We recently started making more use of malloc_usable_size() and rely on
it (see the string_erase() story). Given that we don't really support
sytems where malloc_usable_size() cannot be trusted beyond statistics
anyway, let's go fully in and rework GREEDY_REALLOC() on top of it:
instead of passing around and maintaining the currenly allocated size
everywhere, let's just derive it automatically from
malloc_usable_size().
I am mostly after this for the simplicity this brings. It also brings
minor efficiency improvements I guess, but things become so much nicer
to look at if we can avoid these allocation size variables everywhere.
Note that the malloc_usable_size() man page says relying on it wasn't
"good programming practice", but I think it does this for reasons that
don't apply here: the greedy realloc logic specifically doesn't rely on
the returned extra size, beyond the fact that it is equal or larger than
what was requested.
(This commit was supposed to be a quick patch btw, but apparently we use
the greedy realloc stuff quite a bit across the codebase, so this ends
up touching *a*lot* of code.)
This is a wrapper around malloc_usable_size() but is typesafe, and
divides by the element size.
A test it is also added ensuring what it does it does correcly.
It's a wrapper around malloc_usable_size() that is supposed to be
compatible with _FORTIFY_SOURCES=1, by taking the
__builtin_object_size() data into account, the same way as the
_FORTIFY_SOURCES=1 logic does.
Fixes: #19203
freep() has it's own definition, so I missed it in fd421c4adc.
Again, there is a small growth, but the compiler should be able to optimize it away:
-Dbuildtype=debug:
-rwxrwxr-x 1 zbyszek zbyszek 4106816 Feb 19 12:52 build/libsystemd.so.0.30.0
-rwxrwxr-x 1 zbyszek zbyszek 7492952 Feb 19 12:52 build/src/shared/libsystemd-shared-247.so
-rwxrwxr-x 1 zbyszek zbyszek 4472624 Feb 19 12:53 build/systemd
-rwxrwxr-x 1 zbyszek zbyszek 4107056 Feb 19 13:03 build/libsystemd.so.0.30.0
-rwxrwxr-x 1 zbyszek zbyszek 7493480 Feb 19 13:03 build/src/shared/libsystemd-shared-247.so
-rwxrwxr-x 1 zbyszek zbyszek 4472760 Feb 19 13:03 build/systemd
Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=31055.
sd-boot has a copy of a subset of codes from libbasic. This makes
sd-boot share the code with libbasic, and dedup the code.
Note, startswith_no_case() is dropped from sd-boot, as
- it is not used,
- the previous implementation is not correct,
- gnu-efi does not have StrniCmp() or so.
This decorator tells compilers that the memory we return is shorter than
it actually is, thus triggering misleading bad memory access complaints.
Fixes: #13026
This isn't really necessary for the subsequent commit, but I expect that we'll
need to unpoison more often once we turn on msan in CI, so I think think this
change makes sense in the long run.
Of course, this should never happen, but let's better be safe than
sorry, and abort rather than continue when a too large memory block is
allocated, simply asa safety precaution.
An early abort is better than continuing with a likely memory corruption
later.
All underlying glibc calls are free to return NULL if the size argument
is 0. We most often call those functions with a fixed argument, or at least
something which obviously cannot be zero, but it's too easy to forget.
E.g. coverity complains about "rows = new0(JsonVariant*, n_rows-1);" in
format-table.c There is an assert that n_rows > 0, so we could hit this
corner case here. Let's simplify callers and make those functions "safe".
CID #1397035.
The compiler is mostly able to optimize this away:
$ size build{,-opt}/src/shared/libsystemd-shared-239.so
(before)
text data bss dec hex filename
2643329 580940 3112 3227381 313ef5 build/src/shared/libsystemd-shared-239.so (-O0 -g)
2170013 578588 3089 2751690 29fcca build-opt/src/shared/libsystemd-shared-239.so (-03 -flto -g)
(after)
text data bss dec hex filename
2644017 580940 3112 3228069 3141a5 build/src/shared/libsystemd-shared-239.so
2170765 578588 3057 2752410 29ff9a build-opt/src/shared/libsystemd-shared-239.so
These lines are generally out-of-date, incomplete and unnecessary. With
SPDX and git repository much more accurate and fine grained information
about licensing and authorship is available, hence let's drop the
per-file copyright notice. Of course, removing copyright lines of others
is problematic, hence this commit only removes my own lines and leaves
all others untouched. It might be nicer if sooner or later those could
go away too, making git the only and accurate source of authorship
information.
This part of the copyright blurb stems from the GPL use recommendations:
https://www.gnu.org/licenses/gpl-howto.en.html
The concept appears to originate in times where version control was per
file, instead of per tree, and was a way to glue the files together.
Ultimately, we nowadays don't live in that world anymore, and this
information is entirely useless anyway, as people are very welcome to
copy these files into any projects they like, and they shouldn't have to
change bits that are part of our copyright header for that.
hence, let's just get rid of this old cruft, and shorten our codebase a
bit.
Of course, alloca() shouldn't be used with anything that can grow
without bounds anyway, but let's better safe than sorry, and catch this
early.
Since alloca() is not supposed to return an error we trigger an
assert() instead, which is still better than heap trickery.
Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.
I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
This macro will read a pointer of any type, return it, and set the
pointer to NULL. This is useful as an explicit concept of passing
ownership of a memory area between pointers.
This takes inspiration from Rust:
https://doc.rust-lang.org/std/option/enum.Option.html#method.take
and was suggested by Alan Jenkins (@sourcejedi).
It drops ~160 lines of code from our codebase, which makes me like it.
Also, I think it clarifies passing of ownership, and thus helps
readability a bit (at least for the initiated who know the new macro)
There isn't much difference, but in general we prefer to use the standard
functions. glibc provides reallocarray since version 2.26.
I moved explicit_bzero is configure test to the bottom, so that the two stdlib
functions are at the bottom.
These are similar to memdup() and newdup(), but reserve one extra NUL
byte at the end of the new allocation and initialize it. It's useful
when copying out data from fixed size character arrays where NUL
termination can't be assumed.
It's a common pattern, so add a helper for it. A macro is necessary
because a function that takes a pointer to a pointer would be type specific,
similarly to cleanup functions. Seems better to use a macro.
This patch contains a set of little cleanups for alloc-util.h:
1. The malloc_multiply(), realloc_multiply() and memdup_multiply()
functions check allocation related parameters on overflow. Let's
move them to the separate size_multiply_overflow() function for
simplicity, code duplication prevention and possible reuse in future.
2. use SIZE_MAX from stdlib instead of ((size_t) - 1) to be more
clear.
3. The 'a'/'b' variables are renamed to 'size' and 'need' to be
more clear.'
