Is there a way to remove a type definition from a type library?

[lwerdna]

(a good question posed by a user on Slack)

[lwerdna]

Type libraries are immutable, but you can effectively remove a definition by writing out a new type library using the API with everything except the type to be deleted.

Example script remove_type.py is at the end of this reply. To test:

• run typelib_create.py from the API examples to create test.bntl
• run typelib_dump.py from the API examples to see contents of test.bntl
• run remove_type.py test.bntl Rectangle2
• run typelib_dump.py to verify removal of type Rectangle2

#!/usr/bin/env python
​
import os, sys
import binaryninja
from binaryninja import typelibrary
​
import blacklist
​
def create_typelib(fname, name, arch, guid, dependency_name, alternate_names,
  platform_names, named_objects, named_types):
​
    typelib = binaryninja.typelibrary.TypeLibrary.new(arch, name)
    typelib.guid = guid
​
    if alternate_names and type(alternate_names[0])==bytes:
        alternate_names = [x.decode('utf-8') for x in alternate_names]
    for an in alternate_names:
        typelib.add_alternate_name(an)
​
    if platform_names and type(platform_names[0])==bytes:
        platform_names = [x.decode('utf-8') for x in platform_names]
    for pn in platform_names:
        typelib.add_platform(binaryninja.Platform[pn])
​
    for (name, obj) in named_objects.items():
        typelib.add_named_object(name, obj)
​
    for (name, type_) in named_types.items():
        typelib.add_named_type(name, type_)
​
    typelib.finalize()
    typelib.write_to_file(fname)
​
if __name__ == '__main__':
    binaryninja._init_plugins()
​
    fpath = sys.argv[1]
    typename = sys.argv[2]
    print('removing %s from %s' % (typename, fpath))
​
    # read bntl
    tl = typelibrary.TypeLibrary.load_from_file(fpath)
​
    print('before filtering, typelib had %d named types' % len(tl.named_types))
    named_types = {key:tl.named_types[key] for key in tl.named_types if not key == typename}
    print('after filtering, typelib had %d named types' % len(named_types))
​
    if len(tl.named_types) == len(named_types):
        print('no change, skipping write')
        sys.exit(0)
​
    # write
    print('writing /tmp/tmp.bntl')
    create_typelib('/tmp/tmp.bntl', tl.name, tl.arch, tl.guid,
      tl.dependency_name, tl.alternate_names, [x.decode('utf-8') for x in tl.platform_names],
      tl.named_objects, named_types)
    
    # copy it back
    print('copying it back')
    os.system('cp /tmp/tmp.bntl %s' % fpath)