TTY: Major overhaul, move to built-in getty

The TTY handling in Finit has always been a bit of a patch work.  This
commit is an attempt at a first cleanup and simplification.

Included is a brand new built-in getty which should work fine on both
virtual and serial consoles.  It is however completely untested on the
latter serial consoles.

Still TODO: add support for /etc/securetty, add support for actually
setting TERM when calling /bin/login.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Makefile.am

@@ -1,6 +1,6 @@
 ACLOCAL_AMFLAGS    = -I m4
 sbin_PROGRAMS      = finit initctl reboot
-finit_SOURCES      = finit.c api.c client.c conf.c exec.c helpers.c pid.c \
+finit_SOURCES      = finit.c api.c client.c conf.c exec.c getty.c helpers.c pid.c \
 		     sig.c svc.c service.c plugin.c tty.c cond.c cond-w.c sm.c
 pkginclude_HEADERS = cond.h finit.h helpers.h inetd.h plugin.h svc.h
 if INETD

configure.ac

@@ -122,14 +122,8 @@ AC_ARG_WITH(random-seed,
 AS_IF([test "x$enable_embedded" = "xyes"],[
 	AC_DEFINE(EMBEDDED_SYSTEM, 1,                [Target an embedded system with BusyBox])
 	AC_DEFINE(SETUP_DEVFS,     "/sbin/mdev -s",  [Command to populate /dev])
-	AC_DEFINE(GETTY,           "/sbin/getty -L", [Command to start getty on login prompt])
-        AC_DEFINE(GETTY_BUSYBOX,   1,                [Use BusyBox getty call syntax])
-        AC_DEFINE(BAUDRATE,        115200,           [Default getty baudrate])
 	],[
-        AC_DEFINE(SETUP_DEVFS,     "/sbin/udevd --daemon", [Command to populate /dev])
-	AC_DEFINE(GETTY,           "/sbin/getty -8", [Command to start getty on login prompt])
-        AC_DEFINE(GETTY_AGETTY,    1,                [Use standard agetty call syntax])
-        AC_DEFINE(BAUDRATE,        38400,            [Default getty baudrate])])
+        AC_DEFINE(SETUP_DEVFS,     "/sbin/udevd --daemon", [Command to populate /dev])])
 
 AS_IF([test "x$enable_rw_rootfs" = "xyes"],[
         AC_DEFINE(REMOUNT_ROOTFS,  1, [Remount / as rw at boot])])

doc/config.md

@@ -120,33 +120,21 @@ Syntax:
 * `include <CONF>`  
   Include another configuration file.  Absolute path required.
 
-* `tty [LVLS] <DEV | /path/to/cmd [args]>`  
+* `tty [LVLS] <DEV> [BAUD] [TERM]`  
   Start a getty on the given TTY device DEV, in the given runlevels.  If
-  no tty setting is given in `finit.conf`, or if `/bin/sh` is given as
-  argument instead of a device path, a single shell is started on the
-  default console.  Useful for really bare-bones systems.
-  
-  It is also possible to supply the full command line, with arguments,
-  to your getty.  In this case finit will simply use that command.
-  
-  See `finit.h` for the `#define GETTY` that is called, along with the
-  default baud rate.
+  no tty setting is given in `finit.conf` no login is possible.  Use the
+  `service` stanza to start a stand-alone shell for really bare bones
+  systems.
 
-  **Note:** BusyBox getty, used when Finit is built for embedded
-    systems, can take a `DEV` with *or* without `/dev/` prefix.  Make
-    sure to call the configure script with `--enable-embedded` if this
-	is what you want.
+  Finit comes with a lightweight built-in getty, which after it has
+  opened a TTY and the user has input a username, calls `/bin/login`
+  like any other getty.
 
-* `console <DEV | /path/to/cmd [args]`  
-  Some embedded systems have a dedicated serial console/service port.
-  This command tells finit to not start getty directly, since there may
-  not be anyone there.  To save RAM and CPU finit instead displays a
-  friendly message and waits for the user to activate the console with a
-  key press before starting getty.  Finit also does some other magic and
-  changes the process name to "console".
-  
-  Like the `tty` command, the `console` command can also be used to
-  simply start a UNIX shell, e.g. `/bin/sh`.
+* `console <DEV>`  
+  Use this, along with a matching `tty DEV` line, to mark this TTY as a
+  special "console" port with with `prctl()`.  Useful in use-cases when
+  all logins except the console must be stopped, e.g. when performing a
+  flash upgrade on an embedded system.
 
 When running <kbd>make install</kbd> no default `/etc/finit.conf` will
 be installed since system requirements differ too much.  Try out the

exec.c

@@ -26,16 +26,8 @@
 
 #include <ctype.h>		/* isdigit() */
 #include <dirent.h>
-#include <errno.h>
-#include <fcntl.h>
 #include <stdarg.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <sys/ioctl.h>
 #include <sys/prctl.h>
-#include <sys/socket.h>
-#include <sys/stat.h>
-#include <sys/types.h>
 #include <sys/wait.h>
 #include <lite/lite.h>
 
@@ -220,67 +212,23 @@ int run_interactive(char *cmd, char *fmt, ...)
 	return status;
 }
 
-pid_t run_getty(char *cmd, char *args[], char *tty, int console)
+int getty(char *tty, char *baud, char *term);
+
+pid_t run_getty(char *tty, char *speed, char *term, int console)
 {
 	pid_t pid = fork();
 
 	if (!pid) {
-		int  i, fd;
-		char c;
-		struct sigaction sa;
-
 		/* Reset signal handlers that were set by the parent process */
-		for (i = 1; i < NSIG; i++)
-			DFLSIG(sa, i, 0);
-
-		/* Detach from initial controlling TTY */
-		vhangup();
-
-		close(STDERR_FILENO);
-		close(STDOUT_FILENO);
-		close(STDIN_FILENO);
-
-		/* Attach TTY to console */
-		fd = open(tty, O_RDWR);
-		if (fd != STDIN_FILENO)
-			exit(1);
-
-		dup2(fd, STDIN_FILENO);
-		dup2(fd, STDOUT_FILENO);
-		dup2(fd, STDERR_FILENO);
+		sig_unblock();
+		setsid();
 
 		if (console)
 			prctl(PR_SET_NAME, "console", 0, 0, 0);
 		else
 			prctl(PR_SET_NAME, "finit-getty", 0, 0, 0);
 
-		sig_unblock();
-		setsid();
-
-		if (ioctl(STDIN_FILENO, TIOCSCTTY, 1) < 0)
-			_pe("Failed TIOCSCTTY");
-
-		while (!fexist(SYNC_SHUTDOWN)) {
-			static const char msg[] = "\nPlease press Enter to activate this console.";
-
-			if (fexist(SYNC_STOPPED)) {
-				sleep(1);
-				continue;
-			}
-
-			(void)write(STDERR_FILENO, msg, sizeof(msg));
-			while (read(STDIN_FILENO, &c, 1) == 1 && c != '\n')
-					continue;
-
-			if (fexist(SYNC_STOPPED))
-				continue;
-
-			execv(cmd, args);
-		}
-
-		close(fd);
-		vhangup();
-		exit(0);
+		_exit(getty(tty, speed, term));
 	}
 
 	return pid;

getty.c

@@ -0,0 +1,319 @@
+/* Initialize and serve a login terminal
+ *
+ * Copyright (c) 2016  Joachim Nilsson <troglobit@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <err.h>
+#include <errno.h>
+#include <paths.h>
+#include <signal.h>
+#include <stdio.h>
+#include <sys/ioctl.h>
+#include <sys/utsname.h>
+#include <termios.h>
+
+#include "finit.h"
+#include "helpers.h"
+#include "sig.h"
+
+#ifndef _PATH_LOGIN
+#define _PATH_LOGIN  "/bin/login"
+#endif
+
+#define print(s) (void)write(STDOUT_FILENO, s, strlen(s))
+
+
+/*
+ * Read one character from stdin.
+ */
+static int readch(char *tty)
+{
+	int st;
+	char ch1;
+
+	st = read(STDIN_FILENO, &ch1, 1);
+	if (st == 0) {
+		print("\n");
+		_exit(0);
+	}
+
+	if (st < 0)
+		errx(1, "getty: %s: read error.", tty);
+
+	return ch1 & 0xFF;
+}
+
+static void stty(int fd, speed_t speed)
+{
+	struct termios term;
+
+	tcdrain(fd);
+	if (tcgetattr(fd, &term))
+		return;
+
+	cfsetispeed(&term, speed);
+	cfsetospeed(&term, speed);
+	tcsetattr(fd, TCSAFLUSH, &term);
+
+	tcflush(fd, TCIOFLUSH);
+
+	/* Clear screen -- XXX: add option to disable */
+	print("\033[r\033[H\033[J");
+}
+
+
+/*
+ * Parse and display a line from /etc/issue
+ */
+static void do_parse(char *line, struct utsname *uts, char *tty)
+{
+	char *s, *s0;
+
+	s0 = line;
+	for (s = line; *s != 0; s++) {
+		if (*s == '\\') {
+			(void)write(1, s0, s - s0);
+			s0 = s + 2;
+			switch (*++s) {
+			case 'l':
+				print(tty);
+				break;
+			case 'm':
+				print(uts->machine);
+				break;
+			case 'n':
+				print(uts->nodename);
+				break;
+#ifdef _GNU_SOURCE
+			case 'o':
+				print(uts->domainname);
+				break;
+#endif
+			case 'r':
+				print(uts->release);
+				break;
+			case 's':
+				print(uts->sysname);
+				break;
+			case 'v':
+				print(uts->version);
+				break;
+			case 0:
+				goto leave;
+			default:
+				s0 = s - 1;
+			}
+		}
+	}
+
+leave:
+	(void)write(1, s0, s - s0);
+}
+
+/*
+ * Parse and display /etc/issue
+ */
+static void do_issue(char *tty)
+{
+	FILE *fp;
+	char buf[BUFSIZ] = "Welcome to \\s \\v \\n \\l\n\n";
+	struct utsname uts;
+
+	/*
+	 * Get data about this machine.
+	 */
+	uname(&uts);
+
+	print("\n");
+	fp = fopen("/etc/issue", "r");
+	if (fp) {
+		while (fgets(buf, sizeof(buf), fp))
+			do_parse(buf, &uts, tty);
+
+		fclose(fp);
+	} else {
+		do_parse(buf, &uts, tty);
+	}
+
+	do_parse("\\n login: ", &uts, tty);
+}
+
+/*
+ * Handle the process of a GETTY.
+ */
+static void do_getty(char *tty, char *name, size_t len)
+{
+	int ch;
+	char *np;
+
+	/*
+	 * Clean up tty name.
+	 */
+	if (!strncmp(tty, _PATH_DEV, strlen(_PATH_DEV)))
+		tty += 5;
+
+	/*
+	 * Display prompt.
+	 */
+	ch = ' ';
+	*name = '\0';
+	while (ch != '\n') {
+		do_issue(tty);
+
+		np = name;
+		while ((ch = readch(tty)) != '\n') {
+			if (np < name + len)
+				*np++ = ch;
+		}
+
+		*np = '\0';
+		if (*name == '\0')
+			ch = ' ';	/* blank line typed! */
+	}
+
+	name[len - 1] = 0;
+}
+
+/* Execute the login(1) command with the current
+ * username as its argument. It will reply to the
+ * calling user by typing "Password: "...
+ */
+static int do_login(char *name)
+{
+	struct stat st;
+
+	execl(_PATH_LOGIN, _PATH_LOGIN, name, NULL);
+
+	/*
+	 * Failed to exec login, should be impossible.  Try a starting a
+	 * fallback shell instead.
+	 *
+	 * Note: Add /etc/securetty handling.
+	 */
+	warnx("Failed exec %s, attempting fallback to %s ...", _PATH_LOGIN, _PATH_BSHELL);
+	if (fstat(0, &st) == 0 && S_ISCHR(st.st_mode))
+		execl(_PATH_BSHELL, _PATH_BSHELL, NULL);
+
+	return 1;	/* We shouldn't get here ... */
+}
+
+static speed_t do_parse_speed(char *baud)
+{
+	char *ptr;
+	size_t i;
+	unsigned long val;
+	struct { unsigned long val; speed_t speed; } v2s[] = {
+		{       0, B0       },
+		{      50, B50      },
+		{      75, B75      },
+		{     110, B110     },
+		{     134, B134     },
+		{     150, B150     },
+		{     200, B200     },
+		{     300, B300     },
+		{     600, B600     },
+		{    1200, B1200    },
+		{    1800, B1800    },
+		{    2400, B2400    },
+		{    4800, B4800    },
+		{    9600, B9600    },
+		{   19200, B19200   },
+		{   38400, B38400   },
+		{   57600, B57600   },
+		{  115200, B115200  },
+		{  230400, B230400  },
+		{  460800, B460800  },
+		{  500000, B500000  },
+		{  576000, B576000  },
+		{  921600, B921600  },
+		{ 1000000, B1000000 },
+		{ 1152000, B1152000 },
+		{ 1500000, B1500000 },
+		{ 2000000, B2000000 },
+		{ 2500000, B2500000 },
+		{ 3000000, B3000000 },
+		{ 3500000, B3500000 },
+		{ 4000000, B4000000 },
+	};
+
+	errno = 0;
+	val = strtoul(baud, &ptr, 10);
+	if (errno || ptr == baud)
+		return B0;
+
+	for (i = 0; i < sizeof(v2s) / sizeof(v2s[0]); i++) {
+		if (v2s[i].val == val)
+			return v2s[i].speed;
+	}
+
+	return B0;
+}
+
+int getty(char *tty, char *baud, char *UNUSED(term))
+{
+	int fd;
+	char name[30];
+	speed_t speed = B38400;
+	struct sigaction sa;
+
+	if (baud) {
+		speed = do_parse_speed(baud);
+		if (speed == B0) {
+			FLOG_ERROR("TTY %s: Invalid speed %s", tty, baud);
+			return 1;
+		}
+	}
+
+	/* Detach from initial controlling TTY */
+	vhangup();
+
+	fd = open(tty, O_RDWR);
+	if (fd < 0)
+		err(1, "Failed opening %s", tty);
+
+	dup2(fd, STDIN_FILENO);
+	dup2(fd, STDOUT_FILENO);
+	dup2(fd, STDERR_FILENO);
+
+	if (ioctl(STDIN_FILENO, TIOCSCTTY, 1) < 0)
+		warn("Failed TIOCSCTTY");
+
+	/*
+	 * Don't let QUIT dump core.
+	 */
+	sigemptyset(&sa.sa_mask);
+	sa.sa_flags = 0;
+	sa.sa_handler = _exit;
+	sigaction(SIGQUIT, &sa, NULL);
+
+	stty(fd, speed);
+//	do_utmp();
+
+	do_getty(tty, name, sizeof(name));
+	return do_login(name);
+}
+
+/**
+ * Local Variables:
+ *  indent-tabs-mode: t
+ *  c-file-style: "linux"
+ * End:
+ */

helpers.h

@@ -83,7 +83,7 @@ void    set_hostname    (char **hostname);
 int     complete        (char *cmd, int pid);
 int     run             (char *cmd);
 int     run_interactive (char *cmd, char *fmt, ...);
-pid_t   run_getty       (char *cmd, char *args[], char *tty, int console);
+pid_t   run_getty       (char *tty, char *speed, char *term, int console);
 int     run_parts       (char *dir, char *cmd);
 
 #endif /* FINIT_HELPERS_H_ */

tty.c

@@ -39,8 +39,8 @@ LIST_HEAD(, tty_node) tty_list = LIST_HEAD_INITIALIZER();
 int tty_register(char *line)
 {
 	tty_node_t *entry;
-	int         insert = 0, baud = 0;
-	char       *cmd, *dev;
+	int         insert = 0;
+	char       *cmd, *dev, *baud = NULL;
 	char       *runlevels = NULL, *term = NULL;
 
 	if (!line) {
@@ -66,7 +66,7 @@ int tty_register(char *line)
 
 	cmd = strtok(NULL, " ");
 	if (cmd) {
-		baud = strtonum(cmd, 50, 4000000, NULL);
+		baud = strdup(cmd);
 		term = strtok(NULL, " ");
 	}
 
@@ -79,12 +79,10 @@ int tty_register(char *line)
 	}
 
 	entry->data.name = strdup(dev);
-	if (!baud)
-		baud = BAUDRATE;
 	entry->data.baud = baud;
 	entry->data.term = term ? strdup(term) : NULL;
 	entry->data.runlevels = conf_parse_runlevels(runlevels);
-	_d("Registering tty %s at %d baud with term=%s on runlevels %s", dev, baud, term ?: "N/A", runlevels);
+	_d("Registering tty %s at %s baud with term=%s on runlevels %s", dev, baud ?: "NULL", term ?: "N/A", runlevels);
 
 	if (insert)
 		LIST_INSERT_HEAD(&tty_list, entry, link);
@@ -127,40 +125,43 @@ tty_node_t *tty_find_by_pid(pid_t pid)
 	return NULL;
 }
 
-void tty_start(finit_tty_t *tty)
+static char *canonicalize(char *tty)
 {
-	int i = 0, is_console = 0;
-	char *cmd, *arg;
-	char  line[FILENAME_MAX];
-	char *args[42];
+	struct stat st;
+	static char path[80];
 
-	if (tty->pid)
+	if (!tty)
+		return NULL;
+
+	strlcpy(path, tty, sizeof(path));
+	if (stat(path, &st)) {
+		snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty);
+		if (stat(path, &st))
+			return NULL;
+	}
+
+	if (!S_ISCHR(st.st_mode))
+		return NULL;
+
+	return path;
+}
+
+void tty_start(finit_tty_t *fitty)
+{
+	int is_console = 0;
+	char *tty;
+
+	if (fitty->pid)
 		return;
 
-	if (console && !strcmp(tty->name, console))
+	tty = canonicalize(fitty->name);
+	if (!tty)
+		return;
+
+	if (console && !strcmp(tty, console))
 		is_console = 1;
 
-	if (!strncmp(tty->name, _PATH_DEV, strlen(_PATH_DEV))) {
-#if   defined(GETTY_AGETTY)
-		snprintf(line, sizeof(line), "%s %s %d %s", GETTY, tty->name, tty->baud, tty->term ?: "");
-#elif defined(GETTY_BUSYBOX)
-		snprintf(line, sizeof(line), "%s %d %s %s", GETTY, tty->baud, tty->name, tty->term ?: "");
-#else
-		strlcpy(line, FALLBACK_SHELL, sizeof(line));
-		is_console = 1;
-#endif
-	} else {
-		strlcpy(line, tty->name, sizeof(line));
-		is_console = 1;
-	}
-	cmd = strtok(line, " ");
-	args[i++] = basename(cmd);
-	while ((arg = strtok(NULL, " ")))
-		args[i++] = arg;
-	args[i] = NULL;
-
-	_d("Starting %s: %s on %s", is_console ? "console" : "TTY", cmd, tty->name);
-	tty->pid = run_getty(cmd, args, tty->name, is_console);
+	fitty->pid = run_getty(tty, fitty->baud, fitty->term, is_console);
 }
 
 void tty_stop(finit_tty_t *tty)

tty.h

@@ -32,7 +32,7 @@
 
 typedef struct {
 	char  *name;
-	int    baud;
+	char  *baud;
 	char  *term;
 	int    runlevels;