source: MondoRescue/branches/2.2.5/mindi-busybox/coreutils/uudecode.c@ 1765

/* vi: set sw=4 ts=4: */
/*
 *  Copyright 2003, Glenn McGrath <bug1@iinet.net.au>
 *
 *  Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 *
 *  Based on specification from
 *  http://www.opengroup.org/onlinepubs/007904975/utilities/uuencode.html
 *
 *  Bugs: the spec doesn't mention anything about "`\n`\n" prior to the
 *        "end" line
 */


#include "libbb.h"

static void read_stduu(FILE *src_stream, FILE *dst_stream)
{
    char *line;

    while ((line = xmalloc_getline(src_stream)) != NULL) {
        int length;
        char *line_ptr = line;

        if (strcmp(line, "end") == 0) {
            return;
        }
        length = ((*line_ptr - 0x20) & 0x3f)* 4 / 3;

        if (length <= 0) {
            /* Ignore the "`\n" line, why is it even in the encode file ? */
            continue;
        }
        if (length > 60) {
            bb_error_msg_and_die("line too long");
        }

        line_ptr++;
        /* Tolerate an overly long line to accomodate a possible exta '`' */
        if (strlen(line_ptr) < (size_t)length) {
            bb_error_msg_and_die("short file");
        }

        while (length > 0) {
            /* Merge four 6 bit chars to three 8 bit chars */
            fputc(((line_ptr[0] - 0x20) & 077) << 2 | ((line_ptr[1] - 0x20) & 077) >> 4, dst_stream);
            line_ptr++;
            length--;
            if (length == 0) {
                break;
            }

            fputc(((line_ptr[0] - 0x20) & 077) << 4 | ((line_ptr[1] - 0x20) & 077) >> 2, dst_stream);
            line_ptr++;
            length--;
            if (length == 0) {
                break;
            }

            fputc(((line_ptr[0] - 0x20) & 077) << 6 | ((line_ptr[1] - 0x20) & 077), dst_stream);
            line_ptr += 2;
            length -= 2;
        }
        free(line);
    }
    bb_error_msg_and_die("short file");
}

static void read_base64(FILE *src_stream, FILE *dst_stream)
{
    int term_count = 1;

    while (1) {
        char translated[4];
        int count = 0;

        while (count < 4) {
            char *table_ptr;
            int ch;

            /* Get next _valid_ character.
             * global vector bb_uuenc_tbl_base64[] contains this string:
             * "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=\n"
             */
            do {
                ch = fgetc(src_stream);
                if (ch == EOF) {
                    bb_error_msg_and_die("short file");
                }
                table_ptr = strchr(bb_uuenc_tbl_base64, ch);
            } while (table_ptr == NULL);

            /* Convert encoded character to decimal */
            ch = table_ptr - bb_uuenc_tbl_base64;

            if (*table_ptr == '=') {
                if (term_count == 0) {
                    translated[count] = '\0';
                    break;
                }
                term_count++;
            } else if (*table_ptr == '\n') {
                /* Check for terminating line */
                if (term_count == 5) {
                    return;
                }
                term_count = 1;
                continue;
            } else {
                translated[count] = ch;
                count++;
                term_count = 0;
            }
        }

        /* Merge 6 bit chars to 8 bit */
        if (count > 1) {
            fputc(translated[0] << 2 | translated[1] >> 4, dst_stream);
        }
        if (count > 2) {
            fputc(translated[1] << 4 | translated[2] >> 2, dst_stream);
        }
        if (count > 3) {
            fputc(translated[2] << 6 | translated[3], dst_stream);
        }
    }
}

int uudecode_main(int argc, char **argv);
int uudecode_main(int argc, char **argv)
{
    FILE *src_stream = stdin;
    char *outname = NULL;
    char *line;

    opt_complementary = "?1"; /* 1 argument max */
    getopt32(argv, "o:", &outname);
    argv += optind;

    if (argv[0])
        src_stream = xfopen(argv[0], "r");

    /* Search for the start of the encoding */
    while ((line = xmalloc_getline(src_stream)) != NULL) {
        void (*decode_fn_ptr)(FILE * src, FILE * dst);
        char *line_ptr;
        FILE *dst_stream;
        int mode;

        if (strncmp(line, "begin-base64 ", 13) == 0) {
            line_ptr = line + 13;
            decode_fn_ptr = read_base64;
        } else if (strncmp(line, "begin ", 6) == 0) {
            line_ptr = line + 6;
            decode_fn_ptr = read_stduu;
        } else {
            free(line);
            continue;
        }

        /* begin line found. decode and exit */
        mode = strtoul(line_ptr, NULL, 8);
        if (outname == NULL) {
            outname = strchr(line_ptr, ' ');
            if ((outname == NULL) || (*outname == '\0')) {
                break;
            }
            outname++;
        }
        dst_stream = stdout;
        if (NOT_LONE_DASH(outname)) {
            dst_stream = xfopen(outname, "w");
            chmod(outname, mode & (S_IRWXU | S_IRWXG | S_IRWXO));
        }
        free(line);
        decode_fn_ptr(src_stream, dst_stream);
        /* fclose_if_not_stdin(src_stream); - redundant */
        return EXIT_SUCCESS;
    }
    bb_error_msg_and_die("no 'begin' line");
}

/* Test script.
Put this into an empty dir with busybox binary, an run.

#!/bin/sh
test -x busybox || { echo "No ./busybox?"; exit; }
ln -sf busybox uudecode
ln -sf busybox uuencode
>A_null
echo -n A >A
echo -n AB >AB
echo -n ABC >ABC
echo -n ABCD >ABCD
echo -n ABCDE >ABCDE
echo -n ABCDEF >ABCDEF
cat busybox >A_bbox
for f in A*; do
    echo uuencode $f
    ./uuencode    $f <$f >u_$f
    ./uuencode -m $f <$f >m_$f
done
mkdir unpk_u unpk_m 2>/dev/null
for f in u_*; do
    ./uudecode <$f -o unpk_u/${f:2}
    diff -a ${f:2} unpk_u/${f:2} >/dev/null 2>&1
    echo uudecode $f: $?
done
for f in m_*; do
    ./uudecode <$f -o unpk_m/${f:2}
    diff -a ${f:2} unpk_m/${f:2} >/dev/null 2>&1
    echo uudecode $f: $?
done
*/