Creating a shared library and loading it

[abhi147@gmail.com]

Hi ,

I am trying to create a shared library and trying to load it
usinf dlopen() function . My code and steps to create and load the *.so
is :

/*** test.c ***/
#include <stdio.h>
void test()
{
printf("Hello World\n");
}

/*** Steps for *.so creation ***/
bash-3.00# gcc -fPIC -c test.c
bash-3.00# gcc -o library.so -shared source.o
bash-3.00# gcc -o library.so -Wl,-h,library.so -shared source.o

/***load.c***/
#include <stdio.h>
#include <dlfcn.h>

int main(int argc,char **argv)
{
void *handle;
char *error;

handle = dlopen ("library.so ", RTLD_LAZY);
if (!handle) {
fprintf (stderr, "%s\n", dlerror());
exit(1);
}

}

/*** Steps for creating load executable***/
bash-3.00# gcc test.c -ldl

When I run the "a.out" it gives me the following error

bash-3.00# ./a.out
ld.so.1: a.out: fatal: library.so: open failed: No such file or
directory

Can someone tell me .. where I am wrong ?

Thanks !

[spibou@gmail.com]

Re: Creating a shared library and loading it

abhi147@gmail.c om wrote:

Hi ,
>
I am trying to create a shared library and trying to load it
usinf dlopen() function . My code and steps to create and load the *.so
is :
>
/*** test.c ***/
#include <stdio.h>
void test()
{
printf("Hello World\n");
}
>
/*** Steps for *.so creation ***/
bash-3.00# gcc -fPIC -c test.c
bash-3.00# gcc -o library.so -shared source.o
bash-3.00# gcc -o library.so -Wl,-h,library.so -shared source.o
>
/***load.c***/
#include <stdio.h>
#include <dlfcn.h>
>
int main(int argc,char **argv)
{
void *handle;
char *error;
>
handle = dlopen ("library.so ", RTLD_LAZY);
if (!handle) {
fprintf (stderr, "%s\n", dlerror());
exit(1);
}
>
}
>
/*** Steps for creating load executable***/
bash-3.00# gcc test.c -ldl
>
When I run the "a.out" it gives me the following error
>
bash-3.00# ./a.out
ld.so.1: a.out: fatal: library.so: open failed: No such file or
directory
>
Can someone tell me .. where I am wrong ?

You are wrong in posting here about it. Here we only
deal with standard C and things like dlfcn.h , dlopen()
etc. are not part of standard C. You should ask the
question at comp.unix.progr ammer or
comp.os.linux.d evelopment.apps

Spiros Bousbouras

[Bill Pursell]

Re: Creating a shared library and loading it

abhi147@gmail.c om wrote:

/*** Steps for *.so creation ***/
bash-3.00# gcc -fPIC -c test.c
bash-3.00# gcc -o library.so -shared source.o
bash-3.00# gcc -o library.so -Wl,-h,library.so -shared source.o
>
>
/*** Steps for creating load executable***/
bash-3.00# gcc test.c -ldl

I assume you meant to compile load.c here...

>
When I run the "a.out" it gives me the following error
>
bash-3.00# ./a.out
ld.so.1: a.out: fatal: library.so: open failed: No such file or
directory
>
Can someone tell me .. where I am wrong ?

You should either specify "./library.so" in load.c, or
set LD_LIBRARY_PATH . (At least, that works on
Linux...since dlopen() is not standard C, we are already
OT, and this thread really belongs on a different NG).
For example:

[tmp]$ export LD_LIBRARY_PATH =
[tmp]$ ./a.out
library.so: cannot open shared object file: No such file or directory
[tmp]$ export LD_LIBRARY_PATH =.
[tmp]$ ./a.out
[tmp]$




Stylistically, it's a bit odd to have a file called library.so, since
that implies that the library's name is "rary". The usual
naming convention is libNAME.so.

[abhi147@gmail.com]

Re: Creating a shared library and loading it


Bill Pursell wrote:

abhi147@gmail.c om wrote:
>

/*** Steps for *.so creation ***/
bash-3.00# gcc -fPIC -c test.c
bash-3.00# gcc -o library.so -shared source.o
bash-3.00# gcc -o library.so -Wl,-h,library.so -shared source.o


/*** Steps for creating load executable***/
bash-3.00# gcc test.c -ldl

>
I assume you meant to compile load.c here...

When I run the "a.out" it gives me the following error

bash-3.00# ./a.out
ld.so.1: a.out: fatal: library.so: open failed: No such file or
directory

Can someone tell me .. where I am wrong ?

>
You should either specify "./library.so" in load.c, or
set LD_LIBRARY_PATH . (At least, that works on
Linux...since dlopen() is not standard C, we are already
OT, and this thread really belongs on a different NG).
For example:
>
[tmp]$ export LD_LIBRARY_PATH =
[tmp]$ ./a.out
library.so: cannot open shared object file: No such file or directory
[tmp]$ export LD_LIBRARY_PATH =.
[tmp]$ ./a.out
[tmp]$
>
>
>
>
Stylistically, it's a bit odd to have a file called library.so, since
that implies that the library's name is "rary". The usual
naming convention is libNAME.so.

Thanks Bill . It worked :- )