source: MondoRescue/branches/3.2/mindi-busybox/util-linux/more.c@ 3232

/* vi: set sw=4 ts=4: */
/*
 * Mini more implementation for busybox
 *
 * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
 *
 * Latest version blended together by Erik Andersen <andersen@codepoet.org>,
 * based on the original more implementation by Bruce, and code from the
 * Debian boot-floppies team.
 *
 * Termios corrects by Vladimir Oleynik <dzo@simtreas.ru>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

//usage:#define more_trivial_usage
//usage:       "[FILE]..."
//usage:#define more_full_usage "\n\n"
//usage:       "View FILE (or stdin) one screenful at a time"
//usage:
//usage:#define more_example_usage
//usage:       "$ dmesg | more\n"

#include "libbb.h"

/* Support for FEATURE_USE_TERMIOS */

struct globals {
    int cin_fileno;
    struct termios initial_settings;
    struct termios new_settings;
} FIX_ALIASING;
#define G (*(struct globals*)bb_common_bufsiz1)
#define INIT_G() ((void)0)
#define initial_settings (G.initial_settings)
#define new_settings     (G.new_settings    )
#define cin_fileno       (G.cin_fileno      )

#define setTermSettings(fd, argp) \
do { \
    if (ENABLE_FEATURE_USE_TERMIOS) \
        tcsetattr(fd, TCSANOW, argp); \
} while (0)
#define getTermSettings(fd, argp) tcgetattr(fd, argp)

static void gotsig(int sig UNUSED_PARAM)
{
    /* bb_putchar_stderr doesn't use stdio buffering,
     * therefore it is safe in signal handler */
    bb_putchar_stderr('\n');
    setTermSettings(cin_fileno, &initial_settings);
    _exit(EXIT_FAILURE);
}

#define CONVERTED_TAB_SIZE 8

int more_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int more_main(int argc UNUSED_PARAM, char **argv)
{
    int c = c; /* for compiler */
    int lines;
    int input = 0;
    int spaces = 0;
    int please_display_more_prompt;
    struct stat st;
    FILE *file;
    FILE *cin;
    int len;
    unsigned terminal_width;
    unsigned terminal_height;

    INIT_G();

    argv++;
    /* Another popular pager, most, detects when stdout
     * is not a tty and turns into cat. This makes sense. */
    if (!isatty(STDOUT_FILENO))
        return bb_cat(argv);
    cin = fopen_for_read(CURRENT_TTY);
    if (!cin)
        return bb_cat(argv);

    if (ENABLE_FEATURE_USE_TERMIOS) {
        cin_fileno = fileno(cin);
        getTermSettings(cin_fileno, &initial_settings);
        new_settings = initial_settings;
        new_settings.c_lflag &= ~(ICANON | ECHO);
        new_settings.c_cc[VMIN] = 1;
        new_settings.c_cc[VTIME] = 0;
        setTermSettings(cin_fileno, &new_settings);
        bb_signals(0
            + (1 << SIGINT)
            + (1 << SIGQUIT)
            + (1 << SIGTERM)
            , gotsig);
    }

    do {
        file = stdin;
        if (*argv) {
            file = fopen_or_warn(*argv, "r");
            if (!file)
                continue;
        }
        st.st_size = 0;
        fstat(fileno(file), &st);

        please_display_more_prompt = 0;
        /* never returns w, h <= 1 */
        get_terminal_width_height(fileno(cin), &terminal_width, &terminal_height);
        terminal_height -= 1;

        len = 0;
        lines = 0;
        while (spaces || (c = getc(file)) != EOF) {
            int wrap;
            if (spaces)
                spaces--;
 loop_top:
            if (input != 'r' && please_display_more_prompt) {
                len = printf("--More-- ");
                if (st.st_size != 0) {
                    uoff_t d = (uoff_t)st.st_size / 100;
                    if (d == 0)
                        d = 1;
                    len += printf("(%u%% of %"OFF_FMT"u bytes)",
                        (int) ((uoff_t)ftello(file) / d),
                        st.st_size);
                }
                fflush_all();

                /*
                 * We've just displayed the "--More--" prompt, so now we need
                 * to get input from the user.
                 */
                for (;;) {
                    input = getc(cin);
                    input = tolower(input);
                    if (!ENABLE_FEATURE_USE_TERMIOS)
                        printf("\033[A"); /* cursor up */
                    /* Erase the last message */
                    printf("\r%*s\r", len, "");

                    /* Due to various multibyte escape
                     * sequences, it's not ok to accept
                     * any input as a command to scroll
                     * the screen. We only allow known
                     * commands, else we show help msg. */
                    if (input == ' ' || input == '\n' || input == 'q' || input == 'r')
                        break;
                    len = printf("(Enter:next line Space:next page Q:quit R:show the rest)");
                }
                len = 0;
                lines = 0;
                please_display_more_prompt = 0;

                if (input == 'q')
                    goto end;

                /* The user may have resized the terminal.
                 * Re-read the dimensions. */
                if (ENABLE_FEATURE_USE_TERMIOS) {
                    get_terminal_width_height(cin_fileno, &terminal_width, &terminal_height);
                    terminal_height -= 1;
                }
            }

            /* Crudely convert tabs into spaces, which are
             * a bajillion times easier to deal with. */
            if (c == '\t') {
                spaces = ((unsigned)~len) % CONVERTED_TAB_SIZE;
                c = ' ';
            }

            /*
             * There are two input streams to worry about here:
             *
             * c    : the character we are reading from the file being "mored"
             * input: a character received from the keyboard
             *
             * If we hit a newline in the _file_ stream, we want to test and
             * see if any characters have been hit in the _input_ stream. This
             * allows the user to quit while in the middle of a file.
             */
            wrap = (++len > terminal_width);
            if (c == '\n' || wrap) {
                /* Then outputting this character
                 * will move us to a new line. */
                if (++lines >= terminal_height || input == '\n')
                    please_display_more_prompt = 1;
                len = 0;
            }
            if (c != '\n' && wrap) {
                /* Then outputting this will also put a character on
                 * the beginning of that new line. Thus we first want to
                 * display the prompt (if any), so we skip the putchar()
                 * and go back to the top of the loop, without reading
                 * a new character. */
                goto loop_top;
            }
            /* My small mind cannot fathom backspaces and UTF-8 */
            putchar(c);
            die_if_ferror_stdout(); /* if tty was destroyed (closed xterm, etc) */
        }
        fclose(file);
        fflush_all();
    } while (*argv && *++argv);
 end:
    setTermSettings(cin_fileno, &initial_settings);
    return 0;
}