readlink, readlinkat - read contents of symbolic link

Syntax	#include <unistd.h> int readlink(const char *path, char *buf, size_t bufsize); int readlinkat(int fd, const char *path, char *buf, size_t bufsize);
Description	readlink() places the contents of the symbolic link referred to by path in the buffer buf, which has size bufsize. The contents of the link are not terminated with a null byte when returned. The readlinkat() function is equivalent to the readlink() function except when the path parameter specifies a relative path. In this case the symbolic link whose content is to be read is not searched for in the current directory, but in the directory connected with the file descriptor fd. If the file descriptor was opened without O_SEARCH, the function checks whether a search is permitted in the connected file descriptor with the authorizations applicable for the directory. If the file descriptor was opened with O_SEARCH, the check is not performed. When the value AT_FDCWD was transferred to the readlinkat() function for the fd parameter, the current directory is used.
Return val.	Number of bytes placed in the buffer
		upon successful completion.
	-1	if an error occurs. errno is set to indicate the error. The contents of the buffer remain unchanged.
Errors	readlink() and readlinkat() will fail if:
	EACCES	Search permission is denied for a component of the path prefix of path. Too many symbolic links were encountered in resolving path.
	EFAULT	path or buf are outside the allocated address space of the process.
	EINVAL	path is not a symbolic link.
	Extension
	EINVAL	An attempt was made to access a BS2000 file. (End)
	EIO	An I/O error occurred while reading from or writing to the file system.
	ELOOP	Too many symbolic links were encountered in resolving path.
	ENAMETOOLONG
		The length of the path argument exceeds {PATH_MAX} or the length of a path component exceeds{NAME_MAX}.
	ENOENT	The named file does not exist.
	ENOSYS	The file system does not support symbolic links.
	ENOTDIR	One of the component of the path prefix of path is not a directory.
	In addition, readlinkat() fails if the following applies:
	EACCES	The file descriptor fd was not opened with O_SEARCH, and the authorizations applicable for the directory do not permit the directory to be searched.
	EBADF	The path parameter does not specify an absolute pathname, and the fd parameter does not have the value AT_FDCWD, nor does it contain a valid file descriptor opened for reading or searching.
	ENOTDIR	The path parameter does not specify an absolute pathname, and the file descriptor fd is not connected with a directory.
Notes	readlink() will only access POSIX files.
Syntax	stat(), symlink(), fcntl.h, unistd.h.