File locking on windows

[vermarajeev]

Hi guys,,

What is wrong with below given code. It isnt locking the file???Where m I going wrong???

int main (){
 
   FILE    *pFile = NULL;  
   char    *fileName = "two.txt";
 
   // Open the file in read mode  
   pFile = fopen( fileName ,"r");   
 
   if (!pFile){
         printf("Error opening file %s!\n", fileName);
         exit(1);
   }  
   int beg = 0;
   fseek( pFile, beg, SEEK_END  );
   int end = ftell(pFile);  
 
   cout<<"Press <RETURN> to try to get lock: "<<endl;
   getchar();
   cout<<"Trying to get lock..."<<endl;
 
   if( !LockFile((HANDLE)pFile, end, 0, end, 0) )
   {
       cout<< "Cannot lock:"<<endl;
       return 0;
   }
 
   fseek( pFile, beg, SEEK_SET  );     
   ifstream is(pFile);
   char line[256];
   while( !is.eof() ){  
           is.getline( line, sizeof( line ) );  
           cout<<line;  
   }
   cout<<"Press <RETURN> to release lock: "<<endl;
   getchar();
   UnlockFile((HANDLE)pFile, 0, 0, end, 0);
   cout<<"Unlocked.\n"<<endl;    
   fclose( pFile );
 
   return 0;  
 }

Hi Banfa, can you please help me with this. I want to lock a file on windows (Microsoft Visual Studio .NET 2003) such that other processes are unable to read the same file again. Please help...

[weaknessforcats]

I don't believe LockFile prevents reading from a mapped file view.

You may need to build a semaphore class to prevent reading.