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 source tree.
15 */
16 //config:config MORE
17 //config: bool "more (7 kb)"
18 //config: default y
19 //config: help
20 //config: more is a simple utility which allows you to read text one screen
21 //config: sized page at a time. If you want to read text that is larger than
22 //config: the screen, and you are using anything faster than a 300 baud modem,
23 //config: you will probably find this utility very helpful. If you don't have
24 //config: any need to reading text files, you can leave this disabled.
25
26 //applet:IF_MORE(APPLET(more, BB_DIR_BIN, BB_SUID_DROP))
27
28 //kbuild:lib-$(CONFIG_MORE) += more.o
29
30 //usage:#define more_trivial_usage
31 //usage: "[FILE]..."
32 //usage:#define more_full_usage "\n\n"
33 //usage: "View FILE (or stdin) one screenful at a time"
34 //usage:
35 //usage:#define more_example_usage
36 //usage: "$ dmesg | more\n"
37
38 #include "libbb.h"
39 #include "common_bufsiz.h"
40
41 struct globals {
42 int tty_fileno;
43 unsigned terminal_width;
44 unsigned terminal_height;
45 struct termios initial_settings;
46 } FIX_ALIASING;
47 #define G (*(struct globals*)bb_common_bufsiz1)
48 #define INIT_G() do { setup_common_bufsiz(); } while (0)
49
get_wh(void)50 static void get_wh(void)
51 {
52 /* never returns w, h <= 1 */
53 get_terminal_width_height(G.tty_fileno, &G.terminal_width, &G.terminal_height);
54 G.terminal_height -= 1;
55 }
56
tcsetattr_tty_TCSANOW(struct termios * settings)57 static void tcsetattr_tty_TCSANOW(struct termios *settings)
58 {
59 tcsetattr(G.tty_fileno, TCSANOW, settings);
60 }
61
gotsig(int sig UNUSED_PARAM)62 static void gotsig(int sig UNUSED_PARAM)
63 {
64 /* bb_putchar_stderr doesn't use stdio buffering,
65 * therefore it is safe in signal handler */
66 bb_putchar_stderr('\n');
67 tcsetattr_tty_TCSANOW(&G.initial_settings);
68 _exit(EXIT_FAILURE);
69 }
70
71 #define CONVERTED_TAB_SIZE 8
72
73 int more_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
more_main(int argc UNUSED_PARAM,char ** argv)74 int more_main(int argc UNUSED_PARAM, char **argv)
75 {
76 int c = c; /* for compiler */
77 int input = 0;
78 int spaces = 0;
79 int please_display_more_prompt;
80 FILE *tty;
81
82 INIT_G();
83
84 /* Parse options */
85 /* Accepted but ignored: */
86 /* -d Display help instead of ringing bell */
87 /* -f Count logical lines (IOW: long lines are not folded) */
88 /* -l Do not pause after any line containing a ^L (form feed) */
89 /* -s Squeeze blank lines into one */
90 /* -u Suppress underlining */
91 getopt32(argv, "dflsu");
92 argv += optind;
93
94 /* Another popular pager, most, detects when stdout
95 * is not a tty and turns into cat. This makes sense. */
96 if (!isatty(STDOUT_FILENO))
97 return bb_cat(argv);
98 tty = fopen_for_read(CURRENT_TTY);
99 if (!tty)
100 return bb_cat(argv);
101
102 G.tty_fileno = fileno(tty);
103
104 /* Turn on unbuffered input; turn off echoing */
105 set_termios_to_raw(G.tty_fileno, &G.initial_settings, 0);
106 bb_signals(BB_FATAL_SIGS, gotsig);
107
108 do {
109 struct stat st;
110 FILE *file;
111 int len;
112 int lines;
113
114 file = stdin;
115 if (*argv) {
116 file = fopen_or_warn(*argv, "r");
117 if (!file)
118 continue;
119 }
120 st.st_size = 0;
121 fstat(fileno(file), &st);
122
123 get_wh();
124
125 please_display_more_prompt = 0;
126 len = 0;
127 lines = 0;
128 for (;;) {
129 int wrap;
130
131 if (spaces)
132 spaces--;
133 else {
134 c = getc(file);
135 if (c == EOF) break;
136 }
137 loop_top:
138 if (input != 'r' && please_display_more_prompt) {
139 len = printf("--More-- ");
140 if (st.st_size != 0) {
141 uoff_t d = (uoff_t)st.st_size / 100;
142 if (d == 0)
143 d = 1;
144 len += printf("(%u%% of %"OFF_FMT"u bytes)",
145 (int) ((uoff_t)ftello(file) / d),
146 st.st_size);
147 }
148
149 /*
150 * We've just displayed the "--More--" prompt, so now we need
151 * to get input from the user.
152 */
153 for (;;) {
154 fflush_all();
155 input = getc(tty);
156 input = tolower(input);
157 /* Erase the last message */
158 printf("\r%*s\r", len, "");
159
160 if (input == 'q')
161 goto end;
162 /* Due to various multibyte escape
163 * sequences, it's not ok to accept
164 * any input as a command to scroll
165 * the screen. We only allow known
166 * commands, else we show help msg. */
167 if (input == ' ' || input == '\n' || input == 'r')
168 break;
169 len = printf("(Enter:next line Space:next page Q:quit R:show the rest)");
170 }
171 len = 0;
172 lines = 0;
173 please_display_more_prompt = 0;
174
175 /* The user may have resized the terminal.
176 * Re-read the dimensions. */
177 get_wh();
178 }
179
180 /* Crudely convert tabs into spaces, which are
181 * a bajillion times easier to deal with. */
182 if (c == '\t') {
183 spaces = ((unsigned)~len) % CONVERTED_TAB_SIZE;
184 c = ' ';
185 }
186
187 /*
188 * There are two input streams to worry about here:
189 *
190 * c : the character we are reading from the file being "mored"
191 * input: a character received from the keyboard
192 *
193 * If we hit a newline in the _file_ stream, we want to test and
194 * see if any characters have been hit in the _input_ stream. This
195 * allows the user to quit while in the middle of a file.
196 */
197 wrap = (++len > G.terminal_width);
198 if (c == '\n' || wrap) {
199 /* Then outputting this character
200 * will move us to a new line. */
201 if (++lines >= G.terminal_height || input == '\n')
202 please_display_more_prompt = 1;
203 len = 0;
204 }
205 if (c != '\n' && wrap) {
206 /* Then outputting this will also put a character on
207 * the beginning of that new line. Thus we first want to
208 * display the prompt (if any), so we skip the putchar()
209 * and go back to the top of the loop, without reading
210 * a new character. */
211 goto loop_top;
212 }
213 /* My small mind cannot fathom backspaces and UTF-8 */
214 putchar(c);
215 die_if_ferror_stdout(); /* if tty was destroyed (closed xterm, etc) */
216 }
217 fclose(file);
218 fflush_all();
219 } while (*argv && *++argv);
220 end:
221 tcsetattr_tty_TCSANOW(&G.initial_settings);
222 return 0;
223 }
224