The new transformer uses a different approach to the old one. It starts
exploring the call graph from the entry points, recursively analysing
method calls. Methods are only re-analysed if their possible argument
values change, with the Unknown value being used if we can't identify a
single integer constant at a call site. This prevents us from recursing
infinitely if the client code does.
While this first pass does simplify branches in order to ignore dummy
method calls that are never evaluated at runtime, it operates on a copy
of the method (as we initially ignore more calls while the argument
value sets are smaller, ignoring fewer calls as they build up).
A separate second pass simplifies branches on the original method and
inlines singleton constants, paving the way for the UnusedArgTransformer
to actually remove the newly unused arguments.
This new approach has several benefits:
- It is much faster than the old approach, as we only re-analyse methods
as required by argument value changes, rather than re-analysing every
method during every pass.
- It doesn't require special cases for dealing with mutually recursive
dummy calls. The old approach hard-coded special cases for mutually
recursive calls involving groups of 1 and 2 methods. The code for this
wasn't clean. Furthermore, while it was just about good enough for the
HD client, the SD client contains a mutually recursive group of 3
methods. The new approach is capable of dealing with mutually
recursive groups of any size.
Finally, the new transformer has a much cleaner implementation.
Signed-off-by: Graham <gpe@openrs2.dev>
We only need to check for the ACC_FINAL flag once at the start of
transformCode(), given the insn.owner == clazz.name condition. This
change also removes the redundant getNode() call - we already have a
reference to the ClassNode.
Signed-off-by: Graham <gpe@openrs2.dev>
As I'm splitting it up into smaller modules (e.g. compress and crypto) I
think util is a more appropriate name for the remainder.
Signed-off-by: Graham <gpe@openrs2.dev>
The non-HD client appears to have been compiled with javac 1.1 or 1.2,
which compiles synchronized blocks differently to modern versions of
Java. For example, it uses a single try/catch block (modern versions use
two, the latter of which is recursive), subroutines (modern versions do
not) and the range of the try block is narrower.
Fernflower doesn't understand this old style of bytecode, and produces
empty synchronized blocks that do not cover the correct range.
The MONITORENTER sequence is also slightly different: it uses
ASTORE ALOAD MONITORENTER after pushing the monitor variable, rather
than DUP ASTORE MONITORENTER. This doesn't break Fernflower, but does
make it introduce a pointless assignment to a variable only used in the
synchronized() statement, rather than inlining the expression.
This commit introduces a transformer which fixes up Java 1.1-style
synchronized blocks just enough for Fernflower to be able to decompile
them cleanly. (It doesn't add a recursive try/catch, as Fernflower
ignores them.)
Signed-off-by: Graham <gpe@openrs2.dev>
The unsigned client has a Class.forName() method with two differences:
* The NoClassDefFoundError is created with a slightly different sequence
of instructions.
* The arms of the if/else statement for initializing the synthetic field
if it is null are swapped.
This commit adds support for translating Class.forName() methods with
either or both of these differences to the modern LDC form.
Signed-off-by: Graham <gpe@openrs2.dev>
game_unpacker.dat is the name of the file when downloaded in the
.jagex_cache_32/runescape directory. However, the other files containing
code are all named after the files on the web/JAGGRAB server.
This commit uses unpackclass.pack for consistency with all the other
files.
Signed-off-by: Graham <gpe@openrs2.dev>
This ensures the bundler/deobfuscator can only see classes that are part
of the Java runtime, and not classes from the bundler/deobfuscator
themselves.
Signed-off-by: Graham <gpe@openrs2.dev>
The split is no longer required - we haven't run javah automatically
since splitting the natives out into a separate repository.
Signed-off-by: Graham <gpe@openrs2.dev>
Removes GOTO instructions that point to the next instruction, typically
left over from stripping exceptions inserted by the obfuscator.
Although modern decompilers can handle such GOTOs fine, removing them
makes for a nicer IR representation.
Signed-off-by: Major <major@emulate.rs>
It's possible that future versions of ASM will introduce additional
types of virtual node. Only counting real instructions should make this
more reliable.
Signed-off-by: Graham <gpe@openrs2.dev>
While it isn't useful for retaining the name of the constructor itself,
as they don't really have names, it will be useful for tracking argument
names and positions.
Signed-off-by: Graham <gpe@openrs2.dev>
The transformer does _not_ check for use via reflection. The only cases
in the 550 and OSRS clients where methods are accessed via reflection
are either 1) JRE classes, 2) when the method name is sent from the
server.
PSVM and methods declared in TypedRemapper.EXCLUDED_METHODS are never
removed.
Signed-off-by: Major <major@emulate.rs>
Fernflower fails to decompile any exception handler with an end_pc
(`to` in Fernflower nomenclature) equal to the length of the code array,
even though this is permitted in the class file spec. This transformer
inserts a NOP at the end of any code array that has such an exception
handler.
Signed-off-by: Major <major@emulate.rs>
This commit:
* Renames isMethodImmutable to isMethodRenamable and flips the value of
the boolean it outputs accordingly.
* Updates all uses of isMethodRenamable to account for this.
* Makes the internal implementation more similar to isClassRenamable.
Signed-off-by: Graham <gpe@openrs2.dev>
GETSTATIC, PUTSTATIC and INVOKESTATIC (strangely) use the same field and
method resolution algorithms as their non-static equivalents.
While this doesn't cause problems for 550, as the *STATIC instructions
seem to always refer to the class containing the static definition,
Major reports that OSRS clients sometimes change the owner to a
subclass. This broke the old transformer.
This commit fixes it by applying the old to new owner mapping to an
entire disjoint set at a time.
Signed-off-by: Graham <gpe@openrs2.dev>
This allows us to avoid needing to worry about manipulating stack frames
in individual transformers, which adds lots of complexity. It's much
easier to just make ASM generate them for us.
Signed-off-by: Graham <gpe@openrs2.dev>
Fernflower was previously placing constructors in the middle of instance
methods. They look much nicer at the top.
This commit also ensures static methods appear before instance methods.
By moving all the static fields in a single class in one go, we can just
combine the <clinit> methods together. This allows us to remove all the
really complicated logic for extracting initializers, and also allows us
to move the last few array fields with complex initializers.
Depending on the class loading order, moving them can result in arrays
being empty, which breaks the client's functionality (e.g. it can't get
past the JS5 CRC check).
