Add first cut of replacement for tip/cu. Not linked to the build.

Currently supports only -l and -s (no parity), no variables and ~., ~>,
~$, ~#, ~^Z, ~?. More to come.

Tested by naddy, otto. ok miod deraadt

6 files changed, 747 insertions, 0 deletions

diff --git a/usr.bin/cu/Makefile b/usr.bin/cu/Makefile
new file mode 100644
index 00000000000..fe37a6d0dee
--- /dev/null
+++ b/usr.bin/cu/Makefile
@@ -0,0 +1,11 @@
+# $OpenBSD: Makefile,v 1.1 2012/07/10 08:02:27 nicm Exp $
+
+PROG=	cu
+SRCS=	cu.c command.c input.c
+
+CDIAGFLAGS+= -Wall -W -Wno-unused-parameter
+
+LDADD=  -levent
+DPADD=  ${LIBEVENT}
+
+.include <bsd.prog.mk>
diff --git a/usr.bin/cu/command.c b/usr.bin/cu/command.c
new file mode 100644
index 00000000000..b63ccd08a46
--- /dev/null
+++ b/usr.bin/cu/command.c
@@ -0,0 +1,135 @@
+/* $OpenBSD: command.c,v 1.1 2012/07/10 08:02:27 nicm Exp $ */
+
+/*
+ * Copyright (c) 2012 Nicholas Marriott <nicm@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
+ * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
+ * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include <sys/wait.h>
+
+#include <event.h>
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <paths.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include "cu.h"
+
+void	pipe_command(void);
+void	send_file(void);
+
+void
+pipe_command(void)
+{
+	const char	*cmd;
+	pid_t		 pid;
+	int		 fd;
+
+	cmd = get_input("Local command?");
+	if (cmd == NULL || *cmd == '\0')
+		return;
+
+	switch (pid = fork()) {
+	case -1:
+		err(1, "fork");
+	case 0:
+		fd = open(_PATH_DEVNULL, O_RDWR);
+		if (fd < 0 || dup2(fd, STDIN_FILENO) == -1)
+			_exit(1);
+		close(fd);
+
+		/* attach stdout to line */
+		if (dup2(line_fd, STDOUT_FILENO) == -1)
+			_exit(1);
+
+		if (closefrom(STDOUT_FILENO + 1) != 0)
+			_exit(1);
+
+		execl(_PATH_BSHELL, "sh", "-c", cmd, (void*)NULL);
+		_exit(1);
+	default:
+		while (waitpid(pid, NULL, 0) == -1 && errno == EINTR)
+			/* nothing */;
+		break;
+	}
+}
+
+void
+send_file(void)
+{
+	const char	*file;
+	FILE		*f;
+	char		 buf[BUFSIZ], *expanded;
+	size_t		 len;
+
+	file = get_input("Local file?");
+	if (file == NULL || *file == '\0')
+		return;
+
+	expanded = tilde_expand(file);
+	f = fopen(expanded, "r");
+	if (f == NULL) {
+		warn("%s", file);
+		return;
+	}
+
+	while (!feof(f) && !ferror(f)) {
+		len = fread(buf, 1, sizeof(buf), f);
+		if (len != 0)
+			bufferevent_write(line_ev, buf, len);
+	}
+
+	fclose(f);
+	free(expanded);
+}
+
+void
+do_command(char c)
+{
+	switch (c) {
+	case '.':
+	case '\004': /* ^D */
+		event_loopexit(NULL);
+		break;
+	case '\032': /* ^Z */
+		restore_termios();
+		kill(getpid(), SIGTSTP);
+		set_termios();
+		break;
+	case '$':
+		pipe_command();
+		break;
+	case '>':
+		send_file();
+		break;
+	case '#':
+		ioctl(line_fd, TIOCSBRK, NULL);
+		sleep(1);
+		ioctl(line_fd, TIOCCBRK, NULL);
+		break;
+	case '?':
+		printf("\r\n"
+		    "~>      send file to remote host\r\n"
+		    "~$      pipe local command to remote host\r\n"
+		    "~?      get this summary\r\n"
+		    "~#      send break\r\n");
+		break;
+	}
+}
diff --git a/usr.bin/cu/cu.1 b/usr.bin/cu/cu.1
new file mode 100644
index 00000000000..b5568259e63
--- /dev/null
+++ b/usr.bin/cu/cu.1
@@ -0,0 +1,137 @@
+.\"	$OpenBSD: cu.1,v 1.1 2012/07/10 08:02:27 nicm Exp $
+.\"
+.\" Copyright (c) 1980, 1990, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 3. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"	@(#)tip.1	8.4 (Berkeley) 4/18/94
+.\"
+.Dd $Mdocdate: July 10 2012 $
+.Dt CU 1
+.Os
+.Sh NAME
+.Nm cu
+.Nd serial terminal emulator
+.Sh SYNOPSIS
+.Nm
+.Op Fl l Ar line
+.Op Fl s Ar speed \*(Ba Fl Ar speed
+.Sh DESCRIPTION
+.Nm
+is used to connect to another system over a serial link.
+In the era before modern networks, it was typically used to
+connect to a modem in order to dial in to a remote host.
+It is now frequently used for tasks such as attaching to the
+serial console of another machine for administrative or
+debugging purposes.
+.Pp
+The options are as follows:
+.Bl -tag -width 4n
+.It Fl l Ar line
+Specify the line to use.
+Either of the forms like
+.Pa tty00
+or
+.Pa /dev/tty00
+are permitted.
+The default is
+.Pa /dev/cua00 .
+.Pp
+For reasons outlined in
+.Xr tty 4 ,
+.Xr cua 4
+devices should be used on architectures which have them.
+For those which do not,
+.Xr tty 4
+devices can be used.
+Users in group
+.Dq dialer
+are permitted to use
+.Xr cua 4
+devices by default;
+permissions on
+.Pa /dev/tty00
+or
+.Pa /dev/ttya
+can be changed,
+but they will revert to their defaults
+after an upgrade or (re)install.
+.It Fl s Ar speed \*(Ba Fl Ar speed
+Set the speed of the connection.
+The default is 9600.
+.El
+.Pp
+Typed characters are normally transmitted directly to the remote
+machine (which does the echoing as well).
+A tilde
+.Pq Ql ~
+appearing as the first character of a line is an escape signal; the
+following are recognized:
+.Bl -tag -offset indent -width Fl
+.It Ic ~^D No or Ic ~.
+Drop the connection and exit.
+Only the connection is dropped \(en the login session is not terminated.
+.It Ic ~\*(Gt
+Copy file from local to remote.
+.Nm
+prompts for the name of a local file to transmit.
+.It Ic ~$
+Pipe the output from a local
+.Ux
+process to the remote host.
+The command string sent to the local
+.Ux
+system is processed by the shell.
+.It Ic ~#
+Send a
+.Dv BREAK
+to the remote system.
+.It Ic ~^Z
+Stop
+.Nm
+(only available with job control).
+.It Ic ~?
+Get a summary of the tilde escapes.
+.El
+.Pp
+When
+.Nm
+prompts for an argument, for example during setup of a file transfer,
+the line typed may be edited with the standard erase and kill characters.
+A null line in response to a prompt, or an interrupt, will abort the
+dialogue and return the user to the remote machine.
+.Pp
+.Nm
+guards against multiple users connecting to a remote system by opening
+modems and terminal lines with exclusive access.
+.Sh HISTORY
+The
+.Nm
+command appeared in
+.Bx 4.2 .
+This version was written for
+.Ox 5.2
+by Nicholas Marriott.
diff --git a/usr.bin/cu/cu.c b/usr.bin/cu/cu.c
new file mode 100644
index 00000000000..ad60e9a1b26
--- /dev/null
+++ b/usr.bin/cu/cu.c
@@ -0,0 +1,338 @@
+/* $OpenBSD: cu.c,v 1.1 2012/07/10 08:02:27 nicm Exp $ */
+
+/*
+ * Copyright (c) 2012 Nicholas Marriott <nicm@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
+ * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
+ * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/param.h>
+#include <sys/ioctl.h>
+
+#include <err.h>
+#include <event.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <paths.h>
+#include <pwd.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <termios.h>
+#include <unistd.h>
+
+#include "cu.h"
+
+extern char		*__progname;
+
+struct termios		 saved_tio;
+struct bufferevent	*input_ev;
+struct bufferevent	*output_ev;
+int			 line_fd;
+struct bufferevent	*line_ev;
+struct event		 sigterm_ev;
+enum {
+	STATE_NONE,
+	STATE_NEWLINE,
+	STATE_TILDE
+} last_state = STATE_NEWLINE;
+
+__dead void	usage(void);
+void		signal_event(int, short, void *);
+void		stream_read(struct bufferevent *, void *);
+void		stream_error(struct bufferevent *, short, void *);
+void		line_read(struct bufferevent *, void *);
+void		line_error(struct bufferevent *, short, void *);
+
+__dead void
+usage(void)
+{
+	fprintf(stderr, "usage: %s [-l line] [-s speed]\n", __progname);
+	exit(1);
+}
+
+int
+main(int argc, char **argv)
+{
+	const char	*line, *errstr;
+	char		*tmp;
+	int		 opt, speed, i, ch;
+	struct termios	 tio;
+	static char	 sbuf[12];
+
+	line = "/dev/cua00";
+	speed = 9600;
+
+	/*
+	 * Convert obsolescent -### speed to modern -s### syntax which getopt()
+	 * can handle.
+	 */
+	for (i = 1; i < argc; i++) {
+		if (argv[i][0] == '-') {
+			switch (argv[i][1]) {
+			case '0': case '1': case '2': case '3': case '4':
+			case '5': case '6': case '7': case '8': case '9':
+				ch = snprintf(sbuf, sizeof(sbuf), "-s%s",
+				    &argv[i][1]);
+				if (ch <= 0 || ch >= (int)sizeof(sbuf)) {
+					errx(1, "invalid speed: %s",
+					    &argv[i][1]);
+				}
+				argv[i] = sbuf;
+				break;
+			case '-':
+				/* if we get "--" stop processing args */
+				if (argv[i][2] == '\0')
+					goto getopt;
+				break;
+			}
+		}
+	}
+
+getopt:
+	while ((opt = getopt(argc, argv, "l:s:")) != -1) {
+		switch (opt) {
+		case 'l':
+			line = optarg;
+			break;
+		case 's':
+			speed = strtonum(optarg, 0, UINT_MAX, &errstr);
+			if (errstr != NULL)
+				errx(1, "speed is %s: %s", errstr, optarg);
+			break;
+		default:
+			usage();
+		}
+	}
+	argc -= optind;
+	argv += optind;
+	if (argc != 0)
+		usage();
+
+	if (strchr(line, '/') == NULL) {
+		if (asprintf(&tmp, "%s%s", _PATH_DEV, line) == -1)
+			err(1, "asprintf");
+		line = tmp;
+	}
+
+	line_fd = open(line, O_RDWR);
+	if (line_fd < 0)
+		err(1, "open(\"%s\")", line);
+	if (ioctl(line_fd, TIOCEXCL) != 0)
+		err(1, "ioctl(TIOCEXCL)");
+
+	cfmakeraw(&tio);
+	tio.c_iflag = 0;
+	tio.c_oflag = 0;
+	tio.c_lflag = 0;
+	tio.c_cflag = CREAD|CS8;
+	tio.c_cc[VMIN] = 1;
+	tio.c_cc[VTIME] = 0;
+	cfsetspeed(&tio, speed);
+	if (tcsetattr(line_fd, TCSAFLUSH, &tio) != 0)
+		err(1, "tcsetattr");
+
+	if (isatty(STDIN_FILENO) && tcgetattr(STDIN_FILENO, &saved_tio) != 0)
+		err(1, "tcgetattr");
+
+	event_init();
+	signal_set(&sigterm_ev, SIGTERM, signal_event, NULL);
+	signal_add(&sigterm_ev, NULL);
+
+	set_termios();
+
+	/* stdin and stdout get separate events */
+	input_ev = bufferevent_new(STDIN_FILENO, stream_read, NULL,
+	    stream_error, NULL);
+	bufferevent_enable(input_ev, EV_READ);
+	output_ev = bufferevent_new(STDOUT_FILENO, NULL, NULL, stream_error,
+	    NULL);
+	bufferevent_enable(output_ev, EV_WRITE);
+
+	line_ev = bufferevent_new(line_fd, line_read, NULL, line_error,
+	    NULL);
+	bufferevent_enable(line_ev, EV_READ|EV_WRITE);
+
+	printf("Connected (speed %u)\r\n", speed);
+	event_dispatch();
+
+	if (isatty(STDIN_FILENO))
+		tcsetattr(STDIN_FILENO, TCSAFLUSH, &saved_tio);
+	printf("\r\n[EOT]\n");
+
+	exit(0);
+}
+
+void
+signal_event(int fd, short events, void *data)
+{
+	if (isatty(STDIN_FILENO))
+		tcsetattr(STDIN_FILENO, TCSAFLUSH, &saved_tio);
+	printf("\r\n[SIG%s]\n", sys_signame[fd]);
+
+	exit(0);
+}
+
+void
+set_termios(void)
+{
+	struct termios tio;
+
+	if (!isatty(STDIN_FILENO))
+		return;
+
+	memcpy(&tio, &saved_tio, sizeof(tio));
+	tio.c_lflag &= ~(ICANON|IEXTEN|ECHO);
+	tio.c_iflag &= ~(INPCK|ICRNL);
+	tio.c_oflag &= ~OPOST;
+	tio.c_cc[VMIN] = 1;
+	tio.c_cc[VTIME] = 0;
+	tio.c_cc[VDISCARD] = _POSIX_VDISABLE;
+	tio.c_cc[VDSUSP] = _POSIX_VDISABLE;
+	tio.c_cc[VINTR] = _POSIX_VDISABLE;
+	tio.c_cc[VLNEXT] = _POSIX_VDISABLE;
+	tio.c_cc[VQUIT] = _POSIX_VDISABLE;
+	tio.c_cc[VSUSP] = _POSIX_VDISABLE;
+	if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &tio) != 0)
+		err(1, "tcsetattr");
+}
+
+void
+restore_termios(void)
+{
+	if (!isatty(STDIN_FILENO))
+		return;
+
+	if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &saved_tio) != 0)
+		err(1, "tcsetattr");
+}
+
+void
+stream_read(struct bufferevent *bufev, void *data)
+{
+	char	*new_data, *ptr;
+	size_t	 new_size;
+	int	 state_change;
+
+	new_data = EVBUFFER_DATA(input_ev->input);
+	new_size = EVBUFFER_LENGTH(input_ev->input);
+	if (new_size == 0)
+		return;
+
+	state_change = isatty(STDIN_FILENO);
+	for (ptr = new_data; ptr < new_data + new_size; ptr++) {
+		switch (last_state) {
+		case STATE_NONE:
+			if (state_change && *ptr == '\r')
+				last_state = STATE_NEWLINE;
+			break;
+		case STATE_NEWLINE:
+			if (state_change && *ptr == '~') {
+				last_state = STATE_TILDE;
+				continue;
+			}
+			if (*ptr != '\r')
+				last_state = STATE_NONE;
+			break;
+		case STATE_TILDE:
+			do_command(*ptr);
+			last_state = STATE_NEWLINE;
+			continue;
+		}
+
+		bufferevent_write(line_ev, ptr, 1);
+	}
+
+	evbuffer_drain(input_ev->input, new_size);
+}
+
+void
+stream_error(struct bufferevent *bufev, short what, void *data)
+{
+	event_loopexit(NULL);
+}
+
+void
+line_read(struct bufferevent *bufev, void *data)
+{
+	char	*new_data;
+	size_t	 new_size;
+
+	new_data = EVBUFFER_DATA(line_ev->input);
+	new_size = EVBUFFER_LENGTH(line_ev->input);
+	if (new_size == 0)
+		return;
+
+	bufferevent_write(output_ev, new_data, new_size);
+
+	evbuffer_drain(line_ev->input, new_size);
+}
+
+void
+line_error(struct bufferevent *bufev, short what, void *data)
+{
+	event_loopexit(NULL);
+}
+
+/* Expands tildes in the file name. Based on code from ssh/misc.c. */
+char *
+tilde_expand(const char *filename1)
+{
+	const char	*filename, *path;
+	char		 user[128], ret[MAXPATHLEN], *out;
+	struct passwd	*pw;
+	u_int		 len, slash;
+
+	if (*filename1 != '~')
+		goto no_change;
+	filename = filename1 + 1;
+
+	path = strchr(filename, '/');
+	if (path != NULL && path > filename) {		/* ~user/path */
+		slash = path - filename;
+		if (slash > sizeof(user) - 1)
+			goto no_change;
+		memcpy(user, filename, slash);
+		user[slash] = '\0';
+		if ((pw = getpwnam(user)) == NULL)
+			goto no_change;
+	} else if ((pw = getpwuid(getuid())) == NULL)	/* ~/path */
+		goto no_change;
+
+	if (strlcpy(ret, pw->pw_dir, sizeof(ret)) >= sizeof(ret))
+		goto no_change;
+
+	/* Make sure directory has a trailing '/' */
+	len = strlen(pw->pw_dir);
+	if ((len == 0 || pw->pw_dir[len - 1] != '/') &&
+	    strlcat(ret, "/", sizeof(ret)) >= sizeof(ret))
+		goto no_change;
+
+	/* Skip leading '/' from specified path */
+	if (path != NULL)
+		filename = path + 1;
+	if (strlcat(ret, filename, sizeof(ret)) >= sizeof(ret))
+		goto no_change;
+
+	out = strdup(ret);
+	if (out == NULL)
+		err(1, "strdup");
+	return (out);
+
+no_change:
+	out = strdup(filename1);
+	if (out == NULL)
+		err(1, "strdup");
+	return (out);
+}
diff --git a/usr.bin/cu/cu.h b/usr.bin/cu/cu.h
new file mode 100644
index 00000000000..db669becf31
--- /dev/null
+++ b/usr.bin/cu/cu.h
@@ -0,0 +1,37 @@
+/* $OpenBSD: cu.h,v 1.1 2012/07/10 08:02:27 nicm Exp $ */
+
+/*
+ * Copyright (c) 2012 Nicholas Marriott <nicm@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
+ * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
+ * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef CU_H
+#define CU_H
+
+/* command.c */
+void				 do_command(char);
+
+/* cu.c */
+extern struct bufferevent	*input_ev;
+extern struct bufferevent	*output_ev;
+extern int			 line_fd;
+extern struct bufferevent	*line_ev;
+void				 set_termios(void);
+void				 restore_termios(void);
+char				*tilde_expand(const char *);
+
+/* input.c */
+const char			*get_input(const char *);
+
+#endif
diff --git a/usr.bin/cu/input.c b/usr.bin/cu/input.c
new file mode 100644
index 00000000000..03f8599662d
--- /dev/null
+++ b/usr.bin/cu/input.c
@@ -0,0 +1,89 @@
+/* $OpenBSD: input.c,v 1.1 2012/07/10 08:02:27 nicm Exp $ */
+
+/*
+ * Copyright (c) 2012 Nicholas Marriott <nicm@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
+ * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
+ * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+
+#include <ctype.h>
+#include <err.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdio.h>
+#include <string.h>
+#include <termios.h>
+#include <unistd.h>
+
+#include "cu.h"
+
+/*
+ * Prompt and read a line of user input from stdin. We want to use the termios
+ * we were started with so restore and stick in a signal handler for ^C.
+ */
+
+volatile sig_atomic_t input_stop;
+
+void	input_signal(int);
+
+void
+input_signal(int sig)
+{
+	input_stop = 1;
+}
+
+const char *
+get_input(const char *prompt)
+{
+	static char		s[BUFSIZ];
+	struct sigaction	act, oact;
+	char			c, *cp, *out = NULL;
+	ssize_t			n;
+
+	memset(&act, 0, sizeof(act));
+	sigemptyset(&act.sa_mask);
+	act.sa_flags = 0;
+	act.sa_handler = input_signal;
+	if (sigaction(SIGINT, &act, &oact) != 0)
+		err(1, "sigaction");
+	input_stop = 0;
+
+	restore_termios();
+
+	printf("%s ", prompt);
+	fflush(stdout);
+
+	cp = s;
+	while (cp != s + sizeof(s) - 1) {
+		n = read(STDIN_FILENO, &c, 1);
+		if (n == -1 && errno != EINTR)
+			err(1, "read");
+		if (n != 1 || input_stop)
+			break;
+		if (c == '\n') {
+			out = s;
+			break;
+		}
+		if (!iscntrl((u_char)c))
+			*cp++ = c;
+	}
+	*cp = '\0';
+
+	set_termios();
+
+	sigaction(SIGINT, &oact, NULL);
+
+	return (out);
+}