5187dd2c40
In meson.build we check that functions are available using:
meson.get_compiler('c').has_function('foo')
which checks the following:
- if __stub_foo or __stub___foo are defined, return false
- if foo is declared (a pointer to the function can be taken), return true
- otherwise check for __builtin_memfd_create
_stub is documented by glibc as
It defines a symbol '__stub_FUNCTION' for each function
in the C library which is a stub, meaning it will fail
every time called, usually setting errno to ENOSYS.
So if __stub is defined, we know we don't want to use the glibc version, but
this doesn't tell us if the name itself is defined or not. If it _is_ defined,
and we define our replacement as an inline static function, we get an error:
In file included from ../src/basic/missing.h:1358:0,
from ../src/basic/util.h:47,
from ../src/basic/calendarspec.h:29,
from ../src/basic/calendarspec.c:34:
../src/basic/missing_syscall.h:65:19: error: static declaration of 'memfd_create' follows non-static declaration
static inline int memfd_create(const char *name, unsigned int flags) {
^~~~~~~~~~~~
.../usr/include/bits/mman-shared.h:46:5: note: previous declaration of 'memfd_create' was here
int memfd_create (const char *__name, unsigned int __flags) __THROW;
^~~~~~~~~~~~
To avoid this problem, call our inline functions different than glibc,
and use a #define to map the official name to our replacement.
Fixes #8099.
v2:
- use "missing_" as the prefix instead of "_"
v3:
- rebase and update for statx()
Unfortunately "statx" is also present in "struct statx", so the define
causes issues. Work around this by using a typedef.
I checked that systemd compiles with current glibc
(glibc-devel-2.26-24.fc27.x86_64) if HAVE_MEMFD_CREATE, HAVE_GETTID,
HAVE_PIVOT_ROOT, HAVE_SETNS, HAVE_RENAMEAT2, HAVE_KCMP, HAVE_KEYCTL,
HAVE_COPY_FILE_RANGE, HAVE_BPF, HAVE_STATX are forced to 0.
Setting HAVE_NAME_TO_HANDLE_AT to 0 causes an issue, but it's not because of
the define, but because of struct file_handle.
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|---|---|---|
| .github | ||
| .mkosi | ||
| catalog | ||
| coccinelle | ||
| docs | ||
| factory/etc | ||
| hwdb | ||
| man | ||
| modprobe.d | ||
| network | ||
| po | ||
| presets | ||
| rules | ||
| scripts | ||
| shell-completion | ||
| src | ||
| sysctl.d | ||
| sysusers.d | ||
| test | ||
| tmpfiles.d | ||
| tools | ||
| travis-ci | ||
| units | ||
| xorg | ||
| .dir-locals.el | ||
| .editorconfig | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .travis.yml | ||
| .vimrc | ||
| .ycm_extra_conf.py | ||
| CODING_STYLE | ||
| DISTRO_PORTING | ||
| ENVIRONMENT.md | ||
| HACKING | ||
| LICENSE.GPL2 | ||
| LICENSE.LGPL2.1 | ||
| Makefile | ||
| NEWS | ||
| README | ||
| README.md | ||
| TODO | ||
| TRANSIENT-SETTINGS.md | ||
| UIDS-GIDS.md | ||
| configure | ||
| meson.build | ||
| meson_options.txt | ||
| mkosi.build | ||
| mkosi.default | ||
README.md
systemd - System and Service Manager
Details
General information about systemd can be found in the systemd Wiki.
Information about build requirements are provided in the README file.
Consult our NEWS file for information about what's new in the most recent systemd versions.
Please see the HACKING file for information how to hack on systemd and test your modifications.
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