DF data definitions (DF-structures)

DFHack’s information about DF’s data structures is stored in XML files in the df-structures repository. If you have obtained a local copy of the DFHack source, DF-structures is included as a submodule in library/xml.

Data structure layouts are described in files named with the df.*.xml pattern. This information is transformed by a Perl script (codegen.pl) into C++ headers, as well as metadata for the Lua wrapper. This ultimately allows DFHack code to access DF data directly, with the same speed and capabilities as DF itself, which is an advantage over the older out-of-process approach (used by debuggers and utilities like Dwarf Therapist). The main disadvantage of this approach is that any compiled code relying on these layouts will break when DF’s layout changes, and will need to be recompiled for every new DF version.

Addresses of DF global objects and vtables are stored in a separate file, symbols.xml. Since these are only absolute addresses, they do not need to be compiled in to DFHack code, and are instead loaded at runtime. This makes fixes and additions to global addresses possible without recompiling DFHack. In an installed copy of DFHack, this file can be found at the root of the hack folder.

The following pages contain more detailed information about various aspects of DF-structures: