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myrkraverk(R)

25.11.2010, 00:44
 

HX fails at anonymous memory mapping (DOSX)

Dear HX users,

HX 2.17 runs into an infinite loop or hangs with the following code. I did not bother to find out where it stops though. I am running on Freedos in VirtualBox. It works fine in Wine.

Mappings to actual files work.

#include <windows.h>

#include <iostream>
#include <cstdlib>

int main( int, char *[] )
{

  // Note: hardcoded size.
  HANDLE map = CreateFileMapping( 0, NULL, PAGE_READWRITE, 0, 6, NULL );

  void *buffer = MapViewOfFile( map, FILE_MAP_WRITE, 0, 0, 0 );

  std::memcpy( buffer, "hello", 6 );

  std::cout << static_cast< char * >( buffer ) << std::endl;

  return 0;
}


This is currently my showstopper at supporting DOS (though I don't think anyone will want to use my application, much less in DOS).

This is a practice/demonstration at using memory mappings so "just using new[]" isn't going to "help." In practice I'd probably use something else, honest!

If there is a memory mapper in some other DOS extender I may play with it as well.


Johann

Japheth(R)

Homepage

Germany (South),
25.11.2010, 08:30

@ myrkraverk
 

HX fails at anonymous memory mapping

> HX fails at anonymous memory mapping

[snip]

> // Note: hardcoded size.
> HANDLE map = CreateFileMapping( 0, NULL, PAGE_READWRITE, 0, 6, NULL );

I don't think that 0 as first parameter will trigger "anonymous" memory mapping. Actually, 0 is a valid file handle. Please make yourself familiar with the Win32 API!

---
MS-DOS forever!

myrkraverk(R)

25.11.2010, 10:07

@ Japheth
 

HX fails at anonymous memory mapping

> > HX fails at anonymous memory mapping
>
> [snip]
>
> > // Note: hardcoded size.
> > HANDLE map = CreateFileMapping( 0, NULL, PAGE_READWRITE, 0, 6, NULL );
>
> I don't think that 0 as first parameter will trigger "anonymous" memory
> mapping. Actually, 0 is a valid file handle. Please make yourself familiar
> with the Win32 API!

You're right, I need to pass in INVALID_HANDLE_VALUE. Shame on me. Note to self: Never assume a 0 void * is an invalid value.


Johann

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