Initial lp.

src/cmd/lp/LOCK.c

@@ -0,0 +1,57 @@
+#include <u.h>
+#include <libc.h>
+
+/* MAXHOSTNAMELEN is in sys/param.h */
+#define MAXHOSTNAMELEN	64
+
+char lockstring[MAXHOSTNAMELEN+8];
+
+void
+main(int argc, char *argv[]) {
+	char *lockfile;
+	int fd, ppid, ssize;
+	struct Dir *statbuf;
+
+	if (argc != 4) {
+		fprint(2, "usage: LOCK lockfile hostname ppid\n");
+		exits("lock failed on usage");
+	}
+	lockfile = argv[1];
+	if ((fd=create(lockfile, OLOCK|ORDWR, 0666)) < 0) {
+		exits("lock failed on create");
+	}
+	ppid = atoi(argv[3]);
+	ssize = sprint(lockstring, "%s %s\n", argv[2], argv[3]);
+	if (write(fd, lockstring, ssize) != ssize) {
+		fprint(2, "LOCK:write(): %r\n");
+		exits("lock failed on write to lockfile");
+	}
+
+	switch(fork()) {
+	default:
+		exits("");
+	case 0:
+		break;
+	case -1:
+		fprint(2, "LOCK:fork(): %r\n");
+		exits("lock failed on fork");
+	}
+
+	for(;;) {
+		statbuf = dirfstat(fd);
+		if(statbuf == nil)
+			break;
+		if (statbuf->length == 0){
+			free(statbuf);
+			break;
+		}
+		free(statbuf);
+		if (write(fd, "", 0) < 0)
+			break;
+		sleep(3000);
+	}
+
+	close(fd);
+	postnote(PNGROUP, ppid, "kill");
+	exits("");
+}