I'm trying to prevent a third-party DLL in my process from reading a file I've opened, and I've found it to be... well, impossible.
No matter what I do, no matter what share flags I specify, their call always seems to succeed!
Here is the screenshot from Process Monitor -- the first CreateFile
call is mine, and the rest are theirs:
How is this even possible? Why is the "Share Mode: None" lying to me, and how can I prevent this?
This code below is an example that reproduces the problem:
#include <stdio.h>
#include <Windows.h>
int main()
{
LPCTSTR file = TEXT("C:\\Test1234.xml");
HANDLE hFile1 =
CreateFile(file, FILE_READ_ATTRIBUTES, 0, NULL, OPEN_ALWAYS, 0, NULL);
HANDLE hFile2 =
CreateFile(file, FILE_READ_DATA, 0, NULL, OPEN_ALWAYS, 0, NULL);
DWORD n;
BYTE buf[1];
printf("%d\n", ReadFile(hFile2, buf, sizeof(buf), &n, NULL));
CloseHandle(hFile1);
CloseHandle(hFile2);
DeleteFile(file);
}