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Message-ID: <43F59FF02E07D31199220008C733ED53010FA5F7@exchange-dev.b3.wonderware.com>
From: Greg Clinton <greg DOT clinton AT wonderware DOT com>
To: "'cygwin AT cygwin DOT com'" <cygwin AT cygwin DOT com>
Subject: Question regarding building dlls
Date: Mon, 18 Dec 2000 15:33:10 -0800
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I'm having trouble with dll's that I build with gcc and dlltool. Any
time I try do do anything useful within a dll function, such as call
new or call any Win32 API, I get an access violation. Does anyone see
what I'm doing wrong? Below I provide mydll.cpp, mydll.def, myprog.c,
and build.bat. I'm using gcc version 2.95.2-5 19991024 (cygwin experimental)
Ultimately I intend to build an inproc COM server.

Thanks in advance for your help.
Greg Clinton
greg DOT clinton AT wonderware DOT com

------------------------------mydll.cpp------------------------------
#include <windows.h>

int main()
  {
  return 0;
  }

extern "C" int WINAPI 
mydll_init(HANDLE h, DWORD reason, void *foo)
{
  return 1;
}  
 

extern "C" int WINAPI 
calc()
{ 
  int *p = new int;
  delete p;
  return 34;
}  

------------------------------mydll.def------------------------------
LIBRARY

EXPORTS
  mydll_init
  calc

--------------------------------myprog.c------------------------------
#include <windows.h>

typedef int (WINAPI *CalcProc)();

int main()
  {
  int i;
  HMODULE hModule = LoadLibrary("mydll.dll");
  CalcProc calc = (CalcProc) GetProcAddress(hModule, "calc");
  i = calc();
  FreeLibrary(hModule);
  return i;
  }

------------------------------build.bat------------------------------
set path=%path%;c:\cygwin\bin
set include=c:\cygwin\usr\include;
gcc -c myprog.c
gcc -c mydll.cpp
gcc -s -Wl,--base-file,mydll.base -o mydll.dll mydll.o -Wl,-e,_mydll_init AT 12

dlltool --base-file mydll.base --def mydll.def --output-exp mydll.exp
--dllname mydll.dll
gcc -s -Wl,--base-file,mydll.base,mydll.exp -o mydll.dll mydll.o
-Wl,-e,_mydll_init AT 12
dlltool --base-file mydll.base --def mydll.def --output-exp mydll.exp
--dllname mydll.dll
gcc -Wl,mydll.exp -o mydll.dll mydll.o -Wl,-e,_mydll_init AT 12
gcc -o myprog myprog.o
myprog.exe

-----------------------myprog.exe.stackdump-----------------------------
Exception: STATUS_ACCESS_VIOLATION at eip=6E677963
eax=6E677963 ebx=140D1074 ecx=0240FF08 edx=77FCD348 esi=6107C0E8
edi=00000000
ebp=0240F75C esp=0240FBF8 program=C:\temp\MyDll\myprog.exe
cs=001B ds=0023 es=0023 fs=003B gs=0000 ss=0023
Stack trace:
Frame     Function  Args
0240F75C  6E677963  (00000000, 00000000, 00000000, 00000000)
0240FC04  6E677963  (140D1074, 6107C0E8, 00000000, 0240FCF4)
0240FD24  140D1209  (00000004, 00000000, 00000000, 00000004)
0240FD54  140D1084  (00000004, 0240FDA0, 61040551, 00000004)
0240FD84  00401091  (00000001, 0A011218, 0A010008, FFFFFFFE)
0240FF10  610038AD  (00000000, 03EEDEE4, 8046A640, 87F00280)
0240FF40  61003A8D  (00401054, 03EEDEE4, 8340BAC0, 8049F5BE)
0240FF60  61003ACC  (00000000, 00000000, 8340BC50, 00000005)
0240FF90  004010FF  (00401054, FFFFFFFF, 80430B27, 00000000)
0240FFC0  0040103D  (03EEDEE4, 0000064A, 7FFDF000, 03EEDC7C)
0240FFF0  77E87903  (00401000, 00000000, 000000C8, 00000100)
End of stack trace

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