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From: kulack AT us DOT ibm DOT com
To: cygwin AT sourceware DOT cygnus DOT com
Message-ID: <852568FF.007476F8.00@D51MTA04.pok.ibm.com>
Date: Thu, 15 Jun 2000 16:12:09 -0500
Subject: Can't build a DLL using gcc
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I'm pretty new at Win and gcc development. I've been searching the archives
for details about this, but have only found hints.
I've followed the instrutions at
http://sourceware.cygnus.com/cygwin/cygwin-ug-net/dll.html for building
DLLs using GCC, but get a STATUS_ACCESS_VIOLATION when I attempt to use it.

About my only guess is that I'm doing something wrong with the .DEF file.
Can it get created automatically or should there be a 'SECTIONS' section in
the .DEF file indicating which type of access (EXECUTE, READ, WRITE) the
dll should have?
Not familiar with nm output, but it seems to look ok for the created dll...
Can anyone teach me to fish? 8-)

Bash /db2src/test
 > make libhello.a
gcc  -g -c -I/sqllib/include libhello.c
gcc -s -Wl,--base-file,libhello.base -o libhello.dll libhello.o
-Wl,-e,_mydll_init AT 12
dlltool --base-file libhello.base --def libhello.def --output-exp
libhello.exp --dllname libhello.dll
gcc -s -Wl,--base-file,libhello.base,libhello.exp -o libhello.dll
libhello.o -Wl,-e,_mydll_init AT 12
dlltool --base-file libhello.base --def libhello.def --output-exp
libhello.exp --dllname libhello.dll
gcc -Wl,libhello.exp -o libhello.dll libhello.o -Wl,-e,_mydll_init AT 12
dlltool --def libhello.def --dllname libhello.dll --output-lib libhello.a
cp libhello.dll ..
rm libhello.o

Bash /db2src/test
 > make hello.exe
gcc  -g -c -I/sqllib/include hello.c
gcc  -g hello.o -L/db2src/test -lhello
mv a.exe hello.exe

Bash /db2src/test
 > hello
Hello World
      0 [main] hello 1127 handle_exceptions: Exception:
STATUS_ACCESS_VIOLATION
   9205 [main] hello 1127 stackdump: Dumping stack trace to
hello.exe.stackdump

Bash /db2src/test
 > cat hello.exe.stackdump
Exception: STATUS_ACCESS_VIOLATION at eip=000055CC
eax=00000009 ebx=00000000 ecx=0000000C edx=0245FDF4 esi=00000000
edi=0A041448
ebp=0245FE74 esp=0245FE58 program=c:\db2src\test\hello.exe
cs=001B ds=0023 es=0023 fs=003B gs=0000 ss=0023
Stack trace:
Frame     Function  Args
0245FE74  00401085  (00000009, 0245FEB0, 0245FEA4, 0040106B)
0245FEA4  00401085  (00000001, 0A041448, 0A040008, 00000000)
0245FF00  610022E5  (7FFDF000, 00000000, 00000018, 80452662)
0245FF60  61002735  (00403010, 00000000, 0245FF90, 004011DA)
0245FF90  004011E7  (00401060, FFFFFFFF, 80430B27, 00000000)
0245FFC0  0040103B  (00000018, 00000000, 7FFDF000, 00000000)
0245FFF0  77E87903  (00401000, 00000000, 000000C8, 00000100)
End of stack trace

======= libhello.c
#include <stdio.h>
#include <windows.h>
extern int helloFromDll(int parm);

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

int helloFromDll(int parm) {
   printf("Hello from Dll, parm=%d\n", parm);
   return parm+1;
}

int main(int argc, char **argv) {
   // This doesn't feel right...
   // Was forced to add main() in order to get the
   // instructions for building DLLs at
   //   http://sourceware.cygnus.com/cygwin/cygwin-ug-net/dll.html
   // to work correctly, otherwise, linker failed to
   // find WinMain AT 16 (which I wouldn't have believed it should
   // require).
}

======= libhello.def
LIBRARY LIBHELLO
DESCRIPTION 'LIBHELLO.DLL Testcase'
EXPORTS
   helloFromDll

======= hello.c
#include <stdio.h>
extern int helloFromDll(int parm);
int main(int argc, char **argv)
{
   int         rc;
   printf("Hello World\n");
   rc = helloFromDll(9);
   printf("DLL returned %d\n", rc);
   return 0;
}


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