-// defineclass.cc - defining a class from .class format.
+// verify.cc - verify bytecode
-/* Copyright (C) 2001, 2002, 2003 Free Software Foundation
+/* Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation
This file is part of libgcj.
#include <config.h>
+#include <string.h>
+
#include <jvm.h>
#include <gcj/cni.h>
#include <java-insns.h>
#include <java-interp.h>
+// On Solaris 10/x86, <signal.h> indirectly includes <ia32/sys/reg.h>, which
+// defines PC since g++ predefines __EXTENSIONS__. Undef here to avoid clash
+// with PC member of class _Jv_BytecodeVerifier below.
+#undef PC
+
#ifdef INTERPRETER
#include <java/lang/Class.h>
#include <java/lang/Throwable.h>
#include <java/lang/reflect/Modifier.h>
#include <java/lang/StringBuffer.h>
+#include <java/lang/NoClassDefFoundError.h>
#ifdef VERIFY_DEBUG
#include <stdio.h>
#endif /* VERIFY_DEBUG */
+// This is used to mark states which are not scheduled for
+// verification.
+#define INVALID_STATE ((state *) -1)
+
static void debug_print (const char *fmt, ...)
__attribute__ ((format (printf, 1, 2)));
static inline void
-debug_print (const char *fmt, ...)
+debug_print (MAYBE_UNUSED const char *fmt, ...)
{
#ifdef VERIFY_DEBUG
va_list ap;
#endif /* VERIFY_DEBUG */
}
+// This started as a fairly ordinary verifier, and for the most part
+// it remains so. It works in the obvious way, by modeling the effect
+// of each opcode as it is encountered. For most opcodes, this is a
+// straightforward operation.
+//
+// This verifier does not do type merging. It used to, but this
+// results in difficulty verifying some relatively simple code
+// involving interfaces, and it pushed some verification work into the
+// interpreter.
+//
+// Instead of merging reference types, when we reach a point where two
+// flows of control merge, we simply keep the union of reference types
+// from each branch. Then, when we need to verify a fact about a
+// reference on the stack (e.g., that it is compatible with the
+// argument type of a method), we check to ensure that all possible
+// types satisfy the requirement.
+//
+// Another area this verifier differs from the norm is in its handling
+// of subroutines. The JVM specification has some confusing things to
+// say about subroutines. For instance, it makes claims about not
+// allowing subroutines to merge and it rejects recursive subroutines.
+// For the most part these are red herrings; we used to try to follow
+// these things but they lead to problems. For example, the notion of
+// "being in a subroutine" is not well-defined: is an exception
+// handler in a subroutine? If you never execute the `ret' but
+// instead `goto 1' do you remain in the subroutine?
+//
+// For clarity on what is really required for type safety, read
+// "Simple Verification Technique for Complex Java Bytecode
+// Subroutines" by Alessandro Coglio. Among other things this paper
+// shows that recursive subroutines are not harmful to type safety.
+// We implement something similar to what he proposes. Note that this
+// means that this verifier will accept code that is rejected by some
+// other verifiers.
+//
+// For those not wanting to read the paper, the basic observation is
+// that we can maintain split states in subroutines. We maintain one
+// state for each calling `jsr'. In other words, we re-verify a
+// subroutine once for each caller, using the exact types held by the
+// callers (as opposed to the old approach of merging types and
+// keeping a bitmap registering what did or did not change). This
+// approach lets us continue to verify correctly even when a
+// subroutine is exited via `goto' or `athrow' and not `ret'.
+//
+// In some other areas the JVM specification is (mildly) incorrect,
+// so we diverge. For instance, you cannot
+// violate type safety by allocating an object with `new' and then
+// failing to initialize it, no matter how one branches or where one
+// stores the uninitialized reference. See "Improving the official
+// specification of Java bytecode verification" by Alessandro Coglio.
+//
+// Note that there's no real point in enforcing that padding bytes or
+// the mystery byte of invokeinterface must be 0, but we do that
+// regardless.
+//
+// The verifier is currently neither completely lazy nor eager when it
+// comes to loading classes. It tries to represent types by name when
+// possible, and then loads them when it needs to verify a fact about
+// the type. Checking types by name is valid because we only use
+// names which come from the current class' constant pool. Since all
+// such names are looked up using the same class loader, there is no
+// danger that we might be fooled into comparing different types with
+// the same name.
+//
+// In the future we plan to allow for a completely lazy mode of
+// operation, where the verifier will construct a list of type
+// assertions to be checked later.
+//
+// Some test cases for the verifier live in the "verify" module of the
+// Mauve test suite. However, some of these are presently
+// (2004-01-20) believed to be incorrect. (More precisely the notion
+// of "correct" is not well-defined, and this verifier differs from
+// others while remaining type-safe.) Some other tests live in the
+// libgcj test suite.
class _Jv_BytecodeVerifier
{
private:
struct state;
struct type;
- struct subr_info;
- struct subr_entry_info;
struct linked_utf8;
+ struct ref_intersection;
+
+ template<typename T>
+ struct linked
+ {
+ T *val;
+ linked<T> *next;
+ };
// The current PC.
int PC;
// The current state of the stack, locals, etc.
state *current_state;
- // We store the state at branch targets, for merging. This holds
- // such states.
- state **states;
+ // At each branch target we keep a linked list of all the states we
+ // can process at that point. We'll only have multiple states at a
+ // given PC if they both have different return-address types in the
+ // same stack or local slot. This array is indexed by PC and holds
+ // the list of all such states.
+ linked<state> **states;
- // We keep a linked list of all the PCs which we must reverify.
- // The link is done using the PC values. This is the head of the
- // list.
- int next_verify_pc;
+ // We keep a linked list of all the states which we must reverify.
+ // This is the head of the list.
+ state *next_verify_state;
// We keep some flags for each instruction. The values are the
- // FLAG_* constants defined above.
+ // FLAG_* constants defined above. This is an array indexed by PC.
char *flags;
- // We need to keep track of which instructions can call a given
- // subroutine. FIXME: this is inefficient. We keep a linked list
- // of all calling `jsr's at at each jsr target.
- subr_info **jsr_ptrs;
-
- // We keep a linked list of entries which map each `ret' instruction
- // to its unique subroutine entry point. We expect that there won't
- // be many `ret' instructions, so a linked list is ok.
- subr_entry_info *entry_points;
-
// The bytecode itself.
unsigned char *bytecode;
// The exceptions.
// This method.
_Jv_InterpMethod *current_method;
- // A linked list of utf8 objects we allocate. This is really ugly,
- // but without this our utf8 objects would be collected.
- linked_utf8 *utf8_list;
+ // A linked list of utf8 objects we allocate.
+ linked<_Jv_Utf8Const> *utf8_list;
- struct linked_utf8
- {
- _Jv_Utf8Const *val;
- linked_utf8 *next;
- };
+ // A linked list of all ref_intersection objects we allocate.
+ ref_intersection *isect_list;
+ // Create a new Utf-8 constant and return it. We do this to avoid
+ // having our Utf-8 constants prematurely collected.
_Jv_Utf8Const *make_utf8_const (char *s, int len)
{
- _Jv_Utf8Const *val = _Jv_makeUtf8Const (s, len);
- _Jv_Utf8Const *r = (_Jv_Utf8Const *) _Jv_Malloc (sizeof (_Jv_Utf8Const)
- + val->length
- + 1);
- r->length = val->length;
- r->hash = val->hash;
- memcpy (r->data, val->data, val->length + 1);
-
- linked_utf8 *lu = (linked_utf8 *) _Jv_Malloc (sizeof (linked_utf8));
+ linked<_Jv_Utf8Const> *lu = (linked<_Jv_Utf8Const> *)
+ _Jv_Malloc (sizeof (linked<_Jv_Utf8Const>)
+ + _Jv_Utf8Const::space_needed(s, len));
+ _Jv_Utf8Const *r = (_Jv_Utf8Const *) (lu + 1);
+ r->init(s, len);
lu->val = r;
lu->next = utf8_list;
utf8_list = lu;
return r;
}
- __attribute__ ((__noreturn__)) void verify_fail (char *s, jint pc = -1)
+ __attribute__ ((__noreturn__)) void verify_fail (const char *s, jint pc = -1)
{
using namespace java::lang;
StringBuffer *buf = new StringBuffer ();
buf->append (JvNewStringLatin1 (" in "));
buf->append (current_class->getName());
buf->append ((jchar) ':');
- buf->append (JvNewStringUTF (method->get_method()->name->data));
+ buf->append (method->get_method()->name->toString());
buf->append ((jchar) '(');
- buf->append (JvNewStringUTF (method->get_method()->signature->data));
+ buf->append (method->get_method()->signature->toString());
buf->append ((jchar) ')');
buf->append (JvNewStringLatin1 (": "));
// to indicate an unusable value.
unsuitable_type,
return_address_type,
+ // This is the second word of a two-word value, i.e., a double or
+ // a long.
continuation_type,
- // There is an obscure special case which requires us to note when
- // a local variable has not been used by a subroutine. See
- // push_jump_merge for more information.
- unused_by_subroutine_type,
-
// Everything after `reference_type' must be a reference type.
reference_type,
null_type,
- unresolved_reference_type,
- uninitialized_reference_type,
- uninitialized_unresolved_reference_type
+ uninitialized_reference_type
+ };
+
+ // This represents a merged class type. Some verifiers (including
+ // earlier versions of this one) will compute the intersection of
+ // two class types when merging states. However, this loses
+ // critical information about interfaces implemented by the various
+ // classes. So instead we keep track of all the actual classes that
+ // have been merged.
+ struct ref_intersection
+ {
+ // Whether or not this type has been resolved.
+ bool is_resolved;
+
+ // Actual type data.
+ union
+ {
+ // For a resolved reference type, this is a pointer to the class.
+ jclass klass;
+ // For other reference types, this it the name of the class.
+ _Jv_Utf8Const *name;
+ } data;
+
+ // Link to the next reference in the intersection.
+ ref_intersection *ref_next;
+
+ // This is used to keep track of all the allocated
+ // ref_intersection objects, so we can free them.
+ // FIXME: we should allocate these in chunks.
+ ref_intersection *alloc_next;
+
+ ref_intersection (jclass klass, _Jv_BytecodeVerifier *verifier)
+ : ref_next (NULL)
+ {
+ is_resolved = true;
+ data.klass = klass;
+ alloc_next = verifier->isect_list;
+ verifier->isect_list = this;
+ }
+
+ ref_intersection (_Jv_Utf8Const *name, _Jv_BytecodeVerifier *verifier)
+ : ref_next (NULL)
+ {
+ is_resolved = false;
+ data.name = name;
+ alloc_next = verifier->isect_list;
+ verifier->isect_list = this;
+ }
+
+ ref_intersection (ref_intersection *dup, ref_intersection *tail,
+ _Jv_BytecodeVerifier *verifier)
+ : ref_next (tail)
+ {
+ is_resolved = dup->is_resolved;
+ data = dup->data;
+ alloc_next = verifier->isect_list;
+ verifier->isect_list = this;
+ }
+
+ bool equals (ref_intersection *other, _Jv_BytecodeVerifier *verifier)
+ {
+ if (! is_resolved && ! other->is_resolved
+ && _Jv_equalUtf8Classnames (data.name, other->data.name))
+ return true;
+ if (! is_resolved)
+ resolve (verifier);
+ if (! other->is_resolved)
+ other->resolve (verifier);
+ return data.klass == other->data.klass;
+ }
+
+ // Merge THIS type into OTHER, returning the result. This will
+ // return OTHER if all the classes in THIS already appear in
+ // OTHER.
+ ref_intersection *merge (ref_intersection *other,
+ _Jv_BytecodeVerifier *verifier)
+ {
+ ref_intersection *tail = other;
+ for (ref_intersection *self = this; self != NULL; self = self->ref_next)
+ {
+ bool add = true;
+ for (ref_intersection *iter = other; iter != NULL;
+ iter = iter->ref_next)
+ {
+ if (iter->equals (self, verifier))
+ {
+ add = false;
+ break;
+ }
+ }
+
+ if (add)
+ tail = new ref_intersection (self, tail, verifier);
+ }
+ return tail;
+ }
+
+ void resolve (_Jv_BytecodeVerifier *verifier)
+ {
+ if (is_resolved)
+ return;
+
+ // This is useful if you want to see which classes have to be resolved
+ // while doing the class verification.
+ debug_print("resolving class: %s\n", data.name->chars());
+
+ using namespace java::lang;
+ java::lang::ClassLoader *loader
+ = verifier->current_class->getClassLoaderInternal();
+
+ // Due to special handling in to_array() array classes will always
+ // be of the "L ... ;" kind. The separator char ('.' or '/' may vary
+ // however.
+ if (data.name->limit()[-1] == ';')
+ {
+ data.klass = _Jv_FindClassFromSignature (data.name->chars(), loader);
+ if (data.klass == NULL)
+ throw new java::lang::NoClassDefFoundError(data.name->toString());
+ }
+ else
+ data.klass = Class::forName (_Jv_NewStringUtf8Const (data.name),
+ false, loader);
+ is_resolved = true;
+ }
+
+ // See if an object of type OTHER can be assigned to an object of
+ // type *THIS. This might resolve classes in one chain or the
+ // other.
+ bool compatible (ref_intersection *other,
+ _Jv_BytecodeVerifier *verifier)
+ {
+ ref_intersection *self = this;
+
+ for (; self != NULL; self = self->ref_next)
+ {
+ ref_intersection *other_iter = other;
+
+ for (; other_iter != NULL; other_iter = other_iter->ref_next)
+ {
+ // Avoid resolving if possible.
+ if (! self->is_resolved
+ && ! other_iter->is_resolved
+ && _Jv_equalUtf8Classnames (self->data.name,
+ other_iter->data.name))
+ continue;
+
+ if (! self->is_resolved)
+ self->resolve(verifier);
+
+ // If the LHS of the expression is of type
+ // java.lang.Object, assignment will succeed, no matter
+ // what the type of the RHS is. Using this short-cut we
+ // don't need to resolve the class of the RHS at
+ // verification time.
+ if (self->data.klass == &java::lang::Object::class$)
+ continue;
+
+ if (! other_iter->is_resolved)
+ other_iter->resolve(verifier);
+
+ if (! is_assignable_from_slow (self->data.klass,
+ other_iter->data.klass))
+ return false;
+ }
+ }
+
+ return true;
+ }
+
+ bool isarray ()
+ {
+ // assert (ref_next == NULL);
+ if (is_resolved)
+ return data.klass->isArray ();
+ else
+ return data.name->first() == '[';
+ }
+
+ bool isinterface (_Jv_BytecodeVerifier *verifier)
+ {
+ // assert (ref_next == NULL);
+ if (! is_resolved)
+ resolve (verifier);
+ return data.klass->isInterface ();
+ }
+
+ bool isabstract (_Jv_BytecodeVerifier *verifier)
+ {
+ // assert (ref_next == NULL);
+ if (! is_resolved)
+ resolve (verifier);
+ using namespace java::lang::reflect;
+ return Modifier::isAbstract (data.klass->getModifiers ());
+ }
+
+ jclass getclass (_Jv_BytecodeVerifier *verifier)
+ {
+ if (! is_resolved)
+ resolve (verifier);
+ return data.klass;
+ }
+
+ int count_dimensions ()
+ {
+ int ndims = 0;
+ if (is_resolved)
+ {
+ jclass k = data.klass;
+ while (k->isArray ())
+ {
+ k = k->getComponentType ();
+ ++ndims;
+ }
+ }
+ else
+ {
+ char *p = data.name->chars();
+ while (*p++ == '[')
+ ++ndims;
+ }
+ return ndims;
+ }
+
+ void *operator new (size_t bytes)
+ {
+ return _Jv_Malloc (bytes);
+ }
+
+ void operator delete (void *mem)
+ {
+ _Jv_Free (mem);
+ }
};
// Return the type_val corresponding to a primitive signature
// TARGET haven't been prepared.
static bool is_assignable_from_slow (jclass target, jclass source)
{
- // This will terminate when SOURCE==Object.
- while (true)
+ // First, strip arrays.
+ while (target->isArray ())
+ {
+ // If target is array, source must be as well.
+ if (! source->isArray ())
+ return false;
+ target = target->getComponentType ();
+ source = source->getComponentType ();
+ }
+
+ // Quick success.
+ if (target == &java::lang::Object::class$)
+ return true;
+
+ do
{
if (source == target)
return true;
if (target->isPrimitive () || source->isPrimitive ())
return false;
- if (target->isArray ())
- {
- if (! source->isArray ())
- return false;
- target = target->getComponentType ();
- source = source->getComponentType ();
- }
- else if (target->isInterface ())
+ if (target->isInterface ())
{
for (int i = 0; i < source->interface_count; ++i)
{
// We use a recursive call because we also need to
// check superinterfaces.
- if (is_assignable_from_slow (target, source->interfaces[i]))
- return true;
- }
- source = source->getSuperclass ();
- if (source == NULL)
- return false;
- }
- // We must do this check before we check to see if SOURCE is
- // an interface. This way we know that any interface is
- // assignable to an Object.
- else if (target == &java::lang::Object::class$)
- return true;
- else if (source->isInterface ())
- {
- for (int i = 0; i < target->interface_count; ++i)
- {
- // We use a recursive call because we also need to
- // check superinterfaces.
- if (is_assignable_from_slow (target->interfaces[i], source))
+ if (is_assignable_from_slow (target, source->getInterface (i)))
return true;
}
- target = target->getSuperclass ();
- if (target == NULL)
- return false;
}
- else if (source == &java::lang::Object::class$)
- return false;
- else
- source = source->getSuperclass ();
+ source = source->getSuperclass ();
}
- }
+ while (source != NULL);
- // This is used to keep track of which `jsr's correspond to a given
- // jsr target.
- struct subr_info
- {
- // PC of the instruction just after the jsr.
- int pc;
- // Link.
- subr_info *next;
- };
-
- // This is used to keep track of which subroutine entry point
- // corresponds to which `ret' instruction.
- struct subr_entry_info
- {
- // PC of the subroutine entry point.
- int pc;
- // PC of the `ret' instruction.
- int ret_pc;
- // Link.
- subr_entry_info *next;
- };
+ return false;
+ }
// The `type' class is used to represent a single type in the
// verifier.
struct type
{
- // The type.
+ // The type key.
type_val key;
- // Some associated data.
- union
- {
- // For a resolved reference type, this is a pointer to the class.
- jclass klass;
- // For other reference types, this it the name of the class.
- _Jv_Utf8Const *name;
- } data;
- // This is used when constructing a new object. It is the PC of the
+
+ // For reference types, the representation of the type.
+ ref_intersection *klass;
+
+ // This is used in two situations.
+ //
+ // First, when constructing a new object, it is the PC of the
// `new' instruction which created the object. We use the special
- // value -2 to mean that this is uninitialized, and the special
- // value -1 for the case where the current method is itself the
- // <init> method.
+ // value UNINIT to mean that this is uninitialized. The special
+ // value SELF is used for the case where the current method is
+ // itself the <init> method. the special value EITHER is used
+ // when we may optionally allow either an uninitialized or
+ // initialized reference to match.
+ //
+ // Second, when the key is return_address_type, this holds the PC
+ // of the instruction following the `jsr'.
int pc;
static const int UNINIT = -2;
static const int SELF = -1;
+ static const int EITHER = -3;
// Basic constructor.
type ()
{
key = unsuitable_type;
- data.klass = NULL;
+ klass = NULL;
pc = UNINIT;
}
type (type_val k)
{
key = k;
- data.klass = NULL;
- if (key == reference_type)
- data.klass = &java::lang::Object::class$;
+ // For reference_type, if KLASS==NULL then that means we are
+ // looking for a generic object of any kind, including an
+ // uninitialized reference.
+ klass = NULL;
pc = UNINIT;
}
// Make a new instance given a class.
- type (jclass klass)
+ type (jclass k, _Jv_BytecodeVerifier *verifier)
{
key = reference_type;
- data.klass = klass;
+ klass = new ref_intersection (k, verifier);
pc = UNINIT;
}
// Make a new instance given the name of a class.
- type (_Jv_Utf8Const *n)
+ type (_Jv_Utf8Const *n, _Jv_BytecodeVerifier *verifier)
{
- key = unresolved_reference_type;
- data.name = n;
+ key = reference_type;
+ klass = new ref_intersection (n, verifier);
pc = UNINIT;
}
type (const type &t)
{
key = t.key;
- data = t.data;
+ klass = t.klass;
pc = t.pc;
}
type& operator= (type_val k)
{
key = k;
- data.klass = NULL;
+ klass = NULL;
pc = UNINIT;
return *this;
}
type& operator= (const type& t)
{
key = t.key;
- data = t.data;
+ klass = t.klass;
pc = t.pc;
return *this;
}
return *this;
}
- // If *THIS is an unresolved reference type, resolve it.
- void resolve (_Jv_BytecodeVerifier *verifier)
- {
- if (key != unresolved_reference_type
- && key != uninitialized_unresolved_reference_type)
- return;
-
- using namespace java::lang;
- java::lang::ClassLoader *loader
- = verifier->current_class->getClassLoaderInternal();
- // We might see either kind of name. Sigh.
- if (data.name->data[0] == 'L'
- && data.name->data[data.name->length - 1] == ';')
- data.klass = _Jv_FindClassFromSignature (data.name->data, loader);
- else
- data.klass = Class::forName (_Jv_NewStringUtf8Const (data.name),
- false, loader);
- key = (key == unresolved_reference_type
- ? reference_type
- : uninitialized_reference_type);
- }
-
// Mark this type as the uninitialized result of `new'.
void set_uninitialized (int npc, _Jv_BytecodeVerifier *verifier)
{
if (key == reference_type)
key = uninitialized_reference_type;
- else if (key == unresolved_reference_type)
- key = uninitialized_unresolved_reference_type;
else
verifier->verify_fail ("internal error in type::uninitialized");
pc = npc;
// Mark this type as now initialized.
void set_initialized (int npc)
{
- if (npc != UNINIT && pc == npc
- && (key == uninitialized_reference_type
- || key == uninitialized_unresolved_reference_type))
+ if (npc != UNINIT && pc == npc && key == uninitialized_reference_type)
{
- key = (key == uninitialized_reference_type
- ? reference_type
- : unresolved_reference_type);
+ key = reference_type;
pc = UNINIT;
}
}
+ // Mark this type as a particular return address.
+ void set_return_address (int npc)
+ {
+ pc = npc;
+ }
+
+ // Return true if this type and type OTHER are considered
+ // mergeable for the purposes of state merging. This is related
+ // to subroutine handling. For this purpose two types are
+ // considered unmergeable if they are both return-addresses but
+ // have different PCs.
+ bool state_mergeable_p (const type &other) const
+ {
+ return (key != return_address_type
+ || other.key != return_address_type
+ || pc == other.pc);
+ }
// Return true if an object of type K can be assigned to a variable
// of type *THIS. Handle various special cases too. Might modify
// The `null' type is convertible to any initialized reference
// type.
- if (key == null_type || k.key == null_type)
- return true;
+ if (key == null_type)
+ return k.key != uninitialized_reference_type;
+ if (k.key == null_type)
+ return key != uninitialized_reference_type;
- // Any reference type is convertible to Object. This is a special
- // case so we don't need to unnecessarily resolve a class.
- if (key == reference_type
- && data.klass == &java::lang::Object::class$)
+ // A special case for a generic reference.
+ if (klass == NULL)
return true;
+ if (k.klass == NULL)
+ verifier->verify_fail ("programmer error in type::compatible");
- // An initialized type and an uninitialized type are not
- // compatible.
- if (isinitialized () != k.isinitialized ())
- return false;
-
- // Two uninitialized objects are compatible if either:
- // * The PCs are identical, or
- // * One PC is UNINIT.
- if (! isinitialized ())
+ // Handle the special 'EITHER' case, which is only used in a
+ // special case of 'putfield'. Note that we only need to handle
+ // this on the LHS of a check.
+ if (! isinitialized () && pc == EITHER)
{
- if (pc != k.pc && pc != UNINIT && k.pc != UNINIT)
+ // If the RHS is uninitialized, it must be an uninitialized
+ // 'this'.
+ if (! k.isinitialized () && k.pc != SELF)
return false;
}
+ else if (isinitialized () != k.isinitialized ())
+ {
+ // An initialized type and an uninitialized type are not
+ // otherwise compatible.
+ return false;
+ }
+ else
+ {
+ // Two uninitialized objects are compatible if either:
+ // * The PCs are identical, or
+ // * One PC is UNINIT.
+ if (! isinitialized ())
+ {
+ if (pc != k.pc && pc != UNINIT && k.pc != UNINIT)
+ return false;
+ }
+ }
- // Two unresolved types are equal if their names are the same.
- if (! isresolved ()
- && ! k.isresolved ()
- && _Jv_equalUtf8Consts (data.name, k.data.name))
- return true;
+ return klass->compatible(k.klass, verifier);
+ }
- // We must resolve both types and check assignability.
- resolve (verifier);
- k.resolve (verifier);
- return is_assignable_from_slow (data.klass, k.data.klass);
+ bool equals (const type &other, _Jv_BytecodeVerifier *vfy)
+ {
+ // Only works for reference types.
+ if ((key != reference_type
+ && key != uninitialized_reference_type)
+ || (other.key != reference_type
+ && other.key != uninitialized_reference_type))
+ return false;
+ // Only for single-valued types.
+ if (klass->ref_next || other.klass->ref_next)
+ return false;
+ return klass->equals (other.klass, vfy);
}
bool isvoid () const
// We treat null_type as not an array. This is ok based on the
// current uses of this method.
if (key == reference_type)
- return data.klass->isArray ();
- else if (key == unresolved_reference_type)
- return data.name->data[0] == '[';
+ return klass->isarray ();
return false;
}
bool isinterface (_Jv_BytecodeVerifier *verifier)
{
- resolve (verifier);
if (key != reference_type)
return false;
- return data.klass->isInterface ();
+ return klass->isinterface (verifier);
}
bool isabstract (_Jv_BytecodeVerifier *verifier)
{
- resolve (verifier);
if (key != reference_type)
return false;
- using namespace java::lang::reflect;
- return Modifier::isAbstract (data.klass->getModifiers ());
+ return klass->isabstract (verifier);
}
// Return the element type of an array.
type element_type (_Jv_BytecodeVerifier *verifier)
{
- // FIXME: maybe should do string manipulation here.
- resolve (verifier);
if (key != reference_type)
verifier->verify_fail ("programmer error in type::element_type()", -1);
- jclass k = data.klass->getComponentType ();
+ jclass k = klass->getclass (verifier)->getComponentType ();
if (k->isPrimitive ())
return type (verifier->get_type_val_for_signature (k));
- return type (k);
+ return type (k, verifier);
}
// Return the array type corresponding to an initialized
// types, but currently we don't need to.
type to_array (_Jv_BytecodeVerifier *verifier)
{
- // Resolving isn't ideal, because it might force us to load
- // another class, but it's easy. FIXME?
- if (key == unresolved_reference_type)
- resolve (verifier);
+ if (key != reference_type)
+ verifier->verify_fail ("internal error in type::to_array()");
- if (key == reference_type)
- return type (_Jv_GetArrayClass (data.klass,
- data.klass->getClassLoaderInternal()));
+ // In case the class is already resolved we can simply ask the runtime
+ // to give us the array version.
+ // If it is not resolved we prepend "[" to the classname to make the
+ // array usage verification more lazy. In other words: makes new Foo[300]
+ // pass the verifier if Foo.class is missing.
+ if (klass->is_resolved)
+ {
+ jclass k = klass->getclass (verifier);
+
+ return type (_Jv_GetArrayClass (k, k->getClassLoaderInternal()),
+ verifier);
+ }
else
- verifier->verify_fail ("internal error in type::to_array()");
+ {
+ int len = klass->data.name->len();
+
+ // If the classname is given in the Lp1/p2/cn; format we only need
+ // to add a leading '['. The same procedure has to be done for
+ // primitive arrays (ie. provided "[I", the result should be "[[I".
+ // If the classname is given as p1.p2.cn we have to embed it into
+ // "[L" and ';'.
+ if (klass->data.name->limit()[-1] == ';' ||
+ _Jv_isPrimitiveOrDerived(klass->data.name))
+ {
+ // Reserves space for leading '[' and trailing '\0' .
+ char arrayName[len + 2];
+
+ arrayName[0] = '[';
+ strcpy(&arrayName[1], klass->data.name->chars());
+
+#ifdef VERIFY_DEBUG
+ // This is only needed when we want to print the string to the
+ // screen while debugging.
+ arrayName[len + 1] = '\0';
+
+ debug_print("len: %d - old: '%s' - new: '%s'\n", len, klass->data.name->chars(), arrayName);
+#endif
+
+ return type (verifier->make_utf8_const( arrayName, len + 1 ),
+ verifier);
+ }
+ else
+ {
+ // Reserves space for leading "[L" and trailing ';' and '\0' .
+ char arrayName[len + 4];
+
+ arrayName[0] = '[';
+ arrayName[1] = 'L';
+ strcpy(&arrayName[2], klass->data.name->chars());
+ arrayName[len + 2] = ';';
+
+#ifdef VERIFY_DEBUG
+ // This is only needed when we want to print the string to the
+ // screen while debugging.
+ arrayName[len + 3] = '\0';
+
+ debug_print("len: %d - old: '%s' - new: '%s'\n", len, klass->data.name->chars(), arrayName);
+#endif
+
+ return type (verifier->make_utf8_const( arrayName, len + 3 ),
+ verifier);
+ }
+ }
+
}
bool isreference () const
bool isinitialized () const
{
- return (key == reference_type
- || key == null_type
- || key == unresolved_reference_type);
+ return key == reference_type || key == null_type;
}
bool isresolved () const
void verify_dimensions (int ndims, _Jv_BytecodeVerifier *verifier)
{
// The way this is written, we don't need to check isarray().
- if (key == reference_type)
- {
- jclass k = data.klass;
- while (k->isArray () && ndims > 0)
- {
- k = k->getComponentType ();
- --ndims;
- }
- }
- else
- {
- // We know KEY == unresolved_reference_type.
- char *p = data.name->data;
- while (*p++ == '[' && ndims-- > 0)
- ;
- }
+ if (key != reference_type)
+ verifier->verify_fail ("internal error in verify_dimensions:"
+ " not a reference type");
- if (ndims > 0)
- verifier->verify_fail ("array type has fewer dimensions than required");
+ if (klass->count_dimensions () < ndims)
+ verifier->verify_fail ("array type has fewer dimensions"
+ " than required");
}
- // Merge OLD_TYPE into this. On error throw exception.
+ // Merge OLD_TYPE into this. On error throw exception. Return
+ // true if the merge caused a type change.
bool merge (type& old_type, bool local_semantics,
_Jv_BytecodeVerifier *verifier)
{
verifier->verify_fail ("merging different uninitialized types");
}
- if (! isresolved ()
- && ! old_type.isresolved ()
- && _Jv_equalUtf8Consts (data.name, old_type.data.name))
+ ref_intersection *merged = old_type.klass->merge (klass,
+ verifier);
+ if (merged != klass)
{
- // Types are identical.
- }
- else
- {
- resolve (verifier);
- old_type.resolve (verifier);
-
- jclass k = data.klass;
- jclass oldk = old_type.data.klass;
-
- int arraycount = 0;
- while (k->isArray () && oldk->isArray ())
- {
- ++arraycount;
- k = k->getComponentType ();
- oldk = oldk->getComponentType ();
- }
-
- // Ordinarily this terminates when we hit Object...
- while (k != NULL)
- {
- if (is_assignable_from_slow (k, oldk))
- break;
- k = k->getSuperclass ();
- changed = true;
- }
- // ... but K could have been an interface, in which
- // case we'll end up here. We just convert this
- // into Object.
- if (k == NULL)
- k = &java::lang::Object::class$;
-
- if (changed)
- {
- while (arraycount > 0)
- {
- java::lang::ClassLoader *loader
- = verifier->current_class->getClassLoaderInternal();
- k = _Jv_GetArrayClass (k, loader);
- --arraycount;
- }
- data.klass = k;
- }
+ klass = merged;
+ changed = true;
}
}
}
{
if (local_semantics)
{
- // If we're merging into an "unused" slot, then we
- // simply accept whatever we're merging from.
- if (key == unused_by_subroutine_type)
- {
- *this = old_type;
- changed = true;
- }
- else if (old_type.key == unused_by_subroutine_type)
- {
- // Do nothing.
- }
// If we already have an `unsuitable' type, then we
// don't need to change again.
- else if (key != unsuitable_type)
+ if (key != unsuitable_type)
{
key = unsuitable_type;
changed = true;
case unsuitable_type: c = '-'; break;
case return_address_type: c = 'r'; break;
case continuation_type: c = '+'; break;
- case unused_by_subroutine_type: c = '_'; break;
case reference_type: c = 'L'; break;
case null_type: c = '@'; break;
- case unresolved_reference_type: c = 'l'; break;
case uninitialized_reference_type: c = 'U'; break;
- case uninitialized_unresolved_reference_type: c = 'u'; break;
}
debug_print ("%c", c);
}
type *stack;
// The local variables.
type *locals;
- // This is used in subroutines to keep track of which local
- // variables have been accessed.
- bool *local_changed;
- // If not 0, then we are in a subroutine. The value is the PC of
- // the subroutine's entry point. We can use 0 as an exceptional
- // value because PC=0 can never be a subroutine.
- int subroutine;
- // This is used to keep a linked list of all the states which
- // require re-verification. We use the PC to keep track.
- int next;
// We keep track of the type of `this' specially. This is used to
// ensure that an instance initializer invokes another initializer
// on `this' before returning. We must keep track of this
// assigns to locals[0] (overwriting `this') and then returns
// without really initializing.
type this_type;
- // This is a list of all subroutines that have been seen at this
- // point. Ordinarily this is NULL; it is only allocated and used
- // in relatively weird situations involving non-ret exit from a
- // subroutine. We have to keep track of this in this way to avoid
- // endless recursion in these cases.
- subr_info *seen_subrs;
-
- // INVALID marks a state which is not on the linked list of states
- // requiring reverification.
- static const int INVALID = -1;
- // NO_NEXT marks the state at the end of the reverification list.
- static const int NO_NEXT = -2;
-
- // This is used to mark the stack depth at the instruction just
- // after a `jsr' when we haven't yet processed the corresponding
- // `ret'. See handle_jsr_insn for more information.
- static const int NO_STACK = -1;
+
+ // The PC for this state. This is only valid on states which are
+ // permanently attached to a given PC. For an object like
+ // `current_state', which is used transiently, this has no
+ // meaning.
+ int pc;
+ // We keep a linked list of all states requiring reverification.
+ // If this is the special value INVALID_STATE then this state is
+ // not on the list. NULL marks the end of the linked list.
+ state *next;
+
+ // NO_NEXT is the PC value meaning that a new state must be
+ // acquired from the verification list.
+ static const int NO_NEXT = -1;
state ()
: this_type ()
{
stack = NULL;
locals = NULL;
- local_changed = NULL;
- seen_subrs = NULL;
+ next = INVALID_STATE;
}
state (int max_stack, int max_locals)
for (int i = 0; i < max_stack; ++i)
stack[i] = unsuitable_type;
locals = new type[max_locals];
- local_changed = (bool *) _Jv_Malloc (sizeof (bool) * max_locals);
- seen_subrs = NULL;
for (int i = 0; i < max_locals; ++i)
- {
- locals[i] = unsuitable_type;
- local_changed[i] = false;
- }
- next = INVALID;
- subroutine = 0;
+ locals[i] = unsuitable_type;
+ pc = NO_NEXT;
+ next = INVALID_STATE;
}
- state (const state *orig, int max_stack, int max_locals,
- bool ret_semantics = false)
+ state (const state *orig, int max_stack, int max_locals)
{
stack = new type[max_stack];
locals = new type[max_locals];
- local_changed = (bool *) _Jv_Malloc (sizeof (bool) * max_locals);
- seen_subrs = NULL;
- copy (orig, max_stack, max_locals, ret_semantics);
- next = INVALID;
+ copy (orig, max_stack, max_locals);
+ pc = NO_NEXT;
+ next = INVALID_STATE;
}
~state ()
delete[] stack;
if (locals)
delete[] locals;
- if (local_changed)
- _Jv_Free (local_changed);
- clean_subrs ();
}
void *operator new[] (size_t bytes)
_Jv_Free (mem);
}
- void clean_subrs ()
- {
- subr_info *info = seen_subrs;
- while (info != NULL)
- {
- subr_info *next = info->next;
- _Jv_Free (info);
- info = next;
- }
- }
-
- void copy (const state *copy, int max_stack, int max_locals,
- bool ret_semantics = false)
+ void copy (const state *copy, int max_stack, int max_locals)
{
stacktop = copy->stacktop;
stackdepth = copy->stackdepth;
- subroutine = copy->subroutine;
for (int i = 0; i < max_stack; ++i)
stack[i] = copy->stack[i];
for (int i = 0; i < max_locals; ++i)
- {
- // See push_jump_merge to understand this case.
- if (ret_semantics)
- locals[i] = type (copy->local_changed[i]
- ? unsuitable_type
- : unused_by_subroutine_type);
- else
- locals[i] = copy->locals[i];
- local_changed[i] = copy->local_changed[i];
- }
-
- clean_subrs ();
- if (copy->seen_subrs)
- {
- for (subr_info *info = seen_subrs; info != NULL; info = info->next)
- add_subr (info->pc);
- }
- else
- seen_subrs = NULL;
+ locals[i] = copy->locals[i];
this_type = copy->this_type;
- // Don't modify `next'.
+ // Don't modify `next' or `pc'.
}
// Modify this state to reflect entry to an exception handler.
stack[i] = unsuitable_type;
}
- // Modify this state to reflect entry into a subroutine.
- void enter_subroutine (int npc, int max_locals)
+ inline int get_pc () const
{
- subroutine = npc;
- // Mark all items as unchanged. Each subroutine needs to keep
- // track of its `changed' state independently. In the case of
- // nested subroutines, this information will be merged back into
- // parent by the `ret'.
- for (int i = 0; i < max_locals; ++i)
- local_changed[i] = false;
+ return pc;
}
- // Indicate that we've been in this this subroutine.
- void add_subr (int pc)
+ void set_pc (int npc)
{
- subr_info *n = (subr_info *) _Jv_Malloc (sizeof (subr_info));
- n->pc = pc;
- n->next = seen_subrs;
- seen_subrs = n;
+ pc = npc;
}
// Merge STATE_OLD into this state. Destructively modifies this
// state. Returns true if the new state was in fact changed.
// Will throw an exception if the states are not mergeable.
- bool merge (state *state_old, bool ret_semantics,
- int max_locals, _Jv_BytecodeVerifier *verifier)
+ bool merge (state *state_old, int max_locals,
+ _Jv_BytecodeVerifier *verifier)
{
bool changed = false;
if (this_type.isinitialized ())
this_type = state_old->this_type;
- // Merge subroutine states. Here we just keep track of what
- // subroutine we think we're in. We only check for a merge
- // (which is invalid) when we see a `ret'.
- if (subroutine == state_old->subroutine)
- {
- // Nothing.
- }
- else if (subroutine == 0)
- {
- subroutine = state_old->subroutine;
- changed = true;
- }
- else
- {
- // If the subroutines differ, and we haven't seen this
- // subroutine before, indicate that the state changed. This
- // is needed to detect when subroutines have merged.
- bool found = false;
- for (subr_info *info = seen_subrs; info != NULL; info = info->next)
- {
- if (info->pc == state_old->subroutine)
- {
- found = true;
- break;
- }
- }
- if (! found)
- {
- add_subr (state_old->subroutine);
- changed = true;
- }
- }
-
- // Merge stacks. Special handling for NO_STACK case.
- if (state_old->stacktop == NO_STACK)
- {
- // Nothing to do in this case; we don't care about modifying
- // the old state.
- }
- else if (stacktop == NO_STACK)
- {
- stacktop = state_old->stacktop;
- stackdepth = state_old->stackdepth;
- for (int i = 0; i < stacktop; ++i)
- stack[i] = state_old->stack[i];
- changed = true;
- }
- else if (state_old->stacktop != stacktop)
+ // Merge stacks.
+ if (state_old->stacktop != stacktop) // FIXME stackdepth instead?
verifier->verify_fail ("stack sizes differ");
- else
+ for (int i = 0; i < state_old->stacktop; ++i)
{
- for (int i = 0; i < state_old->stacktop; ++i)
- {
- if (stack[i].merge (state_old->stack[i], false, verifier))
- changed = true;
- }
+ if (stack[i].merge (state_old->stack[i], false, verifier))
+ changed = true;
}
// Merge local variables.
for (int i = 0; i < max_locals; ++i)
{
- // If we're not processing a `ret', then we merge every
- // local variable. If we are processing a `ret', then we
- // only merge locals which changed in the subroutine. When
- // processing a `ret', STATE_OLD is the state at the point
- // of the `ret', and THIS is the state just after the `jsr'.
- if (! ret_semantics || state_old->local_changed[i])
- {
- if (locals[i].merge (state_old->locals[i], true, verifier))
- {
- // Note that we don't call `note_variable' here.
- // This change doesn't represent a real change to a
- // local, but rather a merge artifact. If we're in
- // a subroutine which is called with two
- // incompatible types in a slot that is unused by
- // the subroutine, then we don't want to mark that
- // variable as having been modified.
- changed = true;
- }
- }
-
- // If we're in a subroutine, we must compute the union of
- // all the changed local variables.
- if (state_old->local_changed[i])
- note_variable (i);
+ if (locals[i].merge (state_old->locals[i], true, verifier))
+ changed = true;
}
return changed;
}
- // Throw an exception if there is an uninitialized object on the
- // stack or in a local variable. EXCEPTION_SEMANTICS controls
- // whether we're using backwards-branch or exception-handing
- // semantics.
- void check_no_uninitialized_objects (int max_locals,
- _Jv_BytecodeVerifier *verifier,
- bool exception_semantics = false)
- {
- if (! exception_semantics)
- {
- for (int i = 0; i < stacktop; ++i)
- if (stack[i].isreference () && ! stack[i].isinitialized ())
- verifier->verify_fail ("uninitialized object on stack");
- }
-
- for (int i = 0; i < max_locals; ++i)
- if (locals[i].isreference () && ! locals[i].isinitialized ())
- verifier->verify_fail ("uninitialized object in local variable");
-
- check_this_initialized (verifier);
- }
-
// Ensure that `this' has been initialized.
void check_this_initialized (_Jv_BytecodeVerifier *verifier)
{
this_type = k;
}
- // Note that a local variable was modified.
- void note_variable (int index)
- {
- if (subroutine > 0)
- local_changed[index] = true;
- }
-
// Mark each `new'd object we know of that was allocated at PC as
// initialized.
void set_initialized (int pc, int max_locals)
this_type.set_initialized (pc);
}
- // Return true if this state is the unmerged result of a `ret'.
- bool is_unmerged_ret_state (int max_locals) const
+ // This tests to see whether two states can be considered "merge
+ // compatible". If both states have a return-address in the same
+ // slot, and the return addresses are different, then they are not
+ // compatible and we must not try to merge them.
+ bool state_mergeable_p (state *other, int max_locals,
+ _Jv_BytecodeVerifier *verifier)
{
- if (stacktop == NO_STACK)
- return true;
+ // This is tricky: if the stack sizes differ, then not only are
+ // these not mergeable, but in fact we should give an error, as
+ // we've found two execution paths that reach a branch target
+ // with different stack depths. FIXME stackdepth instead?
+ if (stacktop != other->stacktop)
+ verifier->verify_fail ("stack sizes differ");
+
+ for (int i = 0; i < stacktop; ++i)
+ if (! stack[i].state_mergeable_p (other->stack[i]))
+ return false;
for (int i = 0; i < max_locals; ++i)
+ if (! locals[i].state_mergeable_p (other->locals[i]))
+ return false;
+ return true;
+ }
+
+ void reverify (_Jv_BytecodeVerifier *verifier)
+ {
+ if (next == INVALID_STATE)
{
- if (locals[i].key == unused_by_subroutine_type)
- return true;
+ next = verifier->next_verify_state;
+ verifier->next_verify_state = this;
}
- return false;
}
#ifdef VERIFY_DEBUG
debug_print (".");
debug_print (" [local] ");
for (i = 0; i < max_locals; ++i)
- {
- locals[i].print ();
- debug_print (local_changed[i] ? "+" : " ");
- }
- if (subroutine == 0)
- debug_print (" | None");
- else
- debug_print (" | %4d", subroutine);
+ locals[i].print ();
debug_print (" | %p\n", this);
}
#else
if (index > current_method->max_locals - depth)
verify_fail ("invalid local variable");
current_state->locals[index] = t;
- current_state->note_variable (index);
if (depth == 2)
- {
- current_state->locals[index + 1] = continuation_type;
- current_state->note_variable (index + 1);
- }
+ current_state->locals[index + 1] = continuation_type;
if (index > 0 && current_state->locals[index - 1].iswide ())
- {
- current_state->locals[index - 1] = unsuitable_type;
- // There's no need to call note_variable here.
- }
+ current_state->locals[index - 1] = unsuitable_type;
}
type get_variable (int index, type t)
return npc;
}
+ // Add a new state to the state list at NPC.
+ state *add_new_state (int npc, state *old_state)
+ {
+ state *new_state = new state (old_state, current_method->max_stack,
+ current_method->max_locals);
+ debug_print ("== New state in add_new_state\n");
+ new_state->print ("New", npc, current_method->max_stack,
+ current_method->max_locals);
+ linked<state> *nlink
+ = (linked<state> *) _Jv_Malloc (sizeof (linked<state>));
+ nlink->val = new_state;
+ nlink->next = states[npc];
+ states[npc] = nlink;
+ new_state->set_pc (npc);
+ return new_state;
+ }
+
// Merge the indicated state into the state at the branch target and
- // schedule a new PC if there is a change. If RET_SEMANTICS is
- // true, then we are merging from a `ret' instruction into the
- // instruction after a `jsr'. This is a special case with its own
- // modified semantics.
- void push_jump_merge (int npc, state *nstate, bool ret_semantics = false)
+ // schedule a new PC if there is a change. NPC is the PC of the
+ // branch target, and FROM_STATE is the state at the source of the
+ // branch. This method returns true if the destination state
+ // changed and requires reverification, false otherwise.
+ void merge_into (int npc, state *from_state)
{
- bool changed = true;
- if (states[npc] == NULL)
+ // Iterate over all target states and merge our state into each,
+ // if applicable. FIXME one improvement we could make here is
+ // "state destruction". Merging a new state into an existing one
+ // might cause a return_address_type to be merged to
+ // unsuitable_type. In this case the resulting state may now be
+ // mergeable with other states currently held in parallel at this
+ // location. So in this situation we could pairwise compare and
+ // reduce the number of parallel states.
+ bool applicable = false;
+ for (linked<state> *iter = states[npc]; iter != NULL; iter = iter->next)
{
- // There's a weird situation here. If are examining the
- // branch that results from a `ret', and there is not yet a
- // state available at the branch target (the instruction just
- // after the `jsr'), then we have to construct a special kind
- // of state at that point for future merging. This special
- // state has the type `unused_by_subroutine_type' in each slot
- // which was not modified by the subroutine.
- states[npc] = new state (nstate, current_method->max_stack,
- current_method->max_locals, ret_semantics);
- debug_print ("== New state in push_jump_merge\n");
- states[npc]->print ("New", npc, current_method->max_stack,
- current_method->max_locals);
- }
- else
- {
- debug_print ("== Merge states in push_jump_merge\n");
- nstate->print ("Frm", start_PC, current_method->max_stack,
- current_method->max_locals);
- states[npc]->print (" To", npc, current_method->max_stack,
- current_method->max_locals);
- changed = states[npc]->merge (nstate, ret_semantics,
- current_method->max_locals, this);
- states[npc]->print ("New", npc, current_method->max_stack,
- current_method->max_locals);
+ state *new_state = iter->val;
+ if (new_state->state_mergeable_p (from_state,
+ current_method->max_locals, this))
+ {
+ applicable = true;
+
+ debug_print ("== Merge states in merge_into\n");
+ from_state->print ("Frm", start_PC, current_method->max_stack,
+ current_method->max_locals);
+ new_state->print (" To", npc, current_method->max_stack,
+ current_method->max_locals);
+ bool changed = new_state->merge (from_state,
+ current_method->max_locals,
+ this);
+ new_state->print ("New", npc, current_method->max_stack,
+ current_method->max_locals);
+
+ if (changed)
+ new_state->reverify (this);
+ }
}
- if (changed && states[npc]->next == state::INVALID)
+ if (! applicable)
{
- // The merge changed the state, and the new PC isn't yet on our
- // list of PCs to re-verify.
- states[npc]->next = next_verify_pc;
- next_verify_pc = npc;
+ // Either we don't yet have a state at NPC, or we have a
+ // return-address type that is in conflict with all existing
+ // state. So, we need to create a new entry.
+ state *new_state = add_new_state (npc, from_state);
+ // A new state added in this way must always be reverified.
+ new_state->reverify (this);
}
}
void push_jump (int offset)
{
int npc = compute_jump (offset);
- if (npc < PC)
- current_state->check_no_uninitialized_objects (current_method->max_locals, this);
- push_jump_merge (npc, current_state);
+ // According to the JVM Spec, we need to check for uninitialized
+ // objects here. However, this does not actually affect type
+ // safety, and the Eclipse java compiler generates code that
+ // violates this constraint.
+ merge_into (npc, current_state);
}
void push_exception_jump (type t, int pc)
{
- current_state->check_no_uninitialized_objects (current_method->max_locals,
- this, true);
+ // According to the JVM Spec, we need to check for uninitialized
+ // objects here. However, this does not actually affect type
+ // safety, and the Eclipse java compiler generates code that
+ // violates this constraint.
state s (current_state, current_method->max_stack,
current_method->max_locals);
if (current_method->max_stack < 1)
verify_fail ("stack overflow at exception handler");
s.set_exception (t, current_method->max_stack);
- push_jump_merge (pc, &s);
+ merge_into (pc, &s);
}
- int pop_jump ()
+ state *pop_jump ()
{
- int *prev_loc = &next_verify_pc;
- int npc = next_verify_pc;
-
- while (npc != state::NO_NEXT)
+ state *new_state = next_verify_state;
+ if (new_state == INVALID_STATE)
+ verify_fail ("programmer error in pop_jump");
+ if (new_state != NULL)
{
- // If the next available PC is an unmerged `ret' state, then
- // we aren't yet ready to handle it. That's because we would
- // need all kind of special cases to do so. So instead we
- // defer this jump until after we've processed it via a
- // fall-through. This has to happen because the instruction
- // before this one must be a `jsr'.
- if (! states[npc]->is_unmerged_ret_state (current_method->max_locals))
- {
- *prev_loc = states[npc]->next;
- states[npc]->next = state::INVALID;
- return npc;
- }
-
- prev_loc = &states[npc]->next;
- npc = states[npc]->next;
+ next_verify_state = new_state->next;
+ new_state->next = INVALID_STATE;
}
-
- // Note that we might have gotten here even when there are
- // remaining states to process. That can happen if we find a
- // `jsr' without a `ret'.
- return state::NO_NEXT;
+ return new_state;
}
void invalidate_pc ()
PC = state::NO_NEXT;
}
- void note_branch_target (int pc, bool is_jsr_target = false)
+ void note_branch_target (int pc)
{
// Don't check `pc <= PC', because we've advanced PC after
// fetching the target and we haven't yet checked the next
if (pc < PC && ! (flags[pc] & FLAG_INSN_START))
verify_fail ("branch not to instruction start", start_PC);
flags[pc] |= FLAG_BRANCH_TARGET;
- if (is_jsr_target)
- {
- // Record the jsr which called this instruction.
- subr_info *info = (subr_info *) _Jv_Malloc (sizeof (subr_info));
- info->pc = PC;
- info->next = jsr_ptrs[pc];
- jsr_ptrs[pc] = info;
- }
}
void skip_padding ()
verify_fail ("found nonzero padding byte");
}
- // Return the subroutine to which the instruction at PC belongs.
- int get_subroutine (int pc)
- {
- if (states[pc] == NULL)
- return 0;
- return states[pc]->subroutine;
- }
-
// Do the work for a `ret' instruction. INDEX is the index into the
// local variables.
void handle_ret_insn (int index)
{
- get_variable (index, return_address_type);
-
- int csub = current_state->subroutine;
- if (csub == 0)
- verify_fail ("no subroutine");
-
- // Check to see if we've merged subroutines.
- subr_entry_info *entry;
- for (entry = entry_points; entry != NULL; entry = entry->next)
- {
- if (entry->ret_pc == start_PC)
- break;
- }
- if (entry == NULL)
- {
- entry = (subr_entry_info *) _Jv_Malloc (sizeof (subr_entry_info));
- entry->pc = csub;
- entry->ret_pc = start_PC;
- entry->next = entry_points;
- entry_points = entry;
- }
- else if (entry->pc != csub)
- verify_fail ("subroutines merged");
-
- for (subr_info *subr = jsr_ptrs[csub]; subr != NULL; subr = subr->next)
- {
- // We might be returning to a `jsr' that is at the end of the
- // bytecode. This is ok if we never return from the called
- // subroutine, but if we see this here it is an error.
- if (subr->pc >= current_method->code_length)
- verify_fail ("fell off end");
-
- // Temporarily modify the current state so it looks like we're
- // in the enclosing context.
- current_state->subroutine = get_subroutine (subr->pc);
- if (subr->pc < PC)
- current_state->check_no_uninitialized_objects (current_method->max_locals, this);
- push_jump_merge (subr->pc, current_state, true);
- }
-
- current_state->subroutine = csub;
+ type ret_addr = get_variable (index, return_address_type);
+ // It would be nice if we could do this. However, the JVM Spec
+ // doesn't say that this is what happens. It is implied that
+ // reusing a return address is invalid, but there's no actual
+ // prohibition against it.
+ // set_variable (index, unsuitable_type);
+
+ int npc = ret_addr.get_pc ();
+ // We might be returning to a `jsr' that is at the end of the
+ // bytecode. This is ok if we never return from the called
+ // subroutine, but if we see this here it is an error.
+ if (npc >= current_method->code_length)
+ verify_fail ("fell off end");
+
+ // According to the JVM Spec, we need to check for uninitialized
+ // objects here. However, this does not actually affect type
+ // safety, and the Eclipse java compiler generates code that
+ // violates this constraint.
+ merge_into (npc, current_state);
invalidate_pc ();
}
- // We're in the subroutine SUB, calling a subroutine at DEST. Make
- // sure this subroutine isn't already on the stack.
- void check_nonrecursive_call (int sub, int dest)
- {
- if (sub == 0)
- return;
- if (sub == dest)
- verify_fail ("recursive subroutine call");
- for (subr_info *info = jsr_ptrs[sub]; info != NULL; info = info->next)
- check_nonrecursive_call (get_subroutine (info->pc), dest);
- }
-
void handle_jsr_insn (int offset)
{
int npc = compute_jump (offset);
- if (npc < PC)
- current_state->check_no_uninitialized_objects (current_method->max_locals, this);
- check_nonrecursive_call (current_state->subroutine, npc);
+ // According to the JVM Spec, we need to check for uninitialized
+ // objects here. However, this does not actually affect type
+ // safety, and the Eclipse java compiler generates code that
+ // violates this constraint.
// Modify our state as appropriate for entry into a subroutine.
- push_type (return_address_type);
- push_jump_merge (npc, current_state);
- // Clean up.
- pop_type (return_address_type);
-
- // On entry to the subroutine, the subroutine number must be set
- // and the locals must be marked as cleared. We do this after
- // merging state so that we don't erroneously "notice" a variable
- // change merely on entry.
- states[npc]->enter_subroutine (npc, current_method->max_locals);
-
- // Indicate that we don't know the stack depth of the instruction
- // following the `jsr'. The idea here is that we need to merge
- // the local variable state across the jsr, but the subroutine
- // might change the stack depth, so we can't make any assumptions
- // about it. So we have yet another special case. We know that
- // at this point PC points to the instruction after the jsr. Note
- // that it is ok to have a `jsr' at the end of the bytecode,
- // provided that the called subroutine never returns. So, we have
- // a special case here and another one when we handle the ret.
- if (PC < current_method->code_length)
- {
- current_state->stacktop = state::NO_STACK;
- push_jump_merge (PC, current_state);
- }
+ type ret_addr (return_address_type);
+ ret_addr.set_return_address (PC);
+ push_type (ret_addr);
+ merge_into (npc, current_state);
invalidate_pc ();
}
case unsuitable_type:
case return_address_type:
case continuation_type:
- case unused_by_subroutine_type:
case reference_type:
case null_type:
- case unresolved_reference_type:
case uninitialized_reference_type:
- case uninitialized_unresolved_reference_type:
default:
verify_fail ("unknown type in construct_primitive_array_type");
}
void branch_prepass ()
{
flags = (char *) _Jv_Malloc (current_method->code_length);
- jsr_ptrs = (subr_info **) _Jv_Malloc (sizeof (subr_info *)
- * current_method->code_length);
for (int i = 0; i < current_method->code_length; ++i)
- {
- flags[i] = 0;
- jsr_ptrs[i] = NULL;
- }
-
- bool last_was_jsr = false;
+ flags[i] = 0;
PC = 0;
while (PC < current_method->code_length)
start_PC = PC;
flags[PC] |= FLAG_INSN_START;
- // If the previous instruction was a jsr, then the next
- // instruction is a branch target -- the branch being the
- // corresponding `ret'.
- if (last_was_jsr)
- note_branch_target (PC);
- last_was_jsr = false;
-
java_opcode opcode = (java_opcode) bytecode[PC++];
switch (opcode)
{
break;
case op_jsr:
- last_was_jsr = true;
- // Fall through.
case op_ifeq:
case op_ifne:
case op_iflt:
case op_ifnull:
case op_ifnonnull:
case op_goto:
- note_branch_target (compute_jump (get_short ()), last_was_jsr);
+ note_branch_target (compute_jump (get_short ()));
break;
case op_tableswitch:
break;
case op_jsr_w:
- last_was_jsr = true;
- // Fall through.
case op_goto_w:
- note_branch_target (compute_jump (get_int ()), last_was_jsr);
+ note_branch_target (compute_jump (get_int ()));
break;
// These are unused here, but we call them out explicitly
case op_getstatic_4:
case op_getstatic_8:
case op_getstatic_a:
+ case op_breakpoint:
default:
verify_fail ("unrecognized instruction in branch_prepass",
start_PC);
check_pool_index (index);
_Jv_Constants *pool = ¤t_class->constants;
if (pool->tags[index] == JV_CONSTANT_ResolvedClass)
- return type (pool->data[index].clazz);
+ return type (pool->data[index].clazz, this);
else if (pool->tags[index] == JV_CONSTANT_Class)
- return type (pool->data[index].utf8);
+ return type (pool->data[index].utf8, this);
verify_fail ("expected class constant", start_PC);
}
{
check_pool_index (index);
_Jv_Constants *pool = ¤t_class->constants;
- if (pool->tags[index] == JV_CONSTANT_ResolvedString
- || pool->tags[index] == JV_CONSTANT_String)
- return type (&java::lang::String::class$);
- else if (pool->tags[index] == JV_CONSTANT_Integer)
+ int tag = pool->tags[index];
+ if (tag == JV_CONSTANT_ResolvedString || tag == JV_CONSTANT_String)
+ return type (&java::lang::String::class$, this);
+ else if (tag == JV_CONSTANT_Integer)
return type (int_type);
- else if (pool->tags[index] == JV_CONSTANT_Float)
+ else if (tag == JV_CONSTANT_Float)
return type (float_type);
+ else if (current_method->is_15
+ && (tag == JV_CONSTANT_ResolvedClass || tag == JV_CONSTANT_Class))
+ return type (&java::lang::Class::class$, this);
verify_fail ("String, int, or float constant expected", start_PC);
}
}
// Return field's type, compute class' type if requested.
- type check_field_constant (int index, type *class_type = NULL)
+ // If PUTFIELD is true, use the special 'putfield' semantics.
+ type check_field_constant (int index, type *class_type = NULL,
+ bool putfield = false)
{
_Jv_Utf8Const *name, *field_type;
type ct = handle_field_or_method (index,
&name, &field_type);
if (class_type)
*class_type = ct;
- if (field_type->data[0] == '[' || field_type->data[0] == 'L')
- return type (field_type);
- return get_type_val_for_signature (field_type->data[0]);
+ type result;
+ if (field_type->first() == '[' || field_type->first() == 'L')
+ result = type (field_type, this);
+ else
+ result = get_type_val_for_signature (field_type->first());
+
+ // We have an obscure special case here: we can use `putfield' on
+ // a field declared in this class, even if `this' has not yet been
+ // initialized.
+ if (putfield
+ && ! current_state->this_type.isinitialized ()
+ && current_state->this_type.pc == type::SELF
+ && current_state->this_type.equals (ct, this)
+ // We don't look at the signature, figuring that if it is
+ // wrong we will fail during linking. FIXME?
+ && _Jv_Linker::has_field_p (current_class, name))
+ // Note that we don't actually know whether we're going to match
+ // against 'this' or some other object of the same type. So,
+ // here we set things up so that it doesn't matter. This relies
+ // on knowing what our caller is up to.
+ class_type->set_uninitialized (type::EITHER, this);
+
+ return result;
}
type check_method_constant (int index, bool is_interface,
++p;
++p;
_Jv_Utf8Const *name = make_utf8_const (start, p - start);
- return type (name);
+ return type (name, this);
}
// Casting to jchar here is ok since we are looking at an ASCII
jclass k = construct_primitive_array_type (rt);
while (--arraycount > 0)
k = _Jv_GetArrayClass (k, NULL);
- return type (k);
+ return type (k, this);
}
void compute_argument_types (_Jv_Utf8Const *signature,
type *types)
{
- char *p = signature->data;
+ char *p = signature->chars();
+
// Skip `('.
++p;
type compute_return_type (_Jv_Utf8Const *signature)
{
- char *p = signature->data;
+ char *p = signature->chars();
while (*p != ')')
++p;
++p;
using namespace java::lang::reflect;
if (! Modifier::isStatic (current_method->self->accflags))
{
- type kurr (current_class);
+ type kurr (current_class, this);
if (is_init)
{
kurr.set_uninitialized (type::SELF, this);
// True if we are verifying an instance initializer.
bool this_is_init = initialize_stack ();
- states = (state **) _Jv_Malloc (sizeof (state *)
- * current_method->code_length);
+ states = (linked<state> **) _Jv_Malloc (sizeof (linked<state> *)
+ * current_method->code_length);
for (int i = 0; i < current_method->code_length; ++i)
states[i] = NULL;
- next_verify_pc = state::NO_NEXT;
+ next_verify_state = NULL;
while (true)
{
// If the PC was invalidated, get a new one from the work list.
if (PC == state::NO_NEXT)
{
- PC = pop_jump ();
- if (PC == state::INVALID)
- verify_fail ("can't happen: saw state::INVALID");
- if (PC == state::NO_NEXT)
+ state *new_state = pop_jump ();
+ // If it is null, we're done.
+ if (new_state == NULL)
break;
+
+ PC = new_state->get_pc ();
debug_print ("== State pop from pending list\n");
// Set up the current state.
- current_state->copy (states[PC], current_method->max_stack,
+ current_state->copy (new_state, current_method->max_stack,
current_method->max_locals);
}
else
{
- // Control can't fall off the end of the bytecode. We
- // only need to check this in the fall-through case,
- // because branch bounds are checked when they are
- // pushed.
- if (PC >= current_method->code_length)
- verify_fail ("fell off end");
-
// We only have to do this checking in the situation where
// control flow falls through from the previous
// instruction. Otherwise merging is done at the time we
- // push the branch.
- if (states[PC] != NULL)
+ // push the branch. Note that we'll catch the
+ // off-the-end problem just below.
+ if (PC < current_method->code_length && states[PC] != NULL)
{
// We've already visited this instruction. So merge
- // the states together. If this yields no change then
- // we don't have to re-verify. However, if the new
- // state is an the result of an unmerged `ret', we
- // must continue through it.
- debug_print ("== Fall through merge\n");
- states[PC]->print ("Old", PC, current_method->max_stack,
- current_method->max_locals);
- current_state->print ("Cur", PC, current_method->max_stack,
- current_method->max_locals);
- if (! current_state->merge (states[PC], false,
- current_method->max_locals, this)
- && ! states[PC]->is_unmerged_ret_state (current_method->max_locals))
- {
- debug_print ("== Fall through optimization\n");
- invalidate_pc ();
- continue;
- }
- // Save a copy of it for later.
- states[PC]->copy (current_state, current_method->max_stack,
- current_method->max_locals);
- current_state->print ("New", PC, current_method->max_stack,
- current_method->max_locals);
+ // the states together. It is simplest, but not most
+ // efficient, to just always invalidate the PC here.
+ merge_into (PC, current_state);
+ invalidate_pc ();
+ continue;
}
}
+ // Control can't fall off the end of the bytecode. We need to
+ // check this in both cases, not just the fall-through case,
+ // because we don't check to see whether a `jsr' appears at
+ // the end of the bytecode until we process a `ret'.
+ if (PC >= current_method->code_length)
+ verify_fail ("fell off end");
+
// We only have to keep saved state at branch targets. If
// we're at a branch target and the state here hasn't been set
- // yet, we set it now.
+ // yet, we set it now. You might notice that `ret' targets
+ // won't necessarily have FLAG_BRANCH_TARGET set. This
+ // doesn't matter, since those states will be filled in by
+ // merge_into.
if (states[PC] == NULL && (flags[PC] & FLAG_BRANCH_TARGET))
- {
- states[PC] = new state (current_state, current_method->max_stack,
- current_method->max_locals);
- }
+ add_new_state (PC, current_state);
// Set this before handling exceptions so that debug output is
// sane.
{
if (PC >= exception[i].start_pc.i && PC < exception[i].end_pc.i)
{
- type handler (&java::lang::Throwable::class$);
+ type handler (&java::lang::Throwable::class$, this);
if (exception[i].handler_type.i != 0)
handler = check_class_constant (exception[i].handler_type.i);
push_exception_jump (handler, exception[i].handler_pc.i);
case op_putfield:
{
type klass;
- type field = check_field_constant (get_ushort (), &klass);
+ type field = check_field_constant (get_ushort (), &klass, true);
pop_type (field);
-
- // We have an obscure special case here: we can use
- // `putfield' on a field declared in this class, even if
- // `this' has not yet been initialized.
- if (! current_state->this_type.isinitialized ()
- && current_state->this_type.pc == type::SELF)
- klass.set_uninitialized (type::SELF, this);
pop_type (klass);
}
break;
if (opcode != op_invokespecial)
verify_fail ("can't invoke <init>");
}
- else if (method_name->data[0] == '<')
+ else if (method_name->first() == '<')
verify_fail ("can't invoke method starting with `<'");
// Pop arguments and check types.
{
// In this case the PC doesn't matter.
t.set_uninitialized (type::UNINIT, this);
+ // FIXME: check to make sure that the <init>
+ // call is to the right class.
+ // It must either be super or an exact class
+ // match.
}
type raw = pop_raw ();
- bool ok = false;
- if (! is_init && ! raw.isinitialized ())
- {
- // This is a failure.
- }
- else if (is_init && raw.isnull ())
- {
- // Another failure.
- }
- else if (t.compatible (raw, this))
- {
- ok = true;
- }
- else if (opcode == op_invokeinterface)
- {
- // This is a hack. We might have merged two
- // items and gotten `Object'. This can happen
- // because we don't keep track of where merges
- // come from. This is safe as long as the
- // interpreter checks interfaces at runtime.
- type obj (&java::lang::Object::class$);
- ok = raw.compatible (obj, this);
- }
-
- if (! ok)
+ if (! t.compatible (raw, this))
verify_fail ("incompatible type on stack");
if (is_init)
case op_new:
{
type t = check_class_constant (get_ushort ());
- if (t.isarray () || t.isinterface (this) || t.isabstract (this))
- verify_fail ("type is array, interface, or abstract");
+ if (t.isarray ())
+ verify_fail ("type is array");
t.set_uninitialized (start_PC, this);
push_type (t);
}
if (atype < boolean_type || atype > long_type)
verify_fail ("type not primitive", start_PC);
pop_type (int_type);
- push_type (construct_primitive_array_type (type_val (atype)));
+ type t (construct_primitive_array_type (type_val (atype)), this);
+ push_type (t);
}
break;
case op_anewarray:
}
break;
case op_athrow:
- pop_type (type (&java::lang::Throwable::class$));
+ pop_type (type (&java::lang::Throwable::class$, this));
invalidate_pc ();
break;
case op_checkcast:
case op_getstatic_4:
case op_getstatic_8:
case op_getstatic_a:
+ case op_breakpoint:
default:
// Unrecognized opcode.
verify_fail ("unrecognized instruction in verify_instructions_0",
// We just print the text as utf-8. This is just for debugging
// anyway.
debug_print ("--------------------------------\n");
- debug_print ("-- Verifying method `%s'\n", m->self->name->data);
+ debug_print ("-- Verifying method `%s'\n", m->self->name->chars());
current_method = m;
bytecode = m->bytecode ();
states = NULL;
flags = NULL;
- jsr_ptrs = NULL;
utf8_list = NULL;
- entry_points = NULL;
+ isect_list = NULL;
}
~_Jv_BytecodeVerifier ()
{
- if (states)
- _Jv_Free (states);
if (flags)
_Jv_Free (flags);
- if (jsr_ptrs)
- {
- for (int i = 0; i < current_method->code_length; ++i)
- {
- if (jsr_ptrs[i] != NULL)
- {
- subr_info *info = jsr_ptrs[i];
- while (info != NULL)
- {
- subr_info *next = info->next;
- _Jv_Free (info);
- info = next;
- }
- }
- }
- _Jv_Free (jsr_ptrs);
- }
-
while (utf8_list != NULL)
{
- linked_utf8 *n = utf8_list->next;
- _Jv_Free (utf8_list->val);
+ linked<_Jv_Utf8Const> *n = utf8_list->next;
_Jv_Free (utf8_list);
utf8_list = n;
}
- while (entry_points != NULL)
+ while (isect_list != NULL)
+ {
+ ref_intersection *next = isect_list->alloc_next;
+ delete isect_list;
+ isect_list = next;
+ }
+
+ if (states)
{
- subr_entry_info *next = entry_points->next;
- _Jv_Free (entry_points);
- entry_points = next;
+ for (int i = 0; i < current_method->code_length; ++i)
+ {
+ linked<state> *iter = states[i];
+ while (iter != NULL)
+ {
+ linked<state> *next = iter->next;
+ delete iter->val;
+ _Jv_Free (iter);
+ iter = next;
+ }
+ }
+ _Jv_Free (states);
}
}
};
_Jv_BytecodeVerifier v (meth);
v.verify_instructions ();
}
+
#endif /* INTERPRETER */