petty: re-add old getty

apps/petty.c

@@ -0,0 +1,98 @@
+/* vim: tabstop=4 shiftwidth=4 noexpandtab
+ * This file is part of ToaruOS and is released under the terms
+ * of the NCSA / University of Illinois License - see LICENSE.md
+ * Copyright (C) 2018 K. Lange
+ *
+ * petty - Manage a TTY.
+ *
+ * Wraps a serial port (or other dumb connection) with a pty
+ * and manages a login for it.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <pty.h>
+#include <sys/wait.h>
+#include <sys/fswait.h>
+
+int main(int argc, char * argv[]) {
+	int fd_master, fd_slave, fd_serial;
+	char * file = "/dev/ttyS0";
+	char * user = NULL;
+
+	if (getuid() != 0) {
+		fprintf(stderr, "%s: only root can do that\n", argv[0]);
+		return 1;
+	}
+
+	int opt;
+	while ((opt = getopt(argc, argv, "a:")) != -1) {
+		switch (opt) {
+			case 'a':
+				user = optarg;
+				break;
+		}
+	}
+
+	if (optind < argc) {
+		file = argv[optind];
+	}
+
+	openpty(&fd_master, &fd_slave, NULL, NULL, NULL);
+	fd_serial = open(file, O_RDWR);
+
+	pid_t child = fork();
+
+	if (!child) {
+		setsid();
+		dup2(fd_slave, 0);
+		dup2(fd_slave, 1);
+		dup2(fd_slave, 2);
+
+		system("ttysize -q");
+
+		char * tokens[] = {"/bin/login",NULL,NULL,NULL};
+
+		if (user) {
+			tokens[1] = "-f";
+			tokens[2] = user;
+		}
+
+		execvp(tokens[0], tokens);
+		exit(1);
+	} else {
+
+		int fds[2] = {fd_serial, fd_master};
+
+		while (1) {
+			int index = fswait2(2,fds,200);
+			char buf[1024];
+			int r;
+			switch (index) {
+				case 0: /* fd_serial */
+					r = read(fd_serial, buf, 1);
+					write(fd_master, buf, 1);
+					break;
+				case 1: /* fd_master */
+					r = read(fd_master, buf, 1024);
+					write(fd_serial, buf, r);
+					break;
+				default: /* timeout */
+					{
+						int result = waitpid(child, NULL, WNOHANG);
+						if (result > 0) {
+							/* Child login shell has returned (session ended) */
+							return 0;
+						}
+					}
+					break;
+			}
+
+		}
+
+	}
+
+	return 0;
+}
+