1/* vi: set sw=4 ts=4: */
2/*
3 * Mini more implementation for busybox
4 *
5 * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
6 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
7 *
8 * Latest version blended together by Erik Andersen <andersen@codepoet.org>,
9 * based on the original more implementation by Bruce, and code from the
10 * Debian boot-floppies team.
11 *
12 * Termios corrects by Vladimir Oleynik <dzo@simtreas.ru>
13 *
14 * Licensed under GPLv2 or later, see file License in this tarball for details.
15 */
16
17#include "libbb.h"
18#if ENABLE_FEATURE_USE_TERMIOS
19#include <termios.h>
20#endif /* FEATURE_USE_TERMIOS */
21
22
23#if ENABLE_FEATURE_USE_TERMIOS
24
25struct globals {
26	int cin_fileno;
27	struct termios initial_settings;
28	struct termios new_settings;
29};
30#define G (*(struct globals*)bb_common_bufsiz1)
31//#define G (*ptr_to_globals)
32#define INIT_G() ((void)0)
33//#define INIT_G() PTR_TO_GLOBALS = xzalloc(sizeof(G))
34#define initial_settings (G.initial_settings)
35#define new_settings     (G.new_settings    )
36#define cin_fileno       (G.cin_fileno      )
37
38#define setTermSettings(fd, argp) tcsetattr(fd, TCSANOW, argp)
39#define getTermSettings(fd, argp) tcgetattr(fd, argp)
40
41static void gotsig(int sig)
42{
43	putchar('\n');
44	setTermSettings(cin_fileno, &initial_settings);
45	exit(EXIT_FAILURE);
46}
47
48#else /* !FEATURE_USE_TERMIOS */
49#define INIT_G() ((void)0)
50#define setTermSettings(fd, argp) ((void)0)
51#endif /* FEATURE_USE_TERMIOS */
52
53#define CONVERTED_TAB_SIZE 8
54
55int more_main(int argc, char **argv);
56int more_main(int argc, char **argv)
57{
58	int c = c; /* for gcc */
59	int lines;
60	int input = 0;
61	int spaces = 0;
62	int please_display_more_prompt;
63	struct stat st;
64	FILE *file;
65	FILE *cin;
66	int len;
67	int terminal_width;
68	int terminal_height;
69
70	INIT_G();
71
72	argv++;
73	/* Another popular pager, most, detects when stdout
74	 * is not a tty and turns into cat. This makes sense. */
75	if (!isatty(STDOUT_FILENO))
76		return bb_cat(argv);
77	cin = fopen(CURRENT_TTY, "r");
78	if (!cin)
79		return bb_cat(argv);
80
81#if ENABLE_FEATURE_USE_TERMIOS
82	cin_fileno = fileno(cin);
83	getTermSettings(cin_fileno, &initial_settings);
84	new_settings = initial_settings;
85	new_settings.c_lflag &= ~ICANON;
86	new_settings.c_lflag &= ~ECHO;
87	new_settings.c_cc[VMIN] = 1;
88	new_settings.c_cc[VTIME] = 0;
89	setTermSettings(cin_fileno, &new_settings);
90	signal(SIGINT, gotsig);
91	signal(SIGQUIT, gotsig);
92	signal(SIGTERM, gotsig);
93#endif
94
95	do {
96		file = stdin;
97		if (*argv) {
98			file = fopen_or_warn(*argv, "r");
99			if (!file)
100				continue;
101		}
102		st.st_size = 0;
103		fstat(fileno(file), &st);
104
105		please_display_more_prompt = 0;
106		/* never returns w, h <= 1 */
107		get_terminal_width_height(fileno(cin), &terminal_width, &terminal_height);
108		terminal_height -= 1;
109
110		len = 0;
111		lines = 0;
112		while (spaces || (c = getc(file)) != EOF) {
113			int wrap;
114			if (spaces)
115				spaces--;
116 loop_top:
117			if (input != 'r' && please_display_more_prompt) {
118				len = printf("--More-- ");
119				if (st.st_size > 0) {
120					len += printf("(%d%% of %"OFF_FMT"d bytes)",
121						(int) (ftello(file)*100 / st.st_size),
122						st.st_size);
123				}
124				fflush(stdout);
125
126				/*
127				 * We've just displayed the "--More--" prompt, so now we need
128				 * to get input from the user.
129				 */
130				for (;;) {
131					input = getc(cin);
132					input = tolower(input);
133#if !ENABLE_FEATURE_USE_TERMIOS
134					printf("\033[A"); /* up cursor */
135#endif
136					/* Erase the last message */
137					printf("\r%*s\r", len, "");
138
139					/* Due to various multibyte escape
140					 * sequences, it's not ok to accept
141					 * any input as a command to scroll
142					 * the screen. We only allow known
143					 * commands, else we show help msg. */
144					if (input == ' ' || input == '\n' || input == 'q' || input == 'r')
145						break;
146					len = printf("(Enter:next line Space:next page Q:quit R:show the rest)");
147				}
148				len = 0;
149				lines = 0;
150				please_display_more_prompt = 0;
151
152				if (input == 'q')
153					goto end;
154
155				/* The user may have resized the terminal.
156				 * Re-read the dimensions. */
157#if ENABLE_FEATURE_USE_TERMIOS
158				get_terminal_width_height(cin_fileno, &terminal_width, &terminal_height);
159				terminal_height -= 1;
160#endif
161			}
162
163			/* Crudely convert tabs into spaces, which are
164			 * a bajillion times easier to deal with. */
165			if (c == '\t') {
166				spaces = CONVERTED_TAB_SIZE - 1;
167				c = ' ';
168 			}
169
170			/*
171			 * There are two input streams to worry about here:
172			 *
173			 * c    : the character we are reading from the file being "mored"
174			 * input: a character received from the keyboard
175			 *
176			 * If we hit a newline in the _file_ stream, we want to test and
177			 * see if any characters have been hit in the _input_ stream. This
178			 * allows the user to quit while in the middle of a file.
179			 */
180			wrap = (++len > terminal_width);
181			if (c == '\n' || wrap) {
182				/* Then outputting this character
183				 * will move us to a new line. */
184				if (++lines >= terminal_height || input == '\n')
185					please_display_more_prompt = 1;
186				len = 0;
187			}
188			if (c != '\n' && wrap) {
189				/* Then outputting this will also put a character on
190				 * the beginning of that new line. Thus we first want to
191				 * display the prompt (if any), so we skip the putchar()
192				 * and go back to the top of the loop, without reading
193				 * a new character. */
194				goto loop_top;
195			}
196			/* My small mind cannot fathom backspaces and UTF-8 */
197			putchar(c);
198		}
199		fclose(file);
200		fflush(stdout);
201	} while (*argv && *++argv);
202 end:
203	setTermSettings(cin_fileno, &initial_settings);
204	return 0;
205}
206