Re: [patch+7.5.1] Work around PR libc/13097 "linux-vdso.so.1" #3

[Jan Kratochvil <jan.kratochvil@redhat.com>]

On Fri, 23 Nov 2012 13:02:41 +0100, Pedro Alves wrote:
> Won't real file based DSOs in the loader list _always_ be full paths,
> never relative paths?  I'd think we could always ignore DSOs whose
> path doesn't start with '/', everywhere.

:|gcc -shared -fPIC -o x.so -x c -;echo 'main(){}'|gcc -o x ./x.so -x c -;gdb ./x -ex start -ex 'p *_r_debug.r_map' -ex 'p *_r_debug.r_map.l_next' -ex 'p *_r_debug.r_map.l_next.l_next' -ex 'p *_r_debug.r_map.l_next.l_next.l_next' -ex 'p *_r_debug.r_map.l_next.l_next.l_next.l_next' -ex 'p *_r_debug.r_map.l_next.l_next.l_next.l_next.l_next'

$1 = {l_addr = 0, l_name = 0x37e3a1bd69 "", l_ld = 0x600778, l_next = 0x37e3c23818, l_prev = 0x0}
$2 = {l_addr = 140737363566592, l_name = 0x37e3a1bd69 "", l_ld = 0x7ffff7ffe488, l_next = 0x7ffff7ffd648, l_prev = 0x37e3c23288}
$3 = {l_addr = 140737352024064, l_name = 0x7ffff7ffd640 "./x.so", l_ld = 0x7ffff7ffc5e8, l_next = 0x7ffff7dd5000, l_prev = 0x37e3c23818}
                                                        ^^^^^^^^
$4 = {l_addr = 0, l_name = 0x7ffff7ffdb60 "/lib64/libc.so.6", l_ld = 0x37e45b0b40, l_next = 0x37e3c22998, l_prev = 0x7ffff7ffd648}
$5 = {l_addr = 0, l_name = 0x400200 "/lib64/ld-linux-x86-64.so.2", l_ld = 0x37e3c21de8, l_next = 0x0, l_prev = 0x7ffff7dd5000}

So file based solibs do not have to start with '/'.

Besides that there is no standard for any such rule and I consider this patch
only as a workaround of a WONTFIXed glibc PR.  In such case I believe the
impact should be minimal.

Maybe there is even a way how to make l_name really "x.so" above, not sure.


Jan