Drew DeVault
7 years ago
committed by
GitHub
commit
6d83a59b46
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/*
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* Adapted from https://github.com/littlstar/b64.c
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* License under the MIT License:
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* Copyright (c) 2014 Little Star Media, Inc.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#include <ctype.h>
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#include <stdlib.h>
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#include "util.h"
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static const char b64_table[] = {
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
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'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
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'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
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'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
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'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
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'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
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'w', 'x', 'y', 'z', '0', '1', '2', '3',
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'4', '5', '6', '7', '8', '9', '+', '/'
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};
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char *b64_encode(const char *src, size_t len, size_t *flen) {
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int i = 0;
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int j = 0;
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char *enc = NULL;
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size_t size = len * 4 / 3;
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size_t idx = 0;
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unsigned char buf[4];
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char tmp[3];
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// alloc
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enc = (char *) malloc(size + 1);
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if (NULL == enc) { return NULL; }
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// parse until end of source
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while (len--) {
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// read up to 3 bytes at a time into `tmp'
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tmp[i++] = *(src++);
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// if 3 bytes read then encode into `buf'
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if (3 == i) {
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buf[0] = (tmp[0] & 0xfc) >> 2;
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buf[1] = ((tmp[0] & 0x03) << 4) + ((tmp[1] & 0xf0) >> 4);
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buf[2] = ((tmp[1] & 0x0f) << 2) + ((tmp[2] & 0xc0) >> 6);
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buf[3] = tmp[2] & 0x3f;
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// shouldn't really happen
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if (idx + 4 > size) {
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size += 16;
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enc = (char *) realloc(enc, size + 1);
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}
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for (i = 0; i < 4; ++i) {
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enc[idx++] = b64_table[buf[i]];
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}
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// reset index
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i = 0;
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}
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}
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// remainder
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if (i > 0) {
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// fill `tmp' with `\0' at most 3 times
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for (j = i; j < 3; ++j) {
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tmp[j] = '\0';
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}
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// perform same codec as above
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buf[0] = (tmp[0] & 0xfc) >> 2;
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buf[1] = ((tmp[0] & 0x03) << 4) + ((tmp[1] & 0xf0) >> 4);
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buf[2] = ((tmp[1] & 0x0f) << 2) + ((tmp[2] & 0xc0) >> 6);
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buf[3] = tmp[2] & 0x3f;
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// perform same write to `enc` with new allocation
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size_t delta = (i > 3 ? 0 : 3 - i) + (j > i + 1 ? 0 : i + 1 - j);
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if (idx + delta > size) {
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size += delta;
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enc = (char *) realloc(enc, size + 1);
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}
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for (j = 0; (j < i + 1); ++j) {
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enc[idx++] = b64_table[buf[j]];
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}
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// while there is still a remainder
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// append `=' to `enc'
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while ((i++ < 3)) {
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enc[idx++] = '=';
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}
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}
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enc[idx] = '\0';
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if (flen)
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*flen = size;
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return enc;
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}
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unsigned char *b64_decode(const char *src, size_t len, size_t *decsize) {
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int i = 0;
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int j = 0;
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int l = 0;
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// max size estimate
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size_t size = len * 3 / 4;
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size_t idx = 0;
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unsigned char *dec = NULL;
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unsigned char buf[3];
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unsigned char tmp[4];
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// alloc
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dec = (unsigned char *) malloc(size + 1);
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if (NULL == dec) { return NULL; }
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// parse until end of source
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while (len--) {
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if (isspace(src[j])) { j++; continue; }
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// break if char is `=' or not base64 char
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if ('=' == src[j]) { break; }
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if (!(isalnum(src[j]) || '+' == src[j] || '/' == src[j])) { break; }
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// read up to 4 bytes at a time into `tmp'
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tmp[i++] = src[j++];
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// if 4 bytes read then decode into `buf'
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if (4 == i) {
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// translate values in `tmp' from table
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for (i = 0; i < 4; ++i) {
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// find translation char in `b64_table'
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for (l = 0; l < 64; ++l) {
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if (tmp[i] == b64_table[l]) {
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tmp[i] = l;
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break;
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}
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}
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}
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// decode
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buf[0] = (tmp[0] << 2) + ((tmp[1] & 0x30) >> 4);
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buf[1] = ((tmp[1] & 0xf) << 4) + ((tmp[2] & 0x3c) >> 2);
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buf[2] = ((tmp[2] & 0x3) << 6) + tmp[3];
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// unlikely
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if (idx + 3 > size) {
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size += 16;
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dec = (unsigned char *) realloc(dec, size + 1);
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}
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if (dec != NULL){
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for (i = 0; i < 3; ++i) {
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dec[idx++] = buf[i];
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}
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} else {
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return NULL;
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}
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// reset
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i = 0;
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}
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}
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// remainder
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if (i > 0) {
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// fill `tmp' with `\0' at most 4 times
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for (j = i; j < 4; ++j) {
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tmp[j] = '\0';
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}
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// translate remainder
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for (j = 0; j < 4; ++j) {
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// find translation char in `b64_table'
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for (l = 0; l < 64; ++l) {
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if (tmp[j] == b64_table[l]) {
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tmp[j] = l;
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break;
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}
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}
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}
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// decode remainder
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buf[0] = (tmp[0] << 2) + ((tmp[1] & 0x30) >> 4);
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buf[1] = ((tmp[1] & 0xf) << 4) + ((tmp[2] & 0x3c) >> 2);
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buf[2] = ((tmp[2] & 0x3) << 6) + tmp[3];
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// write remainer decoded buffer to `dec'
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if (idx + (i - 1) > size) {
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size += 16;
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dec = (unsigned char *) realloc(dec, size + 1);
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}
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if (dec != NULL){
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for (j = 0; (j < i - 1); ++j) {
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dec[idx++] = buf[j];
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}
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} else {
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return NULL;
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}
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}
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dec[idx] = '\0';
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// Return back the size of decoded string if demanded.
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if (decsize != NULL) {
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*decsize = size;
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}
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return dec;
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}
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