Indeed that pragma looks like a shared memory macro to me

Actually one thing I found out is that DLLs and Shared Libraries are implemented via shared memory mapped files without giving access to shared memory.��

CodeDmitry I did get your message as you can see by the quote of my last reply. You are basically using Shared Memory IPC , its just an ungly Windows hack via a pragma and from the thread that Phil linked it looks like its also bug prone.��

This is also confirmed by Mircrosoft itself here ->��https://msdn.microsoft.com/en-us/library/h90dkhs0(v=vs.90).aspx

Summary: Use shared memory mapped files, far safer and far more cross platform

On Wed, Oct 12, 2016 at 11:12 AM phil@highoctane.be <phil@highoctane.be> wrote:

#pragma data_seg("SHARED")

looks like this is doing some serious IPC magic behing the scenes.

Check this out for some critters:��https://social.msdn.microsoft.com/Forums/vstudio/en-US/bc93445e-cec3-456d-9596-15528060dc94/sharing-data-between-processes-using-pragma-dataseg-and-windows-7?forum=vcgeneral

Phil

On Wed, Oct 12, 2016 at 9:34 AM, CodeDmitry <dimamakhnin@gmail.com> wrote:
Have you got my modified message? or have I been wasting my revisions all
along O.o? I'll repost.

O.o can you please elaborate?

I wrote a DLL a while ago that successfully shared the global state it
exported between the callers that without any shared memory explicitly being
created.

I'll recreate a test case to make sure that I am not just lying.

*Solution SharingDemo*:
*Project ShareMe*:
*ShareMe.cpp*:
#pragma data_seg("SHARED")
�� extern "C" {
�� __declspec(dllexport)
�� int sharedInteger = 0;
�� }
#pragma data_seg()

#pragma comment(linker, "/section:SHARED,RWS")

*Project Client1*:
*main.cpp*:
#include <Windows.h>
#include <stdio.h>

int main(int argc, char **argv)
{
�� HMODULE module_handle = LoadLibrary("ShareMe.dll");
�� int *shared_integer_handle = (int *)GetProcAddress(module_handle,
"sharedInteger");
�� printf("*(shared_integer_handle) = %d.\n", *shared_integer_handle);

�� *shared_integer_handle = 1337;

�� printf("*(shared_integer_handle) = %d.\n", *shared_integer_handle);

�� system("pause");
�� return 0;
}

*Project Client2*:
*main.cpp*:
#include <Windows.h>
#include <stdio.h>

int main(int argc, char **argv)
{
�� HMODULE module_handle = LoadLibrary("ShareMe.dll");
�� int *shared_integer_handle = (int *)GetProcAddress(module_handle,
"sharedInteger");
�� printf("*(shared_integer_handle) = %d.\n", *shared_integer_handle);

�� *shared_integer_handle = 0;

�� printf("*(shared_integer_handle) = %d.\n", *shared_integer_handle);

�� system("pause");
�� return 0;
}

now, debug client1, then debug client2. Client 2 should start with mutated
shared state(1337).

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