Commit | Line | Data |
---|---|---|
c8eb690c BJ |
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 | char *maillock = ".lock"; /* Lock suffix for mailname */ | |
13 | char *lockname = "/usr/spool/mail/tmXXXXXX"; | |
14 | char locktmp[30]; /* Usable lock temporary */ | |
15 | static char curlock[50]; /* Last used name of lock */ | |
16 | static int locked; /* To note that we locked it */ | |
17 | ||
18 | /* | |
19 | * Lock the specified mail file by setting the file mailfile.lock. | |
20 | * We must, of course, be careful to remove the lock file by a call | |
21 | * to unlock before we stop. The algorithm used here is to see if | |
22 | * the lock exists, and if it does, to check its modify time. If it | |
23 | * is older than 30 seconds, we assume error and set our own file. | |
24 | * Otherwise, we wait for 5 seconds and try again. | |
25 | */ | |
26 | ||
27 | lock(file) | |
28 | char *file; | |
29 | { | |
30 | register int f; | |
31 | struct stat sbuf; | |
32 | long curtime; | |
33 | ||
34 | if (file == NOSTR) { | |
35 | printf("Locked = %d\n", locked); | |
36 | return(0); | |
37 | } | |
38 | if (locked) | |
39 | return(0); | |
40 | strcpy(curlock, file); | |
41 | strcat(curlock, maillock); | |
42 | strcpy(locktmp, lockname); | |
43 | mktemp(locktmp); | |
44 | remove(locktmp); | |
45 | for (;;) { | |
46 | f = lock1(locktmp, curlock); | |
47 | if (f == 0) { | |
48 | locked = 1; | |
49 | return(0); | |
50 | } | |
51 | if (stat(curlock, &sbuf) < 0) | |
52 | return(0); | |
53 | time(&curtime); | |
54 | if (curtime < sbuf.st_ctime + 30) { | |
55 | sleep(5); | |
56 | continue; | |
57 | } | |
58 | remove(curlock); | |
59 | } | |
60 | } | |
61 | ||
62 | /* | |
63 | * Remove the mail lock, and note that we no longer | |
64 | * have it locked. | |
65 | */ | |
66 | ||
67 | unlock() | |
68 | { | |
69 | ||
70 | remove(curlock); | |
71 | locked = 0; | |
72 | } | |
73 | ||
74 | /* | |
75 | * Attempt to set the lock by creating the temporary file, | |
76 | * then doing a link/unlink. If it fails, return -1 else 0 | |
77 | */ | |
78 | ||
79 | lock1(tempfile, name) | |
80 | char tempfile[], name[]; | |
81 | { | |
82 | register int fd; | |
83 | ||
84 | fd = creat(tempfile, 0); | |
85 | if (fd < 0) | |
86 | return(-1); | |
87 | close(fd); | |
88 | if (link(tempfile, name) < 0) { | |
89 | remove(tempfile); | |
90 | return(-1); | |
91 | } | |
92 | remove(tempfile); | |
93 | return(0); | |
94 | } |