1 #include <u.h>
2 #include <libc.h>
3
4 /* MAXHOSTNAMELEN is in sys/param.h */
5 #define MAXHOSTNAMELEN 64
6
7 char lockstring[MAXHOSTNAMELEN+8];
8
9 void
main(int argc,char * argv[])10 main(int argc, char *argv[]) {
11 char *lockfile;
12 int fd, ppid, ssize;
13 struct Dir *statbuf;
14
15 if (argc != 4) {
16 fprint(2, "usage: LOCK lockfile hostname ppid\n");
17 exits("lock failed on usage");
18 }
19 lockfile = argv[1];
20 if ((fd=create(lockfile, ORDWR, DMEXCL|0666)) < 0) {
21 exits("lock failed on create");
22 }
23 ppid = atoi(argv[3]);
24 ssize = sprint(lockstring, "%s %s\n", argv[2], argv[3]);
25 if (write(fd, lockstring, ssize) != ssize) {
26 fprint(2, "LOCK:write(): %r\n");
27 exits("lock failed on write to lockfile");
28 }
29
30 switch(fork()) {
31 default:
32 exits("");
33 case 0:
34 break;
35 case -1:
36 fprint(2, "LOCK:fork(): %r\n");
37 exits("lock failed on fork");
38 }
39
40 for(;;) {
41 statbuf = dirfstat(fd);
42 if(statbuf == nil)
43 break;
44 if (statbuf->length == 0){
45 free(statbuf);
46 break;
47 }
48 free(statbuf);
49 if (write(fd, "", 0) < 0)
50 break;
51 sleep(3000);
52 }
53
54 close(fd);
55 postnote(PNGROUP, ppid, "kill");
56 exits("");
57 }
58