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/*++
Copyright (c) 2005 Microsoft Corporation
All rights reserved.
THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF
ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
PARTICULAR PURPOSE.
File Name:
workbuff.cpp
Abstract:
CWorkingBuffer class implementation. This class provides a means of working
with a local buffer by defining a simple interface that allows the retrieval
of a buffer of an appropriate size, handling reallocation as necessary.
--*/
#include "precomp.h"
#include "debug.h"
#include "globals.h"
#include "xdstring.h"
#include "workbuff.h"
/*++
Routine Name:
CWorkingBuffer::CWorkingBuffer
Routine Description:
CWorkingBuffer class constructor
Arguments:
None
Return Value:
None
Throws CXDException(HRESULT) on an error
--*/
CWorkingBuffer::CWorkingBuffer() :
m_pBuffer(NULL),
m_cbSize(CB_COPY_BUFFER)
{
m_pBuffer = HeapAlloc(GetProcessHeap(), 0, m_cbSize);
if (m_pBuffer == NULL)
{
m_cbSize = 0;
throw CXDException(E_OUTOFMEMORY);
}
}
/*++
Routine Name:
CWorkingBuffer::~CWorkingBuffer
Routine Description:
CWorkingBuffer class destructor
Arguments:
None
Return Value:
None
--*/
CWorkingBuffer::~CWorkingBuffer()
{
if (m_pBuffer != NULL)
{
HeapFree(GetProcessHeap(), 0, m_pBuffer);
m_pBuffer = NULL;
m_cbSize = 0;
}
}
/*++
Routine Name:
CWorkingBuffer::GetBuffer
Routine Description:
This routine returns a pointer to a buffer of at least the requested size. If the internal
buffer is not large enough it will be resized accordingly.
Arguments:
cbSize - Requested size of the buffer
ppBuffer - Pointer to a VOID pointer that recieves the buffer
Return Value:
HRESULT
S_OK - On success
E_* - On error
--*/
HRESULT
CWorkingBuffer::GetBuffer(
_In_ CONST ULONGLONG cbSize,
_Outptr_result_bytebuffer_(cbSize) PVOID* ppBuffer
)
{
HRESULT hr = S_OK;
if (SUCCEEDED(hr = CHECK_POINTER(ppBuffer, E_POINTER)))
{
*ppBuffer = NULL;
if (cbSize == 0)
{
hr = E_INVALIDARG;
}
if (m_cbSize == 0)
{
//
// We have no existing buffer - we should have one
//
hr = E_FAIL;
}
}
if (SUCCEEDED(hr))
{
if (m_cbSize >= cbSize)
{
*ppBuffer = m_pBuffer;
}
else
{
//
// Double the buffer size till it is greater than the requested size
//
SIZE_T cbNewSize = m_cbSize;
while (cbNewSize < cbSize)
{
cbNewSize *= 2;
};
_Analysis_assume_(cbNewSize >= 1);
//
// Reallocate the buffer
//
PVOID pNewBuffer = HeapReAlloc(GetProcessHeap(), 0, m_pBuffer, cbNewSize);
if (pNewBuffer != NULL)
{
m_cbSize = cbNewSize;
m_pBuffer = pNewBuffer;
*ppBuffer = m_pBuffer;
}
else
{
hr = E_OUTOFMEMORY;
}
}
}
ERR_ON_HR(hr);
return hr;
};
/*++
Routine Name:
CWorkingBuffer::GetBufferAt
Routine Description:
This routine returns a pointer into the internal buffer at the requested offset. This will
not grow the size of the buffer.
Arguments:
cbOffset - Offset into the internal buffer
cbSize - Size of the requested buffer
ppBuffer - Pointer to a VOID pointer that recieves the buffer
Return Value:
HRESULT
S_OK - On success
HRESULT_FROM_WIN32(ERROR_INSUFFICIENT_BUFFER) - If the internal buffer is not large enough
E_* - On error
--*/
HRESULT
CWorkingBuffer::GetBufferAt(
_In_ ULONG cbOffset,
_In_ CONST ULONGLONG cbSize,
_Outptr_result_bytebuffer_(cbSize) PVOID* ppBuffer
)
{
HRESULT hr = S_OK;
if (SUCCEEDED(hr = CHECK_POINTER(ppBuffer, E_POINTER)))
{
*ppBuffer = NULL;
if (cbSize + cbOffset < m_cbSize)
{
*ppBuffer = reinterpret_cast<PBYTE>(m_pBuffer) + cbOffset;
}
else
{
hr = HRESULT_FROM_WIN32(ERROR_INSUFFICIENT_BUFFER);
}
}
ERR_ON_HR(hr);
return hr;
}
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