Re: [OE-core] [PATCH] uninative: call patchelf-uninative only when needed

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Fri, 2023-06-23 at 11:33 +0200, Martin Jansa wrote:
> mke2fs.real, mkfs.ext2.real, mkfs.ext3.real, mkfs.ext4.real are indentical
> binary with multiple hardlinks and we end calling patchelf-uninative 4
> times even when the interpreter is already set correctly from the build
> 
> To avoid corrupted binaries created by patchelf-0.18.0 when set-interpreter
> is called multiple times (on some systems like ubuntu-18.04 this leads to
> segfaults elsewhere just ldd complains that the executable is no longer
> dynamically linked, but doesn't fail when executed).
> 
> The issue was reported upstream with mkfs.ext4.real as possible reproducer:
> https://github.com/NixOS/patchelf/issues/492#issuecomment-1602862272
> alternatively we can revert
> https://github.com/NixOS/patchelf/commit/65cdee904431d16668f95d816a495bc35a05a192
> and create new uninative release with update patchelf-uninative, but
> better to wait a bit for upstream to have a look and possibly backport
> proper fix later, until then this change fixes the mkfs.ext4 issues I was
> seeing in kirkstone, mickledore, nanbield since uninative-3.9 upgrade, as
> reported in:
> https://lists.openembedded.org/g/openembedded-core/message/182862
> 
> Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
> ---
>  meta/classes-global/uninative.bbclass | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/meta/classes-global/uninative.bbclass b/meta/classes-global/uninative.bbclass
> index 366f7ac793..b54acdd542 100644
> --- a/meta/classes-global/uninative.bbclass
> +++ b/meta/classes-global/uninative.bbclass
> @@ -175,7 +175,12 @@ python uninative_changeinterp () {
>              if not elf.isDynamic():
>                  continue
>  
> -            os.chmod(f, s[stat.ST_MODE] | stat.S_IWUSR)
> -            subprocess.check_output(("patchelf-uninative", "--set-interpreter", d.getVar("UNINATIVE_LOADER"), f), stderr=subprocess.STDOUT)
> -            os.chmod(f, s[stat.ST_MODE])
> +            current = subprocess.check_output(("patchelf-uninative", "--print-interpreter", f), stderr=subprocess.STDOUT).decode('utf-8').split('\n')[0]
> +            if current != d.getVar("UNINATIVE_LOADER"):
> +                bb.debug(2, "Changing interpreter from %s to %s with %s" % (current, d.getVar("UNINATIVE_LOADER"), ("patchelf-uninative", "--set-interpreter", d.getVar("UNINATIVE_LOADER"), f)))
> +                os.chmod(f, s[stat.ST_MODE] | stat.S_IWUSR)
> +                subprocess.check_output(("patchelf-uninative", "--set-interpreter", d.getVar("UNINATIVE_LOADER"), f), stderr=subprocess.STDOUT)
> +                os.chmod(f, s[stat.ST_MODE])
> +            else:
> +                bb.debug(2, "Interpreter was already set to %s in %s" % (d.getVar("UNINATIVE_LOADER"), f))
>  }

I know why you've done it this way but ideally we should make patchelf
handle this internally? It would be nice to avoid fork calls if we can
in the long run.

Cheers,

Richard