source: MondoRescue/branches/stable/mindi-busybox/coreutils/expand.c

/* expand - convert tabs to spaces
 * unexpand - convert spaces to tabs
 *
 * Copyright (C) 89, 91, 1995-2006 Free Software Foundation, Inc.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 *
 * David MacKenzie <djm@gnu.ai.mit.edu>
 *
 * Options for expand:
 * -t num  --tabs=NUM      Convert tabs to num spaces (default 8 spaces).
 * -i      --initial       Only convert initial tabs on each line to spaces.
 *
 * Options for unexpand:
 * -a      --all           Convert all blanks, instead of just initial blanks.
 * -f      --first-only    Convert only leading sequences of blanks (default).
 * -t num  --tabs=NUM      Have tabs num characters apart instead of 8.
 *
 *  Busybox version (C) 2007 by Tito Ragusa <farmatito@tiscali.it>
 *
 *  Caveat: this versions of expand and unexpand don't accept tab lists.
 */

#include "libbb.h"

enum {
    OPT_INITIAL     = 1 << 0,
    OPT_TABS        = 1 << 1,
    OPT_ALL         = 1 << 2,
};

static void xputchar(char c)
{
    if (putchar(c) < 0)
        bb_error_msg_and_die(bb_msg_write_error);
}

#if ENABLE_EXPAND
static void expand(FILE *file, unsigned tab_size, unsigned opt)
{
    char *line;
    char *ptr;
    int convert;
    int pos;

    /* Increment tab_size by 1 locally.*/
    tab_size++;

    while ((line = xmalloc_fgets(file)) != NULL) {
        convert = 1;
        pos = 0;
        ptr = line;
        while (*line) {
            pos++;
            if (*line == '\t' && convert) {
                for (; pos < tab_size; pos++) {
                    xputchar(' ');
                }
            } else {
                if ((opt & OPT_INITIAL) && !isblank(*line)) {
                    convert = 0;
                }
                xputchar(*line);
            }
            if (pos == tab_size) {
                pos = 0;
            }
            line++;
        }
        free(ptr);
    }
}
#endif

#if ENABLE_UNEXPAND
static void unexpand(FILE *file, unsigned int tab_size, unsigned opt)
{
    char *line;
    char *ptr;
    int convert;
    int pos;
    int i = 0;
    int column = 0;

    while ((line = xmalloc_fgets(file)) != NULL) {
        convert = 1;
        pos = 0;
        ptr = line;
        while (*line) {
            while ((*line == ' ' || *line == '\t') && convert) {
                pos += (*line == ' ') ? 1 : tab_size;
                line++;
                column++;
                if ((opt & OPT_ALL) && column == tab_size) {
                    column = 0;
                    goto put_tab;
                }
            }
            if (pos) {
                i = pos / tab_size;
                if (i) {
                    for (; i > 0; i--) {
 put_tab:
                        xputchar('\t');
                    }
                } else {
                    for (i = pos % tab_size; i > 0; i--) {
                        xputchar(' ');
                    }
                }
                pos = 0;
            } else {
                if (opt & OPT_INITIAL) {
                    convert = 0;
                }
                if (opt & OPT_ALL) {
                    column++;
                }
                xputchar(*line);
                line++;
            }
        }
        free(ptr);
    }
}
#endif

int expand_main(int argc, char **argv);
int expand_main(int argc, char **argv)
{
    /* Default 8 spaces for 1 tab */
    const char *opt_t = "8";
    FILE *file;
    unsigned tab_size;
    unsigned opt;
    int exit_status = EXIT_SUCCESS;

#if ENABLE_FEATURE_EXPAND_LONG_OPTIONS
    static const char expand_longopts[] ALIGN1 =
        /* name, has_arg, val */
        "initial\0"          No_argument       "i"
        "tabs\0"             Required_argument "t"
    ;
#endif
#if ENABLE_FEATURE_UNEXPAND_LONG_OPTIONS
    static const char unexpand_longopts[] ALIGN1 =
        /* name, has_arg, val */
        "first-only\0"       No_argument       "i"
        "tabs\0"             Required_argument "t"
        "all\0"              No_argument       "a"
    ;
#endif

    if (ENABLE_EXPAND && (!ENABLE_UNEXPAND || applet_name[0] == 'e')) {
        USE_FEATURE_EXPAND_LONG_OPTIONS(applet_long_options = expand_longopts);
        opt = getopt32(argv, "it:", &opt_t);
    } else if (ENABLE_UNEXPAND) {
        USE_FEATURE_UNEXPAND_LONG_OPTIONS(applet_long_options = unexpand_longopts);
        /* -t NUM sets also -a */
        opt_complementary = "ta";
        opt = getopt32(argv, "ft:a", &opt_t);
        /* -f --first-only is the default */
        if (!(opt & OPT_ALL)) opt |= OPT_INITIAL;
    }
    tab_size = xatou_range(opt_t, 1, UINT_MAX);

    argv += optind;

    /* If no args are given, read from stdin */
    if (!*argv) {
        *--argv = (char*)bb_msg_standard_input;
        goto use_stdin;
    }

    do {
        if (NOT_LONE_CHAR(*argv, '-')) {
            file = fopen_or_warn(*argv, "r");
            if (!file) {
                exit_status = EXIT_FAILURE;
                continue;
            }
        } else {
 use_stdin:
            file = stdin;
        }

        if (ENABLE_EXPAND && (!ENABLE_UNEXPAND || applet_name[0] == 'e'))
            USE_EXPAND(expand(file, tab_size, opt));
        else if (ENABLE_UNEXPAND)
            USE_UNEXPAND(unexpand(file, tab_size, opt));

        /* Check and close the file */
        /* We do want all of them to execute, thus | instead of || */
        if (ferror(file) | fclose_if_not_stdin(file)) {
            bb_perror_msg("%s", *argv);
            exit_status = EXIT_FAILURE;
        }
        /* If stdin also clear EOF */
        if (file == stdin)
            clearerr(file);
    } while (*++argv);

    /* Now close stdin also */
    /* (if we didn't read from it, it's a no-op) */
    if (fclose(stdin))
        bb_perror_msg_and_die(bb_msg_standard_input);

    fflush_stdout_and_exit(exit_status);
}