Question

With win32api, I want that the following program creates two process and creates a filemap. (using c++)

i don’t know what i should write at Handle CreateFileMapping(....
I’ve tried it with:

PROCCESS_INFORMATION hfile.

Furthermore the first parameter should be INVALID_HANDLE_VALUE, but then i don’t know what to write into MapViewOfFile as first parameter.

the code from the first program: (i didn’t programmed the 2.&3. because even the first doesn’t work)

//Initial process creates proccess 2 and 3 

#include <iostream>
#include <windows.h>
#include <string>

using namespace std;

void main()
{

bool ret;
bool retwait;
bool bhandleclose;

STARTUPINFO startupinfo;
GetStartupInfo (&startupinfo);

PROCESS_INFORMATION pro2info;
PROCESS_INFORMATION pro3info;

//create proccess 2
wchar_t wcsCommandLine[] = L"D:\\betriebssystemePRA2pro2.exe";


 ret = CreateProcess(NULL, wcsCommandLine, NULL, NULL, false, CREATE_NEW_CONSOLE, NULL,
  NULL, &startupinfo, &pro2info);


 if (ret==false){
  cout<<"Prozess konnte nicht erzeugt werden. Fehler:"<<GetLastError();
  ExitProcess(0);
 }

 //***************


 //create process3

wchar_t wcs2CommandLine[] = L"D:\\betriebssystemePRA2pro3.exe";


 ret = CreateProcess(NULL, wcs2CommandLine, NULL, NULL, false, CREATE_NEW_CONSOLE, NULL,
  NULL, &startupinfo, &pro3info);


 if (ret==false){
  cout<<"Prozess konnte nicht erzeugt werden. Fehler:"<<GetLastError();
  ExitProcess(0);
 }



 //***************



 //create mapping object 

 // program2:




 PROCESS_INFORMATION hfile;





  CreateFileMapping(  //erzeugt filemapping obj  returned ein handle
  INVALID_HANDLE_VALUE, //mit dem handle-->kein seperates file nötig
  NULL,
  PAGE_READWRITE,  //rechte (lesen&schreiben)
  0,
  5,
  L"myfile");  //systemweit bekannter name


    LPVOID mappointer = MapViewOfFile( //virtuelle speicherraum, return :zeiger, der auf den bereich zeigt
  INVALID_HANDLE_VALUE, //handle des filemappingobj.
  FILE_MAP_ALL_ACCESS,
  0,
  0,
  100);



    //wait
    cout<<"beliebige Taste druecken"<<endl;
    cin.get();


//close


 bool unmap;

 unmap = UnmapViewOfFile (mappointer);

 if (unmap==true)
  cout<<"Unmap erfolgreich"<<endl;
 else
  cout<<"Unmap nicht erfolgreich"<<endl;


 bhandleclose=CloseHandle (INVALID_HANDLE_VALUE);
 cout<<bhandleclose<<endl;

 bhandleclose=CloseHandle (pro2info.hProcess);
 bhandleclose=CloseHandle (pro3info.hProcess);


 ExitProcess(0);


}

Answer 1

MapViewOfFile takes the handle returned by CreateFileMapping:

HANDLE hFileMapping = CreateFileMapping(...);
LPVOID lpBaseAddress = MapViewOfFile(hFileMapping, ...);