mirror of https://github.com/GNOME/gimp.git
237 lines
7.9 KiB
C
237 lines
7.9 KiB
C
/* base64.h - encode and decode base64 encoding according to RFC 2045
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*
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* Copyright (C) 2005, Raphaël Quinet <raphael@gimp.org>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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/* Yet another implementation of base64 encoding and decoding. I
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* ended up writing this because most of the implementations that I
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* found required a null-terminated buffer, some of the others did not
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* ignore whitespace (especially those written for HTTP usage) and the
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* rest were not compatible with the LGPL (some were GPL, not LGPL).
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* Or at least I haven't been able to find LGPL implementations.
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* Writing this according to RFC 2045 did not take long anyway.
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*/
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#ifndef WITHOUT_GIMP
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# include "config.h"
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# include <string.h>
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# include "base64.h"
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# include "libgimp/stdplugins-intl.h"
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#else
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# include <string.h>
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# include "base64.h"
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# define _(String) (String)
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# define N_(String) (String)
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#endif
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#if HAVE_STDIO_H
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#include <stdio.h>
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#endif
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#if HAVE_STDLIB_H
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#include <stdlib.h>
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#endif
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static const gchar base64_code[] =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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static const gint base64_6bits[256] =
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{
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-2, -3, -3, -3, -3, -3, -3, -3, -3, -1, -1, -1, -1, -1, -3, -3,
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-3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3,
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-1, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, 62, -3, -3, -3, 63,
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52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -3, -3, -3, -2, -3, -3,
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-3, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
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15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -3, -3, -3, -3, -3,
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-3, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
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41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -3, -3, -3, -3, -3,
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-3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3,
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-3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3,
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-3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3,
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-3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3,
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-3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3,
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-3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3,
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-3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3,
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-3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3
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}; /* -1: skip whitespace, -2: end of input, -3: error */
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/**
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* base64_decode:
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* @src_b64: input buffer containing base64-encoded data
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* @src_size: input buffer size (in bytes) or -1 if @src_b64 is nul-terminated
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* @dest: buffer in which the decoded data should be stored
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* @dest_size: size of the destination buffer
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* @ignore_errors: if #TRUE, skip all invalid characters (no data validation)
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*
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* Read base64-encoded data from the input buffer @src_b64 and write
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* the decoded data into @dest.
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*
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* The base64 encoding uses 4 bytes for every 3 bytes of input, so
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* @dest_size should be at least 3/4 of @src_size (or less if the
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* input contains whitespace characters). The base64 encoding has no
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* reliable EOF marker, so this can cause additional data following
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* the base64-encoded block to be misinterpreted if @src_size is not
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* specified correctly. The decoder will stop at the first nul byte
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* or at the first '=' (padding byte) so you should ensure that one of
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* these is present if you supply -1 for @src_size. For more details
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* about the base64 encoding, see RFC 2045, chapter 6.8.
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*
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* Returns: the number of bytes stored in @dest, or -1 if invalid data was found.
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*/
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gssize
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base64_decode (const gchar *src_b64,
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gsize src_size,
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gchar *dest,
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gsize dest_size,
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gboolean ignore_errors)
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{
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gint32 decoded;
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gssize i;
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gint n;
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gint bits;
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g_return_val_if_fail (src_b64 != NULL, -1);
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g_return_val_if_fail (dest != NULL, -1);
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decoded = 0;
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n = 0;
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bits = 0;
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for (i = 0; (src_size != 0) && (i + 3 <= dest_size); src_b64++, src_size--)
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{
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bits = base64_6bits[(int) *src_b64 & 0xff];
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if (bits < 0)
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{
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if (bits == -2)
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break;
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else if ((bits == -3) && !ignore_errors)
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return -1;
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else
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continue;
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}
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decoded <<= 6;
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decoded += bits;
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if (++n >= 4)
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{
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/* we have decoded 4 source chars => 24 bits of output (3 chars) */
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dest[i++] = decoded >> 16;
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dest[i++] = (decoded >> 8) & 0xff;
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dest[i++] = decoded & 0xff;
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decoded = 0;
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n = 0;
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}
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}
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if ((n == 3) && (i + 2 <= dest_size))
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{
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/* 3 source chars (+ 1 padding "=") => 16 bits of output (2 chars) */
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dest[i++] = decoded >> 10;
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dest[i++] = (decoded >> 2) & 0xff;
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}
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else if ((n == 2) && (i + 1 <= dest_size))
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{
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/* 2 source chars (+ 2 padding "=") => 8 bits of output (1 char) */
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dest[i++] = decoded >> 4;
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}
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if (i < dest_size)
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dest[i] = 0;
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return i;
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}
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/**
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* base64_encode:
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* @src: input buffer
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* @src_size: input buffer size (in bytes) or -1 if @src is nul-terminated
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* @dest_b64: buffer in which the base64 encoded data should be stored
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* @dest_size: size of the destination buffer
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* @columns: if > 0, add line breaks in the output after this many columns
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*
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* Read binary data from the input buffer @src and write
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* base64-encoded data into @dest_b64.
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*
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* Since the base64 encoding uses 4 bytes for every 3 bytes of input,
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* @dest_size should be at least 4/3 of @src_size, plus optional line
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* breaks if @columns > 0 and up to two padding bytes at the end. For
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* more details about the base64 encoding, see RFC 2045, chapter 6.8.
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* Note that RFC 2045 recommends setting @columns to 76.
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*
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* Returns: the number of bytes stored in @dest.
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*/
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gssize
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base64_encode (const gchar *src,
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gsize src_size,
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gchar *dest_b64,
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gsize dest_size,
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gint columns)
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{
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guint32 bits;
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gssize i;
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gint n;
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gint c;
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g_return_val_if_fail (src != NULL, -1);
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g_return_val_if_fail (dest_b64 != NULL, -1);
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n = 0;
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bits = 0;
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c = 0;
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for (i = 0; (src_size != 0) && (i + 4 <= dest_size); src++, src_size--)
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{
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bits += *(guchar *)src;
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if (++n == 3)
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{
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dest_b64[i++] = base64_code[(bits >> 18) & 0x3f];
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dest_b64[i++] = base64_code[(bits >> 12) & 0x3f];
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dest_b64[i++] = base64_code[(bits >> 6) & 0x3f];
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dest_b64[i++] = base64_code[bits & 0x3f];
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bits = 0;
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n = 0;
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if (columns > 0)
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{
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c += 4;
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if ((c >= columns) && (i < dest_size))
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{
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dest_b64[i++] = '\n';
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c = 0;
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}
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}
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}
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else
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{
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bits <<= 8;
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}
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}
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if ((n != 0) && (i + 4 <= dest_size))
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{
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if (n == 1)
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{
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dest_b64[i++] = base64_code[(bits >> 10) & 0x3f];
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dest_b64[i++] = base64_code[(bits >> 4) & 0x3f];
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dest_b64[i++] = '=';
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dest_b64[i++] = '=';
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}
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else
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{
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dest_b64[i++] = base64_code[(bits >> 18) & 0x3f];
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dest_b64[i++] = base64_code[(bits >> 12) & 0x3f];
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dest_b64[i++] = base64_code[(bits >> 6) & 0x3f];
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dest_b64[i++] = '=';
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}
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}
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if ((columns > 0) && ((c != 0) || (n != 0)) && (i + 1 < dest_size))
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dest_b64[i++] = '\n';
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if (i < dest_size)
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dest_b64[i] = 0;
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return i;
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}
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