pick.c

#include "config.h"

#include <sys/ioctl.h>

#include <ctype.h>
#include <err.h>
#include <limits.h>
#include <locale.h>
#include <poll.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include <wchar.h>
#include <wctype.h>

#define tty_putp(capability, fatal) do {				\
	if (tputs((capability), 1, tty_putc) == ERR && (fatal))		\
		errx(1, #capability ": unknown terminfo capability");	\
} while (0)

enum key {
	UNKNOWN = 0,
	ALT_ENTER = 1,
	BACKSPACE = 2,
	DEL = 3,
	ENTER = 4,
	CTRL_A = 5,
	CTRL_C = 6,
	CTRL_E = 7,
	CTRL_K = 8,
	CTRL_L = 9,
	CTRL_O = 10,
	CTRL_U = 11,
	CTRL_W = 12,
	CTRL_Z = 13,
	RIGHT = 14,
	LEFT = 15,
	LINE_DOWN = 16,
	LINE_UP = 17,
	PAGE_DOWN = 18,
	PAGE_UP = 19,
	END = 20,
	HOME = 21,
	PRINTABLE = 22,
};

struct choice {
	const char	*description;
	const char	*string;
	size_t		 length;
	ssize_t		 match_start;	/* inclusive match start offset */
	ssize_t		 match_end;	/* exclusive match end offset */
	double		 score;
};

static int			 choicecmp(const void *, const void *);
static void			 delete_between(char *, size_t, size_t, size_t);
static char			*eager_strpbrk(const char *, const char *);
static int			 filter_choices(size_t);
static char			*get_choices(void);
static enum key			 get_key(const char **);
static void			 handle_sigwinch(int);
static int			 isu8cont(unsigned char);
static int			 isu8start(unsigned char);
static int			 isword(const char *);
static size_t			 min_match(const char *, size_t, ssize_t *,
    ssize_t *);
static size_t			 print_choices(size_t, size_t);
static void			 print_line(const char *, size_t, int, ssize_t,
    ssize_t);
static const struct choice	*selected_choice(void);
static size_t			 skipescseq(const char *);
static const char		*strcasechr(const char *, const char *);
static void			 toggle_sigwinch(int);
static int			 tty_getc(void);
static const char		*tty_getcap(char *);
static void			 tty_init(int);
static const char		*tty_parm1(char *, int);
static int			 tty_putc(int);
static void			 tty_restore(int);
static void			 tty_size(void);
static __dead void		 usage(void);
static int			 xmbtowc(wchar_t *, const char *);

static struct termios		 tio;
static struct {
	size_t		 size;
	size_t		 length;
	struct choice	*v;
} choices;
static FILE			*tty_in, *tty_out;
static char			*query;
static size_t			 query_length, query_size;
static volatile sig_atomic_t	 gotsigwinch;
static unsigned int		 choices_lines, tty_columns, tty_lines;
static int			 descriptions;
static int			 sort = 1;
static int			 use_alternate_screen = 1;
static int			 use_keypad = 1;

int
main(int argc, char *argv[])
{
	const struct choice *choice;
	char *input;
	int output_description = 0;
	int rc = 0;
	int c;

	setlocale(LC_CTYPE, "");

	if (pledge("stdio tty rpath wpath cpath", NULL) == -1)
		err(1, "pledge");

	while ((c = getopt(argc, argv, "doq:KSxX")) != -1)
		switch (c) {
		case 'd':
			descriptions = 1;
			break;
		case 'K':
			use_keypad = 0;
			break;
		case 'o':
			/*
			 * Only output description if descriptions are read and
			 * displayed in the list of choices.
			 */
			output_description = descriptions;
			break;
		case 'q':
			if ((query = strdup(optarg)) == NULL)
				err(1, "strdup");
			query_length = strlen(query);
			query_size = query_length + 1;
			break;
		case 'S':
			sort = 0;
			break;
		case 'x':
			use_alternate_screen = 1;
			break;
		case 'X':
			use_alternate_screen = 0;
			break;
		default:
			usage();
		}
	argc -= optind;
	argv += optind;
	if (argc > 0)
		usage();

	if (query == NULL) {
		query_size = 64;
		if ((query = calloc(query_size, sizeof(char))) == NULL)
			err(1, NULL);
	}

	input = get_choices();
	tty_init(1);

	if (pledge("stdio tty", NULL) == -1)
		err(1, "pledge");

	choice = selected_choice();
	tty_restore(1);
	if (choice != NULL) {
		printf("%s\n", choice->string);
		if (output_description)
			printf("%s\n", choice->description);
	} else {
		rc = 1;
	}

	free(input);
	free(choices.v);
	free(query);

	return rc;
}

__dead void
usage(void)
{
	fprintf(stderr, "usage: pick [-dKoSXx] [-q query]\n");
	exit(1);
}

char *
get_choices(void)
{
	char *buf, *description, *ifs, *start, *stop;
	ssize_t n;
	size_t length = 0;
	size_t size = BUFSIZ;

	if ((ifs = getenv("IFS")) == NULL || *ifs == '\0')
		ifs = " ";

	if ((buf = malloc(size)) == NULL)
		err(1, NULL);
	for (;;) {
		if ((n = read(STDIN_FILENO, buf + length, size - length)) == -1)
			err(1, "read");
		else if (n == 0)
			break;

		length += n;
		if (length + 1 < size)
			continue;
		if ((buf = reallocarray(buf, 2, size)) == NULL)
			err(1, NULL);
		size *= 2;
	}
	buf[length] = '\0';

	choices.size = 16;
	if ((choices.v = reallocarray(NULL, choices.size,
	    sizeof(struct choice))) == NULL)
		err(1, NULL);

	start = buf;
	while ((stop = strchr(start, '\n')) != NULL) {
		*stop = '\0';

		if (descriptions && (description = eager_strpbrk(start, ifs)))
			*description++ = '\0';
		else
			description = "";

		choices.v[choices.length].length = stop - start;
		choices.v[choices.length].string = start;
		choices.v[choices.length].description = description;
		choices.v[choices.length].match_start = -1;
		choices.v[choices.length].match_end = -1;
		choices.v[choices.length].score = 0;

		start = stop + 1;

		/* Ensure room for a extra choice when ALT_ENTER is invoked. */
		if (++choices.length + 1 < choices.size)
			continue;
		choices.size *= 2;
		if ((choices.v = reallocarray(choices.v, choices.size,
		    sizeof(struct choice))) == NULL)
			err(1, NULL);
	}

	return buf;
}

char *
eager_strpbrk(const char *string, const char *separators)
{
	char *ptr = NULL;
	char *tmp_ptr;

	for (tmp_ptr = strpbrk(string, separators);
	    tmp_ptr;
	    tmp_ptr = strpbrk(tmp_ptr, separators))
		ptr = tmp_ptr++;

	return ptr;
}

const struct choice *
selected_choice(void)
{
	const char *buf;
	size_t choices_count = 0;
	size_t selection = 0;
	size_t yscroll = 0;
	size_t cursor_position, i, j, length, xscroll;
	int dochoices = 0;
	int dofilter = 1;
	int query_grew = 0;

	cursor_position = query_length;

	for (;;) {
		/*
		 * If the user didn't add more characters to the query all
		 * choices have to be reconsidered as potential matches.
		 * In the opposite scenario, there's no point in reconsidered
		 * all choices again since the ones that didn't match the
		 * previous query will clearly not match the current one due to
		 * the fact that previous query is a left-most substring of the
		 * current one.
		 */
		if (!query_grew)
			choices_count = choices.length;
		query_grew = 0;
		if (dofilter) {
			if ((dochoices = filter_choices(choices_count)))
				dofilter = selection = yscroll = 0;
		}

		tty_putp(cursor_invisible, 0);
		tty_putp(carriage_return, 1); /* move cursor to first column */
		if (cursor_position >= tty_columns)
			xscroll = cursor_position - tty_columns + 1;
		else
			xscroll = 0;
		print_line(&query[xscroll], query_length - xscroll, 0, -1, -1);
		if (dochoices) {
			if (selection - yscroll >= choices_lines)
				yscroll = selection - choices_lines + 1;
			choices_count = print_choices(yscroll, selection);
		}
		tty_putp(carriage_return, 1); /* move cursor to first column */
		for (i = j = 0; i < cursor_position; j++)
			while (isu8cont(query[++i]))
				continue;
		if (j > 0)
			/*
			 * parm_right_cursor interprets 0 as 1, therefore only
			 * move the cursor if the position is non zero.
			 */
			tty_putp(tty_parm1(parm_right_cursor, j), 1);
		tty_putp(cursor_normal, 0);
		fflush(tty_out);

		switch (get_key(&buf)) {
		case ENTER:
			if (choices_count > 0)
				return &choices.v[selection];
			break;
		case ALT_ENTER:
			choices.v[choices.length].string = query;
			choices.v[choices.length].description = "";
			return &choices.v[choices.length];
		case CTRL_C:
			return NULL;
		case CTRL_Z:
			tty_restore(0);
			kill(getpid(), SIGTSTP);
			tty_init(0);
			break;
		case BACKSPACE:
			if (cursor_position > 0) {
				for (length = 1;
				    isu8cont(query[cursor_position - length]);
				    length++)
					continue;
				delete_between(query, query_length,
				    cursor_position - length, cursor_position);
				cursor_position -= length;
				query_length -= length;
				dofilter = 1;
			}
			break;
		case DEL:
			if (cursor_position < query_length) {
				for (length = 1;
				    isu8cont(query[cursor_position + length]);
				    length++)
					continue;
				delete_between(query, query_length,
				    cursor_position, cursor_position + length);
				query_length -= length;
				dofilter = 1;
			}
			break;
		case CTRL_U:
			delete_between(query, query_length, 0, cursor_position);
			query_length -= cursor_position;
			cursor_position = 0;
			dofilter = 1;
			break;
		case CTRL_K:
			delete_between(query, query_length, cursor_position,
			    query_length);
			query_length = cursor_position;
			dofilter = 1;
			break;
		case CTRL_L:
			tty_size();
			break;
		case CTRL_O:
			sort = !sort;
			dofilter = 1;
			break;
		case CTRL_W:
			if (cursor_position == 0)
				break;

			for (i = cursor_position; i > 0;) {
				while (isu8cont(query[--i]))
					continue;
				if (isword(query + i))
					break;
			}
			for (j = i; i > 0; i = j) {
				while (isu8cont(query[--j]))
					continue;
				if (!isword(query + j))
					break;
			}
			delete_between(query, query_length, i, cursor_position);
			query_length -= cursor_position - i;
			cursor_position = i;
			dofilter = 1;
			break;
		case CTRL_A:
			cursor_position = 0;
			break;
		case CTRL_E:
			cursor_position = query_length;
			break;
		case LINE_DOWN:
			if (selection < choices_count - 1) {
				selection++;
				if (selection - yscroll == choices_lines)
					yscroll++;
			}
			break;
		case LINE_UP:
			if (selection > 0) {
				selection--;
				if (yscroll > selection)
					yscroll--;
			}
			break;
		case LEFT:
			while (cursor_position > 0 &&
			    isu8cont(query[--cursor_position]))
				continue;
			break;
		case RIGHT:
			while (cursor_position < query_length &&
			    isu8cont(query[++cursor_position]))
				continue;
			break;
		case PAGE_DOWN:
			if (selection + choices_lines < choices_count)
				yscroll = selection += choices_lines;
			else
				selection = choices_count - 1;
			break;
		case PAGE_UP:
			if (selection > choices_lines)
				yscroll = selection -= choices_lines;
			else
				yscroll = selection = 0;
			break;
		case END:
			if (choices_count > 0)
				selection = choices_count - 1;
			break;
		case HOME:
			yscroll = selection = 0;
			break;
		case PRINTABLE:
			length = strlen(buf);

			if (query_length + length >= query_size) {
				query_size = 2*query_length + length;
				if ((query = reallocarray(query, query_size,
				    sizeof(char))) == NULL)
					err(1, NULL);
			}

			if (cursor_position < query_length) {
				memmove(query + cursor_position + length,
				    query + cursor_position,
				    query_length - cursor_position);
			}

			memcpy(query + cursor_position, buf, length);
			cursor_position += length;
			query_length += length;
			query[query_length] = '\0';
			dofilter = query_grew = 1;
			break;
		case UNKNOWN:
			break;
		}
	}
}

/*
 * Filter the first nchoices number of choices using the current query and
 * regularly check for new user input in order to abort filtering. This
 * improves the performance when the cardinality of the choices is large.
 * Returns non-zero if the filtering was not aborted.
 */
int
filter_choices(size_t nchoices)
{
	struct choice *c;
	struct pollfd pfd;
	size_t i, match_length;
	int nready;

	for (i = 0; i < nchoices; i++) {
		c = &choices.v[i];
		if (min_match(c->string, 0,
		    &c->match_start, &c->match_end) == INT_MAX) {
			c->match_start = c->match_end = -1;
			c->score = 0;
		} else if (!sort) {
			c->score = 1;
		} else {
			match_length = c->match_end - c->match_start;
			c->score = (double)query_length/match_length/c->length;
		}

		if (i > 0 && i % 50 == 0) {
			pfd.fd = fileno(tty_in);
			pfd.events = POLLIN;
			if ((nready = poll(&pfd, 1, 0)) == -1)
				err(1, "poll");
			if (nready == 1 && pfd.revents & (POLLIN | POLLHUP))
				return 0;
		}
	}
	qsort(choices.v, nchoices, sizeof(struct choice), choicecmp);

	return 1;
}

int
choicecmp(const void *p1, const void *p2)
{
	const struct choice *c1, *c2;

	c1 = p1;
	c2 = p2;
	if (c1->score < c2->score)
		return 1;
	if (c1->score > c2->score)
		return -1;
	/*
	 * The two choices have an equal score.
	 * Sort based on the address of string since it reflects the initial
	 * input order.
	 * The comparison is inverted since the choice with the lowest address
	 * must come first.
	 */
	if (c1->string < c2->string)
		return -1;
	if (c1->string > c2->string)
		return 1;
	return 0;
}

size_t
min_match(const char *string, size_t offset, ssize_t *start, ssize_t *end)
{
	const char *e, *q, *s;
	size_t length;

	q = query;
	if (*q == '\0' || (s = e = strcasechr(&string[offset], q)) == NULL)
		return INT_MAX;

	for (;;) {
		for (e++, q++; isu8cont(*q); e++, q++)
			continue;
		if (*q == '\0')
			break;
		if ((e = strcasechr(e, q)) == NULL)
			return INT_MAX;
	}

	length = e - s;
	/* LEQ is used to obtain the shortest left-most match. */
	if (length == query_length ||
	    length <= min_match(string, s - string + 1, start, end)) {
		*start = s - string;
		*end = e - string;
	}

	return *end - *start;
}

/*
 * Returns a pointer to first occurrence of the first character in s2 in s1 with
 * respect to Unicode characters disregarding case.
 */
const char *
strcasechr(const char *s1, const char *s2)
{
	wchar_t wc1, wc2;
	size_t i;
	int nbytes;

	if (xmbtowc(&wc2, s2) == 0)
		return NULL;

	for (i = 0; s1[i] != '\0';) {
		if ((nbytes = skipescseq(s1 + i)) > 0)
			/* A match inside an escape sequence is ignored. */;
		else if ((nbytes = xmbtowc(&wc1, s1 + i)) == 0)
			nbytes = 1;
		else if (wcsncasecmp(&wc1, &wc2, 1) == 0)
			return s1 + i;
		i += nbytes;
	}

	return NULL;
}

/*
 * Returns the length of a CSI or OSC escape sequence located at the beginning
 * of str.
 */
size_t
skipescseq(const char *str)
{
	size_t i;
	int csi = 0;
	int osc = 0;

	if (str[0] == '\033' && str[1] == '[')
		csi = 1;
	else if (str[0] == '\033' && str[1] == ']')
		osc = 1;
	else
		return 0;

	for (i = 2; str[i] != '\0'; i++)
		if ((csi && str[i] >= '@' && str[i] <= '~') ||
		    (osc && str[i] == '\a'))
			break;

	return i + 1;
}

void
tty_init(int doinit)
{
	struct termios new_attributes;

	if (doinit && (tty_in = fopen("/dev/tty", "r")) == NULL)
		err(1, "fopen");

	tcgetattr(fileno(tty_in), &tio);
	new_attributes = tio;
	new_attributes.c_iflag |= ICRNL;	/* map CR to NL */
	new_attributes.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);
	new_attributes.c_cc[VMIN] = 1;
	new_attributes.c_cc[VTIME] = 0;
	new_attributes.c_cc[VDISCARD] = _POSIX_VDISABLE;
	tcsetattr(fileno(tty_in), TCSANOW, &new_attributes);

	if (doinit && (tty_out = fopen("/dev/tty", "w")) == NULL)
		err(1, "fopen");

	if (doinit)
		setupterm((char *)0, fileno(tty_out), (int *)0);

	tty_size();

	if (use_keypad)
		tty_putp(keypad_xmit, 0);
	if (use_alternate_screen)
		tty_putp(enter_ca_mode, 0);

	toggle_sigwinch(0);
}

int
tty_putc(int c)
{
	if (putc(c, tty_out) == EOF)
		err(1, "putc");

	return c;
}

void
handle_sigwinch(int sig)
{
	gotsigwinch = sig == SIGWINCH;
}

void
toggle_sigwinch(int enable)
{
	struct sigaction sa;

	sa.sa_flags = 0;
	sa.sa_handler = enable ? handle_sigwinch : SIG_IGN;
	sigemptyset(&sa.sa_mask);

	if (sigaction(SIGWINCH, &sa, NULL) == -1)
		err(1, "sigaction: SIGWINCH");
}

void
tty_restore(int doclose)
{
	tcsetattr(fileno(tty_in), TCSANOW, &tio);
	if (doclose)
		fclose(tty_in);

	tty_putp(carriage_return, 1);	/* move cursor to first column */
	tty_putp(clr_eos, 1);

	if (use_keypad)
		tty_putp(keypad_local, 0);
	if (use_alternate_screen)
		tty_putp(exit_ca_mode, 0);

	if (doclose)
		fclose(tty_out);
	else
		fflush(tty_out);
}

void
tty_size(void)
{
	struct winsize ws;
	const char *cp;
	int sz;

	if (ioctl(fileno(tty_in), TIOCGWINSZ, &ws) != -1) {
		tty_columns = ws.ws_col;
		tty_lines = ws.ws_row;
	}

	if (tty_columns == 0 && (sz = tigetnum("cols")) > 0)
		tty_columns = sz;
	if (tty_lines == 0 && (sz = tigetnum("lines")) > 0)
		tty_lines = sz;

	if ((cp = getenv("COLUMNS")) != NULL &&
	    (sz = strtonum(cp, 1, INT_MAX, NULL)) > 0)
		tty_columns = sz;
	if ((cp = getenv("LINES")) != NULL &&
	    (sz = strtonum(cp, 1, INT_MAX, NULL)) > 0)
		tty_lines = sz;

	if (tty_columns == 0)
		tty_columns = 80;
	if (tty_lines == 0)
		tty_lines = 24;

	choices_lines = tty_lines - 1;	/* available lines, minus query line */
}

void
print_line(const char *str, size_t len, int standout, ssize_t enter_underline,
    ssize_t exit_underline)
{
	size_t i;
	wchar_t wc;
	unsigned int col;
	int nbytes, width;

	if (standout)
		tty_putp(enter_standout_mode, 1);

	col = i = 0;
	while (col < tty_columns) {
		if (enter_underline == (ssize_t)i)
			tty_putp(enter_underline_mode, 1);
		else if (exit_underline == (ssize_t)i)
			tty_putp(exit_underline_mode, 1);
		if (i == len)
			break;

		if (str[i] == '\t') {
			width = 8 - (col & 7);	/* ceil to multiple of 8 */
			if (col + width > tty_columns)
				break;
			col += width;

			for (; width > 0; width--)
				tty_putc(' ');

			i++;
			continue;
		}

		/*
		 * A NUL will be present prior the NUL-terminator if
		 * descriptions are enabled.
		 */
		if (str[i] == '\0') {
			tty_putc(' ');
			i++;
			col++;
			continue;
		}

		/*
		 * Output every character, even invalid ones and escape
		 * sequences. Even tho they don't occupy any columns.
		 */
		if ((nbytes = skipescseq(str + i)) > 0) {
			width = 0;
		} else if ((nbytes = xmbtowc(&wc, str + i)) == 0) {
			nbytes = 1;
			width = 0;
		} else if ((width = wcwidth(wc)) < 0) {
			width = 0;
		}

		if (col + width > tty_columns)
			break;
		col += width;

		for (; nbytes > 0; nbytes--, i++)
			tty_putc(str[i]);
	}
	for (; col < tty_columns; col++)
		tty_putc(' ');

	/*
	 * If exit_underline is greater than columns the underline attribute
	 * will spill over on the next line unless all attributes are exited.
	 */
	tty_putp(exit_attribute_mode, 1);
}

/*
 * Output as many choices as possible starting from offset and return the number
 * of choices with a positive score. If the query is empty, all choices are
 * considered having a positive score.
 */
size_t
print_choices(size_t offset, size_t selection)
{
	const struct choice *choice;
	size_t i;

	for (i = offset; i < choices.length; i++) {
		choice = choices.v + i;
		if (choice->score == 0 && query_length > 0)
			break;

		if (i - offset < choices_lines) {
			print_line(choice->string, choice->length,
			    i == selection, choice->match_start,
			    choice->match_end);
		}
	}

	if (i - offset < choices.length && i - offset < choices_lines) {
		/*
		 * Printing the choices did not consume all available
		 * lines and there could still be choices left from the
		 * last print in the lines not yet consumed.
		 *
		 * The clr_eos capability clears the screen from the
		 * current column to the end. If the last visible choice
		 * is selected, the standout in the last and current
		 * column will be also be cleared. Therefore, move down
		 * one line before clearing the screen.
		 */
		tty_putc('\n');
		tty_putp(clr_eos, 1);
		tty_putp(tty_parm1(parm_up_cursor, (i - offset) + 1), 1);
	} else if (i > 0) {
		/*
		 * parm_up_cursor interprets 0 as 1, therefore only move
		 * upwards if any choices where printed.
		 */
		tty_putp(tty_parm1(parm_up_cursor,
		    i < choices_lines ? i : choices_lines), 1);
	}

	return i;
}

enum key
get_key(const char **key)
{
#define	CAP(k, s)	{ k,	s,	NULL,	0,		-1 }
#define	KEY(k, s)	{ k,	NULL,	s,	sizeof(s) - 1,	-1 }
#define	TIO(k, i)	{ k,	NULL,	NULL,	0,		i }
	static struct {
		enum key	 key;
		char		*cap;
		const char	*str;
		size_t		 len;
		int		 tio;
	} keys[] = {
		KEY(ALT_ENTER,	"\033\n"),
		KEY(BACKSPACE,	"\177"),
		KEY(BACKSPACE,	"\b"),
		KEY(CTRL_A,	"\001"),
		TIO(CTRL_C,	VINTR),
		KEY(CTRL_E,	"\005"),
		KEY(CTRL_K,	"\013"),
		KEY(CTRL_L,	"\014"),
		KEY(CTRL_O,	"\017"),
		KEY(CTRL_U,	"\025"),
		KEY(CTRL_W,	"\027"),
		KEY(CTRL_W,	"\033\177"),
		KEY(CTRL_W,	"\033\b"),
		TIO(CTRL_Z,	VSUSP),
		CAP(DEL,	"kdch1"),
		KEY(DEL,	"\004"),
		CAP(END,	"kend"),
		KEY(END,	"\033>"),
		KEY(ENTER,	"\n"),
		CAP(ENTER,	"kent"),
		CAP(HOME,	"khome"),
		KEY(HOME,	"\033<"),
		CAP(LEFT,	"kcub1"),
		KEY(LEFT,	"\002"),
		KEY(LEFT,	"\033OD"),
		CAP(LINE_DOWN,	"kcud1"),
		KEY(LINE_DOWN,	"\016"),
		KEY(LINE_DOWN,	"\033OB"),
		CAP(LINE_UP,	"kcuu1"),
		KEY(LINE_UP,	"\020"),
		KEY(LINE_UP,	"\033OA"),
		CAP(PAGE_DOWN,	"knp"),
		KEY(PAGE_DOWN,	"\026"),
		KEY(PAGE_DOWN,	"\033 "),
		CAP(PAGE_UP,	"kpp"),
		KEY(PAGE_UP,	"\033v"),
		CAP(RIGHT,	"kcuf1"),
		KEY(RIGHT,	"\006"),
		KEY(RIGHT,	"\033OC"),
		KEY(UNKNOWN,	NULL),
	};
	static unsigned char buf[8];
	size_t len;
	int c, i;

	memset(buf, 0, sizeof(buf));
	*key = (const char *)buf;
	len = 0;

	/*
	 * Allow SIGWINCH on the first read. If the signal is received, return
	 * CTRL_L which will trigger a resize.
	 */
	toggle_sigwinch(1);
	buf[len++] = tty_getc();
	toggle_sigwinch(0);
	if (gotsigwinch) {
		gotsigwinch = 0;
		return CTRL_L;
	}

	for (;;) {
		for (i = 0; keys[i].key != UNKNOWN; i++) {
			if (keys[i].tio >= 0) {
				if (len == 1 &&
				    tio.c_cc[keys[i].tio] == *buf &&
				    tio.c_cc[keys[i].tio] != _POSIX_VDISABLE)
					return keys[i].key;
				continue;
			}

			if (keys[i].str == NULL) {
				keys[i].str = tty_getcap(keys[i].cap);
				keys[i].len = strlen(keys[i].str);
			}
			if (strncmp(keys[i].str, *key, len) != 0)
				continue;

			if (len == keys[i].len)
				return keys[i].key;

			/* Partial match found, continue reading. */
			break;
		}
		if (keys[i].key == UNKNOWN)
			break;

		if (len == sizeof(buf) - 1)
			break;
		buf[len++] = tty_getc();
	}

	if (len > 1 && buf[0] == '\033' && (buf[1] == '[' || buf[1] == 'O')) {
		/*
		 * An escape sequence which is not a supported key is being
		 * read. Discard the rest of the sequence.
		 */
		c = buf[len - 1];
		while (c < '@' || c > '~')
			c = tty_getc();

		return UNKNOWN;
	}

	if (!isu8start(buf[0])) {
		if (isprint(buf[0]))
			return PRINTABLE;

		return UNKNOWN;
	}

	/*
	 * Ensure a whole Unicode character is read. The number of MSBs in the
	 * first octet of a Unicode character is equal to the number of octets
	 * the character consists of, followed by a zero. Therefore, as long as
	 * the MSB is not zero there is still bytes left to read.
	 */
	for (;;) {
		if (((buf[0] << len) & 0x80) == 0)
			break;
		if (len == sizeof(buf) - 1)
			return UNKNOWN;

		buf[len++] = tty_getc();
	}

	return PRINTABLE;
}

int
tty_getc(void)
{
	int c;

	if ((c = getc(tty_in)) == ERR && !gotsigwinch)
		err(1, "getc");

	return c;
}

const char *
tty_getcap(char *cap)
{
	char *str;

	str = tigetstr(cap);
	if (str == (char *)(-1) || str == NULL)
		return "";

	return str;
}

const char *
tty_parm1(char *cap, int a)
{
	return tparm(cap, a, 0, 0, 0, 0, 0, 0, 0, 0);
}

void
delete_between(char *string, size_t length, size_t start, size_t end)
{
	memmove(string + start, string + end, length - end + 1);
}

int
isu8cont(unsigned char c)
{
	return MB_CUR_MAX > 1 && (c & (0x80 | 0x40)) == 0x80;
}

int
isu8start(unsigned char c)
{
	return MB_CUR_MAX > 1 && (c & (0x80 | 0x40)) == (0x80 | 0x40);
}

int
isword(const char *s)
{
	wchar_t wc;

	if (xmbtowc(&wc, s) == 0)
		return 0;

	return iswalnum(wc) || wc == L'_';
}

int
xmbtowc(wchar_t *wc, const char *s)
{
	int n;

	n = mbtowc(wc, s, MB_CUR_MAX);
	if (n == -1) {
		/* Assign in order to suppress ignored return value warning. */
		n = mbtowc(NULL, NULL, MB_CUR_MAX);
		return 0;
	}

	return n;
}