1 // Copyright 2020 The PDFium Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
6
7 #include "core/fxcrt/string_data_template.h"
8
9 #include <string.h>
10
11 #include <new>
12
13 #include "core/fxcrt/fx_memory.h"
14 #include "core/fxcrt/fx_safe_types.h"
15 #include "third_party/base/check.h"
16 #include "third_party/base/check_op.h"
17
18 namespace fxcrt {
19
20 // static
21 template <typename CharType>
Create(size_t nLen)22 StringDataTemplate<CharType>* StringDataTemplate<CharType>::Create(
23 size_t nLen) {
24 DCHECK_GT(nLen, 0);
25
26 // Calculate space needed for the fixed portion of the struct plus the
27 // NUL char that is not included in |m_nAllocLength|.
28 int overhead = offsetof(StringDataTemplate, m_String) + sizeof(CharType);
29 FX_SAFE_SIZE_T nSize = nLen;
30 nSize *= sizeof(CharType);
31 nSize += overhead;
32
33 // Now round to an 16-byte boundary, assuming the underlying allocator is most
34 // likely PartitionAlloc, which has 16 byte chunks. This will help with cases
35 // where we can save a re-alloc when adding a few characters to a string by
36 // using this otherwise wasted space.
37 nSize += 15;
38 nSize &= ~15;
39 size_t totalSize = nSize.ValueOrDie();
40 size_t usableLen = (totalSize - overhead) / sizeof(CharType);
41 DCHECK(usableLen >= nLen);
42
43 void* pData = FX_StringAlloc(char, totalSize);
44 return new (pData) StringDataTemplate(nLen, usableLen);
45 }
46
47 // static
48 template <typename CharType>
Create(const CharType * pStr,size_t nLen)49 StringDataTemplate<CharType>* StringDataTemplate<CharType>::Create(
50 const CharType* pStr,
51 size_t nLen) {
52 StringDataTemplate* result = Create(nLen);
53 result->CopyContents(pStr, nLen);
54 return result;
55 }
56
57 template <typename CharType>
Release()58 void StringDataTemplate<CharType>::Release() {
59 if (--m_nRefs <= 0)
60 FX_Free(this);
61 }
62
63 template <typename CharType>
CopyContents(const StringDataTemplate & other)64 void StringDataTemplate<CharType>::CopyContents(
65 const StringDataTemplate& other) {
66 DCHECK(other.m_nDataLength <= m_nAllocLength);
67 memcpy(m_String, other.m_String,
68 (other.m_nDataLength + 1) * sizeof(CharType));
69 }
70
71 template <typename CharType>
CopyContents(const CharType * pStr,size_t nLen)72 void StringDataTemplate<CharType>::CopyContents(const CharType* pStr,
73 size_t nLen) {
74 DCHECK_GE(nLen, 0);
75 DCHECK_LE(nLen, m_nAllocLength);
76 memcpy(m_String, pStr, nLen * sizeof(CharType));
77 m_String[nLen] = 0;
78 }
79
80 template <typename CharType>
CopyContentsAt(size_t offset,const CharType * pStr,size_t nLen)81 void StringDataTemplate<CharType>::CopyContentsAt(size_t offset,
82 const CharType* pStr,
83 size_t nLen) {
84 DCHECK_GE(offset, 0);
85 DCHECK_GE(nLen, 0);
86 DCHECK_LE(offset + nLen, m_nAllocLength);
87 memcpy(m_String + offset, pStr, nLen * sizeof(CharType));
88 m_String[offset + nLen] = 0;
89 }
90
91 template <typename CharType>
StringDataTemplate(size_t dataLen,size_t allocLen)92 StringDataTemplate<CharType>::StringDataTemplate(size_t dataLen,
93 size_t allocLen)
94 : m_nDataLength(dataLen), m_nAllocLength(allocLen) {
95 DCHECK_GE(dataLen, 0);
96 DCHECK_LE(dataLen, allocLen);
97 m_String[dataLen] = 0;
98 }
99
100 template class StringDataTemplate<char>;
101 template class StringDataTemplate<wchar_t>;
102
103 } // namespace fxcrt
104