source: MondoRescue/branches/2.2.9/mindi-busybox/libbb/uuencode.c@ 3320

/* vi: set sw=4 ts=4: */
/*
 * Copyright 2003, Glenn McGrath
 * Copyright 2006, Rob Landley <rob@landley.net>
 * Copyright 2010, Denys Vlasenko
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

#include "libbb.h"

/* Conversion table.  for base 64 */
const char bb_uuenc_tbl_base64[65 + 2] ALIGN1 = {
    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
    'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
    'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
    'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
    'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
    'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
    'w', 'x', 'y', 'z', '0', '1', '2', '3',
    '4', '5', '6', '7', '8', '9', '+', '/',
    '=' /* termination character */,
    '\n', '\0' /* needed for uudecode.c */
};

const char bb_uuenc_tbl_std[65] ALIGN1 = {
    '`', '!', '"', '#', '$', '%', '&', '\'',
    '(', ')', '*', '+', ',', '-', '.', '/',
    '0', '1', '2', '3', '4', '5', '6', '7',
    '8', '9', ':', ';', '<', '=', '>', '?',
    '@', 'A', 'B', 'C', 'D', 'E', 'F', 'G',
    'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
    'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
    'X', 'Y', 'Z', '[', '\\', ']', '^', '_',
    '`' /* termination character */
};

/*
 * Encode bytes at S of length LENGTH to uuencode or base64 format and place it
 * to STORE.  STORE will be 0-terminated, and must point to a writable
 * buffer of at least 1+BASE64_LENGTH(length) bytes.
 * where BASE64_LENGTH(len) = (4 * ((LENGTH + 2) / 3))
 */
void FAST_FUNC bb_uuencode(char *p, const void *src, int length, const char *tbl)
{
    const unsigned char *s = src;

    /* Transform the 3x8 bits to 4x6 bits */
    while (length > 0) {
        unsigned s1, s2;

        /* Are s[1], s[2] valid or should be assumed 0? */
        s1 = s2 = 0;
        length -= 3; /* can be >=0, -1, -2 */
        if (length >= -1) {
            s1 = s[1];
            if (length >= 0)
                s2 = s[2];
        }
        *p++ = tbl[s[0] >> 2];
        *p++ = tbl[((s[0] & 3) << 4) + (s1 >> 4)];
        *p++ = tbl[((s1 & 0xf) << 2) + (s2 >> 6)];
        *p++ = tbl[s2 & 0x3f];
        s += 3;
    }
    /* Zero-terminate */
    *p = '\0';
    /* If length is -2 or -1, pad last char or two */
    while (length) {
        *--p = tbl[64];
        length++;
    }
}

/*
 * Decode base64 encoded stream.
 * Can stop on EOF, specified char, or on uuencode-style "====" line:
 * flags argument controls it.
 */
void FAST_FUNC read_base64(FILE *src_stream, FILE *dst_stream, int flags)
{
/* Note that EOF _can_ be passed as exit_char too */
#define exit_char    ((int)(signed char)flags)
#define uu_style_end (flags & BASE64_FLAG_UU_STOP)

    int term_count = 0;

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

        /* Process one group of 4 chars */
        while (count < 4) {
            char *table_ptr;
            int ch;

            /* Get next _valid_ character.
             * bb_uuenc_tbl_base64[] contains this string:
             *  0         1         2         3         4         5         6
             *  012345678901234567890123456789012345678901234567890123456789012345
             * "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=\n"
             */
            do {
                ch = fgetc(src_stream);
                if (ch == exit_char && count == 0)
                    return;
                if (ch == EOF)
                    bb_error_msg_and_die("truncated base64 input");
                table_ptr = strchr(bb_uuenc_tbl_base64, ch);
//TODO: add BASE64_FLAG_foo to die on bad char?
//Note that then we may need to still allow '\r' (for mail processing)
            } while (!table_ptr);

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

            if (ch == 65 /* '\n' */) {
                /* Terminating "====" line? */
                if (uu_style_end && term_count == 4)
                    return; /* yes */
                term_count = 0;
                continue;
            }
            /* ch is 64 if char was '=', otherwise 0..63 */
            translated[count] = ch & 63; /* 64 -> 0 */
            if (ch == 64) {
                term_count++;
                break;
            }
            count++;
            term_count = 0;
        }

        /* Merge 6 bit chars to 8 bit.
         * count can be < 4 when we decode the tail:
         * "eQ==" -> "y", not "y NUL NUL"
         */
        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);
    } /* while (1) */
}