// Copyright 2016 PDFium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
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#ifndef CORE_FXCRT_CFX_STRING_DATA_TEMPLATE_H_
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#define CORE_FXCRT_CFX_STRING_DATA_TEMPLATE_H_
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#include "core/fxcrt/include/fx_memory.h"
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#include "core/fxcrt/include/fx_system.h"
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#include "third_party/base/numerics/safe_math.h"
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template <typename CharType>
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class CFX_StringDataTemplate {
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public:
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static CFX_StringDataTemplate* Create(FX_STRSIZE nLen) {
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ASSERT(nLen > 0);
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// Calculate space needed for the fixed portion of the struct plus the
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// NUL char that is not included in |m_nAllocLength|.
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int overhead =
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offsetof(CFX_StringDataTemplate, m_String) + sizeof(CharType);
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pdfium::base::CheckedNumeric<int> nSize = nLen;
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nSize *= sizeof(CharType);
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nSize += overhead;
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// Now round to an 8-byte boundary. We'd expect that this is the minimum
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// granularity of any of the underlying allocators, so there may be cases
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// where we can save a re-alloc when adding a few characters to a string
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// by using this otherwise wasted space.
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nSize += 7;
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int totalSize = nSize.ValueOrDie() & ~7;
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int usableLen = (totalSize - overhead) / sizeof(CharType);
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ASSERT(usableLen >= nLen);
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void* pData = FX_Alloc(uint8_t, totalSize);
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return new (pData) CFX_StringDataTemplate(nLen, usableLen);
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}
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static CFX_StringDataTemplate* Create(const CFX_StringDataTemplate& other) {
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CFX_StringDataTemplate* result = Create(other.m_nDataLength);
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result->CopyContents(other);
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return result;
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}
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static CFX_StringDataTemplate* Create(const CharType* pStr, FX_STRSIZE nLen) {
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CFX_StringDataTemplate* result = Create(nLen);
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result->CopyContents(pStr, nLen);
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return result;
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}
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void Retain() { ++m_nRefs; }
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void Release() {
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if (--m_nRefs <= 0)
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FX_Free(this);
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}
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bool CanOperateInPlace(FX_STRSIZE nTotalLen) const {
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return m_nRefs <= 1 && nTotalLen <= m_nAllocLength;
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}
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void CopyContents(const CFX_StringDataTemplate& other) {
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ASSERT(other.m_nDataLength <= m_nAllocLength);
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FXSYS_memcpy(m_String, other.m_String,
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(other.m_nDataLength + 1) * sizeof(CharType));
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}
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void CopyContents(const CharType* pStr, FX_STRSIZE nLen) {
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ASSERT(nLen >= 0 && nLen <= m_nAllocLength);
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FXSYS_memcpy(m_String, pStr, nLen * sizeof(CharType));
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m_String[nLen] = 0;
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}
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void CopyContentsAt(FX_STRSIZE offset,
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const CharType* pStr,
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FX_STRSIZE nLen) {
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ASSERT(offset >= 0 && nLen >= 0 && offset + nLen <= m_nAllocLength);
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FXSYS_memcpy(m_String + offset, pStr, nLen * sizeof(CharType));
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m_String[offset + nLen] = 0;
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}
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// To ensure ref counts do not overflow, consider the worst possible case:
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// the entire address space contains nothing but pointers to this object.
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// Since the count increments with each new pointer, the largest value is
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// the number of pointers that can fit into the address space. The size of
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// the address space itself is a good upper bound on it.
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intptr_t m_nRefs; // Would prefer ssize_t, but no windows support.
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// |FX_STRSIZE| is currently typedef'd as |int|.
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// TODO(palmer): It should be a |size_t|, or at least unsigned.
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// These lengths are in terms of number of characters, not bytes, and do not
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// include the terminating NUL character, but the underlying buffer is sized
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// to be capable of holding it.
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FX_STRSIZE m_nDataLength;
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FX_STRSIZE m_nAllocLength;
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// Not really 1, variable size.
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CharType m_String[1];
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private:
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CFX_StringDataTemplate(FX_STRSIZE dataLen, FX_STRSIZE allocLen)
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: m_nRefs(0), m_nDataLength(dataLen), m_nAllocLength(allocLen) {
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ASSERT(dataLen >= 0);
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ASSERT(dataLen <= allocLen);
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m_String[dataLen] = 0;
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}
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~CFX_StringDataTemplate() = delete;
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};
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extern template class CFX_StringDataTemplate<FX_CHAR>;
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extern template class CFX_StringDataTemplate<FX_WCHAR>;
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#endif // CORE_FXCRT_CFX_STRING_DATA_TEMPLATE_H_
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