xref: /illumos-gate/usr/src/boot/libsa/pager.c (revision 22028508fd28d36ff74dc02c5774a8ba1f0db045)

/*
 * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */
/*
 * Simple paged-output and paged-viewing functions
 */

#include <sys/cdefs.h>

#include "stand.h"
#include <string.h>

static int	p_maxlines = -1;
static int	p_freelines;

static char *pager_prompt1 = \
	" --more--  <space> page down <enter> line down <q> quit ";
static char *pager_blank   = \
	"                                                        ";

/*
 * 'open' the pager
 */
void
pager_open(void)
{
	int	nlines;
	char	*cp, *lp;

	nlines = 24;		/* sensible default */
	if ((cp = getenv("screen-#rows")) != NULL) {
		nlines = strtol(cp, &lp, 0);
	}

	p_maxlines = nlines - 1;
	if (p_maxlines < 1)
		p_maxlines = 1;
	p_freelines = p_maxlines;
}

/*
 * 'close' the pager
 */
void
pager_close(void)
{
	p_maxlines = -1;
}

/*
 * Emit lines to the pager; may not return until the user
 * has responded to the prompt.
 *
 * Will return nonzero if the user enters 'q' or 'Q' at the prompt.
 *
 * XXX note that this watches outgoing newlines (and eats them), but
 *     does not handle wrap detection (req. count of columns).
 */

int
pager_output(const char *cp)
{
	int	action;

	if (cp == NULL)
		return (0);

	for (;;) {
		if (*cp == 0)
			return (0);

		putchar(*cp);			/* always emit character */

		if (*(cp++) == '\n') {		/* got a newline? */
			p_freelines--;
			if (p_freelines <= 0) {
				printf("%s", pager_prompt1);
				action = 0;
				while (action == 0) {
					switch (getchar()) {
					case '\r':
					case '\n':
						p_freelines = 1;
						action = 1;
						break;
					case ' ':
						p_freelines = p_maxlines;
						action = 1;
						break;
					case 'q':
					case 'Q':
						action = 2;
						break;
					default:
						break;
					}
				}
				printf("\r%s\r", pager_blank);
				if (action == 2)
					return (1);
			}
		}
	}
}

/*
 * Display from (fd).
 */
int
pager_file(const char *fname)
{
	char	buf[80];
	size_t	hmuch;
	int	fd;
	int	result;

	if ((fd = open(fname, O_RDONLY)) == -1) {
		printf("can't open '%s': %s\n", fname, strerror(errno));
		return (-1);
	}

	for (;;) {
		hmuch = read(fd, buf, sizeof (buf) - 1);
		if (hmuch == -1) {
			result = -1;
			break;
		}
		if (hmuch == 0) {
			result = 0;
			break;
		}
		buf[hmuch] = 0;
		if (pager_output(buf)) {
			result = 1;
			break;
		}
	}
	close(fd);
	return (result);
}