mirror of
https://sourceware.org/git/binutils-gdb.git
synced 2024-12-21 04:42:53 +08:00
cea6ffbd06
When we have a weak reference to a symbol defined in an as-needed library, and that library ends up not-needed, gold simply clears the version information in the symbol table, even if the symbol could have been resolved by a needed library later in the link order. This results in a loss of version information, which can cause the program to bind to the wrong version at run time. This patch lets a dynamic definition override an earlier one if the earlier one is from a not-needed library, so that we can retain the version information from the binding to the needed library. In order to do that, the tracking of needed/not-needed had to be moved up to symbol resolution time, instead of during Symbol_table::set_dynsym_indexes(). In cases where we still end up discarding version information, I've added a warning. For the original problem report and discussion, see: https://stackoverflow.com/questions/50751421/undefined-behavior-in-shared-lib-using-libpthread-but-not-having-it-in-elf-as-d gold/ * resolve.cc (Symbol_table::resolve): Rename tobinding to orig_tobinding. Call set_is_needed() for objects that resolve non-weak references. (Symbol_table::should_override): Allow a dynamic definition to override an earlier one in a not-needed library. * symtab.cc (Symbol_table::set_dynsym_indexes): Remove separate processing for as-needed symbols. Add warning when discarding version informatin. * testsuite/Makefile.am (weak_as_needed): New test case. * testsuite/Makefile.in: Regenerate. * testsuite/weak_as_needed.sh: New test script. * testsuite/weak_as_needed_a.c: New source file. * testsuite/weak_as_needed_b.c: New source file. * testsuite/weak_as_needed_b.script: New version script. * testsuite/weak_as_needed_c.c: New source file. * testsuite/weak_as_needed_c.script: New version script.
63 lines
1.7 KiB
Bash
Executable File
63 lines
1.7 KiB
Bash
Executable File
#!/bin/sh
|
|
|
|
# weak_as_needed.sh -- a test case for version handling with weak symbols
|
|
# and --as-needed libraries.
|
|
|
|
# Copyright (C) 2018 Free Software Foundation, Inc.
|
|
# Written by Cary Coutant <ccoutant@gmail.com>.
|
|
|
|
# This file is part of gold.
|
|
|
|
# This program is free software; you can redistribute it and/or modify
|
|
# it under the terms of the GNU General Public License as published by
|
|
# the Free Software Foundation; either version 3 of the License, or
|
|
# (at your option) any later version.
|
|
|
|
# This program is distributed in the hope that it will be useful,
|
|
# but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
# GNU General Public License for more details.
|
|
|
|
# You should have received a copy of the GNU General Public License
|
|
# along with this program; if not, write to the Free Software
|
|
# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
|
|
# MA 02110-1301, USA.
|
|
|
|
# This test verifies that a weak reference is properly bound to
|
|
# an as-needed library, when it is first resolved to a symbol in
|
|
# a library that ends up being not needed.
|
|
|
|
# Ref: https://stackoverflow.com/questions/50751421/undefined-behavior-in-shared-lib-using-libpthread-but-not-having-it-in-elf-as-d
|
|
|
|
check()
|
|
{
|
|
if ! grep -q "$2" "$1"
|
|
then
|
|
echo "Did not find expected output in $1:"
|
|
echo " $2"
|
|
echo ""
|
|
echo "Actual output below:"
|
|
cat "$1"
|
|
exit 1
|
|
fi
|
|
}
|
|
|
|
check_missing()
|
|
{
|
|
if grep -q "$2" "$1"
|
|
then
|
|
echo "Found unexpected output in $1:"
|
|
echo " $2"
|
|
echo ""
|
|
echo "Actual output below:"
|
|
cat "$1"
|
|
exit 1
|
|
fi
|
|
}
|
|
|
|
check weak_as_needed.stdout "WEAK .* UND *bar@v2"
|
|
check weak_as_needed.stdout "NEEDED.*weak_as_needed_c\.so"
|
|
check_missing weak_as_needed.stdout "NEEDED.*weak_as_needed_b\.so"
|
|
|
|
exit 0
|