fstatat - 得到相对文件的状态到一个目录文件描述符
#include <sys/stat.h> int fstatat(int dirfd, const char *path, struct stat * buf ", int " flags );
The fstatat() system call operates in exactly the same way as stat(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 stat(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 (likestat(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 return information about the link itself, like lstat(2). (By default, fstatat() dereferences symbolic links, likestat(2).)|
On success, fstatat() returns 0. On error, -1 is returned and errno is set to indicate the error.
The same errors that occur for stat(2) can also occur for fstatat(). The following additional errors can occur for fstatat():
|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 fstatat().
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.
fstatat() was added to Linux in kernel 2.6.16.
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