//
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// GTMBase64.m
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//
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// Copyright 2006-2008 Google Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not
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// use this file except in compliance with the License. You may obtain a copy
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// of the License at
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// GitHub地址 https://github.com/penghero/PGGCrypto.git
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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// License for the specific language governing permissions and limitations under
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// the License.
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//
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#import "GTMBase64.h"
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#import "GTMDefines.h"
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static const char *kBase64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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static const char *kWebSafeBase64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
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static const char kBase64PaddingChar = '=';
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static const char kBase64InvalidChar = 99;
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static const char kBase64DecodeChars[] = {
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// This array was generated by the following code:
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// #include <sys/time.h>
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// #include <stdlib.h>
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// #include <string.h>
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// main()
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// {
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// static const char Base64[] =
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// "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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// char *pos;
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// int idx, i, j;
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// printf(" ");
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// for (i = 0; i < 255; i += 8) {
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// for (j = i; j < i + 8; j++) {
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// pos = strchr(Base64, j);
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// if ((pos == NULL) || (j == 0))
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// idx = 99;
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// else
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// idx = pos - Base64;
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// if (idx == 99)
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// printf(" %2d, ", idx);
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// else
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// printf(" %2d/*%c*/,", idx, j);
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// }
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// printf("\n ");
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// }
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// }
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 62/*+*/, 99, 99, 99, 63/*/ */,
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52/*0*/, 53/*1*/, 54/*2*/, 55/*3*/, 56/*4*/, 57/*5*/, 58/*6*/, 59/*7*/,
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60/*8*/, 61/*9*/, 99, 99, 99, 99, 99, 99,
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99, 0/*A*/, 1/*B*/, 2/*C*/, 3/*D*/, 4/*E*/, 5/*F*/, 6/*G*/,
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7/*H*/, 8/*I*/, 9/*J*/, 10/*K*/, 11/*L*/, 12/*M*/, 13/*N*/, 14/*O*/,
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15/*P*/, 16/*Q*/, 17/*R*/, 18/*S*/, 19/*T*/, 20/*U*/, 21/*V*/, 22/*W*/,
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23/*X*/, 24/*Y*/, 25/*Z*/, 99, 99, 99, 99, 99,
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99, 26/*a*/, 27/*b*/, 28/*c*/, 29/*d*/, 30/*e*/, 31/*f*/, 32/*g*/,
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33/*h*/, 34/*i*/, 35/*j*/, 36/*k*/, 37/*l*/, 38/*m*/, 39/*n*/, 40/*o*/,
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41/*p*/, 42/*q*/, 43/*r*/, 44/*s*/, 45/*t*/, 46/*u*/, 47/*v*/, 48/*w*/,
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49/*x*/, 50/*y*/, 51/*z*/, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99
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};
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static const char kWebSafeBase64DecodeChars[] = {
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// This array was generated by the following code:
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// #include <sys/time.h>
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// #include <stdlib.h>
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// #include <string.h>
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// main()
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// {
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// static const char Base64[] =
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// "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
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// char *pos;
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// int idx, i, j;
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// printf(" ");
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// for (i = 0; i < 255; i += 8) {
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// for (j = i; j < i + 8; j++) {
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// pos = strchr(Base64, j);
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// if ((pos == NULL) || (j == 0))
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// idx = 99;
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// else
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// idx = pos - Base64;
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// if (idx == 99)
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// printf(" %2d, ", idx);
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// else
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// printf(" %2d/*%c*/,", idx, j);
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// }
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// printf("\n ");
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// }
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// }
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 62/*-*/, 99, 99,
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52/*0*/, 53/*1*/, 54/*2*/, 55/*3*/, 56/*4*/, 57/*5*/, 58/*6*/, 59/*7*/,
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60/*8*/, 61/*9*/, 99, 99, 99, 99, 99, 99,
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99, 0/*A*/, 1/*B*/, 2/*C*/, 3/*D*/, 4/*E*/, 5/*F*/, 6/*G*/,
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7/*H*/, 8/*I*/, 9/*J*/, 10/*K*/, 11/*L*/, 12/*M*/, 13/*N*/, 14/*O*/,
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15/*P*/, 16/*Q*/, 17/*R*/, 18/*S*/, 19/*T*/, 20/*U*/, 21/*V*/, 22/*W*/,
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23/*X*/, 24/*Y*/, 25/*Z*/, 99, 99, 99, 99, 63/*_*/,
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99, 26/*a*/, 27/*b*/, 28/*c*/, 29/*d*/, 30/*e*/, 31/*f*/, 32/*g*/,
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33/*h*/, 34/*i*/, 35/*j*/, 36/*k*/, 37/*l*/, 38/*m*/, 39/*n*/, 40/*o*/,
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41/*p*/, 42/*q*/, 43/*r*/, 44/*s*/, 45/*t*/, 46/*u*/, 47/*v*/, 48/*w*/,
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49/*x*/, 50/*y*/, 51/*z*/, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99
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};
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// Tests a character to see if it's a whitespace character.
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//
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// Returns:
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// YES if the character is a whitespace character.
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// NO if the character is not a whitespace character.
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//
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GTM_INLINE BOOL IsSpace(unsigned char c) {
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// we use our own mapping here because we don't want anything w/ locale
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// support.
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static BOOL kSpaces[256] = {
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0, 0, 0, 0, 0, 0, 0, 0, 0, 1, // 0-9
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1, 1, 1, 1, 0, 0, 0, 0, 0, 0, // 10-19
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 20-29
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0, 0, 1, 0, 0, 0, 0, 0, 0, 0, // 30-39
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 40-49
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 50-59
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 60-69
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 70-79
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 80-89
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 90-99
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 100-109
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 110-119
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 120-129
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 130-139
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 140-149
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 150-159
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1, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 160-169
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 170-179
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 180-189
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 190-199
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 200-209
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 210-219
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 220-229
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 230-239
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 240-249
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0, 0, 0, 0, 0, 1, // 250-255
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};
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return kSpaces[c];
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}
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// Calculate how long the data will be once it's base64 encoded.
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//
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// Returns:
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// The guessed encoded length for a source length
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//
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GTM_INLINE NSUInteger CalcEncodedLength(NSUInteger srcLen, BOOL padded) {
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NSUInteger intermediate_result = 8 * srcLen + 5;
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NSUInteger len = intermediate_result / 6;
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if (padded) {
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len = ((len + 3) / 4) * 4;
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}
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return len;
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}
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// Tries to calculate how long the data will be once it's base64 decoded.
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// Unlike the above, this is always an upperbound, since the source data
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// could have spaces and might end with the padding characters on them.
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//
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// Returns:
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// The guessed decoded length for a source length
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//
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GTM_INLINE NSUInteger GuessDecodedLength(NSUInteger srcLen) {
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return (srcLen + 3) / 4 * 3;
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}
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@interface GTMBase64 (PrivateMethods)
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+(NSData *)baseEncode:(const void *)bytes
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length:(NSUInteger)length
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charset:(const char *)charset
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padded:(BOOL)padded;
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+(NSData *)baseDecode:(const void *)bytes
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length:(NSUInteger)length
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charset:(const char*)charset
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requirePadding:(BOOL)requirePadding;
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+(NSUInteger)baseEncode:(const char *)srcBytes
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srcLen:(NSUInteger)srcLen
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destBytes:(char *)destBytes
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destLen:(NSUInteger)destLen
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charset:(const char *)charset
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padded:(BOOL)padded;
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+(NSUInteger)baseDecode:(const char *)srcBytes
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srcLen:(NSUInteger)srcLen
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destBytes:(char *)destBytes
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destLen:(NSUInteger)destLen
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charset:(const char *)charset
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requirePadding:(BOOL)requirePadding;
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@end
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@implementation GTMBase64
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//
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// Standard Base64 (RFC) handling
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//
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+(NSData *)encodeData:(NSData *)data {
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return [self baseEncode:[data bytes]
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length:[data length]
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charset:kBase64EncodeChars
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padded:YES];
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}
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+(NSData *)decodeData:(NSData *)data {
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return [self baseDecode:[data bytes]
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length:[data length]
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charset:kBase64DecodeChars
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requirePadding:YES];
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}
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+(NSData *)encodeBytes:(const void *)bytes length:(NSUInteger)length {
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return [self baseEncode:bytes
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length:length
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charset:kBase64EncodeChars
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padded:YES];
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}
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+(NSData *)decodeBytes:(const void *)bytes length:(NSUInteger)length {
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return [self baseDecode:bytes
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length:length
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charset:kBase64DecodeChars
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requirePadding:YES];
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}
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+(NSString *)stringByEncodingData:(NSData *)data {
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NSString *result = nil;
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NSData *converted = [self baseEncode:[data bytes]
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length:[data length]
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charset:kBase64EncodeChars
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padded:YES];
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if (converted) {
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result = [[NSString alloc] initWithData:converted
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encoding:NSASCIIStringEncoding] ;
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}
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return result;
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}
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+(NSString *)stringByEncodingBytes:(const void *)bytes length:(NSUInteger)length {
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NSString *result = nil;
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NSData *converted = [self baseEncode:bytes
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length:length
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charset:kBase64EncodeChars
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padded:YES];
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if (converted) {
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result = [[NSString alloc] initWithData:converted
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encoding:NSASCIIStringEncoding] ;
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}
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return result;
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}
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+(NSData *)decodeString:(NSString *)string {
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NSData *result = nil;
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NSData *data = [string dataUsingEncoding:NSASCIIStringEncoding];
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if (data) {
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result = [self baseDecode:[data bytes]
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length:[data length]
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charset:kBase64DecodeChars
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requirePadding:YES];
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}
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return result;
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}
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//
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// Modified Base64 encoding so the results can go onto urls.
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//
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// The changes are in the characters generated and also the result isn't
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// padded to a multiple of 4.
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// Must use the matching call to encode/decode, won't interop with the
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// RFC versions.
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//
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+(NSData *)webSafeEncodeData:(NSData *)data
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padded:(BOOL)padded {
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return [self baseEncode:[data bytes]
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length:[data length]
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charset:kWebSafeBase64EncodeChars
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padded:padded];
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}
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+(NSData *)webSafeDecodeData:(NSData *)data {
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return [self baseDecode:[data bytes]
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length:[data length]
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charset:kWebSafeBase64DecodeChars
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requirePadding:NO];
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}
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+(NSData *)webSafeEncodeBytes:(const void *)bytes
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length:(NSUInteger)length
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padded:(BOOL)padded {
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return [self baseEncode:bytes
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length:length
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charset:kWebSafeBase64EncodeChars
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padded:padded];
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}
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+(NSData *)webSafeDecodeBytes:(const void *)bytes length:(NSUInteger)length {
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return [self baseDecode:bytes
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length:length
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charset:kWebSafeBase64DecodeChars
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requirePadding:NO];
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}
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+(NSString *)stringByWebSafeEncodingData:(NSData *)data
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padded:(BOOL)padded {
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NSString *result = nil;
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NSData *converted = [self baseEncode:[data bytes]
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length:[data length]
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charset:kWebSafeBase64EncodeChars
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padded:padded];
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if (converted) {
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result = [[NSString alloc] initWithData:converted
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encoding:NSASCIIStringEncoding];
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}
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return result;
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}
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+(NSString *)stringByWebSafeEncodingBytes:(const void *)bytes
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length:(NSUInteger)length
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padded:(BOOL)padded {
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NSString *result = nil;
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NSData *converted = [self baseEncode:bytes
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length:length
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charset:kWebSafeBase64EncodeChars
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padded:padded];
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if (converted) {
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result = [[NSString alloc] initWithData:converted
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encoding:NSASCIIStringEncoding] ;
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}
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return result;
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}
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+(NSData *)webSafeDecodeString:(NSString *)string {
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NSData *result = nil;
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NSData *data = [string dataUsingEncoding:NSASCIIStringEncoding];
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if (data) {
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result = [self baseDecode:[data bytes]
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length:[data length]
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charset:kWebSafeBase64DecodeChars
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requirePadding:NO];
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}
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return result;
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}
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@end
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@implementation GTMBase64 (PrivateMethods)
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//
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// baseEncode:length:charset:padded:
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//
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// Does the common lifting of creating the dest NSData. it creates & sizes the
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// data for the results. |charset| is the characters to use for the encoding
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// of the data. |padding| controls if the encoded data should be padded to a
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// multiple of 4.
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//
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// Returns:
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// an autorelease NSData with the encoded data, nil if any error.
|
//
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+(NSData *)baseEncode:(const void *)bytes
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length:(NSUInteger)length
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charset:(const char *)charset
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padded:(BOOL)padded {
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// how big could it be?
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NSUInteger maxLength = CalcEncodedLength(length, padded);
|
// make space
|
NSMutableData *result = [NSMutableData data];
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[result setLength:maxLength];
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// do it
|
NSUInteger finalLength = [self baseEncode:bytes
|
srcLen:length
|
destBytes:[result mutableBytes]
|
destLen:[result length]
|
charset:charset
|
padded:padded];
|
if (finalLength) {
|
_GTMDevAssert(finalLength == maxLength, @"how did we calc the length wrong?");
|
} else {
|
// shouldn't happen, this means we ran out of space
|
result = nil;
|
}
|
return result;
|
}
|
|
//
|
// baseDecode:length:charset:requirePadding:
|
//
|
// Does the common lifting of creating the dest NSData. it creates & sizes the
|
// data for the results. |charset| is the characters to use for the decoding
|
// of the data.
|
//
|
// Returns:
|
// an autorelease NSData with the decoded data, nil if any error.
|
//
|
//
|
+(NSData *)baseDecode:(const void *)bytes
|
length:(NSUInteger)length
|
charset:(const char *)charset
|
requirePadding:(BOOL)requirePadding {
|
// could try to calculate what it will end up as
|
NSUInteger maxLength = GuessDecodedLength(length);
|
// make space
|
NSMutableData *result = [NSMutableData data];
|
[result setLength:maxLength];
|
// do it
|
NSUInteger finalLength = [self baseDecode:bytes
|
srcLen:length
|
destBytes:[result mutableBytes]
|
destLen:[result length]
|
charset:charset
|
requirePadding:requirePadding];
|
if (finalLength) {
|
if (finalLength != maxLength) {
|
// resize down to how big it was
|
[result setLength:finalLength];
|
}
|
} else {
|
// either an error in the args, or we ran out of space
|
result = nil;
|
}
|
return result;
|
}
|
|
//
|
// baseEncode:srcLen:destBytes:destLen:charset:padded:
|
//
|
// Encodes the buffer into the larger. returns the length of the encoded
|
// data, or zero for an error.
|
// |charset| is the characters to use for the encoding
|
// |padded| tells if the result should be padded to a multiple of 4.
|
//
|
// Returns:
|
// the length of the encoded data. zero if any error.
|
//
|
+(NSUInteger)baseEncode:(const char *)srcBytes
|
srcLen:(NSUInteger)srcLen
|
destBytes:(char *)destBytes
|
destLen:(NSUInteger)destLen
|
charset:(const char *)charset
|
padded:(BOOL)padded {
|
if (!srcLen || !destLen || !srcBytes || !destBytes) {
|
return 0;
|
}
|
|
char *curDest = destBytes;
|
const unsigned char *curSrc = (const unsigned char *)(srcBytes);
|
|
// Three bytes of data encodes to four characters of cyphertext.
|
// So we can pump through three-byte chunks atomically.
|
while (srcLen > 2) {
|
// space?
|
_GTMDevAssert(destLen >= 4, @"our calc for encoded length was wrong");
|
curDest[0] = charset[curSrc[0] >> 2];
|
curDest[1] = charset[((curSrc[0] & 0x03) << 4) + (curSrc[1] >> 4)];
|
curDest[2] = charset[((curSrc[1] & 0x0f) << 2) + (curSrc[2] >> 6)];
|
curDest[3] = charset[curSrc[2] & 0x3f];
|
|
curDest += 4;
|
curSrc += 3;
|
srcLen -= 3;
|
destLen -= 4;
|
}
|
|
// now deal with the tail (<=2 bytes)
|
switch (srcLen) {
|
case 0:
|
// Nothing left; nothing more to do.
|
break;
|
case 1:
|
// One byte left: this encodes to two characters, and (optionally)
|
// two pad characters to round out the four-character cypherblock.
|
_GTMDevAssert(destLen >= 2, @"our calc for encoded length was wrong");
|
curDest[0] = charset[curSrc[0] >> 2];
|
curDest[1] = charset[(curSrc[0] & 0x03) << 4];
|
curDest += 2;
|
destLen -= 2;
|
if (padded) {
|
_GTMDevAssert(destLen >= 2, @"our calc for encoded length was wrong");
|
curDest[0] = kBase64PaddingChar;
|
curDest[1] = kBase64PaddingChar;
|
curDest += 2;
|
}
|
break;
|
case 2:
|
// Two bytes left: this encodes to three characters, and (optionally)
|
// one pad character to round out the four-character cypherblock.
|
_GTMDevAssert(destLen >= 3, @"our calc for encoded length was wrong");
|
curDest[0] = charset[curSrc[0] >> 2];
|
curDest[1] = charset[((curSrc[0] & 0x03) << 4) + (curSrc[1] >> 4)];
|
curDest[2] = charset[(curSrc[1] & 0x0f) << 2];
|
curDest += 3;
|
destLen -= 3;
|
if (padded) {
|
_GTMDevAssert(destLen >= 1, @"our calc for encoded length was wrong");
|
curDest[0] = kBase64PaddingChar;
|
curDest += 1;
|
}
|
break;
|
}
|
// return the length
|
return (curDest - destBytes);
|
}
|
|
//
|
// baseDecode:srcLen:destBytes:destLen:charset:requirePadding:
|
//
|
// Decodes the buffer into the larger. returns the length of the decoded
|
// data, or zero for an error.
|
// |charset| is the character decoding buffer to use
|
//
|
// Returns:
|
// the length of the encoded data. zero if any error.
|
//
|
+(NSUInteger)baseDecode:(const char *)srcBytes
|
srcLen:(NSUInteger)srcLen
|
destBytes:(char *)destBytes
|
destLen:(NSUInteger)destLen
|
charset:(const char *)charset
|
requirePadding:(BOOL)requirePadding {
|
if (!srcLen || !destLen || !srcBytes || !destBytes) {
|
return 0;
|
}
|
|
int decode;
|
NSUInteger destIndex = 0;
|
int state = 0;
|
char ch = 0;
|
while (srcLen-- && (ch = *srcBytes++) != 0) {
|
if (IsSpace(ch)) // Skip whitespace
|
continue;
|
|
if (ch == kBase64PaddingChar)
|
break;
|
|
decode = charset[(unsigned int)ch];
|
if (decode == kBase64InvalidChar)
|
return 0;
|
|
// Four cyphertext characters decode to three bytes.
|
// Therefore we can be in one of four states.
|
switch (state) {
|
case 0:
|
// We're at the beginning of a four-character cyphertext block.
|
// This sets the high six bits of the first byte of the
|
// plaintext block.
|
_GTMDevAssert(destIndex < destLen, @"our calc for decoded length was wrong");
|
destBytes[destIndex] = decode << 2;
|
state = 1;
|
break;
|
case 1:
|
// We're one character into a four-character cyphertext block.
|
// This sets the low two bits of the first plaintext byte,
|
// and the high four bits of the second plaintext byte.
|
_GTMDevAssert((destIndex+1) < destLen, @"our calc for decoded length was wrong");
|
destBytes[destIndex] |= decode >> 4;
|
destBytes[destIndex+1] = (decode & 0x0f) << 4;
|
destIndex++;
|
state = 2;
|
break;
|
case 2:
|
// We're two characters into a four-character cyphertext block.
|
// This sets the low four bits of the second plaintext
|
// byte, and the high two bits of the third plaintext byte.
|
// However, if this is the end of data, and those two
|
// bits are zero, it could be that those two bits are
|
// leftovers from the encoding of data that had a length
|
// of two mod three.
|
_GTMDevAssert((destIndex+1) < destLen, @"our calc for decoded length was wrong");
|
destBytes[destIndex] |= decode >> 2;
|
destBytes[destIndex+1] = (decode & 0x03) << 6;
|
destIndex++;
|
state = 3;
|
break;
|
case 3:
|
// We're at the last character of a four-character cyphertext block.
|
// This sets the low six bits of the third plaintext byte.
|
_GTMDevAssert(destIndex < destLen, @"our calc for decoded length was wrong");
|
destBytes[destIndex] |= decode;
|
destIndex++;
|
state = 0;
|
break;
|
}
|
}
|
|
// We are done decoding Base-64 chars. Let's see if we ended
|
// on a byte boundary, and/or with erroneous trailing characters.
|
if (ch == kBase64PaddingChar) { // We got a pad char
|
if ((state == 0) || (state == 1)) {
|
return 0; // Invalid '=' in first or second position
|
}
|
if (srcLen == 0) {
|
if (state == 2) { // We run out of input but we still need another '='
|
return 0;
|
}
|
// Otherwise, we are in state 3 and only need this '='
|
} else {
|
if (state == 2) { // need another '='
|
while ((ch = *srcBytes++) && (srcLen-- > 0)) {
|
if (!IsSpace(ch))
|
break;
|
}
|
if (ch != kBase64PaddingChar) {
|
return 0;
|
}
|
}
|
// state = 1 or 2, check if all remain padding is space
|
while ((ch = *srcBytes++) && (srcLen-- > 0)) {
|
if (!IsSpace(ch)) {
|
return 0;
|
}
|
}
|
}
|
} else {
|
// We ended by seeing the end of the string.
|
|
if (requirePadding) {
|
// If we require padding, then anything but state 0 is an error.
|
if (state != 0) {
|
return 0;
|
}
|
} else {
|
// Make sure we have no partial bytes lying around. Note that we do not
|
// require trailing '=', so states 2 and 3 are okay too.
|
if (state == 1) {
|
return 0;
|
}
|
}
|
}
|
|
// If then next piece of output was valid and got written to it means we got a
|
// very carefully crafted input that appeared valid but contains some trailing
|
// bits past the real length, so just toss the thing.
|
if ((destIndex < destLen) &&
|
(destBytes[destIndex] != 0)) {
|
return 0;
|
}
|
|
return destIndex;
|
}
|
|
@end
|
