I've been trying to build a DLL using g++, and given the problems I was
having, I decided to try a 'toy' example, which is available at:
http://cygwin.com/cygwin-ug-net/dll.html
I tweaked the two files around thusly:
hello.C:
-----
#include <stdio.h>
int hello() { printf("Hello World\n");}
-----
main.C:
-----
#include <stdio.h>
typedef void (*fn_type)();
extern "C" {
int dlopen(char*);
int dlsym( int, char*);
}
int main() {
int handle = 0;
fn_type fn = 0;
if ((handle = dlopen( "hello.dll")) == 0) {
printf( "Cannot open hello.dll\n");
}
if ((fn = (fn_type) dlsym( handle, "hello")) == 0) {
printf( "Cannot open hello()\n");
}
fn();
}
-----
This way, hello.C is a valid C or C++ application, and main.C is a
valid C++ application. I build main.exe by:
g++ -o main main.C
If I build hello.dll this way, it works:
gcc -shared -o hello.dll hello.C
./main
Hello world!
But if I build hello.dll this way, it doesn't work:
g++ -shared -o hello.dll hello.C
./main
bash: [2084: 2] testaddr: Inappropriate ioctl for device
Why? What am I doing wrong?
~David Svoboda