This is a follow-up for 9f83091e3c.
Instead of reading the mtime off the configuration files after reading,
let's do so before reading, but with the fd we read the data from. This
is not only cleaner (as it allows us to save one stat()), but also has
the benefit that we'll detect changes that happen while we read the
files.
This also reworks unit file drop-ins to use the common code for
determining drop-in mtime, instead of reading system clock for that.
https://clang.llvm.org/docs/MemorySanitizer.html#id5 documents this
check as the way to detect MemorySanitizer at compilation time. We
only need to skip the test if MemorySanitizer is used.
Also, use this condition in cg_slice_to_path(). There, the code that is
conditionalized is not harmful in any way (it's just unnecessary), so remove
the FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION condition.
Fixes#8482.
The test for ListenNetlink would abort the loop if a line longer then LINE_MAX
was encountered (read_line() returns -ENOBUFS in that case). Let's use the
the line length limit that the unit file parses uses.
https://oss-fuzz.com/v2/issue/5546208027213824/7094.
msan doesn't understand sscanf with %ms, so it falsely reports unitialized
memory. Using sscanf with %ms is quite convenient in
socket_address_parse_netlink(), so let's just not run the fuzzer for
ListenNetlink= at all for now. If msan is fixed, we can remove this.
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=6884
fuzz-unit-file generated too much logs about invalid config lines. This just
slows things down and fills the logs. If necessary, it's better to rerun the
interesting cases with SYSTEMD_LOG_LEVEL=debug.
