1/*-
2 * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26/*
27 * Simple paged-output and paged-viewing functions
28 */
29
30#include <sys/cdefs.h>
31__FBSDID("$FreeBSD$");
32
33#include "stand.h"
34#include <string.h>
35
36static int	p_maxlines = -1;
37static int	p_freelines;
38
39static char *pager_prompt1 = " --more--  <space> page down <enter> line down <q> quit ";
40static char *pager_blank   = "                                                        ";
41
42/*
43 * 'open' the pager
44 */
45void
46pager_open(void)
47{
48    int		nlines;
49    char	*cp, *lp;
50
51    nlines = 24;		/* sensible default */
52    if ((cp = getenv("LINES")) != NULL) {
53	nlines = strtol(cp, &lp, 0);
54    }
55
56    p_maxlines = nlines - 1;
57    if (p_maxlines < 1)
58	p_maxlines = 1;
59    p_freelines = p_maxlines;
60}
61
62/*
63 * 'close' the pager
64 */
65void
66pager_close(void)
67{
68    p_maxlines = -1;
69}
70
71/*
72 * Emit lines to the pager; may not return until the user
73 * has responded to the prompt.
74 *
75 * Will return nonzero if the user enters 'q' or 'Q' at the prompt.
76 *
77 * XXX note that this watches outgoing newlines (and eats them), but
78 *     does not handle wrap detection (req. count of columns).
79 */
80
81int
82pager_output(const char *cp)
83{
84    int		action;
85
86    if (cp == NULL)
87	return(0);
88
89    for (;;) {
90	if (*cp == 0)
91	    return(0);
92
93	putchar(*cp);			/* always emit character */
94
95	if (*(cp++) == '\n') {		/* got a newline? */
96	    p_freelines--;
97	    if (p_freelines <= 0) {
98		printf("%s", pager_prompt1);
99		action = 0;
100		while (action == 0) {
101		    switch(getchar()) {
102		    case '\r':
103		    case '\n':
104			p_freelines = 1;
105			action = 1;
106			break;
107		    case ' ':
108			p_freelines = p_maxlines;
109			action = 1;
110			break;
111		    case 'q':
112		    case 'Q':
113			action = 2;
114			break;
115		    default:
116			break;
117		    }
118		}
119		printf("\r%s\r", pager_blank);
120		if (action == 2)
121		    return(1);
122	    }
123	}
124    }
125}
126
127/*
128 * Display from (fd).
129 */
130int
131pager_file(const char *fname)
132{
133    char	buf[80];
134    size_t	hmuch;
135    int		fd;
136    int		result;
137
138    if ((fd = open(fname, O_RDONLY)) == -1) {
139	printf("can't open '%s': %s\n", fname, strerror(errno));
140	return(-1);
141    }
142
143    for (;;) {
144	hmuch = read(fd, buf, sizeof(buf) - 1);
145	if (hmuch == -1) {
146	    result = -1;
147	    break;
148	}
149	if (hmuch == 0) {
150	    result = 0;
151	    break;
152	}
153	buf[hmuch] = 0;
154	if (pager_output(buf)) {
155	    result = 1;
156	    break;
157	}
158    }
159    close(fd);
160    return(result);
161}
162