MtpStringBuffer.cpp revision ab063847e6e893740749029a04cce1f6b7345ed5 
1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#define LOG_TAG "MtpStringBuffer"
18
19#include <string.h>
20
21#include "MtpDataPacket.h"
22#include "MtpStringBuffer.h"
23
24namespace android {
25
26MtpStringBuffer::MtpStringBuffer()
27    :   mCharCount(0),
28        mByteCount(1)
29{
30    mBuffer[0] = 0;
31}
32
33MtpStringBuffer::MtpStringBuffer(const char* src)
34    :   mCharCount(0),
35        mByteCount(1)
36{
37    set(src);
38}
39
40MtpStringBuffer::MtpStringBuffer(const uint16_t* src)
41    :   mCharCount(0),
42        mByteCount(1)
43{
44    set(src);
45}
46
47MtpStringBuffer::MtpStringBuffer(const MtpStringBuffer& src)
48    :   mCharCount(src.mCharCount),
49        mByteCount(src.mByteCount)
50{
51    memcpy(mBuffer, src.mBuffer, mByteCount);
52}
53
54
55MtpStringBuffer::~MtpStringBuffer() {
56}
57
58void MtpStringBuffer::set(const char* src) {
59    // count the characters
60    int count = 0;
61    char ch;
62    char* dest = (char*)mBuffer;
63
64    while ((ch = *src++) != 0 && count < MTP_STRING_MAX_CHARACTER_NUMBER) {
65        if ((ch & 0x80) == 0) {
66            // single byte character
67            *dest++ = ch;
68        } else if ((ch & 0xE0) == 0xC0) {
69            // two byte character
70            char ch1 = *src++;
71            if (! ch1) {
72                // last character was truncated, so ignore last byte
73                break;
74            }
75
76            *dest++ = ch;
77            *dest++ = ch1;
78        } else if ((ch & 0xF0) == 0xE0) {
79            // 3 byte char
80            char ch1 = *src++;
81            if (! ch1) {
82                // last character was truncated, so ignore last byte
83                break;
84            }
85            char ch2 = *src++;
86            if (! ch2) {
87                // last character was truncated, so ignore last byte
88                break;
89            }
90
91            *dest++ = ch;
92            *dest++ = ch1;
93            *dest++ = ch2;
94        }
95        count++;
96    }
97
98    *dest++ = 0;
99    mByteCount = dest - (char*)mBuffer;
100    mCharCount = count;
101}
102
103void MtpStringBuffer::set(const uint16_t* src) {
104    int count = 0;
105    uint16_t ch;
106    uint8_t* dest = mBuffer;
107
108    while ((ch = *src++) != 0 && count < MTP_STRING_MAX_CHARACTER_NUMBER) {
109        if (ch >= 0x0800) {
110            *dest++ = (uint8_t)(0xE0 | (ch >> 12));
111            *dest++ = (uint8_t)(0x80 | ((ch >> 6) & 0x3F));
112            *dest++ = (uint8_t)(0x80 | (ch & 0x3F));
113        } else if (ch >= 0x80) {
114            *dest++ = (uint8_t)(0xC0 | (ch >> 6));
115            *dest++ = (uint8_t)(0x80 | (ch & 0x3F));
116        } else {
117            *dest++ = ch;
118        }
119        count++;
120    }
121    *dest++ = 0;
122    mCharCount = count;
123    mByteCount = dest - mBuffer;
124}
125
126bool MtpStringBuffer::readFromPacket(MtpDataPacket* packet) {
127    uint8_t count;
128    if (!packet->getUInt8(count))
129        return false;
130
131    uint8_t* dest = mBuffer;
132    for (int i = 0; i < count; i++) {
133        uint16_t ch;
134
135        if (!packet->getUInt16(ch))
136            return false;
137        if (ch >= 0x0800) {
138            *dest++ = (uint8_t)(0xE0 | (ch >> 12));
139            *dest++ = (uint8_t)(0x80 | ((ch >> 6) & 0x3F));
140            *dest++ = (uint8_t)(0x80 | (ch & 0x3F));
141        } else if (ch >= 0x80) {
142            *dest++ = (uint8_t)(0xC0 | (ch >> 6));
143            *dest++ = (uint8_t)(0x80 | (ch & 0x3F));
144        } else {
145            *dest++ = ch;
146        }
147    }
148    *dest++ = 0;
149    mCharCount = count;
150    mByteCount = dest - mBuffer;
151    return true;
152}
153
154void MtpStringBuffer::writeToPacket(MtpDataPacket* packet) const {
155    int count = mCharCount;
156    const uint8_t* src = mBuffer;
157    packet->putUInt8(count > 0 ? count + 1 : 0);
158
159    // expand utf8 to 16 bit chars
160    for (int i = 0; i < count; i++) {
161        uint16_t ch;
162        uint16_t ch1 = *src++;
163        if ((ch1 & 0x80) == 0) {
164            // single byte character
165            ch = ch1;
166        } else if ((ch1 & 0xE0) == 0xC0) {
167            // two byte character
168            uint16_t ch2 = *src++;
169            ch = ((ch1 & 0x1F) << 6) | (ch2 & 0x3F);
170        } else {
171            // three byte character
172            uint16_t ch2 = *src++;
173            uint16_t ch3 = *src++;
174            ch = ((ch1 & 0x0F) << 12) | ((ch2 & 0x3F) << 6) | (ch3 & 0x3F);
175        }
176        packet->putUInt16(ch);
177    }
178    // only terminate with zero if string is not empty
179    if (count > 0)
180        packet->putUInt16(0);
181}
182
183}  // namespace android
184