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| author |   Miklos Szeredi <mszeredi@redhat.com> | 2020-05-14 16:44:25 +0200 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2020-05-14 16:44:25 +0200 |
| commit | c8ffd8bcdd28296a198f237cc595148a8d4adfbe (patch) | |
| tree | 71ce857ad8d9feea14cfe9619013e84a88bb374c /include/uapi/linux/fcntl.h | |
| parent | vfs: don't parse "silent" option (diff) | |
| download | linux-dev-c8ffd8bcdd28296a198f237cc595148a8d4adfbe.tar.xz linux-dev-c8ffd8bcdd28296a198f237cc595148a8d4adfbe.zip | |
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>
Diffstat (limited to 'include/uapi/linux/fcntl.h')
| -rw-r--r-- | include/uapi/linux/fcntl.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h index ca88b7bce553..2f86b2ad6d7e 100644 --- a/include/uapi/linux/fcntl.h +++ b/include/uapi/linux/fcntl.h @@ -84,10 +84,20 @@ #define DN_ATTRIB 0x00000020 /* File changed attibutes */ #define DN_MULTISHOT 0x80000000 /* Don't remove notifier */ +/* + * The constants AT_REMOVEDIR and AT_EACCESS have the same value. AT_EACCESS is + * meaningful only to faccessat, while AT_REMOVEDIR is meaningful only to + * unlinkat. The two functions do completely different things and therefore, + * the flags can be allowed to overlap. For example, passing AT_REMOVEDIR to + * faccessat would be undefined behavior and thus treating it equivalent to + * AT_EACCESS is valid undefined behavior. + */ #define AT_FDCWD -100 /* Special value used to indicate openat should use the current working directory. */ #define AT_SYMLINK_NOFOLLOW 0x100 /* Do not follow symbolic links. */ +#define AT_EACCESS 0x200 /* Test access permitted for + effective IDs, not real IDs. */ #define AT_REMOVEDIR 0x200 /* Remove directory instead of unlinking file. */ #define AT_SYMLINK_FOLLOW 0x400 /* Follow symbolic links. */ |