projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 9552e6b8 DF |
1 | /* |
| 2 | * Copyright (c) 1980 Regents of the University of California. | |
| 3 | * All rights reserved. The Berkeley software License Agreement | |
| 4 | * specifies the terms and conditions for redistribution. | |
| 5 | */ | |
| 6 | ||
| 2ae9f53f | 7 | #ifndef lint |
| 2fd8b883 | 8 | static char *sccsid = "@(#)lock.c 5.2 (Berkeley) %G%"; |
| 9552e6b8 | 9 | #endif not lint |
| 2c554823 KS |
10 | |
| 11 | /* | |
| 12 | * A mailing program. | |
| 13 | * | |
| 14 | * Stuff to do version 7 style locking. | |
| 15 | */ | |
| 16 | ||
| 17 | #include "rcv.h" | |
| 18 | #include <sys/stat.h> | |
| 19 | ||
| 1a27a241 | 20 | char *maillock = ".mail"; /* Lock suffix for mailname */ |
| 2c554823 KS |
21 | char *lockname = "/usr/spool/mail/tmXXXXXX"; |
| 22 | char locktmp[30]; /* Usable lock temporary */ | |
| 23 | static char curlock[50]; /* Last used name of lock */ | |
| 24 | static int locked; /* To note that we locked it */ | |
| 25 | ||
| 26 | /* | |
| 27 | * Lock the specified mail file by setting the file mailfile.lock. | |
| 28 | * We must, of course, be careful to remove the lock file by a call | |
| 29 | * to unlock before we stop. The algorithm used here is to see if | |
| 30 | * the lock exists, and if it does, to check its modify time. If it | |
| 7a36cf49 | 31 | * is older than 5 minutes, we assume error and set our own file. |
| 2c554823 KS |
32 | * Otherwise, we wait for 5 seconds and try again. |
| 33 | */ | |
| 34 | ||
| 35 | lock(file) | |
| 36 | char *file; | |
| 37 | { | |
| 38 | register int f; | |
| 39 | struct stat sbuf; | |
| 40 | long curtime; | |
| 41 | ||
| 42 | if (file == NOSTR) { | |
| 43 | printf("Locked = %d\n", locked); | |
| 44 | return(0); | |
| 45 | } | |
| 46 | if (locked) | |
| 47 | return(0); | |
| 48 | strcpy(curlock, file); | |
| 49 | strcat(curlock, maillock); | |
| 50 | strcpy(locktmp, lockname); | |
| 51 | mktemp(locktmp); | |
| 52 | remove(locktmp); | |
| 53 | for (;;) { | |
| 54 | f = lock1(locktmp, curlock); | |
| 55 | if (f == 0) { | |
| 56 | locked = 1; | |
| 57 | return(0); | |
| 58 | } | |
| 59 | if (stat(curlock, &sbuf) < 0) | |
| 60 | return(0); | |
| 61 | time(&curtime); | |
| 7a36cf49 | 62 | if (curtime < sbuf.st_ctime + 300) { |
| 2c554823 KS |
63 | sleep(5); |
| 64 | continue; | |
| 65 | } | |
| 66 | remove(curlock); | |
| 67 | } | |
| 68 | } | |
| 69 | ||
| 70 | /* | |
| 71 | * Remove the mail lock, and note that we no longer | |
| 72 | * have it locked. | |
| 73 | */ | |
| 74 | ||
| 75 | unlock() | |
| 76 | { | |
| 77 | ||
| 78 | remove(curlock); | |
| 79 | locked = 0; | |
| 80 | } | |
| 81 | ||
| 82 | /* | |
| 83 | * Attempt to set the lock by creating the temporary file, | |
| 84 | * then doing a link/unlink. If it fails, return -1 else 0 | |
| 85 | */ | |
| 86 | ||
| 87 | lock1(tempfile, name) | |
| 88 | char tempfile[], name[]; | |
| 89 | { | |
| 90 | register int fd; | |
| 91 | ||
| 92 | fd = creat(tempfile, 0); | |
| 93 | if (fd < 0) | |
| 94 | return(-1); | |
| 95 | close(fd); | |
| 96 | if (link(tempfile, name) < 0) { | |
| 97 | remove(tempfile); | |
| 98 | return(-1); | |
| 99 | } | |
| 100 | remove(tempfile); | |
| 101 | return(0); | |
| 102 | } |