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#include <u.h>
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#include <libc.h>
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/* MAXHOSTNAMELEN is in sys/param.h */
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#define MAXHOSTNAMELEN	64
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char lockstring[MAXHOSTNAMELEN+8];
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void
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main(int argc, char *argv[]) {
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	char *lockfile;
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	int fd, ppid, ssize;
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	struct Dir *statbuf;
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	if (argc != 4) {
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		fprint(2, "usage: LOCK lockfile hostname ppid\n");
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		exits("lock failed on usage");
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	}
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	lockfile = argv[1];
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	if ((fd=create(lockfile, ORDWR, DMEXCL|0666)) < 0) {
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		exits("lock failed on create");
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	}
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	ppid = atoi(argv[3]);
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	ssize = sprint(lockstring, "%s %s\n", argv[2], argv[3]);
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	if (write(fd, lockstring, ssize) != ssize) {
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		fprint(2, "LOCK:write(): %r\n");
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		exits("lock failed on write to lockfile");
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	}
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	switch(fork()) {
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	default:
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		exits("");
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	case 0:
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		break;
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	case -1:
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		fprint(2, "LOCK:fork(): %r\n");
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		exits("lock failed on fork");
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	}
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	for(;;) {
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		statbuf = dirfstat(fd);
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		if(statbuf == nil)
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			break;
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		if (statbuf->length == 0){
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			free(statbuf);
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			break;
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		}
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		free(statbuf);
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		if (write(fd, "", 0) < 0)
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			break;
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		sleep(3000);
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	}
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	close(fd);
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	postnote(PNGROUP, ppid, "kill");
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	exits("");
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}