Date: Mon, 14 Feb 2000 06:00:21 -0800 From: "Pradesh Chanderpaul" <archiver@db.geocrawler.com> To: freebsd-hackers@freebsd.org Subject: Help me understand dlopen/dlsy Message-ID: <200002141400.GAA29194@www.geocrawler.com>
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Hello All
I know that this question is more suited to the general
questions mailing group, but I tried, and failed to obtain
a response. So could someone please provide guidance with this
topic. I have searched the mailing lists, man pages and the
net at large without getting a satisfactory understanding.
Consider the following scenario.
I need to compile a program consisting of two source files
and a makefile
file1.c
-------
#include <stdio.h>
#include <stdlib.h>
#include <dlfcn.h>
int main() {
void *handle;
void (*myhellofunc)(void);
char *c;
handle = dlopen(NULL, 1);
c = dlerror();
if (c) abort_with_error(c);
myhellofunc = dlsym(handle, "_helloworld");
c = dlerror();
if(c) abort_with_error(c);
myhellofunc();
dlclose(handle);
}
file2.c
-------
#include <stdio.h>
void helloworld(void) {
printf(" Hello cruel worldn");
}
Makefile
--------
file1.o : file1.c
gcc -fPIC -c file1.c
file1.o : file1.c
gcc -fPIC -c file1.c
fileit : file1.o file2.o
cc -export-dynamic -o fileit file1.o file2.o
The two source files will be linked into a single executable,
using GCC running on FreeBSD 3.2-RELEASE.
Q1 : Are my flags sufficient to compile the individual
source files?
Q2 : What flags are required to link the object files into
the single executable?
Q3 : Is there anything else I should be wary of?
I have tried various options (like using -rdynamic and -shared
but to no avail. dlerror() reports an undefined symbol for
_helloworld from calling dlsym.
This issue has been "bugging" me for weeks now, so I need to
try and get it sorted out. Please assist if you can.
Thanking you in advance.
Pradesh Chanderpaul
Geocrawler.com - The Knowledge Archive
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