cryptfile.cpp

详细的MFC资料

#include "stdafx.h"
#include "cryptfile.h"

BOOL CCryptFile::Open( LPCTSTR lpszFileName, UINT nOpenFlags, CFileException* pError)
{
	CFile raw;
	
	// you'd like to test for modeRead, but since it is 0, that doesn't work
	if ((nOpenFlags & (CFile::modeReadWrite|CFile::modeWrite))==0) 
	{
		if (!raw.Open(lpszFileName,nOpenFlags,pError))
		{
			return FALSE;
		}
		unsigned n;
		n=raw.GetLength();
		unsigned char *p=(unsigned char *)malloc(n);
		raw.Read(p,n); // read entire file
		raw.Close();
		// decrypt
		for (unsigned i=0;i<n;i++)
			p[i]^=0xFF;
		Attach(p,n);
	}
	else
		basefile=lpszFileName;
	return TRUE;
}

void CCryptFile::Close( )
{
	CFileException pError;
	CFile raw;
	// if saving, encrypt data and write to real file
	if (!basefile.IsEmpty())
	{
		unsigned n=GetLength();
		if (!raw.Open(basefile,CFile::modeWrite|CFile::modeCreate|CFile::shareExclusive,&pError))
			throw &pError;
		unsigned char *p=Detach();
		// encrypt
		for (unsigned i=0;i<n;i++)
			p[i]^=0xFF;
		raw.Write(p,n);
		raw.Close();
		free(p);
	}
}