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

[David Gibson <david@gibson.dropbear.id.au>]

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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.

> 
> 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

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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