MemorySanitizer is a compile-time instrumentation layer in clang and GCC.
Together with AddressSanitizer mostly makes the run-time instrumentation
of Valgrind redundant. It is a little more tricky to set up, because
running with uninstrumented libraries will lead into false positives.
You will need an instrumented libc++, and you should use
-stdlib=libc++ instead of the default libstdc++. To build the
instrumented library, you can refer to
https://github.com/google/sanitizers/wiki/MemorySanitizerLibcxxHowTo
or you can adapt these steps that worked for me, for clang-8 version 8.0.1:
cd /mariadb
sudo apt source libc++-8-dev
cd llvm-toolchain-8-8.0.1
mkdir libc++msan; cd libc++msan
cmake ../libcxx -DCMAKE_BUILD_TYPE=Release -DLLVM_USE_SANITIZER=Memory \
-DCMAKE_C_COMPILER=clang-8 -DCMAKE_CXX_COMPILER=clang++-8
Then, in your MariaDB build directory, you have to compile with
libc++ and bundled libraries, such as WITH_SSL=bundled, WITH_ZLIB=bundled.
For uninstrumented system libraries, you will get false positives for
uninitialized values. Like this:
cmake -DWITH_MSAN=ON -DWITH_SSL=bundled -DWITH_ZLIB=bundled \
-DCMAKE_CXX_FLAGS='-stdlib=libc++' ..
Note: you should also add -O2 to the compiler options, or you may
get crashes due to stack overflow.
Finally, to run tests, you must replace libc++ with the instrumented one:
LD_LIBRARY_PATH=/mariadb/llvm-toolchain-8-8.0.1/libc++msan/lib \
MSAN_OPTIONS=abort_on_error=1 \
./mtr --big-test --parallel=auto --force --retry=0
Failure to do so will report numerous false positives related to
operations on std::string and the like.
This is work in progress. Some issues will still have to be fixed
for WITH_MSAN to be usable. See MDEV-20377 for details.
don't ignore LIBSYSTEMD_LDFLAGS when trying out systemd
(and put them in LIBSYSTEMD, because MYSQLD_LINK_FLAGS has stuff like
-lmtmalloc and is used only for mysqld, not for, say, explain_filename-t)
LIBSYSTEMD_LDFLAGS come from libsystemd.pc via pkg-config
special cases:
* change systemd detection to use CHECK_LIBRARY_EXISTS at least once,
to have it detected by build_depends.cmake
* similarly, use find_library for pam
* unixODBC is weird, libodbc.so is in the unixODBC package, not
in the unixODBC-devel, where normally all .so files belong.
Packaging bug? As a workaround, use find_file(sql.h) instead of
find_path(sql.h) to make sure that /usr/include/sql.h (not /usr/include)
is cached by cmake, and later build_depends.cmake will select
unixODBC-devel, as a package owning /usr/include/sql.h file.
automatic BuildRequires for source RPM: for every FILEPATH and
"Have library XXX" cached variable, detect what rpm package it comes from
and add it to the list of dependencies.
That is, the source RPM will BuildRequire all those packages that
were found by cmake when the source RPM was built. Presumably, our
CMakeLists.txt won't check for libraries that aren't needed for a build.
It supports libraries/executables/files found with
FIND_LIBRARY
FIND_FILE
FIND_PROGRAM
CHECK_LIBRARY_EXISTS
create source RPM cpack-way
when building binary packages, this source rpm will use
same BUILD_CONFIG and WITH_SSL values that were used when
creating the source RPM.
Only do it for a reasonably new cmake, where
source rpms are known to work (3.10.2 is ok, 3.5.2 is not).
And force a shorter CPACK_RPM_BUILD_SOURCE_DIRS_PREFIX so that
a source rpm could be built from a standard location in /usr/src
now we can afford it. Fix -Werror errors. Note:
* old gcc is bad at detecting uninit variables, disable it.
* time_t is int or long, cast it for printf's
Disable LOAD DATA LOCAL INFILE suport by default and
auto-enable it for the duration of one query, if the query
string starts with the word "load". In all other cases the application
should enable LOAD DATA LOCAL INFILE support explicitly.
