feat: implemented ASM pattern matcher

4 files changed, 310 insertions, 0 deletions

diff --git a/src/main/java/ftbsc/lll/exception/InstructionMismatchException.java b/src/main/java/ftbsc/lll/exception/InstructionMismatchException.java
new file mode 100644
index 0000000..7dda1e6
--- /dev/null
+++ b/src/main/java/ftbsc/lll/exception/InstructionMismatchException.java
@@ -0,0 +1,19 @@
+package ftbsc.lll.exception;
+
+/**
+ * Thrown when attempting to build an InstructionSequence between two
+ * unconnected nodes.
+ */
+public class InstructionMismatchException extends RuntimeException {
+	public InstructionMismatchException(String message) {
+		super(message);
+	}
+
+	public InstructionMismatchException(String message, Throwable cause) {
+		super(message, cause);
+	}
+
+	public InstructionMismatchException(Throwable cause) {
+		super(cause);
+	}
+}
diff --git a/src/main/java/ftbsc/lll/exception/PatternNotFoundException.java b/src/main/java/ftbsc/lll/exception/PatternNotFoundException.java
new file mode 100644
index 0000000..e6d75b3
--- /dev/null
+++ b/src/main/java/ftbsc/lll/exception/PatternNotFoundException.java
@@ -0,0 +1,18 @@
+package ftbsc.lll.exception;
+
+/**
+ * Thrown when failing to find a pattern
+ */
+public class PatternNotFoundException extends RuntimeException {
+	public PatternNotFoundException(String message) {
+		super(message);
+	}
+
+	public PatternNotFoundException(String message, Throwable cause) {
+		super(message, cause);
+	}
+
+	public PatternNotFoundException(Throwable cause) {
+		super(cause);
+	}
+}
diff --git a/src/main/java/ftbsc/lll/tools/InsnSequence.java b/src/main/java/ftbsc/lll/tools/InsnSequence.java
new file mode 100644
index 0000000..fbd5f5c
--- /dev/null
+++ b/src/main/java/ftbsc/lll/tools/InsnSequence.java
@@ -0,0 +1,31 @@
+package ftbsc.lll.tools;
+
+import ftbsc.lll.exception.InstructionMismatchException;
+import org.objectweb.asm.Opcodes;
+import org.objectweb.asm.tree.AbstractInsnNode;
+import org.objectweb.asm.tree.InsnList;
+
+import java.util.Objects;
+
+/**
+ * Represents a sequence of instructions contained within two given nodes.
+ * Extends InsnList, but provides additional flexibility.
+ */
+public class InsnSequence extends InsnList implements Opcodes {
+	/**
+	 * Public constructor.
+	 * Must be given two non-null, connected nodes.
+	 * @param startNode the starting node of the pattern
+	 * @param endNode the first node of the pattern
+	 */
+	public InsnSequence(AbstractInsnNode startNode, AbstractInsnNode endNode) {
+		Objects.requireNonNull(startNode);
+		Objects.requireNonNull(endNode);
+		for(; startNode != endNode && startNode != null; startNode = startNode.getNext())
+			super.add(startNode);
+		if (startNode == null)
+			throw new InstructionMismatchException("Nodes" + getFirst() + " and " + getLast() + " are not connected.");
+	}
+
+	//TODO replace
+}
diff --git a/src/main/java/ftbsc/lll/tools/PatternMatcher.java b/src/main/java/ftbsc/lll/tools/PatternMatcher.java
new file mode 100644
index 0000000..04631fd
--- /dev/null
+++ b/src/main/java/ftbsc/lll/tools/PatternMatcher.java
@@ -0,0 +1,242 @@
+package ftbsc.lll.tools;
+
+import ftbsc.lll.exception.PatternNotFoundException;
+import org.objectweb.asm.tree.AbstractInsnNode;
+import org.objectweb.asm.tree.MethodNode;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Predicate;
+
+/**
+ * Describes a pattern to match on a list of ASM instructions.
+ */
+public class PatternMatcher {
+	/**
+	 * The list of predicates to match.
+	 */
+	private final List<Predicate<AbstractInsnNode>> predicates;
+
+	/**
+	 * Whether pattern search should be done from the end.
+	 */
+	private final boolean reverse;
+
+	/**
+	 * Patterns flagged with this ignore labels.
+	 */
+	private final boolean ignoreLabels;
+
+	/**
+	 * Patterns flagged with this ignore FRAME instructions.
+	 */
+	private final boolean ignoreFrames;
+
+	/**
+	 * Patterns flagged with this ignore LINENUMBER instructions.
+	 */
+	private final boolean ignoreLineNumbers;
+
+	/**
+	 * Private constructor because a PatternMatcher should only ever be initialized
+	 * through the builder.
+	 * @param predicates the list of predicates to match
+	 * @param reverse search direction
+	 * @param ignoreLabels whether LABEL instructions should be ignored
+	 * @param ignoreFrames whether FRAME instructions should be ignored
+	 * @param ignoreLineNumbers whether LINENUMBER instructions should be ignored
+	 */
+	private PatternMatcher(List<Predicate<AbstractInsnNode>> predicates, boolean reverse,
+	                       boolean ignoreLabels, boolean ignoreFrames, boolean ignoreLineNumbers) {
+		this.predicates = predicates;
+		this.reverse = reverse;
+		this.ignoreLabels = ignoreLabels;
+		this.ignoreFrames = ignoreFrames;
+		this.ignoreLineNumbers = ignoreLineNumbers;
+	}
+
+	/**
+	 * @return the Builder object for this PatternMatcher
+	 */
+	public static Builder builder() {
+		return new Builder();
+	}
+
+	/**
+	 * Tries to match the given pattern on a given MethodNode.
+	 * @param node the MethodNode to search
+	 * @return the InsnSequence object representing the matched pattern
+	 */
+	public InsnSequence find(MethodNode node) {
+		return find(reverse ? node.instructions.getLast() : node.instructions.getFirst());
+	}
+
+	/**
+	 * Tries to match the given pattern starting from a given node.
+	 * @param node the node to start the search on
+	 * @return the InsnSequence object representing the matched pattern
+	 */
+	public InsnSequence find(AbstractInsnNode node) {
+		if(node != null) {
+			int match = 0;
+			AbstractInsnNode first = null;
+			AbstractInsnNode last = null;
+			for(AbstractInsnNode cur = node; cur != null; cur = reverse ? cur.getPrevious() : cur.getNext()) {
+				if(ignoreLabels && cur.getType() == AbstractInsnNode.LABEL) continue;
+				if(ignoreFrames && cur.getType() == AbstractInsnNode.FRAME) continue;
+				if(ignoreLineNumbers && cur.getType() == AbstractInsnNode.LINE) continue;
+				if(predicates.get(match).test(cur)) {
+					match++;
+					if(first == null)
+						first = cur;
+				} else if(match == predicates.size()) {
+					last = cur.getPrevious(); //it was actually the preiovus run in this case
+					break;
+				} else break;
+			}
+			if(first != null && last != null)
+				return new InsnSequence(first, last);
+		}
+		throw new PatternNotFoundException("Failed to find pattern!");
+	}
+
+	/**
+	 * The Builder object for PatternMatcher.
+	 */
+	private static class Builder {
+
+		/**
+		 * List of predicates the pattern has to match.
+		 */
+		private final List<Predicate<AbstractInsnNode>> predicates = new ArrayList<>();
+
+		/**
+		 * Whether the pattern matching should proceed in reversed order.
+		 */
+		private boolean reverse = false;
+
+		/**
+		 * Patterns flagged with this ignore labels.
+		 */
+		private boolean ignoreLabels = false;
+
+		/**
+		 * Patterns flagged with this ignore FRAME instructions.
+		 */
+		private boolean ignoreFrames = false;
+
+		/**
+		 * Patterns flagged with this ignore LINENUMBER instructions.
+		 */
+		private boolean ignoreLineNumbers = false;
+
+		/**
+		 * Builds the pattern defined so far.
+		 * @return the built PatternMatcher
+		 */
+		public PatternMatcher build() {
+			return new PatternMatcher(predicates, reverse, ignoreLabels, ignoreFrames, ignoreLineNumbers);
+		}
+
+		/**
+		 * Sets the pattern to match starting from the end.
+		 * @return the builder's state after the operation
+		 */
+		public Builder reverse() {
+			this.reverse = true;
+			return this;
+		}
+
+		/**
+		 * Adds a custom predicate to the list. Also used internally.
+		 * @param predicate the predicate to add
+		 * @return the builder's state after the operation
+		 */
+		public Builder check(Predicate<AbstractInsnNode> predicate) {
+			predicates.add(predicate);
+			return this;
+		}
+
+		/**
+		 * Wildcard, matches any kind of node.
+		 * @return the builder's state after the operation
+		 */
+		public Builder any() {
+			return check(i -> true);
+		}
+
+		/**
+		 * Matches a specific opcode.
+		 * @param opcode opcode to match
+		 * @return the builder's state after the operation
+		 */
+		public Builder opcode(int opcode) {
+			return check(i -> i.getOpcode() == opcode);
+		}
+
+		/**
+		 * Matches a list of opcodes.
+		 * @param opcodes list of opcodes to match
+		 * @return the builder's state after the operation
+		 */
+		public Builder opcodes(int... opcodes) {
+			Builder res = this;
+			for(int o : opcodes)
+				res = opcode(o);
+			return res;
+		}
+
+		/**
+		 * Matches a method invokation of any kind: one of INVOKEVIRTUAL,
+		 * INVOKESPECIAL, INVOKESTATIC or INVOKEINTERFACE.
+		 * @return the builder's state after the operation
+		 */
+		public Builder method() {
+			return check(i -> i.getType() == AbstractInsnNode.METHOD_INSN);
+		}
+
+		/**
+		 * Matches a field invokation of any kind: one of GETSTATIC, PUTSTATIC,
+		 * GETFIELD or PUTFIELD.
+		 * @return the builder's state after the operation
+		 */
+		public Builder field() {
+			return check(i -> i.getType() == AbstractInsnNode.FIELD_INSN);
+		}
+
+		/**
+		 * Matches any kind of jump instruction.
+		 * @return the builder's state after the operation
+		 */
+		public Builder jump() {
+			return check(i -> i.getType() == AbstractInsnNode.JUMP_INSN);
+		}
+
+		/**
+		 * Tells the pattern matcher to ignore LABEL instructions.
+		 * @return the builder's state after the operation
+		 */
+		public Builder ignoreLabels() {
+			this.ignoreLabels = true;
+			return this;
+		}
+
+		/**
+		 * Tells the pattern matcher to ignore FRAME instructions.
+		 * @return the builder's state after the operation
+		 */
+		public Builder ignoreFrames() {
+			this.ignoreFrames = true;
+			return this;
+		}
+
+		/**
+		 * Tells the pattern matcher to ignore LINENUMBER instructions.
+		 * @return the builder's state after the operation
+		 */
+		public Builder ignoreLineNumbers() {
+			this.ignoreLineNumbers = true;
+			return this;
+		}
+	}
+}