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181 lines
5.7 KiB
181 lines
5.7 KiB
//
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// The MIT License
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//
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// Copyright (c) 2010 James E Beveridge
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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// This sample code is for my blog entry titled, "Understanding ReadDirectoryChangesW"
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// http://qualapps.blogspot.com/2010/05/understanding-readdirectorychangesw.html
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// See ReadMe.txt for overview information.
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#include "stdafx.h"
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#include "ReadDirectoryChanges.h"
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#include "ReadDirectoryChangesPrivate.h"
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// The namespace is a convenience to emphasize that these are internals
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// interfaces. The namespace can be safely removed if you need to.
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namespace ReadDirectoryChangesPrivate
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{
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///////////////////////////////////////////////////////////////////////////
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// CReadChangesRequest
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CReadChangesRequest::CReadChangesRequest(CReadChangesServer* pServer, LPCTSTR sz, BOOL b, DWORD dw, DWORD size)
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{
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m_pServer = pServer;
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m_dwFilterFlags = dw;
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m_bIncludeChildren = b;
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m_wstrDirectory = sz;
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m_hDirectory = 0;
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::ZeroMemory(&m_Overlapped, sizeof(OVERLAPPED));
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// The hEvent member is not used when there is a completion
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// function, so it's ok to use it to point to the object.
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m_Overlapped.hEvent = this;
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m_Buffer.resize(size);
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m_BackupBuffer.resize(size);
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}
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CReadChangesRequest::~CReadChangesRequest()
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{
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// RequestTermination() must have been called successfully.
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_ASSERTE(m_hDirectory == NULL);
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}
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bool CReadChangesRequest::OpenDirectory()
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{
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// Allow this routine to be called redundantly.
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if (m_hDirectory)
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return true;
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m_hDirectory = ::CreateFileW(
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m_wstrDirectory.c_str(), // pointer to the file name
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FILE_LIST_DIRECTORY, // access (read/write) mode
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FILE_SHARE_READ // share mode
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| FILE_SHARE_WRITE
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| FILE_SHARE_DELETE,
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NULL, // security descriptor
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OPEN_EXISTING, // how to create
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FILE_FLAG_BACKUP_SEMANTICS // file attributes
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| FILE_FLAG_OVERLAPPED,
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NULL); // file with attributes to copy
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if (m_hDirectory == INVALID_HANDLE_VALUE)
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{
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return false;
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}
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return true;
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}
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void CReadChangesRequest::BeginRead()
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{
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DWORD dwBytes=0;
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// This call needs to be reissued after every APC.
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BOOL success = ::ReadDirectoryChangesW(
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m_hDirectory, // handle to directory
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&m_Buffer[0], // read results buffer
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m_Buffer.size(), // length of buffer
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m_bIncludeChildren, // monitoring option
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m_dwFilterFlags, // filter conditions
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&dwBytes, // bytes returned
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&m_Overlapped, // overlapped buffer
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&NotificationCompletion); // completion routine
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}
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//static
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VOID CALLBACK CReadChangesRequest::NotificationCompletion(
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DWORD dwErrorCode, // completion code
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DWORD dwNumberOfBytesTransfered, // number of bytes transferred
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LPOVERLAPPED lpOverlapped) // I/O information buffer
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{
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CReadChangesRequest* pBlock = (CReadChangesRequest*)lpOverlapped->hEvent;
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if (dwErrorCode == ERROR_OPERATION_ABORTED)
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{
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::InterlockedDecrement(&pBlock->m_pServer->m_nOutstandingRequests);
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delete pBlock;
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return;
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}
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// Can't use sizeof(FILE_NOTIFY_INFORMATION) because
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// the structure is padded to 16 bytes.
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_ASSERTE(dwNumberOfBytesTransfered >= offsetof(FILE_NOTIFY_INFORMATION, FileName) + sizeof(WCHAR));
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// This might mean overflow? Not sure.
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if(!dwNumberOfBytesTransfered)
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return;
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pBlock->BackupBuffer(dwNumberOfBytesTransfered);
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// Get the new read issued as fast as possible. The documentation
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// says that the original OVERLAPPED structure will not be used
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// again once the completion routine is called.
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pBlock->BeginRead();
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pBlock->ProcessNotification();
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}
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void CReadChangesRequest::ProcessNotification()
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{
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BYTE* pBase = m_BackupBuffer.data();
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for (;;)
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{
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FILE_NOTIFY_INFORMATION& fni = (FILE_NOTIFY_INFORMATION&)*pBase;
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std::wstring wstrFilename(fni.FileName, fni.FileNameLength/sizeof(wchar_t));
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// Handle a trailing backslash, such as for a root directory.
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if (m_wstrDirectory.find_last_of(L"\\") != std::wstring::npos)
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wstrFilename = m_wstrDirectory + L"\\" + wstrFilename;
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else
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wstrFilename = m_wstrDirectory + wstrFilename;
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// If it could be a short filename, expand it.
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LPCWSTR wszFilename = PathFindFileNameW(wstrFilename.c_str());
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int len = lstrlenW(wszFilename);
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// The maximum length of an 8.3 filename is twelve, including the dot.
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if (len <= 12 && wcschr(wszFilename, L'~'))
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{
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// Convert to the long filename form. Unfortunately, this
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// does not work for deletions, so it's an imperfect fix.
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wchar_t wbuf[MAX_PATH];
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if (::GetLongPathNameW(wstrFilename.c_str(), wbuf, _countof(wbuf)) > 0)
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wstrFilename = wbuf;
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}
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m_pServer->m_pBase->Push(fni.Action, wstrFilename);
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if (!fni.NextEntryOffset)
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break;
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pBase += fni.NextEntryOffset;
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};
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}
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}
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