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> 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> 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) { if(reverse) return new InsnSequence(last, first); else return new InsnSequence(first, last); } } throw new PatternNotFoundException("Failed to find pattern!"); } /** * The Builder object for PatternMatcher. */ public static class Builder { /** * List of predicates the pattern has to match. */ private final List> 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 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); } /** * Matches any kind of label. * @return the builder's state after the operation */ public Builder label() { return check(i -> i.getType() == AbstractInsnNode.LABEL); } /** * 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; } } }