win32 - ReadDirectoryChangesW的使用

任务：创建一个进程，并在进程内创建一个文本，再创建另一个进程来监控第一个进程内的文本变化

//Process 1
#include <windows.h>
#include <iostream>
int wmain(int argc, wchar_t* argv[])
{
    std::string buffer;
    while (1)
    {
        std::cin >> buffer;
        HANDLE hFile = CreateFile(L"log.txt", FILE_APPEND_DATA, FILE_SHARE_DELETE | FILE_SHARE_READ | FILE_SHARE_WRITE, 0, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0);
        DWORD written = 0;
        WriteFile(hFile, buffer.c_str(), buffer.size(), &written, NULL);
        CloseHandle(hFile);
    }
    return 0;
}

//Process 2
#include <windows.h>
#include <iostream>

int wmain(int argc, wchar_t* argv[])
{
    DWORD returned = 0;
    DWORD dwOffset = 0;
    FILE_NOTIFY_INFORMATION* pInfo = NULL;

    HANDLE hFile = CreateFile(L"Directory of log.txt", GENERIC_READ, FILE_SHARE_DELETE | FILE_SHARE_READ | FILE_SHARE_WRITE, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_BACKUP_SEMANTICS, 0);

    while (1)
    {
        BYTE szBuffer[1024] = { 0 };

        ReadDirectoryChangesW(hFile, szBuffer, sizeof(szBuffer), false, FILE_NOTIFY_CHANGE_SIZE, &returned, NULL, NULL);
        do
        {
            pInfo = (FILE_NOTIFY_INFORMATION*)&szBuffer[dwOffset];
            if (wcscmp(pInfo->FileName, L"log.txt") == 0)
            {
                HANDLE hFile = CreateFile(L"path\\log.txt", FILE_APPEND_DATA, 0, 0, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0);
                DWORD size = GetFileSize(hFile, NULL);
                std::cout << "File Size: " << size << std::endl;
                CloseHandle(hFile);
            }
            dwOffset += pInfo->NextEntryOffset;
        } while (pInfo->NextEntryOffset != 0);
    }
    return 0;
}

相关：https://stackoverflow.com/questions/63620862/using-file-as-a-mutex-with-createfile/63627936#63627936