-char *file;
-{
- register int f;
- struct stat sbuf;
- long curtime;
- int statfailed;
-
- if (locked || flgf)
- return(0);
- strcpy(curlock, file);
- strcat(curlock, maillock);
- strcpy(locktmp, lockname);
- mktemp(locktmp);
- unlink(locktmp);
- statfailed = 0;
- for (;;) {
- f = lock1(locktmp, curlock);
- if (f == 0) {
- locked = 1;
- return(0);
- }
- if (stat(curlock, &sbuf) < 0) {
- if (statfailed++ > 5)
- return(-1);
- sleep(5);
- continue;
- }
- statfailed = 0;
- time(&curtime);
- if (curtime < sbuf.st_ctime + 30) {
- sleep(5);
- continue;
- }
- unlink(curlock);
- }
-}
-
-/*
- * Remove the mail lock, and note that we no longer
- * have it locked.
- */
-
-unlock()
-{
-
- unlink(curlock);
- locked = 0;
-}
-
-/*
- * Attempt to set the lock by creating the temporary file,
- * then doing a link/unlink. If it fails, return -1 else 0
- */
-
-lock1(tempfile, name)
- char tempfile[], name[];
-{
- register int fd;
-
- fd = creat(tempfile, 0);
- if (fd < 0)
- return(-1);
- close(fd);
- if (link(tempfile, name) < 0) {
- unlink(tempfile);
- return(-1);
- }
- unlink(tempfile);
- return(0);
-}
-
projects / unix-history / blobdiff