Re: [Mingw-users] Unable to read large files with -mrtd.

[<dan...@ya...>]

I think the problem is that none of the C runtime prototypes in mingw
headers are explicitly marked as __cdecl.  

-mrtd declares everything __stdcall (but doesn't use __stdcall
decoration so no link time error)

Sooner or later at runtime there will be a stack overflow 

You have two options:
1) declare all (or at least the ones you use) the C runtime prototypes
as __cdecl, then -mrtd should work

2) don't use -mrtd, but explicitly mark your dllexports/imports as
__stdcall 

eg 

#if BUILDING_DLL
# define DLLIMPORT __declspec (dllexport) __stdcall
#else /* Not BUILDING_DLL */
# define DLLIMPORT __declspec (dllimport) __stdcall
#endif /* Not BUILDING_DLL */#

and

void DLLIMPORT filetest(char *fname)

Danny


--- Erik Terpstra <er...@so...> wrote: > When I build hunks.dll
in the example below, and use its filetest
> function in usedll.exe, it crashes with a stack error when reading
> large
> files (postscript files several MB's in size).
> However, when I remove the -mrtd options from the build instructions,
> it
> works fine. But then I can't use the DLL in Visual Basic, because VB
> only supports the stdcall mechanism (which is activated using the
> -mrtd
> option).
> 
> I'm aware that this particular DLL doesn't do anything useful yet,
> but
> (when supporting stdcalls) it cannot read large files in the first
> place.
> 
> Ideas anyone?
> 
> TIA,
> 
>     Erik.
> 
> 
> gcc -c -DBUILDING_DLL=1 -mrtd -I. -g -Wall --pedantic -o hunks.o
> hunks.c
> 
> gcc -c -DBUILDING_DLL=1 -mrtd -I. -g -Wall -o dllinit.o dllinit.c
> dllwrap --export-all --output-def hunks.def --implib libhunks.a -o
> hunks.dll hunks.o dllinit.o
> gcc -c -I. -g -Wall  -o usedll.o usedll.c
> dllwrap --export-all --output-def hunks.def --implib libhunks.a -o
> hunks.dll hunks.o dllinit.o
> gcc -o usedll.exe -g -Wall usedll.o -L./ -lhunks
> 
> 
> 
> /*-- usedll.c ------------------------------------------*/
> #include <stdio.h>
> #include "hunks.h"
> 
> int main(int argc,char *argv[]){
>         printf("BEGIN\n");
>         filetest("verybigfile.ps");
>         return 0;
> }
> 
> /*-- hunks.c ------------------------------------------*/
> #include <stdio.h>
> #include "hunks.h"
> 
> DLLIMPORT void filetest(char *fname){
>         char ch;
>         FILE *f;
> 
>         if((f=fopen(fname,"rb"))){
>                 while(!feof(f)){
>                         ch=getc(f);
>                 }
>                 fclose(f);
>         }
> }
> 
> /*-- dllinit.c ------------------------------------------*/
> #define WIN32_LEAN_AND_MEAN
> #include <windows.h>
> #undef WIN32_LEAN_AND_MEAN
> #include <stdio.h>
> 
> BOOL APIENTRY DllMain (HINSTANCE hInst, DWORD reason,
>                        LPVOID reserved /* Not used. */ );
> 
> BOOL APIENTRY
> DllMain (
>          HINSTANCE hInst /* Library instance handle. */ ,
>          DWORD reason /* Reason this function is being called. */ ,
>          LPVOID reserved /* Not used. */ )
> {
> 
>   switch (reason)
>     {
>     case DLL_PROCESS_ATTACH:
>       break;
> 
>     case DLL_PROCESS_DETACH:
>       break;
> 
>     case DLL_THREAD_ATTACH:
>       break;
> 
>     case DLL_THREAD_DETACH:
>       break;
>     }
>   return TRUE;
> }
> 
> /*-- hunks.h ------------------------------------------*/
> #ifndef hunks_h_included
> #define hunks_h_included
> #if BUILDING_DLL
> # define DLLIMPORT __declspec (dllexport)
> #else /* Not BUILDING_DLL */
> # define DLLIMPORT __declspec (dllimport)
> #endif /* Not BUILDING_DLL */
> 
> DLLIMPORT void filetest(char *fname);
> 
> #endif /* hunks_h_included */
> 
> 
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