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.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
Lennart Poettering
parent
7b13a721f5
commit
5187dd2c40
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@ -26,9 +26,11 @@
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#include <sys/types.h>
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#if !HAVE_PIVOT_ROOT
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static inline int pivot_root(const char *new_root, const char *put_old) {
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static inline int missing_pivot_root(const char *new_root, const char *put_old) {
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return syscall(SYS_pivot_root, new_root, put_old);
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}
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# define pivot_root missing_pivot_root
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#endif
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/* ======================================================================= */
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@ -62,7 +64,7 @@ static inline int pivot_root(const char *new_root, const char *put_old) {
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# endif
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# endif
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static inline int memfd_create(const char *name, unsigned int flags) {
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static inline int missing_memfd_create(const char *name, unsigned int flags) {
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# ifdef __NR_memfd_create
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return syscall(__NR_memfd_create, name, flags);
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# else
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@ -70,6 +72,8 @@ static inline int memfd_create(const char *name, unsigned int flags) {
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return -1;
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# endif
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}
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# define memfd_create missing_memfd_create
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#endif
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/* ======================================================================= */
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@ -109,7 +113,7 @@ static inline int memfd_create(const char *name, unsigned int flags) {
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# endif
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# endif
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static inline int getrandom(void *buffer, size_t count, unsigned flags) {
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static inline int missing_getrandom(void *buffer, size_t count, unsigned flags) {
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# ifdef __NR_getrandom
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return syscall(__NR_getrandom, buffer, count, flags);
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# else
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@ -117,14 +121,18 @@ static inline int getrandom(void *buffer, size_t count, unsigned flags) {
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return -1;
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# endif
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}
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# define getrandom missing_getrandom
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#endif
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/* ======================================================================= */
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#if !HAVE_GETTID
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static inline pid_t gettid(void) {
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static inline pid_t missing_gettid(void) {
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return (pid_t) syscall(SYS_gettid);
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}
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# define gettid missing_gettid
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#endif
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/* ======================================================================= */
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@ -152,7 +160,7 @@ struct file_handle {
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unsigned char f_handle[0];
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};
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static inline int name_to_handle_at(int fd, const char *name, struct file_handle *handle, int *mnt_id, int flags) {
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static inline int missing_name_to_handle_at(int fd, const char *name, struct file_handle *handle, int *mnt_id, int flags) {
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# ifdef __NR_name_to_handle_at
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return syscall(__NR_name_to_handle_at, fd, name, handle, mnt_id, flags);
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# else
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@ -160,6 +168,8 @@ static inline int name_to_handle_at(int fd, const char *name, struct file_handle
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return -1;
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# endif
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}
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# define name_to_handle_at missing_name_to_handle_at
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#endif
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/* ======================================================================= */
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@ -177,7 +187,7 @@ static inline int name_to_handle_at(int fd, const char *name, struct file_handle
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# endif
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# endif
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static inline int setns(int fd, int nstype) {
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static inline int missing_setns(int fd, int nstype) {
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# ifdef __NR_setns
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return syscall(__NR_setns, fd, nstype);
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# else
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@ -185,6 +195,8 @@ static inline int setns(int fd, int nstype) {
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return -1;
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# endif
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}
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# define setns missing_setns
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#endif
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/* ======================================================================= */
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@ -230,7 +242,7 @@ static inline pid_t raw_getpid(void) {
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# endif
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# endif
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static inline int renameat2(int oldfd, const char *oldname, int newfd, const char *newname, unsigned flags) {
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static inline int missing_renameat2(int oldfd, const char *oldname, int newfd, const char *newname, unsigned flags) {
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# ifdef __NR_renameat2
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return syscall(__NR_renameat2, oldfd, oldname, newfd, newname, flags);
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# else
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@ -238,12 +250,14 @@ static inline int renameat2(int oldfd, const char *oldname, int newfd, const cha
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return -1;
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# endif
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}
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# define renameat2 missing_renameat2
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#endif
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/* ======================================================================= */
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#if !HAVE_KCMP
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static inline int kcmp(pid_t pid1, pid_t pid2, int type, unsigned long idx1, unsigned long idx2) {
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static inline int missing_kcmp(pid_t pid1, pid_t pid2, int type, unsigned long idx1, unsigned long idx2) {
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# ifdef __NR_kcmp
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return syscall(__NR_kcmp, pid1, pid2, type, idx1, idx2);
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# else
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@ -251,36 +265,45 @@ static inline int kcmp(pid_t pid1, pid_t pid2, int type, unsigned long idx1, uns
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return -1;
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# endif
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}
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# define kcmp missing_kcmp
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#endif
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/* ======================================================================= */
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#if !HAVE_KEYCTL
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static inline long keyctl(int cmd, unsigned long arg2, unsigned long arg3, unsigned long arg4,unsigned long arg5) {
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static inline long missing_keyctl(int cmd, unsigned long arg2, unsigned long arg3, unsigned long arg4,unsigned long arg5) {
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# ifdef __NR_keyctl
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return syscall(__NR_keyctl, cmd, arg2, arg3, arg4, arg5);
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# else
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errno = ENOSYS;
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return -1;
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# endif
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# define keyctl missing_keyctl
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}
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static inline key_serial_t add_key(const char *type, const char *description, const void *payload, size_t plen, key_serial_t ringid) {
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static inline key_serial_t missing_add_key(const char *type, const char *description, const void *payload, size_t plen, key_serial_t ringid) {
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# ifdef __NR_add_key
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return syscall(__NR_add_key, type, description, payload, plen, ringid);
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# else
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errno = ENOSYS;
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return -1;
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# endif
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# define add_key missing_add_key
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}
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static inline key_serial_t request_key(const char *type, const char *description, const char * callout_info, key_serial_t destringid) {
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static inline key_serial_t missing_request_key(const char *type, const char *description, const char * callout_info, key_serial_t destringid) {
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# ifdef __NR_request_key
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return syscall(__NR_request_key, type, description, callout_info, destringid);
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# else
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errno = ENOSYS;
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return -1;
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# endif
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# define request_key missing_request_key
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}
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#endif
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@ -307,10 +330,10 @@ static inline key_serial_t request_key(const char *type, const char *description
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# endif
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# endif
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static inline ssize_t copy_file_range(int fd_in, loff_t *off_in,
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int fd_out, loff_t *off_out,
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size_t len,
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unsigned int flags) {
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static inline ssize_t missing_copy_file_range(int fd_in, loff_t *off_in,
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int fd_out, loff_t *off_out,
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size_t len,
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unsigned int flags) {
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# ifdef __NR_copy_file_range
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return syscall(__NR_copy_file_range, fd_in, off_in, fd_out, off_out, len, flags);
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# else
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@ -318,6 +341,8 @@ static inline ssize_t copy_file_range(int fd_in, loff_t *off_in,
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return -1;
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# endif
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}
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# define copy_file_range missing_copy_file_range
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#endif
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/* ======================================================================= */
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@ -345,7 +370,7 @@ static inline ssize_t copy_file_range(int fd_in, loff_t *off_in,
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union bpf_attr;
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static inline int bpf(int cmd, union bpf_attr *attr, size_t size) {
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static inline int missing_bpf(int cmd, union bpf_attr *attr, size_t size) {
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#ifdef __NR_bpf
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return (int) syscall(__NR_bpf, cmd, attr, size);
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#else
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@ -354,6 +379,7 @@ static inline int bpf(int cmd, union bpf_attr *attr, size_t size) {
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#endif
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}
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# define bpf missing_bpf
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#endif
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/* ======================================================================= */
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@ -384,6 +410,8 @@ static inline int bpf(int cmd, union bpf_attr *attr, size_t size) {
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# endif
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#endif
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/* ======================================================================= */
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#if !HAVE_STATX
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# ifndef __NR_statx
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# if defined __i386__
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@ -396,8 +424,13 @@ static inline int bpf(int cmd, union bpf_attr *attr, size_t size) {
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# endif
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struct statx;
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#endif
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static inline ssize_t statx(int dfd, const char *filename, unsigned flags, unsigned int mask, struct statx *buffer) {
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/* This typedef is supposed to be always defined. */
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typedef struct statx struct_statx;
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#if !HAVE_STATX
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static inline ssize_t missing_statx(int dfd, const char *filename, unsigned flags, unsigned int mask, struct statx *buffer) {
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# ifdef __NR_statx
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return syscall(__NR_statx, dfd, filename, flags, mask, buffer);
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# else
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@ -405,4 +438,6 @@ static inline ssize_t statx(int dfd, const char *filename, unsigned flags, unsig
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return -1;
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# endif
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}
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# define statx missing_statx
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#endif
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@ -151,7 +151,7 @@ static int parse_crtime(le64_t le, usec_t *usec) {
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}
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int fd_getcrtime_at(int dirfd, const char *name, usec_t *ret, int flags) {
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struct statx sx;
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struct_statx sx;
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usec_t a, b;
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le64_t le;
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ssize_t n;
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