LXR busybox/util-linux/more.c

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