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From: pierre <pierre@silentlife.com>
Newsgroups: gmane.linux.lib.musl.general
Subject: Re: dladdr()
Date: Wed, 16 Jan 2013 12:00:18 +0100
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To: musl@lists.openwall.com, Rich Felker <dalias@aerifal.cx>
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Rich,

> Are you using static or dynamic linking?

Dynamic. Before posting here, I checked the musl source 
code, and the binary:

'objdump -z -d hello' gives: callq 4003e0 <dladdr@plt>

Further, 'musl-gcc -static hello.c -o hello_s' weights
23KB while the shared binary above weights only 7KB.

Finally, my example provided the compilation/linking 
cmd line, which, by default, is dynamic:

   // glibc:
   // gcc hello.c -o hello -ldl

   // musl:
   // musl-gcc hello.c -o hello

I am attaching the source code linked with musl 0.9.8
so you can duplicate this issue without wasting time.

Besides knowing how to enable dladdr() in dynamic mode,
I am interested in knowing what other steps are needed
beyond replacing the #ifdef SHARED by another custom 
define (#ifdef __FORCE_DL) for musl's dl implementation
to do the job in static binaries (with exported symbols).

Thank you for musl, a much-needed alternative.

Pierre

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// ------------------------------
// glibc:
// gcc hello.c -o hello -ldl
//
// ret:1
// dli_fname:./hello:0x400000
// dli_sname:puts:0x4004c0
// ------------------------------
// musl:
// musl-gcc hello.c -o hello
//
// ret:0
// dli_fname:(null):0
// dli_sname:(null):0
// ------------------------------
#define _GNU_SOURCE

#include <stdio.h>
#include <stdlib.h>
#include <dlfcn.h>

int main(void)
{
   puts("\nhello world!\n");

   Dl_info dl = {0};
   int ret = dladdr(puts + 0, &dl);

   printf("ret:%d\n"
           "dli_fname:%s:%p\n"
           "dli_sname:%s:%p\n\n",
           ret,
           dl.dli_fname, dl.dli_fbase,
           dl.dli_sname, dl.dli_saddr);

	return 0;
}


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