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
14static const char default_encode[] =
15    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
16    "abcdefghijklmnopqrstuvwxyz"
17    "0123456789+/=";
18
19static 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
28SkBase64::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
36SkBase64::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;
68handlePad:
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    }
102goHome:
103    fLength = dst - dstStart;
104    return kNoError;
105}
106
107#if defined _WIN32
108#pragma warning ( pop )
109#endif
110
111size_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
155SkBase64::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