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8218755: Refix Symbol leak in prepend_host_package_name

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Fix Symbol refcounting again, add comment and a test.

Reviewed-by: kbarrett, dholmes
This commit is contained in:
Coleen Phillimore 2019-02-13 07:22:09 -05:00
parent 2e4ac80e0c
commit 24b8feeb30
5 changed files with 172 additions and 35 deletions
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20
src/hotspot/share/classfile/classFileParser.cpp
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@ -5720,9 +5720,8 @@ void ClassFileParser::fill_instance_klass(InstanceKlass* ik, bool changed_by_loa
void ClassFileParser::update_class_name(Symbol* new_class_name) {
// Decrement the refcount in the old name, since we're clobbering it.
if (_class_name != NULL) {
_class_name->decrement_refcount();
}
_class_name->decrement_refcount();
_class_name = new_class_name;
// Increment the refcount of the new name.
// Now the ClassFileParser owns this name and will decrement in
@ -5753,11 +5752,16 @@ void ClassFileParser::prepend_host_package_name(const InstanceKlass* unsafe_anon
// characters. So, do a strncpy instead of using sprintf("%s...").
strncpy(new_anon_name + host_pkg_len + 1, (char *)_class_name->base(), class_name_len);
// Decrement old _class_name to avoid leaking.
_class_name->decrement_refcount();
// Create a symbol and update the anonymous class name.
Symbol* new_name = SymbolTable::new_symbol(new_anon_name,
// The new class name is created with a refcount of one. When installed into the InstanceKlass,
// it'll be two and when the ClassFileParser destructor runs, it'll go back to one and get deleted
// when the class is unloaded.
_class_name = SymbolTable::new_symbol(new_anon_name,
(int)host_pkg_len + 1 + class_name_len,
CHECK);
update_class_name(new_name);
}
}
@ -5861,7 +5865,8 @@ ClassFileParser::ClassFileParser(ClassFileStream* stream,
_has_vanilla_constructor(false),
_max_bootstrap_specifier_index(-1) {
update_class_name(name != NULL ? name : vmSymbols::unknown_class_name());
_class_name = name != NULL ? name : vmSymbols::unknown_class_name();
_class_name->increment_refcount();
assert(THREAD->is_Java_thread(), "invariant");
assert(_loader_data != NULL, "invariant");
@ -6086,8 +6091,7 @@ void ClassFileParser::parse_stream(const ClassFileStream* const stream,
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");
// Update _class_name which could be null previously
// to reflect the name in the constant pool
// Update _class_name to reflect the name in the constant pool
update_class_name(class_name_in_cp);
// Don't need to check whether this class name is legal or not.