vfs: add faccessat2 syscall

POSIX defines faccessat() as having a fourth "flags" argument, while the
linux syscall doesn't have it.  Glibc tries to emulate AT_EACCESS and
AT_SYMLINK_NOFOLLOW, but AT_EACCESS emulation is broken.

Add a new faccessat(2) syscall with the added flags argument and implement
both flags.

The value of AT_EACCESS is defined in glibc headers to be the same as
AT_REMOVEDIR.  Use this value for the kernel interface as well, together
with the explanatory comment.

Also add AT_EMPTY_PATH support, which is not documented by POSIX, but can
be useful and is trivial to implement.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Miklos Szeredi
2020-05-14 16:44:25 +02:00
parent 55923e4d7d
commit c8ffd8bcdd
23 changed files with 62 additions and 13 deletions

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@@ -376,3 +376,4 @@
435 n32 clone3 __sys_clone3
437 n32 openat2 sys_openat2
438 n32 pidfd_getfd sys_pidfd_getfd
439 n32 faccessat2 sys_faccessat2

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@@ -352,3 +352,4 @@
435 n64 clone3 __sys_clone3
437 n64 openat2 sys_openat2
438 n64 pidfd_getfd sys_pidfd_getfd
439 n64 faccessat2 sys_faccessat2

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@@ -425,3 +425,4 @@
435 o32 clone3 __sys_clone3
437 o32 openat2 sys_openat2
438 o32 pidfd_getfd sys_pidfd_getfd
439 o32 faccessat2 sys_faccessat2