READLINK(2)                   System Calls Manual                  READLINK(2)

NAME
     readlink, readlinkat, freadlink – read value of a symbolic link

SYNOPSIS
     #include <unistd.h>

     ssize_t
     readlink(const char *restrict path, char *restrict buf, size_t bufsize);

     ssize_t
     readlinkat(int fd, const char *restrict path, char *restrict buf,
         size_t bufsize);

     ssize_t
     freadlink(int fd, char *restrict buf, size_t bufsize);

DESCRIPTION
     readlink() places the contents of the symbolic link path in the buffer
     buf, which has size bufsize.  Readlink does not append a NUL character to
     buf.

     The readlinkat() system call is equivalent to readlink() except in the
     case where path specifies a relative path.  In this case the symbolic
     link whose content is read relative to the directory associated with the
     file descriptor fd instead of the current working directory.  If
     readlinkat() is passed the special value AT_FDCWD in the fd parameter,
     the current working directory is used and the behavior is identical to a
     call to readlink().  The freadlink() system call returns the same
     information about an open symbolic link file referenced by descriptor fd.

RETURN VALUES
     The call returns the count of characters placed in the buffer if it
     succeeds, or a -1 if an error occurs, placing the error code in the
     global variable errno.

ERRORS
     readlink() will fail if:

     [EACCES]           Search permission is denied for a component of the
                        path prefix.

     [EFAULT]           Buf extends outside the process's allocated address
                        space.

     [EINVAL]           The named file is not a symbolic link.

     [EIO]              An I/O error occurred while reading from the file
                        system.

     [ELOOP]            Too many symbolic links are encountered in translating
                        the pathname.  This is taken to be indicative of a
                        looping symbolic link.

     [ENAMETOOLONG]     A component of a pathname exceeded {NAME_MAX}
                        characters, or an entire path name (possibly expanded
                        by a symbolic link) exceeded {PATH_MAX} characters.

     [ENOENT]           The named file does not exist.

     [ENOTDIR]          A component of the path prefix is not a directory.

     In addition to the errors returned by the readlink(), the readlinkat()
     may fail if:

     [EBADF]            The path argument does not specify an absolute path
                        and the fd argument is neither AT_FDCWD nor a valid
                        file descriptor open for searching.

     [ENOTDIR]          The path argument is not an absolute path and fd is
                        neither AT_FDCWD nor a file descriptor associated with
                        a directory.

LEGACY SYNOPSIS
     #include <unistd.h>

     int
     readlink(const char *path, char *buf, int bufsize);

     The function type and the type of bufsize have changed.

SEE ALSO
     lstat(2), stat(2), symlink(2), compat(5), symlink(7)

STANDARDS
     The readlinkat() system call is expected to conform to POSIX.1-2008 .

HISTORY
     The readlink() function call appeared in 4.2BSD.  The readlinkat() system
     call appeared in OS X 10.10.  The freadlink() system call appeared in
     macOS 13.0.

BSD 4.2                          June 4, 1993                          BSD 4.2