The gfs_opendir() function opens a directory stream
corresponding to the directory gfarm_url, and returns the
directory stream to the address pointed by dirp. The stream is
positioned at the first entry in the directory.
RETURN VALUES
NULL
The function terminated successfully.
GFARM_ERR_NO_MEMORY
Insufficient memory was available.
GFARM_ERR_AUTHENTICATION
User authentication failed when connecting to gfmd(8).
GFARM_ERR_PERMISSION_DENIED
gfarm_url
points outside your accessible address space.
GFARM_ERR_NO_SUCH_OBJECT
Directory does not exist.
Others
An error except the above occurred. The reason is shown by its
pointed strings.