OUT: External link flags, packed as a bitmap (Reserved as a bitmap for flags; no flags are currently defined, so the only valid value is 0.)
const char **filename
OUT: Returned filename
const char **obj_path
OUT: Returned object path, relative to filename
H5L_UNPACK_ELINK_VAL decodes the external link information returned by H5L_GET_VALin the ext_linkval buffer.
ext_linkval should be the buffer set by H5L_GET_VAL and will consist of two NULL-terminated strings, the filename and object path, one after the other.
Given this buffer, H5L_UNPACK_ELINK_VAL creates pointers to the filename and object path within the buffer and returns them in filename and obj_path, unless they are passed in as NULL.
H5L_UNPACK_ELINK_VAL requires that ext_linkval contain a concatenated pair of null-terminated strings, so use of this function on a string that is not an external link udata buffer may result in a segmentation fault. This failure can be avoided by adhering to the following procedure:
Call H5L_GET_INFO to get the link type and the size of the link value.
Verify that the link is an external link, i.e., that its link type is H5L_TYPE_EXTERNAL.