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Diffstat (limited to 'core/fxcrt/cfx_string_data_template.h')
-rw-r--r-- | core/fxcrt/cfx_string_data_template.h | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/core/fxcrt/cfx_string_data_template.h b/core/fxcrt/cfx_string_data_template.h new file mode 100644 index 0000000000..b53b2511c2 --- /dev/null +++ b/core/fxcrt/cfx_string_data_template.h @@ -0,0 +1,115 @@ +// Copyright 2016 PDFium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com + +#ifndef CORE_FXCRT_CFX_STRING_DATA_TEMPLATE_H_ +#define CORE_FXCRT_CFX_STRING_DATA_TEMPLATE_H_ + +#include "core/fxcrt/include/fx_memory.h" +#include "core/fxcrt/include/fx_system.h" +#include "third_party/base/numerics/safe_math.h" + +template <typename CharType> +class CFX_StringDataTemplate { + public: + static CFX_StringDataTemplate* Create(FX_STRSIZE nLen) { + FXSYS_assert(nLen > 0); + + // Calculate space needed for the fixed portion of the struct plus the + // NUL char that is not included in |m_nAllocLength|. + int overhead = + offsetof(CFX_StringDataTemplate, m_String) + sizeof(CharType); + pdfium::base::CheckedNumeric<int> nSize = nLen; + nSize *= sizeof(CharType); + nSize += overhead; + + // Now round to an 8-byte boundary. We'd expect that this is the minimum + // granularity of any of the underlying allocators, so there may be cases + // where we can save a re-alloc when adding a few characters to a string + // by using this otherwise wasted space. + nSize += 7; + int totalSize = nSize.ValueOrDie() & ~7; + int usableLen = (totalSize - overhead) / sizeof(CharType); + FXSYS_assert(usableLen >= nLen); + + void* pData = FX_Alloc(uint8_t, totalSize); + return new (pData) CFX_StringDataTemplate(nLen, usableLen); + } + + static CFX_StringDataTemplate* Create(const CFX_StringDataTemplate& other) { + CFX_StringDataTemplate* result = Create(other.m_nDataLength); + result->CopyContents(other); + return result; + } + + static CFX_StringDataTemplate* Create(const CharType* pStr, FX_STRSIZE nLen) { + CFX_StringDataTemplate* result = Create(nLen); + result->CopyContents(pStr, nLen); + return result; + } + + void Retain() { ++m_nRefs; } + void Release() { + if (--m_nRefs <= 0) + FX_Free(this); + } + + bool CanOperateInPlace(FX_STRSIZE nTotalLen) const { + return m_nRefs <= 1 && nTotalLen <= m_nAllocLength; + } + + void CopyContents(const CFX_StringDataTemplate& other) { + FXSYS_assert(other.m_nDataLength <= m_nAllocLength); + FXSYS_memcpy(m_String, other.m_String, + (other.m_nDataLength + 1) * sizeof(CharType)); + } + + void CopyContents(const CharType* pStr, FX_STRSIZE nLen) { + FXSYS_assert(nLen >= 0 && nLen <= m_nAllocLength); + FXSYS_memcpy(m_String, pStr, nLen * sizeof(CharType)); + m_String[nLen] = 0; + } + + void CopyContentsAt(FX_STRSIZE offset, + const CharType* pStr, + FX_STRSIZE nLen) { + FXSYS_assert(offset >= 0 && nLen >= 0 && offset + nLen <= m_nAllocLength); + FXSYS_memcpy(m_String + offset, pStr, nLen * sizeof(CharType)); + m_String[offset + nLen] = 0; + } + + // To ensure ref counts do not overflow, consider the worst possible case: + // the entire address space contains nothing but pointers to this object. + // Since the count increments with each new pointer, the largest value is + // the number of pointers that can fit into the address space. The size of + // the address space itself is a good upper bound on it. + intptr_t m_nRefs; // Would prefer ssize_t, but no windows support. + + // |FX_STRSIZE| is currently typedef'd as |int|. + // TODO(palmer): It should be a |size_t|, or at least unsigned. + // These lengths are in terms of number of characters, not bytes, and do not + // include the terminating NUL character, but the underlying buffer is sized + // to be capable of holding it. + FX_STRSIZE m_nDataLength; + FX_STRSIZE m_nAllocLength; + + // Not really 1, variable size. + CharType m_String[1]; + + private: + CFX_StringDataTemplate(FX_STRSIZE dataLen, FX_STRSIZE allocLen) + : m_nRefs(0), m_nDataLength(dataLen), m_nAllocLength(allocLen) { + FXSYS_assert(dataLen >= 0); + FXSYS_assert(dataLen <= allocLen); + m_String[dataLen] = 0; + } + + ~CFX_StringDataTemplate() = delete; +}; + +extern template class CFX_StringDataTemplate<FX_CHAR>; +extern template class CFX_StringDataTemplate<FX_WCHAR>; + +#endif // CORE_FXCRT_CFX_STRING_DATA_TEMPLATE_H_ |