diff options
author | Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> | 2018-02-21 14:04:50 +0100 |
---|---|---|
committer | Sven Eden <yamakuzure@gmx.net> | 2018-04-09 18:26:06 +0200 |
commit | e468ac3a1841e47f656fe5fb246cfa65a1ccffce (patch) | |
tree | 96d03cfb9d6cd58a2a93536ff6a168107fe4e090 /man/sd_bus_message_get_monotonic_usec.xml | |
parent | 2cf68b85429bf1700e0d617ff0b31b14611dad66 (diff) |
missing_syscall: when adding syscall replacements, use different names (#8229)
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.
Diffstat (limited to 'man/sd_bus_message_get_monotonic_usec.xml')
0 files changed, 0 insertions, 0 deletions