fchownat - 改变文件的一个相对的所有权到一个目录文件描述符
<unistd.h> int fchownat(int dirfd, const char *path, uid_t owner, gid_t group, int flags);
The fchownat() system call operates in exactly the same way as chown(2), except for the differences described in this manual page.
If the pathname given in path is relative, then it is interpreted relative to the directory referred to by the file descriptor dirfd (rather than relative to the current working directory of the calling process, as is done by chown(2) for a relative pathname).
If the pathname given in path is relative and dirfd is the special value AT_FDCWD, thenpath is interpreted relative to the current working directory of the calling process (likechown(2)).
If the pathname given in path is absolute, then dirfd is ignored.
flags can either be 0, or include the following flag:
|AT_SYMLINK_NOFOLLOW||If path is a symbolic link, do not dereference it: instead operate on the link itself, like lchown(2). (By default,fchownat() dereferences symbolic links, like chown(2).)|
On success, fchownat() returns 0. On error, -1 is returned and errno is set to indicate the error.
The same errors that occur for chown(2) can also occur for fchownat(). The following additional errors can occur for fchownat():
|EBADF||dirfd is not a valid file descriptor.|
|EINVAL||Invalid flag specified in flags.|
|ENOTDIR||path is a relative path and dirfd is a file descriptor referring to a file other than a directory.|
See openat(2) for an explanation of the need for fchownat().
This system call is non-standard but is proposed for inclusion in a future revision of POSIX.1. A similar system call exists on Solaris.
fchownat() was added to Linux in kernel 2.6.16.
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