1# Copyright 2023 The Chromium Authors 2# Use of this source code is governed by a BSD-style license that can be 3# found in the LICENSE file. 4"""Logic related to proxying calls through GEN_JNI.java.""" 5 6import base64 7import hashlib 8 9import common 10import java_types 11 12# 'Proxy' native methods are declared in an @NativeMethods interface without 13# a native qualifier and indicate that the JNI annotation processor should 14# generate code to link between the equivalent native method as if it were 15# declared statically. 16 17_MAX_CHARS_FOR_HASHED_NATIVE_METHODS = 8 18 19 20def get_gen_jni_class(*, short=False, name_prefix=None, package_prefix=None): 21 """Returns the JavaClass for GEN_JNI.""" 22 package = 'J' if short else 'org/jni_zero' 23 name_prefix = name_prefix + '_' if name_prefix else '' 24 name = name_prefix + ('N' if short else 'GEN_JNI') 25 26 return java_types.JavaClass(f'{package}/{name}').make_prefixed(package_prefix) 27 28 29def _create_hashed_method_name(non_hashed_name, is_test_only): 30 md5 = hashlib.md5(non_hashed_name.encode('utf8')).digest() 31 hash_b64 = base64.b64encode(md5, altchars=b'$_').decode('utf-8') 32 33 long_hash = ('M' + hash_b64).rstrip('=') 34 hashed_name = long_hash[:_MAX_CHARS_FOR_HASHED_NATIVE_METHODS] 35 36 # If the method is a test-only method, we don't care about saving size on 37 # the method name, since it shouldn't show up in the binary. Additionally, 38 # if we just hash the name, our checkers which enforce that we have no 39 # "ForTesting" methods by checking for the suffix "ForTesting" will miss 40 # these. We could preserve the name entirely and not hash anything, but 41 # that risks collisions. So, instead, we just append "ForTesting" to any 42 # test-only hashes, to ensure we catch any test-only methods that 43 # shouldn't be in our final binary. 44 if is_test_only: 45 return hashed_name + '_ForTesting' 46 return hashed_name 47 48 49def create_method_names(java_class, method_name, is_test_only): 50 """Returns the method name used in GEN_JNI (both hashed an non-hashed).""" 51 proxy_name = common.escape_class_name( 52 f'{java_class.full_name_with_slashes}/{method_name}') 53 hashed_proxy_name = _create_hashed_method_name(proxy_name, is_test_only) 54 return proxy_name, hashed_proxy_name 55