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 "include/utils/SkBase64.h"
10
11 #include <cstdint>
12
13 #define DecodePad -2
14 #define EncodePad 64
15
16 static const char default_encode[] =
17 "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
18 "abcdefghijklmnopqrstuvwxyz"
19 "0123456789+/=";
20
21 static const signed char decodeData[] = {
22 62, -1, -1, -1, 63,
23 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, DecodePad, -1, -1,
24 -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
25 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
26 -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
27 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
28 };
29
30 #if defined _WIN32 // disable 'two', etc. may be used without having been initialized
31 #pragma warning ( push )
32 #pragma warning ( disable : 4701 )
33 #endif
34
Decode(const void * srcv,size_t srcLength,void * dstv,size_t * dstLength)35 SkBase64::Error SkBase64::Decode(const void* srcv, size_t srcLength, void* dstv, size_t* dstLength){
36 const unsigned char* src = static_cast<const unsigned char*>(srcv);
37 unsigned char* dst = static_cast<unsigned char*>(dstv);
38
39 int i = 0;
40 bool padTwo = false;
41 bool padThree = false;
42 char unsigned const * const end = src + srcLength;
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 (dst) {
79 int one = (uint8_t) (bytes[0] << 2);
80 two = bytes[1];
81 one |= two >> 4;
82 two = (uint8_t) ((two << 4) & 0xFF);
83 three = bytes[2];
84 two |= three >> 2;
85 three = (uint8_t) ((three << 6) & 0xFF);
86 three |= bytes[3];
87 SkASSERT(one < 256 && two < 256 && three < 256);
88 dst[i] = (unsigned char) one;
89 }
90 i++;
91 if (padTwo)
92 break;
93 if (dst)
94 dst[i] = (unsigned char) two;
95 i++;
96 if (padThree)
97 break;
98 if (dst)
99 dst[i] = (unsigned char) three;
100 i++;
101 }
102 goHome:
103 *dstLength = i;
104 return kNoError;
105 }
106
107 #if defined _WIN32
108 #pragma warning ( pop )
109 #endif
110
Encode(const void * srcv,size_t length,void * dstv,const char * encodeMap)111 size_t SkBase64::Encode(const void* srcv, size_t length, void* dstv, const char* encodeMap) {
112 const unsigned char* src = static_cast<const unsigned char*>(srcv);
113 unsigned char* dst = static_cast<unsigned char*>(dstv);
114
115 const char* encode;
116 if (nullptr == encodeMap) {
117 encode = default_encode;
118 } else {
119 encode = encodeMap;
120 }
121 if (dst) {
122 size_t remainder = length % 3;
123 char unsigned const * const end = &src[length - remainder];
124 while (src < end) {
125 unsigned a = *src++;
126 unsigned b = *src++;
127 unsigned c = *src++;
128 int d = c & 0x3F;
129 c = (c >> 6 | b << 2) & 0x3F;
130 b = (b >> 4 | a << 4) & 0x3F;
131 a = a >> 2;
132 *dst++ = encode[a];
133 *dst++ = encode[b];
134 *dst++ = encode[c];
135 *dst++ = encode[d];
136 }
137 if (remainder > 0) {
138 int k1 = 0;
139 int k2 = EncodePad;
140 int a = (uint8_t) *src++;
141 if (remainder == 2)
142 {
143 int b = *src++;
144 k1 = b >> 4;
145 k2 = (b << 2) & 0x3F;
146 }
147 *dst++ = encode[a >> 2];
148 *dst++ = encode[(k1 | a << 4) & 0x3F];
149 *dst++ = encode[k2];
150 *dst++ = encode[EncodePad];
151 }
152 }
153 return (length + 2) / 3 * 4;
154 }
155