In particular, define a static LibC library *in LibC's CMakeLists* and
use it in DynamicLoader. This is similar to the way LibELF is included
in DynamicLoader.
Additionally, compile DynamicLoader with -ffunction-sections,
-fdata-sections, and -Wl,--gc-sections. This brings the loader size from
~2Mb to ~1Mb with debug symbols and from ~500Kb to ~150Kb without. Also,
this makes linking DynamicLoader with LibTimeZone unnecessary.
Static libc on Serenity is broken in a more than one way and requires a
lot of patches to bring it to a usable and useful state. Therefore,
instead of keeping it around (and breaking even more) during the
upcoming libc build refactor, let's just delete it.
Since https://reviews.llvm.org/D131441, libc++ must be included before
LibC. As clang includes libc++ as one of the system includes, LibC
must be included after those, and the only correct way to do that is
to install LibC's headers into the sysroot.
Targets that don't link with LibC yet require its headers for one
reason or another must add install_libc_headers as a dependency to
ensure that the correct headers have been (re)installed into the
sysroot.
LibC/stddef.h has been dropped since the built-in stddef.h receives
a higher include priority.
In addition, string.h and wchar.h must
define __CORRECT_ISO_CPP_STRING_H_PROTO and
_LIBCPP_WCHAR_H_HAS_CONST_OVERLOADS respectively in order to tell
libc++ to not try to define methods implemented by LibC.
This option sets -fprofile-instr-generate -fcoverage-mapping for Clang
builds only on almost all of Userland. Loader and LibTimeZone are
exempt. This can be used for generating code coverage reports, or even
PGO in the future.
With this change, System::foo() becomes Core::System::foo().
Since LibCore builds on other systems than SerenityOS, we now have to
make sure that wrappers work with just a standard C library underneath.
This is a hack to avoid a circular dependency issue with the stack check
failure handler being in LibC.
This is not ideal, and there's most likely a better way to solve this.
That said, LibSystem should not have anything but thin wrappers around
system calls, so stack protectors have limited utility here anyway.
Previously, libc.a contained undefined symbols from ssp and libsystem,
which caused static compilation to fail.
We now generate libc.a with a custom CMake rule that combines all
object files from libc, ssp and libsystem to form libc.a
Closes#5758.
This achieves two things:
- Programs can now intentionally perform arbitrary syscalls by calling
syscall(). This allows us to work on things like syscall fuzzing.
- It restricts the ability of userspace to make syscalls to a single
4KB page of code. In order to call the kernel directly, an attacker
must now locate this page and call through it.
