Refactor built-in getty into a standalone getty in /libexec

This patch moves the built-in getty out of Finit into /libexec/finit/,
reducing the size of the Finit binary and simplifying the code.

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

src/.gitignore

@@ -1,5 +1,6 @@
 .deps/*
 finit
+getty
 initctl
 keventd
 logit

src/Makefile.am

@@ -8,7 +8,7 @@ AM_LDFLAGS         = -export-dynamic
 endif
 
 sbin_PROGRAMS        = finit initctl
-pkglibexec_PROGRAMS  = logit sulogin
+pkglibexec_PROGRAMS  = getty logit sulogin
 if KEVENTD
 pkglibexec_PROGRAMS += keventd
 endif
@@ -19,6 +19,11 @@ endif
 finit_pkglibdir      = $(pkglibdir)
 finit_pkglib_SCRIPTS = rescue.conf sample.conf
 
+getty_SOURCES        = getty.c helpers.h logrotate.c stty.c utmp-api.c utmp-api.h
+getty_CFLAGS         = -W -Wall -Wextra -std=gnu99
+getty_CFLAGS        += $(lite_CFLAGS)
+getty_LDADD          = $(lite_LIBS)
+
 keventd_SOURCES      = keventd.c iwatch.c iwatch.h util.c util.h
 keventd_CFLAGS       = -W -Wall -Wextra -std=gnu99
 keventd_CFLAGS      += $(lite_CFLAGS)
@@ -37,7 +42,7 @@ finit_SOURCES      = api.c	cgroup.c	cgroup.h	\
 		     cond.c	cond-w.c	cond.h		\
 		     conf.c	conf.h				\
 		     exec.c	finit.c		finit.h		\
-		     getty.c	stty.c				\
+		     		stty.c				\
 		     helpers.c	helpers.h			\
 		     iwatch.c   iwatch.h			\
 		     log.c	log.h				\

src/exec.c

@@ -26,6 +26,7 @@
 
 #include <ctype.h>		/* isdigit() */
 #include <dirent.h>
+#include <err.h>
 #include <stdarg.h>
 #include <sys/ioctl.h>
 #include <sys/prctl.h>
@@ -388,9 +389,19 @@ pid_t run_getty(char *tty, char *baud, char *term, int noclear, int nowait, stru
 	speed = stty_parse_speed(baud);
 	prepare_tty(tty, speed, "tty", rlimit);
 	if (activate_console(noclear, nowait)) {
-		logit(LOG_INFO, "Starting built-in getty on %s, speed %u", tty, speed);
-		rc = getty(tty, speed, term, NULL);
+		char spd[15];
+		char *args[5] = {
+			"getty",
+			tty,
+			spd,
+			term,
+			NULL
+		};
+		snprintf(spd, sizeof(spd), "%d", speed);
+		logit(LOG_ERR, "Starting built-in getty on %s, speed %u", tty, speed);
+		rc = execv("/libexec/finit/getty", args);
 	}
+	logit(LOG_ERR, "Failed starting built-in getty on %s, speed %u", tty, speed);
 
 	return rc;
 }
@@ -414,6 +425,32 @@ pid_t run_getty2(char *tty, char *cmd, char *args[], int noclear, int nowait, st
 	return rc;
 }
 
+int sh(char *tty)
+{
+	char *args[2] = {
+		NULL,
+		NULL
+	};
+	char *arg0;
+	size_t len;
+
+	/* The getty process is usually responsible for the UTMP login record */
+	utmp_set_login(tty, NULL);
+
+	/* Start /bin/sh as a login shell, i.e. with a prefix '-' */
+	len = strlen(_PATH_BSHELL) + 2;
+	arg0 = malloc(len);
+	if (!arg0)
+		err(1, "Failed allocating memory");
+	snprintf(arg0, len, "-%s", _PATH_BSHELL);
+	args[0] = arg0;
+
+	/* Unblock signals inherited from parent */
+	sig_unblock();
+
+	return execv(_PATH_BSHELL, args);
+}
+
 pid_t run_sh(char *tty, int noclear, int nowait, struct rlimit rlimit[])
 {
 	int rc = 1;

src/getty.c

@@ -26,15 +26,13 @@
 #include <paths.h>
 #include <signal.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <sys/ioctl.h>
 #include <sys/utsname.h>
 #include <sys/ttydefaults.h>	/* Not included by default in musl libc */
 #include <termios.h>
 
-#include "finit.h"
-#include "cgroup.h"
 #include "helpers.h"
-#include "sig.h"
 #include "utmp-api.h"
 
 #ifndef _PATH_LOGIN
@@ -44,19 +42,14 @@
 /*
  * Read one character from stdin.
  */
-static int readch(char *tty)
+static int readch(void)
 {
-	int st;
 	char ch1;
+	int st;
 
 	st = read(STDIN_FILENO, &ch1, 1);
-	if (st == 0) {
-		dprint(STDOUT_FILENO, "\n", 0);
-		_exit(0);
-	}
-
-	if (st < 0)
-		errx(1, "getty: %s: read error", tty);
+	if (st <= 0)
+		return -1;
 
 	return ch1 & 0xFF;
 }
@@ -141,10 +134,10 @@ static void do_issue(char *tty)
 /*
  * Handle the process of a GETTY.
  */
-static void do_getty(char *tty, char *name, size_t len)
+static int get_logname(char *tty, char *name, size_t len)
 {
-	int ch;
 	char *np;
+	int ch;
 
 	/*
 	 * Display prompt.
@@ -155,14 +148,9 @@ static void do_getty(char *tty, char *name, size_t len)
 		do_issue(tty);
 
 		np = name;
-		while ((ch = readch(tty)) != '\n') {
-			if (ch == CTRL('U')) {
-				while (np > name) {
-					dprint(STDOUT_FILENO, "\b \b", 3);
-					np--;
-				}
-				continue;
-			}
+		while ((ch = readch()) != '\n') {
+			if (ch < 0)
+				return 1;
 
 			if (np < name + len)
 				*np++ = ch;
@@ -174,6 +162,7 @@ static void do_getty(char *tty, char *name, size_t len)
 	}
 
 	name[len - 1] = 0;
+	return 0;
 }
 
 /*
@@ -185,7 +174,6 @@ static int do_login(char *name)
 {
 	struct stat st;
 
-	cgroup_user(name, 0);
 	execl(_PATH_LOGIN, _PATH_LOGIN, name, NULL);
 
 	/*
@@ -196,12 +184,12 @@ static int do_login(char *name)
 	 */
 	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);
+		execl(_PATH_BSHELL, _PATH_BSHELL, NULL); /* XXX: run sulogin instead! */
 
 	return 1;	/* We shouldn't get here ... */
 }
 
-int getty(char *tty, speed_t speed, char *term, char *user)
+static int getty(char *tty, speed_t speed, char *term, char *user)
 {
 	const char cln[] = "\r\e[2K\n";
 	char name[33];		/* useradd(1) limit at 32 chars */
@@ -212,15 +200,20 @@ int getty(char *tty, speed_t speed, char *term, char *user)
 	if (!strncmp(tty, _PATH_DEV, strlen(_PATH_DEV)))
 		tty += 5;
 
-	/* Set up TTY, re-enabling ISIG et al. */
-	stty(STDIN_FILENO, speed);
-	dprint(STDERR_FILENO, cln, strlen(cln));
-
 	/* The getty process is responsible for the UTMP login record */
 	utmp_set_login(tty, NULL);
-	if (!user)
-		do_getty(tty, name, sizeof(name));
-	else
+
+	/* Replace "Please press enter ..." with login: */
+	dprint(STDERR_FILENO, cln, strlen(cln));
+
+restart:
+	stty(STDIN_FILENO, speed);
+	if (!user) {
+		if (get_logname(tty, name, sizeof(name))) {
+			sleep(5);
+			goto restart;
+		}
+	} else
 		strlcpy(name, user, sizeof(name));
 
 	if (term && term[0])
@@ -229,42 +222,14 @@ int getty(char *tty, speed_t speed, char *term, char *user)
 	return do_login(name);
 }
 
-int sh(char *tty)
+int main(int argc, char *argv[])
 {
-	struct termios term;
-	char *args[2] = {
-		NULL,
-		NULL
-	};
-	char *arg0;
-	size_t len;
-
-	/* The getty process is usually responsible for the UTMP login record */
-	utmp_set_login(tty, NULL);
-
-	/* Set up TTY, re-enabling ISIG et al. */
-	stty(STDIN_FILENO, B0);
-
-	/* Start /bin/sh as a login shell, i.e. with a prefix '-' */
-	len = strlen(_PATH_BSHELL) + 2;
-	arg0 = malloc(len);
-	if (!arg0)
-		err(1, "Failed allocating memory");
-	snprintf(arg0, len, "-%s", _PATH_BSHELL);
-	args[0] = arg0;
-
-	/* Reenable Ctrl-D and Ctrl-C, and ... */
-	if (!tcgetattr(STDIN_FILENO, &term)) {
-		term.c_lflag    |= ISIG;
-		term.c_cc[VEOF]  = CEOF;
-		term.c_cc[VINTR] = CINTR;
-		tcsetattr(STDIN_FILENO, TCSAFLUSH, &term);
+	if (argc < 4) {
+		warnx("usage: getty tty speed term");
+		return 1;
 	}
 
-	/* ... unblock signals in general */
-	sig_unblock();
-
-	return execv(_PATH_BSHELL, args);
+	return getty(argv[1], atoi(argv[2]), argv[3], NULL);
 }
 
 /**

src/helpers.h

@@ -68,11 +68,8 @@ char   *strip_line      (char *line);
 void    enable_progress (int onoff);
 void    show_progress   (pstyle_t style);
 
-int     getty           (char *tty, speed_t speed, char *term, char *user);
-int     sh              (char *tty);
-
-void    stty            (int fd, speed_t speed);
 speed_t stty_parse_speed(char *baud);
+void    stty            (int fd, speed_t speed);
 
 void    print_banner    (const char *heading);
 void    printv          (const char *fmt, va_list ap);

src/initctl.c

@@ -41,6 +41,7 @@
 #include "service.h"
 #include "cgutil.h"
 #include "util.h"
+#include "utmp-api.h"
 
 struct cmd {
 	char        *cmd;

src/util.c

@@ -229,16 +229,6 @@ int fngetint(char *path, int *val)
 	return 0;
 }
 
-/*
- * musl libc default to /dev/null/utmp and /dev/null/wtmp, respectively.
- * See https://www.openwall.com/lists/musl/2012/03/04/4 for reasoning.
- * Also, there's no __MUSL__, so we cannot make a libc-specific #ifdef
- */
-int has_utmp(void)
-{
-	return strncmp(_PATH_UTMP, "/dev/null", 9);
-}
-
 int strtobytes(char *arg)
 {
 	int mod = 0, bytes;

src/util.h

@@ -54,7 +54,6 @@ int   fnread       (char *buf, size_t len, char *fmt, ...);
 int   fnwrite      (char *value, char *fmt, ...);
 int   fngetint     (char *path, int *val);
 
-int   has_utmp     (void);
 int   strtobytes   (char *arg);
 char *sig2str      (int sig);
 char *code2str     (int code);

src/utmp-api.h

@@ -42,6 +42,16 @@ int utmp_show        (char *file);
 
 void runlevel_set    (int pre, int now);
 
+/*
+ * musl libc default to /dev/null/utmp and /dev/null/wtmp, respectively.
+ * See https://www.openwall.com/lists/musl/2012/03/04/4 for reasoning.
+ * Also, there's no __MUSL__, so we cannot make a libc-specific #ifdef
+ */
+static inline int has_utmp(void)
+{
+	return strncmp(_PATH_UTMP, "/dev/null", 9);
+}
+
 #endif /* FINIT_UTMP_API_H_ */
 
 /**