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lib: rework how we "override" assert()

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The previous method, using zassert.h and hoping nothing includes
assert.h (which, on glibc at least, just does "#undef assert" and puts
its own definition in...) was fragile - and actually broke undetected.

Just provide our own assert.h and control overriding by putting it in a
separate directory to add to the include path (or not.)

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
This commit is contained in:
David Lamparter 2021-03-16 11:03:44 +01:00 committed by David Lamparter
parent 642ac49da4
commit 64dd77361f
12 changed files with 271 additions and 23 deletions
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10
Makefile.am
View File

@ -11,11 +11,19 @@ AM_CFLAGS = \
$(SAN_FLAGS) \
$(WERROR) \
# end
AM_CPPFLAGS = \
# CPPFLAGS_BASE does not contain the include path for overriding assert.h,
# therefore should be used in tools that do *not* link libfrr or do not want
# assert() overridden
CPPFLAGS_BASE = \
-I$(top_srcdir) -I$(top_srcdir)/include -I$(top_srcdir)/lib \
-I$(top_builddir) \
$(LUA_INCLUDE) \
# end
AM_CPPFLAGS = \
-I$(top_srcdir)/lib/assert \
$(CPPFLAGS_BASE) \
# end
AM_LDFLAGS = \
-export-dynamic \
$(AC_LDFLAGS) \

98
lib/assert/assert.h Normal file
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@ -0,0 +1,98 @@
/*
* Copyright (c) 2021 David Lamparter, for NetDEF, Inc.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/* WARNING: this file is "special" in that it overrides the system-provided
* assert.h by being on the include path before it. That means it should
* provide the functional equivalent.
*
* This is intentional because FRR extends assert() to write to the log and
* add backtraces. Overriding the entire file is the simplest and most
* reliable way to get this to work; there were problems previously with the
* system assert.h getting included afterwards and redefining assert() back to
* the system variant.
*/
#ifndef _FRR_ASSERT_H
#define _FRR_ASSERT_H
#include "xref.h"
#ifdef __cplusplus
extern "C" {
#endif
#ifndef __cplusplus
/* C++ has this built-in, but C provides it in assert.h for >=C11. Since we
* replace assert.h entirely, we need to provide it here too.
*/
#define static_assert _Static_assert
#endif
struct xref_assert {
struct xref xref;
const char *expr;
const char *extra, *args;
};
extern void _zlog_assert_failed(const struct xref_assert *xref,
const char *extra, ...) PRINTFRR(2, 3)
__attribute__((noreturn));
/* the "do { } while (expr_)" is there to get a warning for assignments inside
* the assert expression aka "assert(x = 1)". The (necessary) braces around
* expr_ in the if () statement would suppress these warnings. Since
* _zlog_assert_failed() is noreturn, the while condition will never be
* checked.
*/
#define assert(expr_) \
({ \
static const struct xref_assert _xref __attribute__( \
(used)) = { \
.xref = XREF_INIT(XREFT_ASSERT, NULL, __func__), \
.expr = #expr_, \
}; \
XREF_LINK(_xref.xref); \
if (__builtin_expect((expr_) ? 0 : 1, 0)) \
do { \
_zlog_assert_failed(&_xref, NULL); \
} while (expr_); \
})
#define assertf(expr_, extra_, ...) \
({ \
static const struct xref_assert _xref __attribute__( \
(used)) = { \
.xref = XREF_INIT(XREFT_ASSERT, NULL, __func__), \
.expr = #expr_, \
.extra = extra_, \
.args = #__VA_ARGS__, \
}; \
XREF_LINK(_xref.xref); \
if (__builtin_expect((expr_) ? 0 : 1, 0)) \
do { \
_zlog_assert_failed(&_xref, extra_, \
##__VA_ARGS__); \
} while (expr_); \
})
#define zassert assert
#ifdef __cplusplus
}
#endif
#endif /* _FRR_ASSERT_H */

9
lib/clippy.c
View File

@ -115,15 +115,6 @@ void vzlogx(const struct xref_logmsg *xref, int prio,
fputs("\n", stderr);
}
void _zlog_assert_failed(const char *assertion, const char *file,
unsigned int line, const char *function)
{
fprintf(stderr,
"Assertion `%s' failed in file %s, line %u, function %s",
assertion, file, line, (function ? function : "?"));
abort();
}
void memory_oom(size_t size, const char *name)
{
abort();

11
lib/log.c
View File

@ -311,17 +311,6 @@ void zlog_thread_info(int log_level)
zlog(log_level, "Current thread not known/applicable");
}
void _zlog_assert_failed(const char *assertion, const char *file,
unsigned int line, const char *function)
{
zlog(LOG_CRIT, "Assertion `%s' failed in file %s, line %u, function %s",
assertion, file, line, (function ? function : "?"));
zlog_backtrace(LOG_CRIT);
zlog_thread_info(LOG_CRIT);
log_memstats(stderr, "log");
abort();
}
void memory_oom(size_t size, const char *name)
{
zlog(LOG_CRIT,

4
lib/subdir.am
View File

@ -284,6 +284,8 @@ pkginclude_HEADERS += \
lib/zlog_targets.h \
lib/pbr.h \
lib/routing_nb.h \
\
lib/assert/assert.h \
# end
@ -412,7 +414,7 @@ lib_grammar_sandbox_SOURCES = \
lib_grammar_sandbox_LDADD = \
lib/libfrr.la
lib_clippy_CPPFLAGS = $(AM_CPPFLAGS) -D_GNU_SOURCE -DBUILDING_CLIPPY
lib_clippy_CPPFLAGS = $(CPPFLAGS_BASE) -D_GNU_SOURCE -DBUILDING_CLIPPY
lib_clippy_CFLAGS = $(AC_CFLAGS) $(PYTHON_CFLAGS)
lib_clippy_LDADD = $(PYTHON_LIBS) $(UST_LIBS) -lelf
lib_clippy_LDFLAGS = -export-dynamic

1
lib/xref.h
View File

@ -33,6 +33,7 @@ enum xref_type {
XREFT_THREADSCHED = 0x100,
XREFT_LOGMSG = 0x200,
XREFT_ASSERT = 0x280,
XREFT_DEFUN = 0x300,
XREFT_INSTALL_ELEMENT = 0x301,

30
lib/zlog.c
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@ -521,6 +521,36 @@ void zlog_sigsafe(const char *text, size_t len)
}
}
void _zlog_assert_failed(const struct xref_assert *xref, const char *extra, ...)
{
va_list ap;
static bool assert_in_assert; /* "global-ish" variable, init to 0 */
if (assert_in_assert)
abort();
assert_in_assert = true;
if (extra) {
struct va_format vaf;
va_start(ap, extra);
vaf.fmt = extra;
vaf.va = &ap;
zlog(LOG_CRIT,
"%s:%d: %s(): assertion (%s) failed, extra info: %pVA",
xref->xref.file, xref->xref.line, xref->xref.func,
xref->expr, &vaf);
va_end(ap);
} else
zlog(LOG_CRIT, "%s:%d: %s(): assertion (%s) failed",
xref->xref.file, xref->xref.line, xref->xref.func,
xref->expr);
/* abort() prints backtrace & memstats in SIGABRT handler */
abort();
}
int zlog_msg_prio(struct zlog_msg *msg)
{

1
tests/.gitignore vendored
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@ -21,6 +21,7 @@
/lib/cli/test_commands_defun.c
/lib/northbound/test_oper_data
/lib/cxxcompat
/lib/test_assert
/lib/test_atomlist
/lib/test_buffer
/lib/test_checksum

64
tests/lib/test_assert.c Normal file
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@ -0,0 +1,64 @@
/*
* Quick test for assert()
* Copyright (C) 2021 David Lamparter for NetDEF, Inc.
*
* 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 2 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; see the file COPYING; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
/* make sure this works with assert.h & nothing else. also check the include
* shadowing, we don't want to pick up system assert.h
*/
#include <assert.h>
__attribute__((noinline))
void func_for_bt(int number)
{
assert(number > 2);
assertf(number > 3, "(A) the number was %d", number);
}
#include <zebra.h>
#include "lib/zlog.h"
#include "lib/thread.h"
#include "lib/sigevent.h"
int main(int argc, char **argv)
{
int number = 10;
struct thread_master *master;
zlog_aux_init("NONE: ", LOG_DEBUG);
if (argc > 1)
number = atoi(argv[1]);
assert(number > 0);
assertf(number > 1, "(B) the number was %d", number);
/* set up SIGABRT handler */
master = thread_master_create("test");
signal_init(master, 0, NULL);
func_for_bt(number);
assert(number > 4);
assertf(number > 5, "(C) the number was %d", number);
assertf(number > 10, "(D) the number was %d", number);
return 0;
}

56
tests/lib/test_assert.py Normal file
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@ -0,0 +1,56 @@
import frrtest
import os
import re
import subprocess
import inspect
basedir = os.path.dirname(__file__)
program = os.path.join(basedir, "test_assert")
def check(number, rex=None):
proc = subprocess.Popen(
[frrtest.binpath(program), str(number)],
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
)
out, err = proc.communicate()
exitcode = proc.wait()
if rex is None:
assert exitcode == 0
else:
assert exitcode != 0
text = out.decode("US-ASCII") + err.decode("US-ASCII")
rex = re.compile(rex, re.M | re.S)
m = rex.search(text)
assert m is not None, "non-matching output: %s" % text
def test_assert_0():
check(0, r"test_assert\.c:\d+.*number > 0")
def test_assert_1():
check(1, r"test_assert\.c:\d+.*number > 1.*\(B\) the number was 1")
def test_assert_2():
check(2, r"test_assert\.c:\d+.*number > 2")
def test_assert_3():
check(3, r"test_assert\.c:\d+.*number > 3.*\(A\) the number was 3")
def test_assert_4():
check(4, r"test_assert\.c:\d+.*number > 4")
def test_assert_10():
check(10, r"test_assert\.c:\d+.*number > 10.*\(D\) the number was 10")
def test_assert_11():
check(11)

6
tests/subdir.am
View File

@ -66,6 +66,7 @@ clippy_scan += \
check_PROGRAMS = \
tests/lib/cxxcompat \
tests/lib/test_assert \
tests/lib/test_atomlist \
tests/lib/test_buffer \
tests/lib/test_checksum \
@ -249,6 +250,10 @@ tests_lib_northbound_test_oper_data_CPPFLAGS = $(TESTS_CPPFLAGS)
tests_lib_northbound_test_oper_data_LDADD = $(ALL_TESTS_LDADD)
tests_lib_northbound_test_oper_data_SOURCES = tests/lib/northbound/test_oper_data.c
nodist_tests_lib_northbound_test_oper_data_SOURCES = yang/frr-test-module.yang.c
tests_lib_test_assert_CFLAGS = $(TESTS_CFLAGS)
tests_lib_test_assert_CPPFLAGS = $(TESTS_CPPFLAGS)
tests_lib_test_assert_LDADD = $(ALL_TESTS_LDADD)
tests_lib_test_assert_SOURCES = tests/lib/test_assert.c
tests_lib_test_atomlist_CFLAGS = $(TESTS_CFLAGS)
tests_lib_test_atomlist_CPPFLAGS = $(TESTS_CPPFLAGS)
tests_lib_test_atomlist_LDADD = $(ALL_TESTS_LDADD)
@ -404,6 +409,7 @@ EXTRA_DIST += \
tests/lib/northbound/test_oper_data.in \
tests/lib/northbound/test_oper_data.py \
tests/lib/northbound/test_oper_data.refout \
tests/lib/test_assert.py \
tests/lib/test_atomlist.py \
tests/lib/test_nexthop_iter.py \
tests/lib/test_ntop.py \

2
tools/subdir.am
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@ -34,9 +34,11 @@ tools_gen_yang_deviations_SOURCES = tools/gen_yang_deviations.c
tools_gen_yang_deviations_LDADD = lib/libfrr.la $(LIBYANG_LIBS)
tools_ssd_SOURCES = tools/start-stop-daemon.c
tools_ssd_CPPFLAGS =
# don't bother autoconf'ing these for a simple optional tool
llvm_version = $(shell echo __clang_major__ | $(CC) -xc -P -E -)
tools_frr_llvm_cg_CPPFLAGS = $(CPPFLAGS_BASE)
tools_frr_llvm_cg_CFLAGS = $(AM_CFLAGS) `llvm-config-$(llvm_version) --cflags`
tools_frr_llvm_cg_LDFLAGS = `llvm-config-$(llvm_version) --ldflags --libs`
tools_frr_llvm_cg_SOURCES = \