source: vscpl/src/hu/varadiistvan/scpl/io/DataStream.cc@ 27:3c2f8c4beb2c

Last change on this file since 27:3c2f8c4beb2c was 22:ad3d8242e8a1, checked in by István Váradi <ivaradi@…>, 9 years ago

Fixed the reading of the variable-length size

File size: 3.7 KB
Line 
1// Copyright (c) 2013 by István Váradi
2
3// This file is part of VSCPL, a simple cross-platform utility library
4
5// Redistribution and use in source and binary forms, with or without
6// modification, are permitted provided that the following conditions are met:
7
8// 1. Redistributions of source code must retain the above copyright notice, this
9// list of conditions and the following disclaimer.
10// 2. Redistributions in binary form must reproduce the above copyright notice,
11// this list of conditions and the following disclaimer in the documentation
12// and/or other materials provided with the distribution.
13
14// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
15// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
16// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
17// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
18// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
19// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
20// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
21// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
23// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24
25// The views and conclusions contained in the software and documentation are those
26// of the authors and should not be interpreted as representing official policies,
27// either expressed or implied, of the FreeBSD Project.
28
29//------------------------------------------------------------------------------
30
31#include "DataStream.h"
32
33//------------------------------------------------------------------------------
34
35using hu::varadiistvan::scpl::io::DataStream;
36
37using std::string;
38using std::min;
39
40//------------------------------------------------------------------------------
41
42size_t DataStream::readLength()
43{
44 size_t length = 0;
45
46 uint8_t d = 0;
47 unsigned shift = 0;
48 do {
49 d = readU8();
50 length |= static_cast<size_t>(d&0x7f)<<shift;
51 shift += 7;
52 } while( (d&0x80)==0x80 );
53
54 return length;
55}
56
57//------------------------------------------------------------------------------
58
59string DataStream::readString()
60{
61 size_t length = readLength();
62 if (!*this) return "";
63
64 char* buffer = new char[length];
65 if (read(buffer, length)) {
66 string str(buffer, length);
67 delete buffer;
68 return str;
69 } else {
70 delete buffer;
71 return "";
72 }
73}
74
75//------------------------------------------------------------------------------
76
77size_t DataStream::readString(char* dest, size_t capacity)
78{
79 size_t length = readLength();
80 size_t destLength = 0;
81 if (*this && length>0) {
82 size_t destLength = min(length, capacity - 1);
83 if (read(dest, destLength)) {
84 if (destLength<length) {
85 if (!skip(length - destLength)) {
86 length = destLength = 0;
87 }
88 }
89 } else {
90 length = destLength = 0;
91 }
92 } else {
93 length = 0;
94 }
95
96 dest[destLength] = '\0';
97
98 return length;
99}
100
101//------------------------------------------------------------------------------
102
103bool DataStream::writeLength(size_t length)
104{
105 do {
106 uint8_t x = length&0x7f;
107 length >>= 7;
108 if (length>0) x |= 0x80;
109 if (!writeU8(x)) return false;
110 } while(length>0);
111 return true;
112}
113
114//------------------------------------------------------------------------------
115
116// Local Variables:
117// mode: C++
118// c-basic-offset: 4
119// indent-tabs-mode: nil
120// End:
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