www.digitalmars.com         C & C++   DMDScript  

c++.windows.32-bits - DllMain Not Being Executed

reply JimP <JimP_member pathlink.com> writes:
Ihave a dll program that compiles with no warnings or errors.  It is compiled
with the options:
dmc.exe -mn -c   -x -WD -w-

and linked with the options:
link.exe /NOLOGO /DELEXECUTABLE /EXETYPE:NT /SUBSYSTEM:WINDOWS

The calling program uses explicit linking with LoadLibrary and GetProcAddress.
Both of these functions execute without getting an error.  But the DllMain
function is never called.  I put a messagebox in the DllMain function to verify
this.

Why isn't the DllMain function being called????
Dec 21 2005
parent reply JimP <JimP_member pathlink.com> writes:
In article <doc7a5$2veo$1 digitaldaemon.com>, JimP says...

Ihave a dll program that compiles with no warnings or errors.  It is compiled
with the options:
dmc.exe -mn -c   -x -WD -w-

and linked with the options:
link.exe /NOLOGO /DELEXECUTABLE /EXETYPE:NT /SUBSYSTEM:WINDOWS

The calling program uses explicit linking with LoadLibrary and GetProcAddress.
Both of these functions execute without getting an error.  But the DllMain
function is never called.  I put a messagebox in the DllMain function to verify
this.

Why isn't the DllMain function being called????



I tried this with the Borland and GCC (MinGW) compilers.  It worked OK with
both.  It must be something about the Digital Mars compiler.  An option?
Something I am omitting?  Or is it just not executed with explicit linking?

Any suggestions would be appreciated.
Dec 22 2005
parent reply "Gisle Vanem" <giva users.sourceforge.net> writes:
"JimP" <JimP_member pathlink.com> wrote:


 I tried this with the Borland and GCC (MinGW) compilers.  It worked OK with
 both.  It must be something about the Digital Mars compiler.  An option?
 Something I am omitting?  Or is it just not executed with explicit linking?


How did you declare DllMain()?

--gv
Dec 24 2005
parent reply Alex Roschin <Alex_member pathlink.com> writes:
In article <dojkr4$gum$1 digitaldaemon.com>, Gisle Vanem says...

"JimP" <JimP_member pathlink.com> wrote:


 I tried this with the Borland and GCC (MinGW) compilers.  It worked OK with
 both.  It must be something about the Digital Mars compiler.  An option?
 Something I am omitting?  Or is it just not executed with explicit linking?


How did you declare DllMain()?

--gv


I have the same problem - neither DllMain, nor constructors for global objects
are executed. I am making a C++ DLL that should be loaded by LoadLibrary call.
Here is a sample code:

// dll.cpp
#include<windows.h>

extern "C" BOOL WINAPI DllMain(HINSTANCE hinst,DWORD reason,LPVOID lpReserved)
{
MessageBox(NULL,"DllMain","dll",MB_OK);
return TRUE;
}

// Global object
class TSomeClass
{ public:
int i;
TSomeClass(void){MessageBox(NULL,"Constructor","dll",MB_OK);};
};
TSomeClass SomeObject;

// Function
extern "C" __declspec(dllexport)
int CALLBACK DoSomething(int CallMode,LPVOID Data,LPVOID ExtParam)
{ static BOOL FirstCall=TRUE;
if(FirstCall)
{ FirstCall=FALSE;
MessageBox(NULL,"Function","dll",MB_OK);
}
return 0;
}

The compiler command line:
c:\prog\dm\bin\dmc.exe dll.cpp -c -mn -WD -Ae -I"c:\prog\dm\include"
-I"c:\prog\dm\include\Win32"
Linker command line:
c:\prog\dm\bin\link.exe /DELEXECUTABLE /NODEBUG /EXETYPE:NT dll.obj ,
testdll.dll , , user32.lib kernel32.lib

Everything compiles without errors. When I call LoadLibrary I see neither
"DllMain" message, nor "Constructor" message, but function DoSomething executes
normally and produces "Function" message at first call.

I tried to add "/ENTRY:_DllMainCRTStartup" linker switch as I've seen in some
examples, but nothing changes.

Please tell me what am I doing wrong.
Mar 27 2006
parent reply Bertel Brander <bertel post4.tele.dk> writes:
Alex Roschin wrote:

 Please tell me what am I doing wrong.


I took my code from:
http://home20.inet.tele.dk/midgaard/tipwin20060212.html

And changed the source code for the dll to:
#include <windows.h>
#include "mydll.h"

class DllClass
{
public:
    DllClass()
    {
       MessageBox(0, "Hello World", "DllClass", MB_OK);
    }
};

DllClass DllObject;

__declspec(dllexport) BOOL APIENTRY DllMain(HANDLE hModule, DWORD 
ul_reason_for_call, LPVOID lpReserved)
{
    switch (ul_reason_for_call)
    {
    case DLL_PROCESS_ATTACH:
    case DLL_THREAD_ATTACH:
    case DLL_THREAD_DETACH:
    case DLL_PROCESS_DETACH:
       MessageBox(0, "Something", "DllMain", MB_OK);
       break;
    }
    return TRUE;
}

__declspec(dllexport) int DoSomething(int a, int b)
{
    return a*b*2;
}

__declspec(dllexport) Whatever::Whatever(int aX, int aY) : X(aX), Y(aY)
{
}

__declspec(dllexport) int Whatever::Get()
{
    return X*Y;
}

And build with these commands:
dmc -mn -WD mydll.cpp kernel32.lib
implib.exe /noi mydll.lib mydll.dll
dmc mytest.cpp mydll.lib

And the MessageBox'es popup as expected.

It can be noted that I don't use LoadLibrary, but use the
dll throug a .lib created by implib.exe. I don't know
if it will make any difference.

-- 
Absolutely not the best homepage on the net:
http://home20.inet.tele.dk/midgaard
But it's mine - Bertel
Mar 28 2006
parent reply Alex Roschin <Alex_member pathlink.com> writes:
In article <e0bupn$2v9n$1 digitaldaemon.com>, Bertel Brander says...

I took my code from:
http://home20.inet.tele.dk/midgaard/tipwin20060212.html


Thank you! I've found the thing that caused the problem:

1) When I compile and link the example with the single command (without "-c"
option), everything works fine - I see all message boxes. 

2) When I try to compile and to link separately with
dmc.exe -c -mn -WD mydll.cpp
link.exe mydll.obj , testdll.dll , , kernel32.lib
neither DllMain, nor constructor message boxes show up. 

I believe that in first case dmc.exe calls link.exe with certain options which I
don't know. I tried to play with some, but in vain. 

Since the single command build works fine, I think I will use it.

Thanks again.
Mar 29 2006
parent reply Nic Tiger <g_tiger progtech.ru> writes:
Alex Roschin пишет:


 In article <e0bupn$2v9n$1 digitaldaemon.com>, Bertel Brander says...

 I took my code from:
 http://home20.inet.tele.dk/midgaard/tipwin20060212.html


 
 Thank you! I've found the thing that caused the problem:
 
 1) When I compile and link the example with the single command (without "-c"
 option), everything works fine - I see all message boxes. 
 
 2) When I try to compile and to link separately with
 dmc.exe -c -mn -WD mydll.cpp
 link.exe mydll.obj , testdll.dll , , kernel32.lib
 neither DllMain, nor constructor message boxes show up. 
 
 I believe that in first case dmc.exe calls link.exe with certain options which
I
 don't know. I tried to play with some, but in vain. 
 
 Since the single command build works fine, I think I will use it.
 
 Thanks again.
 
 


It seems that OPTLINK will not generate valid DLL when .def is not 
specified.

DMC.EXE in fact generates simple .DEF and supplies it to linker:

LIBRARY "tasklet.dll"
DESCRIPTION 'tasklet'
EXETYPE NT
SUBSYSTEM WINDOWS
CODE SHARED EXECUTE
DATA WRITE

Neither LIBRARY, nor CODE SHARED cannot be specified with OPTLINK 
switches, hence I think they (or their absence) are cause of troubles.


Nic Tiger.
Dec 16 2009
parent Name <e-mail test.com> writes:
Web News test...
Apr 26 2010