[PATCH v2 0/4] mbuto: Make it work on Arch Linux

[PATCH v2 0/4] mbuto: Make it work on Arch Linux

[Lukasz Gut]

Hi Stefano,

This set of patches makes mbuto work also on Arch Linux.
I have changed PATCH 4/4 based on your comments.

Thank you for pointing out the correct recepient list.

Cheers,
Lukasz

[PATCH v2 1/4] mbuto: Pick a src when ld reported as link by ldd

[Lukasz Gut]

On Arch Linux ldd /bin/sh reports:
    /lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2
Use a regex to pick only right side and use it for path processing.

Signed-off-by: Lukasz Gut <lgut@lgut.eu>
---
 mbuto | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/mbuto b/mbuto
index b80ea78..1c3b347 100755
--- a/mbuto
+++ b/mbuto
@@ -704,9 +704,14 @@ __libs_copy() {
 	for __l in $("${LDD}" "${1}" 2>/dev/null); do
 		case ${__l} in "/"*" "*) __ld_so="${__l% *}" ;; *) ;; esac
 	done
-	if [ -n "${__ld_so}" ]; then
-		libs_copy_ld_so "${__ld_so}"
-		libs_path_add "${__ld_so##${wd}}"
+	# On Arch Linux ld is reported by ldd in form:
+	# /lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2
+	# Make sure to take only right part in this case.
+	__ld_path="${__ld_so##*=> }"
+
+	if [ -n "${__ld_path}" ]; then
+		libs_copy_ld_so "${__ld_path}"
+		libs_path_add "${__ld_path##${wd}}"
 	fi
 }
 
-- 
@@ -704,9 +704,14 @@ __libs_copy() {
 	for __l in $("${LDD}" "${1}" 2>/dev/null); do
 		case ${__l} in "/"*" "*) __ld_so="${__l% *}" ;; *) ;; esac
 	done
-	if [ -n "${__ld_so}" ]; then
-		libs_copy_ld_so "${__ld_so}"
-		libs_path_add "${__ld_so##${wd}}"
+	# On Arch Linux ld is reported by ldd in form:
+	# /lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2
+	# Make sure to take only right part in this case.
+	__ld_path="${__ld_so##*=> }"
+
+	if [ -n "${__ld_path}" ]; then
+		libs_copy_ld_so "${__ld_path}"
+		libs_path_add "${__ld_path##${wd}}"
 	fi
 }
 
-- 
2.46.1

[PATCH v2 2/4] mbuto: Use realpath to copy ld

[Lukasz Gut]

Place ld in exact physical location as on host, not being confused by
links. Use realpath, that was already on the list of default PROGS.

Signed-off-by: Lukasz Gut <lgut@lgut.eu>
---
 mbuto | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/mbuto b/mbuto
index 1c3b347..1f92bd9 100755
--- a/mbuto
+++ b/mbuto
@@ -644,12 +644,13 @@ libs_path_add() {
 # libs_copy_ld_so() - Copy run-time linker program, mimic location from host
 # $1:	Path to run-time linker
 libs_copy_ld_so() {
-	[ -f "${wd}/${1}" ] && return
+	__srcfile="$("${REALPATH}" "${1}")"
+	__destfile="${wd}""${__srcfile}"
+	[ -f "${__destfile}" ] && return
 
-	__destdir="$("${DIRNAME}" "${wd}/${1}")"
+	__destdir="$("${DIRNAME}" "${__destfile}")"
 	"${MKDIR}" -p "${__destdir}"
-
-	"${CP}" --parents --preserve=all "${1}" "${wd}"
+	"${CP}" --parents --preserve=all "${__srcfile}" "${wd}"
 }
 
 # libs_dlopen_copy() - Recursively copy matching libraries from LIBS_DLOPEN
-- 
@@ -644,12 +644,13 @@ libs_path_add() {
 # libs_copy_ld_so() - Copy run-time linker program, mimic location from host
 # $1:	Path to run-time linker
 libs_copy_ld_so() {
-	[ -f "${wd}/${1}" ] && return
+	__srcfile="$("${REALPATH}" "${1}")"
+	__destfile="${wd}""${__srcfile}"
+	[ -f "${__destfile}" ] && return
 
-	__destdir="$("${DIRNAME}" "${wd}/${1}")"
+	__destdir="$("${DIRNAME}" "${__destfile}")"
 	"${MKDIR}" -p "${__destdir}"
-
-	"${CP}" --parents --preserve=all "${1}" "${wd}"
+	"${CP}" --parents --preserve=all "${__srcfile}" "${wd}"
 }
 
 # libs_dlopen_copy() - Recursively copy matching libraries from LIBS_DLOPEN
-- 
2.46.1

[PATCH v2 3/4] mbuto: Don't try to add ld when adding libraries

[Lukasz Gut]

There is a function to add linker, but it was also added while copying
other librares (as dep of libc).
Now it is explicitely skipped.

Signed-off-by: Lukasz Gut <lgut@lgut.eu>
---
 mbuto | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mbuto b/mbuto
index 1f92bd9..4f860cd 100755
--- a/mbuto
+++ b/mbuto
@@ -685,6 +685,10 @@ __libs_copy() {
 		[ "$("${BASENAME}" "${__path}")" = "libfakeroot-sysv.so" ] && \
 			continue
 
+		# ld is handled below, skip one reported by libc
+		[ "$("${BASENAME}" "${__path}")" = "ld-linux-x86-64.so.2" ] && \
+			continue
+
 		__destpath="${wd}${__path}"
 		[ -f "${__destpath}" ] && continue
 
-- 
@@ -685,6 +685,10 @@ __libs_copy() {
 		[ "$("${BASENAME}" "${__path}")" = "libfakeroot-sysv.so" ] && \
 			continue
 
+		# ld is handled below, skip one reported by libc
+		[ "$("${BASENAME}" "${__path}")" = "ld-linux-x86-64.so.2" ] && \
+			continue
+
 		__destpath="${wd}${__path}"
 		[ -f "${__destpath}" ] && continue
 
-- 
2.46.1

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

[Lukasz Gut]

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.

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
-- 
@@ -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
-- 
2.46.1

Re: [PATCH v2 0/4] mbuto: Make it work on Arch Linux

[David Gibson]

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On Wed, Sep 18, 2024 at 12:12:54PM +0200, Lukasz Gut wrote:
> Hi Stefano,
> 
> This set of patches makes mbuto work also on Arch Linux.
> I have changed PATCH 4/4 based on your comments.
> 
> Thank you for pointing out the correct recepient list.

One overall nit in the commit messages, rather than the patches themslves:

To me "ld" without clarification means the static linker not the
dynamic linker (that's "ld.so").  But many of your messages are
referring to the dynamic linker as "ld".

-- 
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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Re: [PATCH v2 1/4] mbuto: Pick a src when ld reported as link by ldd

[David Gibson]

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On Wed, Sep 18, 2024 at 12:12:56PM +0200, Lukasz Gut wrote:
> On Arch Linux ldd /bin/sh reports:
>     /lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2
> Use a regex to pick only right side and use it for path processing.

I think this approach is overly specific.  The broader point here is
that ldd can list libraries (including the dynamic linker) as either a
link, or directly as a file.  In the cases Stefano wrote for, it was
always a single file for the dynamic linker and a link for everything
else.  For Arch it seems to be a link for everything, but both of
those might not be true everywhere.

It would make more sense to alter the loop above which processes all
libraries to handle both the link and no-link cases, and remove the
special case handling of ld.so.

> Signed-off-by: Lukasz Gut <lgut@lgut.eu>
> ---
>  mbuto | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/mbuto b/mbuto
> index b80ea78..1c3b347 100755
> --- a/mbuto
> +++ b/mbuto
> @@ -704,9 +704,14 @@ __libs_copy() {
>  	for __l in $("${LDD}" "${1}" 2>/dev/null); do
>  		case ${__l} in "/"*" "*) __ld_so="${__l% *}" ;; *) ;; esac
>  	done
> -	if [ -n "${__ld_so}" ]; then
> -		libs_copy_ld_so "${__ld_so}"
> -		libs_path_add "${__ld_so##${wd}}"
> +	# On Arch Linux ld is reported by ldd in form:
> +	# /lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2
> +	# Make sure to take only right part in this case.
> +	__ld_path="${__ld_so##*=> }"
> +
> +	if [ -n "${__ld_path}" ]; then
> +		libs_copy_ld_so "${__ld_path}"
> +		libs_path_add "${__ld_path##${wd}}"
>  	fi
>  }
>  

-- 
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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Re: [PATCH v2 2/4] mbuto: Use realpath to copy ld

[David Gibson]

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On Wed, Sep 18, 2024 at 12:12:57PM +0200, Lukasz Gut wrote:
> Place ld in exact physical location as on host, not being confused by
> links. Use realpath, that was already on the list of default PROGS.

It's not clear to me why this change is necessary.

> 
> Signed-off-by: Lukasz Gut <lgut@lgut.eu>
> ---
>  mbuto | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/mbuto b/mbuto
> index 1c3b347..1f92bd9 100755
> --- a/mbuto
> +++ b/mbuto
> @@ -644,12 +644,13 @@ libs_path_add() {
>  # libs_copy_ld_so() - Copy run-time linker program, mimic location from host
>  # $1:	Path to run-time linker
>  libs_copy_ld_so() {
> -	[ -f "${wd}/${1}" ] && return
> +	__srcfile="$("${REALPATH}" "${1}")"
> +	__destfile="${wd}""${__srcfile}"
> +	[ -f "${__destfile}" ] && return
>  
> -	__destdir="$("${DIRNAME}" "${wd}/${1}")"
> +	__destdir="$("${DIRNAME}" "${__destfile}")"
>  	"${MKDIR}" -p "${__destdir}"
> -
> -	"${CP}" --parents --preserve=all "${1}" "${wd}"
> +	"${CP}" --parents --preserve=all "${__srcfile}" "${wd}"
>  }
>  
>  # libs_dlopen_copy() - Recursively copy matching libraries from LIBS_DLOPEN

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

[David Gibson]

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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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Re: [PATCH v2 0/4] mbuto: Make it work on Arch Linux

[Lukasz Gut]

On Mon, 2024-09-23 at 13:45 +1000, David Gibson wrote:
> On Wed, Sep 18, 2024 at 12:12:54PM +0200, Lukasz Gut wrote:
> > Hi Stefano,
> > 
> > This set of patches makes mbuto work also on Arch Linux.
> > I have changed PATCH 4/4 based on your comments.
> > 
> > Thank you for pointing out the correct recepient list.
> 
> One overall nit in the commit messages, rather than the patches themslves:
> 
> To me "ld" without clarification means the static linker not the
> dynamic linker (that's "ld.so").  But many of your messages are
> referring to the dynamic linker as "ld".

Thanks David for pointing that out, I will be more specific next time.


--
Lukasz

Re: [PATCH v2 1/4] mbuto: Pick a src when ld reported as link by ldd

[Lukasz Gut]

On Mon, 2024-09-23 at 13:51 +1000, David Gibson wrote:
> On Wed, Sep 18, 2024 at 12:12:56PM +0200, Lukasz Gut wrote:
> > On Arch Linux ldd /bin/sh reports:
> >     /lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2
> > Use a regex to pick only right side and use it for path processing.
> 
> I think this approach is overly specific.  The broader point here is
> that ldd can list libraries (including the dynamic linker) as either a
> link, or directly as a file.  In the cases Stefano wrote for, it was
> always a single file for the dynamic linker and a link for everything
> else.  For Arch it seems to be a link for everything, but both of
> those might not be true everywhere.
> 
> It would make more sense to alter the loop above which processes all
> libraries to handle both the link and no-link cases, and remove the
> special case handling of ld.so.

That's a very good point. I have even briefly tried that before, since
that should produce less code instead of more, but I've had some
difficulties. I will attempt it again.
> 
> > Signed-off-by: Lukasz Gut <lgut@lgut.eu>
> > ---
> >  mbuto | 11 ++++++++---
> >  1 file changed, 8 insertions(+), 3 deletions(-)
> > 
> > diff --git a/mbuto b/mbuto
> > index b80ea78..1c3b347 100755
> > --- a/mbuto
> > +++ b/mbuto
> > @@ -704,9 +704,14 @@ __libs_copy() {
> >  	for __l in $("${LDD}" "${1}" 2>/dev/null); do
> >  		case ${__l} in "/"*" "*) __ld_so="${__l% *}" ;; *) ;; esac
> >  	done
> > -	if [ -n "${__ld_so}" ]; then
> > -		libs_copy_ld_so "${__ld_so}"
> > -		libs_path_add "${__ld_so##${wd}}"
> > +	# On Arch Linux ld is reported by ldd in form:
> > +	# /lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2
> > +	# Make sure to take only right part in this case.
> > +	__ld_path="${__ld_so##*=> }"
> > +
> > +	if [ -n "${__ld_path}" ]; then
> > +		libs_copy_ld_so "${__ld_path}"
> > +		libs_path_add "${__ld_path##${wd}}"
> >  	fi
> >  }
> >  
> 
--
Lukasz

Re: [PATCH v2 2/4] mbuto: Use realpath to copy ld

[Lukasz Gut]

On Mon, 2024-09-23 at 13:53 +1000, David Gibson wrote:
> On Wed, Sep 18, 2024 at 12:12:57PM +0200, Lukasz Gut wrote:
> > Place ld in exact physical location as on host, not being confused by
> > links. Use realpath, that was already on the list of default PROGS.
> 
> It's not clear to me why this change is necessary.
I would like `ld-linux.so` to be copied to the exact same location as
in host. Without this change, it was copied to `/usr/lib64` directory.
There is no such a directory on the host, but there is a link `lib64 ->
lib` inside of `/usr` directory.

I thought to:
1. Copy things to exactly the same locations as they are on the host.
2. Recreate necessary links.

> 
> > 
> > Signed-off-by: Lukasz Gut <lgut@lgut.eu>
> > ---
> >  mbuto | 9 +++++----
> >  1 file changed, 5 insertions(+), 4 deletions(-)
> > 
> > diff --git a/mbuto b/mbuto
> > index 1c3b347..1f92bd9 100755
> > --- a/mbuto
> > +++ b/mbuto
> > @@ -644,12 +644,13 @@ libs_path_add() {
> >  # libs_copy_ld_so() - Copy run-time linker program, mimic location from host
> >  # $1:	Path to run-time linker
> >  libs_copy_ld_so() {
> > -	[ -f "${wd}/${1}" ] && return
> > +	__srcfile="$("${REALPATH}" "${1}")"
> > +	__destfile="${wd}""${__srcfile}"
> > +	[ -f "${__destfile}" ] && return
> >  
> > -	__destdir="$("${DIRNAME}" "${wd}/${1}")"
> > +	__destdir="$("${DIRNAME}" "${__destfile}")"
> >  	"${MKDIR}" -p "${__destdir}"
> > -
> > -	"${CP}" --parents --preserve=all "${1}" "${wd}"
> > +	"${CP}" --parents --preserve=all "${__srcfile}" "${wd}"
> >  }
> >  
> >  # libs_dlopen_copy() - Recursively copy matching libraries from LIBS_DLOPEN
> 
--
Lukasz

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

[Lukasz Gut]

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