The readlink() function places the contents of the symbolic link referred to by path in the buffer buf which has size bufsiz. If the number of bytes in the symbolic link is less than bufsiz, the contents of the remainder of buf are unspecified.

Upon successful completion, readlink() returns the count of bytes placed in the buffer. Otherwise, it returns -1, leaves the buffer unchanged, and sets errno to indicate the error.

The readlink() function will fail if:

EACCES

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

EFAULT

path or buf points to an illegal address.

EINVAL

The path argument names a file that is not a symbolic link.

EIO

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

ENOENT

A component of path does not name an existing file or path is an empty string.

ELOOP

Too many symbolic links were encountered in resolving path.

ENAMETOOLONG

The length of path exceeds PATH_MAX, or a pathname component is longer than NAME_MAX while _POSIX_NO_TRUNC is in effect.

ENOTDIR

A component of the path prefix is not a directory.

ENOSYS

The file system does not support symbolic links.

The readlink() function may fail if:

EACCES

Read permission is denied for the directory.

ENAMETOOLONG

Path name resolution of a symbolic link produced an intermediate result whose length exceeds PATH_MAX.

Portable applications should not assume that the returned contents of the symbolic link are null-terminated.

stat(2), symlink(2)