MtpStringBuffer.cpp revision dde372033b4da75ebde7ea2afdec1c1b86ab5a42 
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    int length = strlen(src);
60    if (length >= sizeof(mBuffer))
61        length = sizeof(mBuffer) - 1;
62    memcpy(mBuffer, src, length);
63
64    // count the characters
65    int count = 0;
66    char ch;
67    while ((ch = *src++) != 0) {
68        if ((ch & 0x80) == 0) {
69            // single byte character
70        } else if ((ch & 0xE0) == 0xC0) {
71            // two byte character
72            if (! *src++) {
73                // last character was truncated, so ignore last byte
74                length--;
75                break;
76            }
77        } else if ((ch & 0xF0) == 0xE0) {
78            // 3 byte char
79            if (! *src++) {
80                // last character was truncated, so ignore last byte
81                length--;
82                break;
83            }
84            if (! *src++) {
85                // last character was truncated, so ignore last two bytes
86                length -= 2;
87                break;
88            }
89        }
90        count++;
91    }
92
93    mByteCount = length + 1;
94    mBuffer[length] = 0;
95    mCharCount = count;
96}
97
98void MtpStringBuffer::set(const uint16_t* src) {
99    int count = 0;
100    uint16_t ch;
101    uint8_t* dest = mBuffer;
102
103    while ((ch = *src++) != 0 && count < 255) {
104        if (ch >= 0x0800) {
105            *dest++ = (uint8_t)(0xE0 | (ch >> 12));
106            *dest++ = (uint8_t)(0x80 | ((ch >> 6) & 0x3F));
107            *dest++ = (uint8_t)(0x80 | (ch & 0x3F));
108        } else if (ch >= 0x80) {
109            *dest++ = (uint8_t)(0xC0 | (ch >> 6));
110            *dest++ = (uint8_t)(0x80 | (ch & 0x3F));
111        } else {
112            *dest++ = ch;
113        }
114        count++;
115    }
116    *dest++ = 0;
117    mCharCount = count;
118    mByteCount = dest - mBuffer;
119}
120
121void MtpStringBuffer::readFromPacket(MtpDataPacket* packet) {
122    int count = packet->getUInt8();
123    uint8_t* dest = mBuffer;
124    for (int i = 0; i < count; i++) {
125        uint16_t ch = packet->getUInt16();
126        if (ch >= 0x0800) {
127            *dest++ = (uint8_t)(0xE0 | (ch >> 12));
128            *dest++ = (uint8_t)(0x80 | ((ch >> 6) & 0x3F));
129            *dest++ = (uint8_t)(0x80 | (ch & 0x3F));
130        } else if (ch >= 0x80) {
131            *dest++ = (uint8_t)(0xC0 | (ch >> 6));
132            *dest++ = (uint8_t)(0x80 | (ch & 0x3F));
133        } else {
134            *dest++ = ch;
135        }
136    }
137    *dest++ = 0;
138    mCharCount = count;
139    mByteCount = dest - mBuffer;
140}
141
142void MtpStringBuffer::writeToPacket(MtpDataPacket* packet) const {
143    int count = mCharCount;
144    const uint8_t* src = mBuffer;
145    packet->putUInt8(count > 0 ? count + 1 : 0);
146
147    // expand utf8 to 16 bit chars
148    for (int i = 0; i < count; i++) {
149        uint16_t ch;
150        uint16_t ch1 = *src++;
151        if ((ch1 & 0x80) == 0) {
152            // single byte character
153            ch = ch1;
154        } else if ((ch1 & 0xE0) == 0xC0) {
155            // two byte character
156            uint16_t ch2 = *src++;
157            ch = ((ch1 & 0x1F) << 6) | (ch2 & 0x3F);
158        } else {
159            // three byte character
160            uint16_t ch2 = *src++;
161            uint16_t ch3 = *src++;
162            ch = ((ch1 & 0x0F) << 12) | ((ch2 & 0x3F) << 6) | (ch3 & 0x3F);
163        }
164        packet->putUInt16(ch);
165    }
166    // only terminate with zero if string is not empty
167    if (count > 0)
168        packet->putUInt16(0);
169}
170
171}  // namespace android
172