Re: dladdr()

[Rich Felker <dalias@aerifal.cx>]

On Tue, Jan 15, 2013 at 03:54:44PM +0100, pierre wrote:
> Latest musl-libc dladdr() fails here:
> 
>    // 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
> 
>    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);
> 
> What is missing to make this work?

Are you using static or dynamic linking? If static, dladdr is just a
stub that always fails. It could be implemented to work under some
conditions, but it would be highly dependent on what options you
compile the binary with, since by default static binaries do not
contain the bloat that would be needed to perform introspection.

Rich