openjdk17 jvm加载class文件，解析字段和方法源码
##构造方法ClassFileParser，parse_stream解析文件流
ClassFileParser::ClassFileParser(ClassFileStream* stream,
Symbol* name,
ClassLoaderData* loader_data,
const ClassLoadInfo* cl_info,
Publicity pub_level,
TRAPS) :
_stream(stream),
_class_name(NULL),
_loader_data(loader_data),
_is_hidden(cl_info->is_hidden()),
_can_access_vm_annotations(cl_info->can_access_vm_annotations()),
_orig_cp_size(0),
_super_klass(),
_cp(NULL),
_fields(NULL),
_methods(NULL),
_inner_classes(NULL),
_nest_members(NULL),
_nest_host(0),
_permitted_subclasses(NULL),
_record_components(NULL),
_local_interfaces(NULL),
_transitive_interfaces(NULL),
_combined_annotations(NULL),
_class_annotations(NULL),
_class_type_annotations(NULL),
_fields_annotations(NULL),
_fields_type_annotations(NULL),
_klass(NULL),
_klass_to_deallocate(NULL),
_parsed_annotations(NULL),
_fac(NULL),
_field_info(NULL),
_method_ordering(NULL),
_all_mirandas(NULL),
_vtable_size(0),
_itable_size(0),
_num_miranda_methods(0),
_rt(REF_NONE),
_protection_domain(cl_info->protection_domain()),
_access_flags(),
_pub_level(pub_level),
_bad_constant_seen(0),
_synthetic_flag(false),
_sde_length(false),
_sde_buffer(NULL),
_sourcefile_index(0),
_generic_signature_index(0),
_major_version(0),
_minor_version(0),
_this_class_index(0),
_super_class_index(0),
_itfs_len(0),
_java_fields_count(0),
_need_verify(false),
_relax_verify(false),
_has_nonstatic_concrete_methods(false),
_declares_nonstatic_concrete_methods(false),
_has_final_method(false),
_has_contended_fields(false),
_has_finalizer(false),
_has_empty_finalizer(false),
_has_vanilla_constructor(false),
_max_bootstrap_specifier_index(-1) {
_class_name = name != NULL ? name : vmSymbols::unknown_class_name();
_class_name->increment_refcount();
assert(_loader_data != NULL, "invariant");
assert(stream != NULL, "invariant");
assert(_stream != NULL, "invariant");
assert(_stream->buffer() == _stream->current(), "invariant");
assert(_class_name != NULL, "invariant");
assert(0 == _access_flags.as_int(), "invariant");
// Figure out whether we can skip format checking (matching classic VM behavior)
if (DumpSharedSpaces) {
// verify == true means it's a 'remote' class (i.e., non-boot class)
// Verification decision is based on BytecodeVerificationRemote flag
// for those classes.
_need_verify = (stream->need_verify()) ? BytecodeVerificationRemote :
BytecodeVerificationLocal;
}
else {
_need_verify = Verifier::should_verify_for(_loader_data->class_loader(),
stream->need_verify());
}
// synch back verification state to stream
stream->set_verify(_need_verify);
// Check if verification needs to be relaxed for this class file
// Do not restrict it to jdk1.0 or jdk1.1 to maintain backward compatibility (4982376)
_relax_verify = relax_format_check_for(_loader_data);
parse_stream(stream, CHECK);
post_process_parsed_stream(stream, _cp, CHECK);
}##parse_stream方法
void ClassFileParser::parse_stream(const ClassFileStream* const stream,
TRAPS) {
assert(stream != NULL, "invariant");
assert(_class_name != NULL, "invariant");
// BEGIN STREAM PARSING
stream->guarantee_more(8, CHECK); // magic, major, minor
// Magic value
const u4 magic = stream->get_u4_fast();
guarantee_property(magic == JAVA_CLASSFILE_MAGIC,
"Incompatible magic value %u in class file %s",
magic, CHECK);
// Version numbers
_minor_version = stream->get_u2_fast();
_major_version = stream->get_u2_fast();
// Check version numbers - we check this even with verifier off
verify_class_version(_major_version, _minor_version, _class_name, CHECK);
stream->guarantee_more(3, CHECK); // length, first cp tag
u2 cp_size = stream->get_u2_fast();
guarantee_property(
cp_size >= 1, "Illegal constant pool size %u in class file %s",
cp_size, CHECK);
_orig_cp_size = cp_size;
if (is_hidden()) { // Add a slot for hidden class name.
cp_size++;
}
_cp = ConstantPool::allocate(_loader_data,
cp_size,
CHECK);
ConstantPool* const cp = _cp;
parse_constant_pool(stream, cp, _orig_cp_size, CHECK);
assert(cp_size == (const u2)cp->length(), "invariant");
// ACCESS FLAGS
stream->guarantee_more(8, CHECK); // flags, this_class, super_class, infs_len
// Access flags
jint flags;
// JVM_ACC_MODULE is defined in JDK-9 and later.
if (_major_version >= JAVA_9_VERSION) {
flags = stream->get_u2_fast() & (JVM_RECOGNIZED_CLASS_MODIFIERS | JVM_ACC_MODULE);
} else {
flags = stream->get_u2_fast() & JVM_RECOGNIZED_CLASS_MODIFIERS;
}
if ((flags & JVM_ACC_INTERFACE) && _major_version < JAVA_6_VERSION) {
// Set abstract bit for old class files for backward compatibility
flags |= JVM_ACC_ABSTRACT;
}
verify_legal_class_modifiers(flags, CHECK);
short bad_constant = class_bad_constant_seen();
if (bad_constant != 0) {
// Do not throw CFE until after the access_flags are checked because if
// ACC_MODULE is set in the access flags, then NCDFE must be thrown, not CFE.
classfile_parse_error("Unknown constant tag %u in class file %s", bad_constant, THREAD);
return;
}
_access_flags.set_flags(flags);
// This class and superclass
_this_class_index = stream->get_u2_fast();
check_property(
valid_cp_range(_this_class_index, cp_size) &&
cp->tag_at(_this_class_index).is_unresolved_klass(),
"Invalid this class index %u in constant pool in class file %s",
_this_class_index, CHECK);
Symbol* const class_name_in_cp = cp->klass_name_at(_this_class_index);
assert(class_name_in_cp != NULL, "class_name can't be null");
// Don't need to check whether this class name is legal or not.
// It has been checked when constant pool is parsed.
// However, make sure it is not an array type.
if (_need_verify) {
guarantee_property(class_name_in_cp->char_at(0) != JVM_SIGNATURE_ARRAY,
"Bad class name in class file %s",
CHECK);
}
#ifdef ASSERT
// Basic sanity checks
if (_is_hidden) {
assert(_class_name != vmSymbols::unknown_class_name(), "hidden classes should have a special name");
}
#endif
// Update the _class_name as needed depending on whether this is a named, un-named, or hidden class.
if (_is_hidden) {
assert(_class_name != NULL, "Unexpected null _class_name");
#ifdef ASSERT
if (_need_verify) {
verify_legal_class_name(_class_name, CHECK);
}
#endif
} else {
// Check if name in class file matches given name
if (_class_name != class_name_in_cp) {
if (_class_name != vmSymbols::unknown_class_name()) {
ResourceMark rm(THREAD);
Exceptions::fthrow(THREAD_AND_LOCATION,
vmSymbols::java_lang_NoClassDefFoundError(),
"%s (wrong name: %s)",
class_name_in_cp->as_C_string(),
_class_name->as_C_string()
);
return;
} else {
// The class name was not known by the caller so we set it from
// the value in the CP.
update_class_name(class_name_in_cp);
}
// else nothing to do: the expected class name matches what is in the CP
}
}
// Verification prevents us from creating names with dots in them, this
// asserts that that's the case.
assert(is_internal_format(_class_name), "external class name format used internally");
if (!is_internal()) {
LogTarget(Debug, class, preorder) lt;
if (lt.is_enabled()){
ResourceMark rm(THREAD);
LogStream ls(lt);
ls.print("%s", _class_name->as_klass_external_name());
if (stream->source() != NULL) {
ls.print(" source: %s", stream->source());
}
ls.cr();
}
}
// SUPERKLASS
_super_class_index = stream->get_u2_fast();
_super_klass = parse_super_class(cp,
_super_class_index,
_need_verify,
CHECK);
// Interfaces
_itfs_len = stream->get_u2_fast();
parse_interfaces(stream,
_itfs_len,
cp,
&_has_nonstatic_concrete_methods,
CHECK);
assert(_local_interfaces != NULL, "invariant");
// Fields (offsets are filled in later)
_fac = new FieldAllocationCount();
parse_fields(stream,
_access_flags.is_interface(),
_fac,
cp,
cp_size,
&_java_fields_count,
CHECK);
assert(_fields != NULL, "invariant");
// Methods
AccessFlags promoted_flags;
parse_methods(stream,
_access_flags.is_interface(),
&promoted_flags,
&_has_final_method,
&_declares_nonstatic_concrete_methods,
CHECK);
assert(_methods != NULL, "invariant");
// promote flags from parse_methods() to the klass' flags
_access_flags.add_promoted_flags(promoted_flags.as_int());
if (_declares_nonstatic_concrete_methods) {
_has_nonstatic_concrete_methods = true;
}
// Additional attributes/annotations
_parsed_annotations = new ClassAnnotationCollector();
parse_classfile_attributes(stream, cp, _parsed_annotations, CHECK);
assert(_inner_classes != NULL, "invariant");
// Finalize the Annotations metadata object,
// now that all annotation arrays have been created.
create_combined_annotations(CHECK);
// Make sure this is the end of class file stream
guarantee_property(stream->at_eos(),
"Extra bytes at the end of class file %s",
CHECK);
// all bytes in stream read and parsed
}##parse_fields解析class文件字段
// Side-effects: populates the _fields, _fields_annotations,
// _fields_type_annotations fields
void ClassFileParser::parse_fields(const ClassFileStream* const cfs,
bool is_interface,
FieldAllocationCount* const fac,
ConstantPool* cp,
const int cp_size,
u2* const java_fields_count_ptr,
TRAPS) {
assert(cfs != NULL, "invariant");
assert(fac != NULL, "invariant");
assert(cp != NULL, "invariant");
assert(java_fields_count_ptr != NULL, "invariant");
assert(NULL == _fields, "invariant");
assert(NULL == _fields_annotations, "invariant");
assert(NULL == _fields_type_annotations, "invariant");
cfs->guarantee_more(2, CHECK); // length
const u2 length = cfs->get_u2_fast();
*java_fields_count_ptr = length;
int num_injected = 0;
const InjectedField* const injected = JavaClasses::get_injected(_class_name,
&num_injected);
const int total_fields = length + num_injected;
// The field array starts with tuples of shorts
// [access, name index, sig index, initial value index, byte offset].
// A generic signature slot only exists for field with generic
// signature attribute. And the access flag is set with
// JVM_ACC_FIELD_HAS_GENERIC_SIGNATURE for that field. The generic
// signature slots are at the end of the field array and after all
// other fields data.
//
// f1: [access, name index, sig index, initial value index, low_offset, high_offset]
// f2: [access, name index, sig index, initial value index, low_offset, high_offset]
// ...
// fn: [access, name index, sig index, initial value index, low_offset, high_offset]
// [generic signature index]
// [generic signature index]
// ...
//
// Allocate a temporary resource array for field data. For each field,
// a slot is reserved in the temporary array for the generic signature
// index. After parsing all fields, the data are copied to a permanent
// array and any unused slots will be discarded.
ResourceMark rm(THREAD);
u2* const fa = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD,
u2,
total_fields * (FieldInfo::field_slots + 1));
// The generic signature slots start after all other fields' data.
int generic_signature_slot = total_fields * FieldInfo::field_slots;
int num_generic_signature = 0;
for (int n = 0; n < length; n++) {
// access_flags, name_index, descriptor_index, attributes_count
cfs->guarantee_more(8, CHECK);
AccessFlags access_flags;
const jint flags = cfs->get_u2_fast() & JVM_RECOGNIZED_FIELD_MODIFIERS;
verify_legal_field_modifiers(flags, is_interface, CHECK);
access_flags.set_flags(flags);
const u2 name_index = cfs->get_u2_fast();
check_property(valid_symbol_at(name_index),
"Invalid constant pool index %u for field name in class file %s",
name_index, CHECK);
const Symbol* const name = cp->symbol_at(name_index);
verify_legal_field_name(name, CHECK);
const u2 signature_index = cfs->get_u2_fast();
check_property(valid_symbol_at(signature_index),
"Invalid constant pool index %u for field signature in class file %s",
signature_index, CHECK);
const Symbol* const sig = cp->symbol_at(signature_index);
verify_legal_field_signature(name, sig, CHECK);
u2 constantvalue_index = 0;
bool is_synthetic = false;
u2 generic_signature_index = 0;
const bool is_static = access_flags.is_static();
FieldAnnotationCollector parsed_annotations(_loader_data);
const u2 attributes_count = cfs->get_u2_fast();
if (attributes_count > 0) {
parse_field_attributes(cfs,
attributes_count,
is_static,
signature_index,
&constantvalue_index,
&is_synthetic,
&generic_signature_index,
&parsed_annotations,
CHECK);
if (parsed_annotations.field_annotations() != NULL) {
if (_fields_annotations == NULL) {
_fields_annotations = MetadataFactory::new_array<AnnotationArray*>(
_loader_data, length, NULL,
CHECK);
}
_fields_annotations->at_put(n, parsed_annotations.field_annotations());
parsed_annotations.set_field_annotations(NULL);
}
if (parsed_annotations.field_type_annotations() != NULL) {
if (_fields_type_annotations == NULL) {
_fields_type_annotations =
MetadataFactory::new_array<AnnotationArray*>(_loader_data,
length,
NULL,
CHECK);
}
_fields_type_annotations->at_put(n, parsed_annotations.field_type_annotations());
parsed_annotations.set_field_type_annotations(NULL);
}
if (is_synthetic) {
access_flags.set_is_synthetic();
}
if (generic_signature_index != 0) {
access_flags.set_field_has_generic_signature();
fa[generic_signature_slot] = generic_signature_index;
generic_signature_slot ++;
num_generic_signature ++;
}
}
FieldInfo* const field = FieldInfo::from_field_array(fa, n);
field->initialize(access_flags.as_short(),
name_index,
signature_index,
constantvalue_index);
const BasicType type = cp->basic_type_for_signature_at(signature_index);
// Update FieldAllocationCount for this kind of field
fac->update(is_static, type);
// After field is initialized with type, we can augment it with aux info
if (parsed_annotations.has_any_annotations()) {
parsed_annotations.apply_to(field);
if (field->is_contended()) {
_has_contended_fields = true;
}
}
}
int index = length;
if (num_injected != 0) {
for (int n = 0; n < num_injected; n++) {
// Check for duplicates
if (injected[n].may_be_java) {
const Symbol* const name = injected[n].name();
const Symbol* const signature = injected[n].signature();
bool duplicate = false;
for (int i = 0; i < length; i++) {
const FieldInfo* const f = FieldInfo::from_field_array(fa, i);
if (name == cp->symbol_at(f->name_index()) &&
signature == cp->symbol_at(f->signature_index())) {
// Symbol is desclared in Java so skip this one
duplicate = true;
break;
}
}
if (duplicate) {
// These will be removed from the field array at the end
continue;
}
}
// Injected field
FieldInfo* const field = FieldInfo::from_field_array(fa, index);
field->initialize((u2)JVM_ACC_FIELD_INTERNAL,
(u2)(injected[n].name_index),
(u2)(injected[n].signature_index),
0);
const BasicType type = Signature::basic_type(injected[n].signature());
// Update FieldAllocationCount for this kind of field
fac->update(false, type);
index++;
}
}
assert(NULL == _fields, "invariant");
_fields =
MetadataFactory::new_array<u2>(_loader_data,
index * FieldInfo::field_slots + num_generic_signature,
CHECK);
// Sometimes injected fields already exist in the Java source so
// the fields array could be too long. In that case the
// fields array is trimed. Also unused slots that were reserved
// for generic signature indexes are discarded.
{
int i = 0;
for (; i < index * FieldInfo::field_slots; i++) {
_fields->at_put(i, fa[i]);
}
for (int j = total_fields * FieldInfo::field_slots;
j < generic_signature_slot; j++) {
_fields->at_put(i++, fa[j]);
}
assert(_fields->length() == i, "");
}
if (_need_verify && length > 1) {
// Check duplicated fields
ResourceMark rm(THREAD);
NameSigHash** names_and_sigs = NEW_RESOURCE_ARRAY_IN_THREAD(
THREAD, NameSigHash*, HASH_ROW_SIZE);
initialize_hashtable(names_and_sigs);
bool dup = false;
const Symbol* name = NULL;
const Symbol* sig = NULL;
{
debug_only(NoSafepointVerifier nsv;)
for (AllFieldStream fs(_fields, cp); !fs.done(); fs.next()) {
name = fs.name();
sig = fs.signature();
// If no duplicates, add name/signature in hashtable names_and_sigs.
if (!put_after_lookup(name, sig, names_and_sigs)) {
dup = true;
break;
}
}
}
if (dup) {
classfile_parse_error("Duplicate field name \"%s\" with signature \"%s\" in class file %s",
name->as_C_string(), sig->as_klass_external_name(), THREAD);
}
}
}##parse_methods解析class文件方法
// The promoted_flags parameter is used to pass relevant access_flags
// from the methods back up to the containing klass. These flag values
// are added to klass's access_flags.
// Side-effects: populates the _methods field in the parser
void ClassFileParser::parse_methods(const ClassFileStream* const cfs,
bool is_interface,
AccessFlags* promoted_flags,
bool* has_final_method,
bool* declares_nonstatic_concrete_methods,
TRAPS) {
assert(cfs != NULL, "invariant");
assert(promoted_flags != NULL, "invariant");
assert(has_final_method != NULL, "invariant");
assert(declares_nonstatic_concrete_methods != NULL, "invariant");
assert(NULL == _methods, "invariant");
cfs->guarantee_more(2, CHECK); // length
const u2 length = cfs->get_u2_fast();
if (length == 0) {
_methods = Universe::the_empty_method_array();
} else {
_methods = MetadataFactory::new_array<Method*>(_loader_data,
length,
NULL,
CHECK);
for (int index = 0; index < length; index++) {
Method* method = parse_method(cfs,
is_interface,
_cp,
promoted_flags,
CHECK);
if (method->is_final()) {
*has_final_method = true;
}
// declares_nonstatic_concrete_methods: declares concrete instance methods, any access flags
// used for interface initialization, and default method inheritance analysis
if (is_interface && !(*declares_nonstatic_concrete_methods)
&& !method->is_abstract() && !method->is_static()) {
*declares_nonstatic_concrete_methods = true;
}
_methods->at_put(index, method);
}
if (_need_verify && length > 1) {
// Check duplicated methods
ResourceMark rm(THREAD);
NameSigHash** names_and_sigs = NEW_RESOURCE_ARRAY_IN_THREAD(
THREAD, NameSigHash*, HASH_ROW_SIZE);
initialize_hashtable(names_and_sigs);
bool dup = false;
const Symbol* name = NULL;
const Symbol* sig = NULL;
{
debug_only(NoSafepointVerifier nsv;)
for (int i = 0; i < length; i++) {
const Method* const m = _methods->at(i);
name = m->name();
sig = m->signature();
// If no duplicates, add name/signature in hashtable names_and_sigs.
if (!put_after_lookup(name, sig, names_and_sigs)) {
dup = true;
break;
}
}
}
if (dup) {
classfile_parse_error("Duplicate method name \"%s\" with signature \"%s\" in class file %s",
name->as_C_string(), sig->as_klass_external_name(), THREAD);
}
}
}
}原文地址：https://blog.csdn.net/u014200244/article/details/144322101
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