The entries in the two-level namespace lookup hints table are
twolevel_hint structs. These provide hints to the dynamic link editor
where to start looking for an undefined symbol in a two-level namespace
image. The isub_image field is an index into the sub-images
(sub-frameworks and sub-umbrellas list) that made up the two-level image
that the undefined symbol was found in when it was built by the static
link editor. If isub-image is 0 the symbol is expected to be defined
in library and not in the sub-images. If isub-image is non-zero it is an
index into the array of sub-images for the umbrella with the first index
in the sub-images being 1. The array of sub-images is the ordered list of
sub-images of the umbrella that would be searched for a symbol that has
the umbrella recorded as its primary library. The table of contents index
is an index into the library's table of contents. This is used as the
starting point of the binary search or a directed linear search.
The entries in the two-level namespace lookup hints table are twolevel_hint structs. These provide hints to the dynamic link editor where to start looking for an undefined symbol in a two-level namespace image. The isub_image field is an index into the sub-images (sub-frameworks and sub-umbrellas list) that made up the two-level image that the undefined symbol was found in when it was built by the static link editor. If isub-image is 0 the symbol is expected to be defined in library and not in the sub-images. If isub-image is non-zero it is an index into the array of sub-images for the umbrella with the first index in the sub-images being 1. The array of sub-images is the ordered list of sub-images of the umbrella that would be searched for a symbol that has the umbrella recorded as its primary library. The table of contents index is an index into the library's table of contents. This is used as the starting point of the binary search or a directed linear search.