libabigail/tests/test-lookup-syms.cc
Dodji Seketeli b1b0586dc2 dwarf-reader: Fix bloom filter access in GNU_HASH section
The bloom filter of the GNU_HASH section of binaries is made of words
(bitmasks) that are either 32-bits for ELFCLASS32 binaries or 64-bits
for ELFCLASS64 binaries.

By using the GElf_Word type to hold the content of each bitmask we
assume the bitmask to be of a size of at most 'sizeof(Elf64_Word)'.
Unfortunately, the name Elf64_Word is a bit misleading because it's a
32-bits wide type (uint32_t).  That type is thus too short to hold an
entire bitmask for 64-bits binaries.

I won't give too many details here about how the bloom filter works as
it's described in details in the documentation for the GNU_HASH
section at http://www.linker-aliens.org/blogs/ali/entry/gnu_hash_elf_sections/.

Suffice it to say that in practise, we were comparing the least
significant bytes of a 64-bits bloom bitmask to a 32-bits value.
Depending on if we read those least significant bytes on a big or
little endian, we obviously don't get the same result.  Hence the
recent buid breakage at
https://builder.wildebeest.org/buildbot/#builders/14/builds/352 where
the runtestlookupsyms test fails.

This patch thus changes the code of lookup_symbol_from_gnu_hash_tab to
use a 64-bits type to hold the value of the bloom bitmask.  That way,
we never have any information loss.  The function bloom_word_at is
also changed to read the bloom bitmask as a 64-bits value when looking
at an ELFCLASS64 binary and to always return a 64-bits value.

It also adds a test to access the bloom filter of an ELFCLASS32
binary.

	* src/abg-dwarf-reader.cc (bloom_word_at): Properly read an
	element from the bloom bitmasks array of 32-bits values as a
	64-bits value in a portable way.  Always return a 64 bits value.
	(lookup_symbol_from_gnu_hash_tab): Use a 64-bits value to store
	the bloom bitmask.
	* tests/data/test-lookup-syms/test1-32bits.so: New test input,
	compiled as a 32bits binary to test for ELFCLASS32 binaries.
	* tests/data/test-lookup-syms/test1.c.compiling.txt: Documentation
	about how to compile the test1[-21bits].so files.
	* tests/data/Makefile.am: Add the new test material above to
	source distribution.
        * tests/test-lookup-syms.cc (in_out_specs): Add the
	test1-32bits.so test case to this test harness.

Signed-off-by: Dodji Seketeli <dodji@redhat.com>
2020-03-20 13:35:00 +01:00

151 lines
3.9 KiB
C++

// -*- Mode: C++ -*-
//
// Copyright (C) 2013-2020 Red Hat, Inc.
//
// This file is part of the GNU Application Binary Interface Generic
// Analysis and Instrumentation Library (libabigail). This library is
// free software; you can redistribute it and/or modify it under the
// terms of the GNU Lesser General Public License as published by the
// Free Software Foundation; either version 3, or (at your option) any
// later version.
// This library 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 Lesser Public License for more details.
// You should have received a copy of the GNU Lesser General Public
// License along with this program; see the file COPYING-LGPLV3. If
// not, see <http://www.gnu.org/licenses/>.
// Author: Dodji Seketeli
/// @file
///
/// This program tests the ELF symbols lookup APIs from
/// abigail::dwarf_reader. It uses the lookupsym tool from the
/// libabigail distribution.
#include <iostream>
#include <cstdlib>
#include "abg-tools-utils.h"
#include "test-utils.h"
using std::cerr;
using std::string;
struct InOutSpec
{
const char* in_elf_path;
const char* symbol;
const char* abisym_options;
const char* in_report_path;
const char* out_report_path;
}; // end struct InOutSpec
InOutSpec in_out_specs[] =
{
{
"data/test-lookup-syms/test0.o",
"main",
"",
"data/test-lookup-syms/test0-report.txt",
"output/test-lookup-syms/test0-report.txt"
},
{
"data/test-lookup-syms/test0.o",
"foo",
"",
"data/test-lookup-syms/test01-report.txt",
"output/test-lookup-syms/test01-report.txt"
},
{
"data/test-lookup-syms/test0.o",
"\"bar(char)\"",
"--demangle",
"data/test-lookup-syms/test02-report.txt",
"output/test-lookup-syms/test02-report.txt"
},
{
"data/test-lookup-syms/test1.so",
"foo",
"",
"data/test-lookup-syms/test1-1-report.txt",
"output/test-lookup-syms/test1-1-report.txt"
},
{
"data/test-lookup-syms/test1-32bits.so",
"foo",
"",
"data/test-lookup-syms/test1-1-report.txt",
"output/test-lookup-syms/test1-1-report.txt"
},
{
"data/test-lookup-syms/test1.so",
"_foo1",
"--no-absolute-path",
"data/test-lookup-syms/test1-2-report.txt",
"output/test-lookup-syms/test-2-report.txt"
},
{
"data/test-lookup-syms/test1.so",
"_foo2",
"--no-absolute-path",
"data/test-lookup-syms/test1-3-report.txt",
"output/test-lookup-syms/test-3-report.txt"
},
// This should always be the last entry.
{NULL, NULL, NULL, NULL, NULL}
};
int
main()
{
using abigail::tests::get_src_dir;
using abigail::tests::get_build_dir;
using abigail::tools_utils::ensure_parent_dir_created;
bool is_ok = true;
string in_elf_path, symbol, abisym, abisym_options,
ref_report_path, out_report_path;
for (InOutSpec* s = in_out_specs; s->in_elf_path; ++s)
{
in_elf_path = string(get_src_dir()) + "/tests/" + s->in_elf_path;
symbol = s->symbol;
abisym_options = s->abisym_options;
ref_report_path = string(get_src_dir()) + "/tests/" + s->in_report_path;
out_report_path =
string(get_build_dir()) + "/tests/" + s->out_report_path;
if (!ensure_parent_dir_created(out_report_path))
{
cerr << "could not create parent directory for "
<< out_report_path;
is_ok = false;
continue;
}
abisym = string(get_build_dir()) + "/tools/abisym";
abisym += " " + abisym_options;
string cmd = abisym + " " + in_elf_path + " " + symbol;
cmd += " > " + out_report_path;
bool abisym_ok = true;
if (system(cmd.c_str()))
abisym_ok = false;
if (abisym_ok)
{
cmd = "diff -u " + ref_report_path + " "+ out_report_path;
if (system(cmd.c_str()))
is_ok = false;
}
else
is_ok = false;
}
return !is_ok;
}