readlinkat - read value of a symbolic link relative to a directory file
#include <fcntl.h> /* Definition of AT_* constants */
int readlinkat(int dirfd, const char *pathname,
char *buf, size_t bufsiz);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
Since glibc 2.10: _XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
Before glibc 2.10: _ATFILE_SOURCE
The readlinkat() system call operates in exactly the same way as
readlink(2), except for the differences described in this manual page.
If the pathname given in pathname 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 readlink(2) for a relative pathname).
If pathname is relative and dirfd is the special value AT_FDCWD, then
pathname is interpreted relative to the current working directory of
the calling process (like readlink(2)).
If pathname is absolute, then dirfd is ignored.
On success, readlinkat() returns the number of bytes placed in buf. On
error, -1 is returned and errno is set to indicate the error.
The same errors that occur for readlink(2) can also occur for
readlinkat(). The following additional errors can occur for
EBADF dirfd is not a valid file descriptor.
pathname is relative and dirfd is a file descriptor referring to
a file other than a directory.
readlinkat() was added to Linux in kernel 2.6.16.
See openat(2) for an explanation of the need for readlinkat().
openat(2), readlink(2), path_resolution(7)
This page is part of release 3.24 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.