Re: [PATCH v2 4/4] mbuto: Automatically add links related to linker

[Lukasz Gut <lgut@lgut.eu>]

On Mon, 2024-09-23 at 13:54 +1000, David Gibson wrote:
> On Wed, Sep 18, 2024 at 12:12:59PM +0200, Lukasz Gut wrote:
> > Fix dynamic linking on Arch Linux by adding (some of) missing links.
> > 
> > The ldd reports linker in many ways:
> > ldd /usr/lib/libreadline.so.8
> >     /usr/lib64/ld-linux-x86-64.so.2 (0x000071244211c000)
> > ldd /bin/sh
> >     /lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2
> >     (0x000077457d5ec000)
> > ldd /usr/lib/libc.so.6
> >     /usr/lib/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2
> >     (0x000075d218b8b000)
> > 
> > This patch looks at the left side and determines if there is a link
> > there, then adds it.
> 
> Again, having this be specific to ld.so looks bogus to me.  AFAICT the
> same considerations could apply in theory to any shared library.
Yes, I will rework it to use a single function for every shared
library.
> 
> > 
> > Signed-off-by: Lukasz Gut <lgut@lgut.eu>
> > ---
> >  mbuto | 28 +++++++++++++++++++++++++++-
> >  1 file changed, 27 insertions(+), 1 deletion(-)
> > 
> > diff --git a/mbuto b/mbuto
> > index 4f860cd..7d67160 100755
> > --- a/mbuto
> > +++ b/mbuto
> > @@ -668,6 +668,27 @@ libs_dlopen_copy() {
> >  	done
> >  }
> >  
> > +# libs_add_links() - Rebuild alternate links to ld as they appear on the host
> > +# $1:	String returned by ldd in form 's => d' describing location of ld
> > +libs_add_links() {
> > +	__ld_path="${1##*=> }"
> > +	__ld_link="${1%%=>*}"
> > +	[ -z "${__ld_link}" ] && return
> > +	[ "${__ld_path}" = "${__ld_link}" ] && return
> > +	while [ "${__ld_link}" != "/" ]; do
> > +		if [ -L "${__ld_link}" ]; then
> > +			__target="$("${READLINK}" -f "${__ld_link}")"
> > +			__link="$("${REALPATH}" -s "${__ld_link}" --relative-to "/")"
> > +			__link="${wd}"/"${__link}"
> > +			[ -L "${__link}" ] && break
> > +			__destdir="$("${DIRNAME}" "${__link}")"
> > +			"${MKDIR}" -p "${__destdir}"
> > +			"${LN}" -s "${__target}" "${__link}"
> > +		fi
> > +		__ld_link="$("${DIRNAME}" "${__ld_link}")"
> > +	done
> > +}
> > +
> >  # __libs_copy() - Recursively copy shared dependencies for programs, libraries
> >  # $1:	Host path to program or library
> >  __libs_copy() {
> > @@ -716,8 +737,13 @@ __libs_copy() {
> >  
> >  	if [ -n "${__ld_path}" ]; then
> >  		libs_copy_ld_so "${__ld_path}"
> > -		libs_path_add "${__ld_path##${wd}}"
> > +		libs_path_add "${__ld_path##"${wd}"}"
> >  	fi
> > +
> > +	# On Arch Linux, to execute /bin/sh, the system expects the linker
> > +	# to be under /lib64. Linker is located in /usr/lib, and there is
> > +	# a link /lib64 => /usr/lib.
> > +	libs_add_links "${__ld_so}"
> >  }
> >  
> >  # libs_copy() - Call __libs_copy with tabs and newlines as IFS
> 
--
Lukasz