READLINK(2)

NAME
readlink, readlinkat - read value of a symbolic link

LIBRARY
libc

SYNOPSIS
#include <unistd.h>
ssize_t
readlink(const char * restrict path, char * restrict buf, size_t bufsiz);
ssize_t
readlinkat(int fd, const char * restrict path, char * restrict buf, size_t bufsiz);

DESCRIPTION
readlink() 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.

readlinkat() works the same way as readlink() except if path is relative. In that case, it is looked up from a directory whose file descriptor was passed as fd. Search permission is required on this directory. fd can be set to AT_FDCWD in order to specify the current directory.

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.

EXAMPLES
A typical use is illustrated in the following piece of code which reads the contents of a symbolic link named /symbolic/link and stores them as null-terminated string:

    #include <limits.h>
    #include <unistd.h>
    char buf[PATH_MAX];
    ssize_t len;
    if ((len = readlink("/symbolic/link", buf, sizeof(buf)-1)) == -1)
    	error handling;
    buf[len] = '\0';

ERRORS
readlink() and readlinkat() 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 were encountered in translating the pathname.

[ENAMETOOLONG]
    A component of a pathname exceeded {NAME_MAX} characters, or an entire path name exceeded {PATH_MAX} characters.

[ENOENT]
    The named file does not exist.

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

In addition, readlinkat() will fail if:

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

[ENOTDIR]
    path is not an absolute path and fd is a file descriptor associated with a non-directory file.

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

STANDARDS
The readlink() function conforms to p1003.1-2001. readlinkat() conforms to p1003.1-2008.

HISTORY
The readlink() function appeared in 4.2BSD. The type returned was changed from int to ssize_t in NetBSD 2.1.