Date: Tue, 1 Sep 1998 15:20:45 -0400 (EDT) From: Brian Feldman <green@unixhelp.org> To: John Polstra <jdp@polstra.com> Cc: current@FreeBSD.ORG Subject: Re: E-day problems: rtld-elf dlsym() broken? Message-ID: <Pine.BSF.4.02.9809011511060.28074-100000@zone.syracuse.net> In-Reply-To: <199809011801.LAA14263@austin.polstra.com>
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Actually, no. The program does no munging of the input at all, it looks up
with or without the _, whichever you input by typing "lookup
whatever\n"... it's not my program's fault, watch:
green@feldman:/home/green/C$ cc -aout -O3 dl.c -o dl -lreadline
green@feldman:/home/green/C$ echo lookup main | ./dl
(dl) lookup main
main: 0x15ac
green@feldman:/home/green/C$ cc -O3 dl.c -o dl -lreadline dline
green@feldman:/home/green/C$ echo lookup main | ./dl
(dl) lookup main
main: not found
(dl) green@feldman:/home/green/C$
Look at my source, it should work fine.
-Brian
On Tue, 1 Sep 1998, John Polstra wrote:
> In article <Pine.BSD.4.00.9809010729170.18315-200000@feldman.dyn.ml.org>,
> Brian Feldman <green@unixhelp.org> wrote:
>
> > there is a problem now: dlsym, for me, seems to have stopped working.
> > Entirely.... Returning NULL always it seems.
>
> I bet you're adding a leading '_' to symbols you're passing to
> dlsym(), right? That used to be necessary for a.out, but it doesn't
> work for ELF. It hasn't been necessary even for a.out since August,
> 1997 in -current (September, 1997 in -stable). I'd recommend ditching
> the underscores unconditionally.
>
> Here's the test program I tried, which worked:
>
> #include <dlfcn.h>
> #include <err.h>
> #include <stdio.h>
>
> typedef int (*prf)(const char *, ...);
>
> int
> main(int argc, char *argv[])
> {
> void *h;
> void *fp1;
>
> if ((h = dlopen("/usr/lib/libc.so.3", RTLD_LAZY)) == NULL)
> errx(1, "dlopen: %s", dlerror());
> if ((fp1 = dlsym(h, "printf")) == NULL)
> errx(1, "dlsym: %s", dlerror());
> (*(prf)fp1)("Hooray! It worked!\n");
> dlclose(h);
> return 0;
> }
>
> John
> --
> John Polstra jdp@polstra.com
> John D. Polstra & Co., Inc. Seattle, Washington USA
> "Self-knowledge is always bad news." -- John Barth
>
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