base85.c

Go to the documentation of this file.

// SPDX-FileCopyrightText: 2011 Remy Oukaour
// SPDX-FileCopyrightText: 2017 pancake
// SPDX-License-Identifier: MIT
 
/*
 * ascii85 - Ascii85 encode/decode data and print to standard output
 *
 * Copyright (C) 2011 Remy Oukaour
 *  Updated by pancake in 2017
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <ctype.h>
#include <rz_types.h>
 
static int getc_nospace(FILE *f) {
    int c;
    while (isspace(c = getc(f))) {
        ;
    }
    return c;
}
 
static void putc_wrap(char c, int wrap, int *len) {
    if (wrap && *len >= wrap) {
        putchar('\n');
        *len = 0;
    }
    putchar(c);
    (*len)++;
}
 
static void encode_tuple(unsigned long tuple, int count, int wrap, int *plen, int y_abbr) {
    int i, lim;
    char out[5];
    if (tuple == 0 && count == 4) {
        putc_wrap('z', wrap, plen);
    } else if (tuple == 0x20202020 && count == 4 && y_abbr) {
        putc_wrap('y', wrap, plen);
    } else {
        for (i = 0; i < 5; i++) {
            out[i] = tuple % 85 + '!';
            tuple /= 85;
        }
        lim = 4 - count;
        for (i = 4; i >= lim; i--) {
            putc_wrap(out[i], wrap, plen);
        }
    }
}
 
RZ_API void rz_base85_decode_tuple(unsigned long tuple, int count) {
    int i;
    for (i = 1; i < count; i++) {
        putchar(tuple >> ((4 - i) * 8));
    }
}
 
RZ_API void rz_base85_encode(FILE *fp, int delims, int wrap, int y_abbr) {
    int c, count = 0, len = 0;
    unsigned long tuple = 0;
    if (delims) {
        putc_wrap('<', wrap, &len);
        putc_wrap('~', wrap, &len);
    }
    for (;;) {
        c = getc(fp);
        if (c != EOF) {
            tuple |= c << ((3 - count++) * 8);
            if (count < 4) {
                continue;
            }
        } else if (count == 0) {
            break;
        }
        encode_tuple(tuple, count, wrap, &len, y_abbr);
        if (c == EOF) {
            break;
        }
        tuple = 0;
        count = 0;
    }
    if (delims) {
        putc_wrap('~', wrap, &len);
        putc_wrap('>', wrap, &len);
    }
}
 
RZ_API bool rz_base85_decode(FILE *fp, int delims, int ignore_garbage) {
    int c, count = 0, end = 0;
    unsigned long tuple = 0, pows[] = { 85 * 85 * 85 * 85, 85 * 85 * 85, 85 * 85, 85, 1 };
    while (delims) {
        c = getc_nospace(fp);
        if (c == '<') {
            c = getc_nospace(fp);
            if (c == '~') {
                break;
            }
            ungetc(c, fp);
        } else if (c == EOF) {
            eprintf("ascii85: missing <~");
            return false;
        }
    }
    for (;;) {
        c = getc_nospace(fp);
        if (c == 'z' && count == 0) {
            rz_base85_decode_tuple(0, 5);
            continue;
        }
        if (c == 'y' && count == 0) {
            rz_base85_decode_tuple(0x20202020, 5);
            continue;
        }
        if (c == '~' && delims) {
            c = getc_nospace(fp);
            if (c != '>') {
                eprintf("ascii85: ~ without >\n");
                return false;
            }
            c = EOF;
            end = 1;
        }
        if (c == EOF) {
            if (delims && !end) {
                eprintf("ascii85: missing ~>");
                return false;
            }
            if (count > 0) {
                tuple += pows[count - 1];
                rz_base85_decode_tuple(tuple, count);
            }
            break;
        }
        if (c < '!' || c > 'u') {
            if (ignore_garbage) {
                continue;
            }
            eprintf("ascii85: invalid character '%c'\n", c);
            return false;
        }
        tuple += (c - '!') * pows[count++];
        if (count == 5) {
            rz_base85_decode_tuple(tuple, count);
            tuple = 0;
            count = 0;
        }
    }
    return true;
}