323 lines
8.6 KiB
C++
323 lines
8.6 KiB
C++
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//
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// SafeReg.cpp
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//
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// Functions to ensure strings read from the registry are null-terminated.
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//
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// History:
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//
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// 2002-03-20 KenSh Created
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//
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// Copyright (c) 2002 Microsoft Corporation
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//
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#include "stdafx.h"
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#include "SafeReg.h"
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// SafeRegQueryValueCchHelper [private]
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//
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// Implementation of both "safe" kinds of string registry reads.
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//
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static HRESULT SafeRegQueryValueCchHelper
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(
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IN DWORD dwExpectedType,
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IN HKEY hkey,
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IN LPCTSTR pszValueName,
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OUT LPTSTR pszBuf,
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IN int cchBuf,
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OUT OPTIONAL int* pcchValueSize,
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OUT OPTIONAL BOOL* pfExpandSz
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)
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{
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HRESULT hr = S_OK;
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int cchValueSize = 0;
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BOOL fExpandSz = FALSE;
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// BLOCK
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{
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if ((!pszBuf && cchBuf != 0) || cchBuf < 0) // note: pszValueName can be null
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{
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hr = E_INVALIDARG;
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goto done;
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}
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DWORD dwType;
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DWORD cbData = cchBuf * sizeof(TCHAR);
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DWORD dwResult = RegQueryValueEx(
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hkey, pszValueName, NULL, &dwType, (LPBYTE)pszBuf, &cbData);
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if (dwResult != ERROR_SUCCESS)
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{
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hr = HRESULT_FROM_WIN32(dwResult);
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}
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else if (!pszBuf && cbData > 0)
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{
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hr = HRESULT_FROM_WIN32(ERROR_MORE_DATA);
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}
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if (SUCCEEDED(hr))
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{
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fExpandSz = (dwType == REG_EXPAND_SZ);
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if ((dwType != dwExpectedType) &&
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!(dwExpectedType == REG_SZ && dwType == REG_EXPAND_SZ))
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{
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hr = HRESULT_FROM_WIN32(ERROR_DATATYPE_MISMATCH);
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}
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}
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if (hr == HRESULT_FROM_WIN32(ERROR_MORE_DATA))
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{
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// Add 1-2 extra chars in case the registry data is not big enough.
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cchValueSize = cbData / sizeof(TCHAR);
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cchValueSize += (dwExpectedType == REG_MULTI_SZ) ? 2 : 1;
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}
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else if (SUCCEEDED(hr))
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{
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cchValueSize = cbData / sizeof(TCHAR);
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// check for lack of null-termination
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if (cchValueSize == 0 || pszBuf[cchValueSize-1] != _T('\0'))
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cchValueSize++;
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// check for lack of double null-termination (multi-sz only)
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if (dwExpectedType == REG_MULTI_SZ && (cchValueSize < 2 || pszBuf[cchValueSize-2] != _T('\0')))
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cchValueSize++;
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// check for overflow
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if (cchValueSize > cchBuf)
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{
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hr = HRESULT_FROM_WIN32(ERROR_MORE_DATA);
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}
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else
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{
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cchValueSize--; // when successful, count doesn't include trailing null
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pszBuf[cchValueSize] = _T('\0');
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if (dwExpectedType == REG_MULTI_SZ)
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pszBuf[cchValueSize-1] = _T('\0');
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}
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}
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} // end BLOCK
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done:
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if (FAILED(hr) && pszBuf && cchBuf > 0)
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pszBuf[0] = _T('\0');
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if (pcchValueSize)
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*pcchValueSize = cchValueSize;
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if (pfExpandSz)
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*pfExpandSz = fExpandSz;
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return hr;
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}
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// SafeRegQueryValueCchAllocHelper [private]
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//
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// Implementation of the 2 "alloc" versions of the safe reg string functions.
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//
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HRESULT WINAPI SafeRegQueryValueCchAllocHelper
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(
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IN DWORD dwExpectedType,
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IN HKEY hkey,
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IN LPCTSTR pszValueName,
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OUT LPTSTR* ppszBuf,
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OUT OPTIONAL int* pcchValueSize,
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OUT OPTIONAL BOOL* pfExpandSz
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)
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{
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LPTSTR pszResult = NULL;
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int cchValueSize = 0;
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BOOL fExpandSz = FALSE;
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HRESULT hr = E_INVALIDARG;
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// BLOCK
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{
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if (!ppszBuf)
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{
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goto done; // hr is already E_INVALIDARG
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}
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DWORD cbNeeded = 0;
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DWORD dwErr = RegQueryValueEx(hkey, pszValueName, NULL, NULL, NULL, &cbNeeded);
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if (dwErr != 0 && dwErr != ERROR_MORE_DATA)
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{
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hr = HRESULT_FROM_WIN32(dwErr);
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goto done;
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}
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int cchBuf = (cbNeeded / sizeof(TCHAR)) + 2;
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pszResult = (LPTSTR)SafeRegMalloc(sizeof(TCHAR) * cchBuf);
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if (!pszResult)
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{
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hr = E_OUTOFMEMORY;
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goto done;
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}
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hr = SafeRegQueryValueCchHelper(dwExpectedType, hkey, pszValueName, pszResult, cchBuf, &cchValueSize, &fExpandSz);
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}
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done:
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if (FAILED(hr))
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{
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SafeRegFree(pszResult);
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pszResult = NULL;
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}
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if (ppszBuf)
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*ppszBuf = pszResult;
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if (pcchValueSize)
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*pcchValueSize = cchValueSize;
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if (pfExpandSz)
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*pfExpandSz = fExpandSz;
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return hr;
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}
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// SafeRegQueryStringValueCch [public]
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//
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// Reads a string out of the registry and ensures the result is null-
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// terminated. Optionally returns the number of characters retrieved,
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// excluding the trailing null.
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//
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// If the buffer is not big enough, the function returns REG_E_MORE_DATA
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// and stores the required size, in characters, in the pcchValueSize
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// parameter (including room for the trailing null). Note that the size
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// returned may be bigger than the actual size of the data in the registry.
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//
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HRESULT WINAPI SafeRegQueryStringValueCch
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(
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IN HKEY hkey,
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IN LPCTSTR pszValueName,
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OUT LPTSTR pszBuf,
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IN int cchBuf,
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OUT OPTIONAL int* pcchValueSize, // S_OK: chars written, excluding trailing null
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// REG_E_MORE_DATA: required size, including null
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OUT OPTIONAL BOOL* pfExpandSz // TRUE if reg string is actually REG_EXPAND_SZ
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)
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{
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return SafeRegQueryValueCchHelper(REG_SZ, hkey, pszValueName, pszBuf, cchBuf, pcchValueSize, pfExpandSz);
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}
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HRESULT WINAPI SafeRegQueryStringValueCb
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(
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IN HKEY hkey,
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IN LPCTSTR pszValueName,
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OUT LPTSTR pszBuf,
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IN int cbBuf,
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OUT OPTIONAL int* pcbValueSize, // S_OK: bytes written, excluding trailing null
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// REG_E_MORE_DATA: required size, including null
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OUT OPTIONAL BOOL* pfExpandSz // TRUE if reg string is actually REG_EXPAND_SZ
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)
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{
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int cchBuf = cbBuf / sizeof(TCHAR); // note: odd #'s for cbBuf are rounded down
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HRESULT hr = SafeRegQueryValueCchHelper(REG_SZ, hkey, pszValueName, pszBuf, cchBuf, pcbValueSize, pfExpandSz);
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if (pcbValueSize)
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*pcbValueSize *= sizeof(TCHAR);
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return hr;
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}
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// SafeRegQueryMultiStringValueCch [public]
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//
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// Reads a multi-string out of the registry and ensures the result is double
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// null-terminated. Optionally returns the number of characters retrieved,
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// excluding the second trailing NULL.
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//
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// If the buffer is not big enough, the function returns REG_E_MORE_DATA
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// and stores the required size, in characters, in the pcchValueSize
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// parameter (including room for the trailing nulls). Note that the size
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// returned may be bigger than the actual size of the data in the registry.
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//
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HRESULT WINAPI SafeRegQueryMultiStringValueCch
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(
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IN HKEY hkey,
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IN LPCTSTR pszValueName,
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OUT LPTSTR pszBuf,
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IN int cchBuf,
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OUT OPTIONAL int* pcchValueSize // S_OK: chars written, excluding final trailing null
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// REG_E_MORE_DATA: required size, including nulls
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)
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{
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return SafeRegQueryValueCchHelper(REG_MULTI_SZ, hkey, pszValueName, pszBuf, cchBuf, pcchValueSize, NULL);
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}
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HRESULT WINAPI SafeRegQueryMultiStringValueCb
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(
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IN HKEY hkey,
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IN LPCTSTR pszValueName,
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OUT LPTSTR pszBuf,
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IN int cbBuf,
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OUT OPTIONAL int* pcbValueSize // S_OK: bytes written, excluding final trailing null
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// REG_E_MORE_DATA: required size, including nulls
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)
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{
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int cchBuf = cbBuf / sizeof(TCHAR); // note: odd #'s for cbBuf are rounded down
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HRESULT hr = SafeRegQueryValueCchHelper(REG_MULTI_SZ, hkey, pszValueName, pszBuf, cchBuf, pcbValueSize, NULL);
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if (pcbValueSize)
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*pcbValueSize *= sizeof(TCHAR);
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return hr;
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}
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// SafeRegQueryStringValueCchAlloc [public]
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//
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// Allocates room for the registry string via SafeRegMalloc, and returns
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// the resulting string. Caller should free via SafeRegFree.
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//
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HRESULT WINAPI SafeRegQueryStringValueCchAlloc
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(
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IN HKEY hkey,
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IN LPCTSTR pszValueName,
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OUT LPTSTR* ppszBuf,
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OUT OPTIONAL int* pcchValueSize, // chars written, excluding trailing null
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OUT OPTIONAL BOOL* pfExpandSz // TRUE if reg string is actually REG_EXPAND_SZ
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)
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{
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return SafeRegQueryValueCchAllocHelper(REG_SZ, hkey, pszValueName, ppszBuf, pcchValueSize, pfExpandSz);
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}
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HRESULT WINAPI SafeRegQueryStringValueCbAlloc
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(
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IN HKEY hkey,
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IN LPCTSTR pszValueName,
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OUT LPTSTR* ppszBuf,
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OUT OPTIONAL int* pcbValueSize, // bytes written, excluding trailing null
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OUT OPTIONAL BOOL* pfExpandSz // TRUE if reg string is actually REG_EXPAND_SZ
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)
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{
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HRESULT hr = SafeRegQueryValueCchAllocHelper(REG_SZ, hkey, pszValueName, ppszBuf, pcbValueSize, pfExpandSz);
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if (pcbValueSize)
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*pcbValueSize *= sizeof(TCHAR);
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return hr;
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}
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// SafeRegQueryMultiStringValueCchAlloc [public]
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//
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// Allocates room for the registry string via SafeRegMalloc, and returns
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// the resulting string. Caller should free via SafeRegFree.
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//
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HRESULT WINAPI SafeRegQueryMultiStringValueCchAlloc
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(
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IN HKEY hkey,
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IN LPCTSTR pszValueName,
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OUT LPTSTR* ppszBuf,
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OUT OPTIONAL int* pcchValueSize // chars written, excluding final trailing null
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)
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{
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return SafeRegQueryValueCchAllocHelper(REG_MULTI_SZ, hkey, pszValueName, ppszBuf, pcchValueSize, NULL);
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}
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HRESULT WINAPI SafeRegQueryMultiStringValueCbAlloc
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(
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IN HKEY hkey,
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IN LPCTSTR pszValueName,
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OUT LPTSTR* ppszBuf,
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OUT OPTIONAL int* pcbValueSize // bytes written, excluding final trailing null
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)
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{
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HRESULT hr = SafeRegQueryValueCchAllocHelper(REG_MULTI_SZ, hkey, pszValueName, ppszBuf, pcbValueSize, NULL);
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if (pcbValueSize)
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*pcbValueSize *= sizeof(TCHAR);
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return hr;
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}
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