Hi Folks,
	When using dlsym() to get a symbol address, and that lookup
succeeds (i.e. there was no error), dlerror() will still return a
string based on error 0: "Undefined error: 0"

Here is a code snippet that represents the logic often used
(this is from the Utah glx project):

static int any_error;
static void *my_dlsym(void *handle, const char *name)
{
   void *tmp = dlsym(handle, name);
   char *error;
   if ((error = dlerror()) != 0) {
       fprintf( stderr, "%s\n", error );
       any_error = 1;
       return 0;
   }
   return tmp;
}

This code fails even if the symbol is found because dlerror returns
something other than NULL.  From the man page for dlerror, it
appears that dlerror should return NULL after a successful call
to dlsym.  But it doesn't... and so I hack the code to check 
whether tmp was indeed NULL.

This is the second time I've come across this, I've also seen this
situation/problem in the gmodule subsystem of glib-1.2.7, but....

My reading of csu/common_aout/common.c seems to indicate that this
cannot happen...

	Whats the deal here?  Has anyone else come across this?  Thanks.

	- Scott Presnell (srp@zgi.com)



(I'm running NetBSD 1.4.1 on a Pentium Pro, custom kernel, but no mods
to the system libraries).

csu/common_aout/common.c:

char *
dlerror()
{
        int     error;

        if ((*ld_entry) == NULL ||
            (*(*ld_entry)->dlctl)(NULL, DL_GETERRNO, &error) == -1)
                return "Service unavailable";

        return ((char *)(error == 0 ? NULL : strerror(error)));
}