lpd: now with "svn add"...

printutils/lpd.c

@@ -0,0 +1,79 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * micro lpd - a small non-queueing lpd
+ *
+ * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
+ *
+ * Licensed under GPLv2, see file LICENSE in this tarball for details.
+ */
+#include "libbb.h"
+
+int lpd_main(int argc, char *argv[]) MAIN_EXTERNALLY_VISIBLE;
+int lpd_main(int argc, char *argv[])
+{
+	char *s;
+
+	// goto spool directory
+	// spool directory contains either links to real printer devices or just simple files
+	// these links or files are called "queues"
+	if (!argv[1])
+		bb_show_usage();
+
+	xchdir(argv[1]);
+
+	xdup2(1, 2);
+
+	// read command
+	s = xmalloc_reads(STDIN_FILENO, NULL);
+
+	// N.B. we keep things simple
+	// only "receive job" command is meaningful here...
+	if (2 == *s) {
+		char *queue;
+
+		// parse command: "\x2QUEUE_NAME\n"
+		queue = s + 1;
+		*strchrnul(s, '\n') = '\0';
+
+		while (1) {
+			// signal OK
+			write(STDOUT_FILENO, "", 1);
+			// get subcommand
+			s = xmalloc_reads(STDIN_FILENO, NULL);
+			if (!s)
+				return EXIT_SUCCESS; // EOF (probably)
+			// valid s must be of form: SUBCMD | LEN | SP | FNAME
+			// N.B. we bail out on any error
+			// control or data file follows
+			if (2 == s[0] || 3 == s[0]) {
+				int fd;
+				size_t len;
+				// 2: control file (ignoring), 3: data file
+				fd = -1;
+				if (3 == s[0])
+					fd = xopen(queue, O_RDWR | O_APPEND);
+				// get data length
+				*strchrnul(s, ' ') = '\0';
+				len = xatou(s + 1);
+				// dump exactly len bytes to file, or die
+				bb_copyfd_exact_size(STDIN_FILENO, fd, len);
+				close(fd); // NB: can do close(-1). Who cares?
+				free(s);
+				// got no ACK? -> bail out
+				if (safe_read(STDIN_FILENO, s, 1) <= 0 || s[0]) {
+					// don't talk to peer - it obviously
+					// don't follow the protocol
+					return EXIT_FAILURE;
+				}
+			} else {
+				// any other subcommand aborts receiving job
+				// N.B. abort subcommand itself doesn't contain
+				// fname so it failed earlier...
+				break;
+			}
+		}
+	}
+
+	printf("Command %02x not supported\n", (unsigned char)*s);
+	return EXIT_FAILURE;
+}