READLINK(2) BSD System Calls Manual READLINK(2)
readlink, readlinkat -- read value of a symbolic link
readlink(const char *restrict path, char *restrict buf, size_t bufsiz);
readlinkat(int fd, const char *path, char *buf, size_t bufsiz);
The readlink() function places the contents of the symbolic link path in
the buffer buf, which has size bufsiz. readlink does not append a NUL
character to buf.
The readlinkat() function is equivalent to readlink() except that where
path specifies a relative path, the symbolic link whose contents are read
is determined relative to the directory associated with file descriptor
fd instead of the current working directory.
If readlinkat() is passed the special value AT_FDCWD (defined in
<fcntl.h>) in the fd parameter, the current working directory is used and
the behavior is identical to a call to readlink().
The call returns the count of characters placed in the buffer if it suc-
ceeds, or a -1 if an error occurs, placing the error code in the global
readlink() and readlinkat() will fail if:
[ENOTDIR] A component of the path prefix is not a directory.
[ENAMETOOLONG] A component of a pathname exceeded NAME_MAX charac-
ters, or an entire pathname (including the terminating
NUL) exceeded PATH_MAX bytes.
[ENOENT] The named file does not exist.
[EACCES] Search permission is denied for a component of the
[ELOOP] Too many symbolic links were encountered in translat-
ing the pathname.
[EINVAL] The named file is not a symbolic link.
[EIO] An I/O error occurred while reading from the file sys-
[EFAULT] buf or path extends outside the process's allocated
Additionally, readlinkat() will fail if:
[EBADF] The path argument specifies a relative path and the fd
argument is neither AT_FDCWD nor a valid file descrip-
[ENOTDIR] The path argument specifies a relative path and the fd
argument is a valid file descriptor but it does not
reference a directory.
[EACCES] The path argument specifies a relative path but search
permission is denied for the directory which the fd
file descriptor references.
lstat(2), stat(2), symlink(2), symlink(7)
The readlink() and readlinkat() functions conform to IEEE Std 1003.1-2008
The readlink() system call first appeared in 4.1cBSD. The readlinkat()
system call has been available since OpenBSD 5.0.
BSD April 28, 2017 BSD