1 /*
2 * Copyright 2006 The Android Open Source Project
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8
9 #include "SkBase64.h"
10
11 #define DecodePad -2
12 #define EncodePad 64
13
14 static const char default_encode[] =
15 "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
16 "abcdefghijklmnopqrstuvwxyz"
17 "0123456789+/=";
18
19 static const signed char decodeData[] = {
20 62, -1, -1, -1, 63,
21 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, DecodePad, -1, -1,
22 -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
23 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
24 -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
25 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
26 };
27
SkBase64()28 SkBase64::SkBase64() : fLength((size_t) -1), fData(nullptr) {
29 }
30
31 #if defined _WIN32 // disable 'two', etc. may be used without having been initialized
32 #pragma warning ( push )
33 #pragma warning ( disable : 4701 )
34 #endif
35
decode(const void * srcPtr,size_t size,bool writeDestination)36 SkBase64::Error SkBase64::decode(const void* srcPtr, size_t size, bool writeDestination) {
37 unsigned char* dst = (unsigned char*) fData;
38 const unsigned char* dstStart = (const unsigned char*) fData;
39 const unsigned char* src = (const unsigned char*) srcPtr;
40 bool padTwo = false;
41 bool padThree = false;
42 const unsigned char* end = src + size;
43 while (src < end) {
44 unsigned char bytes[4];
45 int byte = 0;
46 do {
47 unsigned char srcByte = *src++;
48 if (srcByte == 0)
49 goto goHome;
50 if (srcByte <= ' ')
51 continue; // treat as white space
52 if (srcByte < '+' || srcByte > 'z')
53 return kBadCharError;
54 signed char decoded = decodeData[srcByte - '+'];
55 bytes[byte] = decoded;
56 if (decoded < 0) {
57 if (decoded == DecodePad)
58 goto handlePad;
59 return kBadCharError;
60 } else
61 byte++;
62 if (*src)
63 continue;
64 if (byte == 0)
65 goto goHome;
66 if (byte == 4)
67 break;
68 handlePad:
69 if (byte < 2)
70 return kPadError;
71 padThree = true;
72 if (byte == 2)
73 padTwo = true;
74 break;
75 } while (byte < 4);
76 int two = 0;
77 int three = 0;
78 if (writeDestination) {
79 int one = (uint8_t) (bytes[0] << 2);
80 two = bytes[1];
81 one |= two >> 4;
82 two = (uint8_t) (two << 4);
83 three = bytes[2];
84 two |= three >> 2;
85 three = (uint8_t) (three << 6);
86 three |= bytes[3];
87 SkASSERT(one < 256 && two < 256 && three < 256);
88 *dst = (unsigned char) one;
89 }
90 dst++;
91 if (padTwo)
92 break;
93 if (writeDestination)
94 *dst = (unsigned char) two;
95 dst++;
96 if (padThree)
97 break;
98 if (writeDestination)
99 *dst = (unsigned char) three;
100 dst++;
101 }
102 goHome:
103 fLength = dst - dstStart;
104 return kNoError;
105 }
106
107 #if defined _WIN32
108 #pragma warning ( pop )
109 #endif
110
Encode(const void * srcPtr,size_t length,void * dstPtr,const char * encodeMap)111 size_t SkBase64::Encode(const void* srcPtr, size_t length, void* dstPtr, const char* encodeMap) {
112 const char* encode;
113 if (nullptr == encodeMap) {
114 encode = default_encode;
115 } else {
116 encode = encodeMap;
117 }
118 const unsigned char* src = (const unsigned char*) srcPtr;
119 unsigned char* dst = (unsigned char*) dstPtr;
120 if (dst) {
121 size_t remainder = length % 3;
122 const unsigned char* end = &src[length - remainder];
123 while (src < end) {
124 unsigned a = *src++;
125 unsigned b = *src++;
126 unsigned c = *src++;
127 int d = c & 0x3F;
128 c = (c >> 6 | b << 2) & 0x3F;
129 b = (b >> 4 | a << 4) & 0x3F;
130 a = a >> 2;
131 *dst++ = encode[a];
132 *dst++ = encode[b];
133 *dst++ = encode[c];
134 *dst++ = encode[d];
135 }
136 if (remainder > 0) {
137 int k1 = 0;
138 int k2 = EncodePad;
139 int a = (uint8_t) *src++;
140 if (remainder == 2)
141 {
142 int b = *src++;
143 k1 = b >> 4;
144 k2 = (b << 2) & 0x3F;
145 }
146 *dst++ = encode[a >> 2];
147 *dst++ = encode[(k1 | a << 4) & 0x3F];
148 *dst++ = encode[k2];
149 *dst++ = encode[EncodePad];
150 }
151 }
152 return (length + 2) / 3 * 4;
153 }
154
decode(const char * src,size_t len)155 SkBase64::Error SkBase64::decode(const char* src, size_t len) {
156 Error err = decode(src, len, false);
157 SkASSERT(err == kNoError);
158 if (err != kNoError)
159 return err;
160 fData = new char[fLength]; // should use sk_malloc/sk_free
161 decode(src, len, true);
162 return kNoError;
163 }
164