projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 2c554823 KS |
1 | # |
| 2 | ||
| 3 | /* | |
| 4 | * A mailing program. | |
| 5 | * | |
| 6 | * Stuff to do version 7 style locking. | |
| 7 | */ | |
| 8 | ||
| 9 | #include "rcv.h" | |
| 10 | #include <sys/stat.h> | |
| 11 | ||
| 12 | static char *SccsId = "@(#)lock.c 1.1 %G%"; | |
| 13 | ||
| 14 | char *maillock = ".lock"; /* Lock suffix for mailname */ | |
| 15 | char *lockname = "/usr/spool/mail/tmXXXXXX"; | |
| 16 | char locktmp[30]; /* Usable lock temporary */ | |
| 17 | static char curlock[50]; /* Last used name of lock */ | |
| 18 | static int locked; /* To note that we locked it */ | |
| 19 | ||
| 20 | /* | |
| 21 | * Lock the specified mail file by setting the file mailfile.lock. | |
| 22 | * We must, of course, be careful to remove the lock file by a call | |
| 23 | * to unlock before we stop. The algorithm used here is to see if | |
| 24 | * the lock exists, and if it does, to check its modify time. If it | |
| 25 | * is older than 30 seconds, we assume error and set our own file. | |
| 26 | * Otherwise, we wait for 5 seconds and try again. | |
| 27 | */ | |
| 28 | ||
| 29 | lock(file) | |
| 30 | char *file; | |
| 31 | { | |
| 32 | register int f; | |
| 33 | struct stat sbuf; | |
| 34 | long curtime; | |
| 35 | ||
| 36 | if (file == NOSTR) { | |
| 37 | printf("Locked = %d\n", locked); | |
| 38 | return(0); | |
| 39 | } | |
| 40 | if (locked) | |
| 41 | return(0); | |
| 42 | strcpy(curlock, file); | |
| 43 | strcat(curlock, maillock); | |
| 44 | strcpy(locktmp, lockname); | |
| 45 | mktemp(locktmp); | |
| 46 | remove(locktmp); | |
| 47 | for (;;) { | |
| 48 | f = lock1(locktmp, curlock); | |
| 49 | if (f == 0) { | |
| 50 | locked = 1; | |
| 51 | return(0); | |
| 52 | } | |
| 53 | if (stat(curlock, &sbuf) < 0) | |
| 54 | return(0); | |
| 55 | time(&curtime); | |
| 56 | if (curtime < sbuf.st_ctime + 30) { | |
| 57 | sleep(5); | |
| 58 | continue; | |
| 59 | } | |
| 60 | remove(curlock); | |
| 61 | } | |
| 62 | } | |
| 63 | ||
| 64 | /* | |
| 65 | * Remove the mail lock, and note that we no longer | |
| 66 | * have it locked. | |
| 67 | */ | |
| 68 | ||
| 69 | unlock() | |
| 70 | { | |
| 71 | ||
| 72 | remove(curlock); | |
| 73 | locked = 0; | |
| 74 | } | |
| 75 | ||
| 76 | /* | |
| 77 | * Attempt to set the lock by creating the temporary file, | |
| 78 | * then doing a link/unlink. If it fails, return -1 else 0 | |
| 79 | */ | |
| 80 | ||
| 81 | lock1(tempfile, name) | |
| 82 | char tempfile[], name[]; | |
| 83 | { | |
| 84 | register int fd; | |
| 85 | ||
| 86 | fd = creat(tempfile, 0); | |
| 87 | if (fd < 0) | |
| 88 | return(-1); | |
| 89 | close(fd); | |
| 90 | if (link(tempfile, name) < 0) { | |
| 91 | remove(tempfile); | |
| 92 | return(-1); | |
| 93 | } | |
| 94 | remove(tempfile); | |
| 95 | return(0); | |
| 96 | } |