Arch Linux

Description:

with:

shared linking to these files outside binutils
rm -f "$pkgdir"/usr/lib/lib{bfd,opcodes}.so
echo 'INPUT( /usr/lib/libbfd.a -lsframe -liberty -lz -lzstd -ldl )' > "$pkgdir/usr/lib/libbfd.so"
echo 'INPUT( /usr/lib/libopcodes.a -lbfd )' > "$pkgdir/usr/lib/libopcodes.so"

you will get:

ldconfig: /usr/lib/libbfd.so is not an ELF file - it has the wrong magic bytes at the start.

Looking at ldconfig.c I see:

elf_header = (ElfW(Ehdr) *) file_contents;
if (memcmp (elf_header->e_ident, ELFMAG, SELFMAG) != 0)
{
/* The file is neither ELF nor aout. Check if it's a linker
script, like libc.so - otherwise complain. Only search the
beginning of the file. */
size_t len = MIN (statbuf.st_size, 512);
if (memmem (file_contents, len, "GROUP", 5) == NULL
&& memmem (file_contents, len, "GNU ld script", 13) == NULL
&& !is_gdb_python_file (file_name))
error (0, 0, _("%s is not an ELF file - it has the wrong magic bytes at the start.\n"),
file_name);
ret = 1;
}

So probably libbfd.so should have a "GNU ld script" header to make
this ELF detection in ldconfig.c happy:

/* GNU ld script */

https://github.com/archlinux/svntogit-packages/blob/packages/binutils/trunk/PKGBUILD#L113

Funnily /usr/lib/libopcodes.so is not showing this behaviour.