util-linux-2.41 breaks static build of btrfs-progs

util-linux-2.41 breaks static build of btrfs-progs

[Stanislav Brabec]

Static build of btrfs-progs fails with util-linux-2.41 with a simple 
problem:
Symbol parse_range becomes visible in libblkid.a, breaking parse-utils.c 
in btrfs-progs, using the same symbol.

The question is:
Should be this fixed by util-linux by prefixing of ul_ to all symbols 
that are not declared as static?
Or should it be fixed by btrfs-progs?
Or could there be applied any type of symbol hiding in the static library?

/usr/lib64/gcc/x86_64-suse-linux/14/../../../../x86_64-suse-linux/bin/ld: 
/usr/lib64/gcc/x86_64-suse-linux/14/../../../../lib64/libblkid.a(libcommon_la-strutils.o): 
in function `parse_range':
[   29s] 
/home/abuild/rpmbuild/BUILD/util-linux-2.41-build/util-linux-2.41/lib/strutils.c:867: 
multiple definition of `parse_range'; common/parse-utils.static.o 
(symbol from plugin):(.text+0x0): first defined here

-- 
Best Regards / S pozdravem,

Stanislav Brabec
software developer
---------------------------------------------------------------------
SUSE LINUX, s. r. o.                         e-mail: sbrabec@suse.com
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Re: util-linux-2.41 breaks static build of btrfs-progs

[Karel Zak]

On Sun, Apr 20, 2025 at 09:24:43PM +0200, Stanislav Brabec wrote:
> Static build of btrfs-progs fails with util-linux-2.41 with a simple
> problem:
> Symbol parse_range becomes visible in libblkid.a, breaking parse-utils.c in
> btrfs-progs, using the same symbol.
> 
> The question is:
> Should be this fixed by util-linux by prefixing of ul_ to all symbols that
> are not declared as static?

I think the ul_ prefix should be used for all generic names like
parse_range(). I'm not sure if I want to use it strictly for all
functions, as the set of functions is large and such conflicts are
very rare.

ChatGPT has an interesting suggestion: add the prefix to the .a
library using "objcopy --redefine-syms" for all non-API and non-static
functions.

        #!/bin/bash
        PREFIX=foo_

        # Extract all global (non-static) function symbols from the .a file
        nm -g --defined-only libmylib.a | awk '{print $3}' | grep -v "^$PREFIX" | sort -u > tmp.syms

        # Generate rename list: <old> <new>
        awk -v pfx="$PREFIX" '{print $1 " " pfx $1}' tmp.syms > rename.syms

        # Apply symbol renaming
        objcopy --redefine-syms=rename.syms libmylib.a libmylib_prefixed.a


Maybe it's elegant way to go. Not sure, not tested :-)

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com

Re: util-linux-2.41 breaks static build of btrfs-progs

[Karel Zak]

On Mon, May 05, 2025 at 11:34:11AM +0200, Karel Zak wrote:
> On Sun, Apr 20, 2025 at 09:24:43PM +0200, Stanislav Brabec wrote:
> > Static build of btrfs-progs fails with util-linux-2.41 with a simple
> > problem:
> > Symbol parse_range becomes visible in libblkid.a, breaking parse-utils.c in
> > btrfs-progs, using the same symbol.
> > 
> > The question is:
> > Should be this fixed by util-linux by prefixing of ul_ to all symbols that
> > are not declared as static?
> 
> I think the ul_ prefix should be used for all generic names like
> parse_range(). I'm not sure if I want to use it strictly for all
> functions, as the set of functions is large and such conflicts are
> very rare.
> 
> ChatGPT has an interesting suggestion: add the prefix to the .a
> library using "objcopy --redefine-syms" for all non-API and non-static
> functions.
> 
>         #!/bin/bash
>         PREFIX=foo_
> 
>         # Extract all global (non-static) function symbols from the .a file
>         nm -g --defined-only libmylib.a | awk '{print $3}' | grep -v "^$PREFIX" | sort -u > tmp.syms

Note that the list of symbols should also be filtered according to
libblkid.sym to keep the API functions unmodified.

>         # Generate rename list: <old> <new>
>         awk -v pfx="$PREFIX" '{print $1 " " pfx $1}' tmp.syms > rename.syms
> 
>         # Apply symbol renaming
>         objcopy --redefine-syms=rename.syms libmylib.a libmylib_prefixed.a


Updated, not tested version:

#!/bin/bash

set -e

LIB=libfoo.a
VERSION_SCRIPT=libfoo.sym
PREFIX=foo_
TMPDIR=$(mktemp -d)
RENAME_SYMS="$TMPDIR/rename.syms"

# 1. Get all defined global symbols in the .a (non-static functions/vars)
nm -g --defined-only "$LIB" | awk '{print $3}' | sort -u > "$TMPDIR/all_syms.txt"

# 2. Extract exported (API) symbols from the version script
awk '/global:/{flag=1; next} /local:/{flag=0} flag' "$VERSION_SCRIPT" | \
    tr -d '; \t' | grep -v '^$' | sort -u > "$TMPDIR/exported_syms.txt"

# 3. Compute symbols to rename (non-exported global ones)
comm -23 "$TMPDIR/all_syms.txt" "$TMPDIR/exported_syms.txt" | \
    awk -v pfx="$PREFIX" '{print $1 " " pfx $1}' > "$RENAME_SYMS"

# 4. Apply renaming to the archive
cp "$LIB" "${LIB%.a}_prefixed.a"
objcopy --redefine-syms="$RENAME_SYMS" "${LIB%.a}_prefixed.a"

echo "Renamed library created: ${LIB%.a}_prefixed.a"
echo "Renamed symbols:"
cat "$RENAME_SYMS"

# 5. Optional cleanup
# rm -r "$TMPDIR"



-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com

Re: util-linux-2.41 breaks static build of btrfs-progs

[Karel Zak]

On Sun, Apr 20, 2025 at 09:24:43PM +0200, Stanislav Brabec wrote:
> The question is:
> Should be this fixed by util-linux by prefixing of ul_ to all symbols that
> are not declared as static?

I have added the "ul_" prefix to some functions to make the names less
generic: https://github.com/util-linux/util-linux/pull/3569

I'm going to backport it to stable/v2.41 too.

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com

Re: util-linux-2.41 breaks static build of btrfs-progs

[Stanislav Brabec]

Karel Zak wrote:
> On Sun, Apr 20, 2025 at 09:24:43PM +0200, Stanislav Brabec wrote:
>> The question is:
>> Should be this fixed by util-linux by prefixing of ul_ to all symbols that
>> are not declared as static?
> I have added the "ul_" prefix to some functions to make the names less
> generic: https://github.com/util-linux/util-linux/pull/3569
>
> I'm going to backport it to stable/v2.41 too.
Done:
https://github.com/util-linux/util-linux/pull/3603
btrfs-progs-v6.14 static build works again out of the box.

-- 
Best Regards / S pozdravem,

Stanislav Brabec
software developer
---------------------------------------------------------------------
SUSE LINUX, s. r. o.                         e-mail: sbrabec@suse.com
Křižíkova 148/34 (Corso IIa)                    tel: +420 284 084 060
186 00 Praha 8-Karlín                          fax:  +420 284 084 001
Czech Republic                                    http://www.suse.cz/
PGP: 830B 40D5 9E05 35D8 5E27 6FA3 717C 209F A04F CD76