readlinkat — read value of a symbolic link relative to a directory file descriptor
#define _ATFILE_SOURCE #include <fcntl.h> /* Definition of AT_* constants */ #include <unistd.h>
int
readlinkat( |
int | dirfd, |
| const char * | pathname, | |
| char * | buf, | |
| size_t | bufsiz); |
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 0. 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 readlinkat():
dirfd is not
a valid file descriptor.
pathname is
relative and dirfd is a file
descriptor referring to a file other than a
directory.
This system call is non-standard but is proposed for inclusion in a future revision of POSIX.1.