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407a281a8e
This reverts commit e4b980c853.
When a binary links against a .a archive (as opposed to a shared library),
any symbols which are marked as 'weak' get silently dropped. As a result
when the binary later runs, those 'weak' functions have an address of
0x0 and thus crash when run.
This happened with virtlogd and virtlockd because they don't link to
libvirt.so, but instead just libvirt_util.a and libvirt_rpc.a. The
virRandomBits symbols was weak and so left out of the virtlogd &
virtlockd binaries, despite being required by virHashTable functions.
Various other binaries like libvirt_lxc, libvirt_iohelper, etc also
link directly to .a files instead of libvirt.so, so are potentially
at risk of dropping symbols leading to a later runtime crash.
This is normal linker behaviour because a weak symbol is not treated
as undefined, so nothing forces it to be pulled in from the .a You
have to force the linker to pull in weak symbols using -u$SYMNAME
which is not a practical approach.
This risk is silent bad linkage that affects runtime behaviour is
not acceptable for a fix that was merely trying to fix the test
suite. So stop using __weak__ again.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
71 lines
1.7 KiB
Perl
Executable File
71 lines
1.7 KiB
Perl
Executable File
#!/usr/bin/perl
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# Copyright (C) 2012-2013 Red Hat, Inc.
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library. If not, see
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# <http://www.gnu.org/licenses/>.
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die "syntax: $0 SYMFILE ELFLIB(S)" unless int(@ARGV) >= 2;
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my $symfile = shift @ARGV;
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my @elflibs = @ARGV;
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my %wantsyms;
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my %gotsyms;
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my $ret = 0;
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open SYMFILE, $symfile or die "cannot read $symfile: $!";
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while (<SYMFILE>) {
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next if /{/;
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next if /}/;
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next if /global:/;
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next if /local:/;
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next if /^\s*$/;
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next if /^\s*#/;
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next if /\*/;
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die "malformed line $_" unless /^\s*(\S+);$/;
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if (exists $wantsyms{$1}) {
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print STDERR "Symbol $1 is listed twice\n";
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$ret = 1;
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} else {
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$wantsyms{$1} = 1;
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}
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}
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close SYMFILE;
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foreach my $elflib (@elflibs) {
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open NM, "-|", "nm", $elflib or die "cannot run 'nm $elflib': $!";
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while (<NM>) {
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next unless /^\S+\s(?:[TBD])\s(\S+)\s*$/;
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$gotsyms{$1} = 1;
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}
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close NM;
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}
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foreach my $sym (keys(%wantsyms)) {
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next if exists $gotsyms{$sym};
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print STDERR "Expected symbol $sym is not in ELF library\n";
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$ret = 1;
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}
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exit($ret);
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