From 8052a90d04202667819b20b88f2059db8664edac Mon Sep 17 00:00:00 2001
From: Bob Flavin <riboribo@gmail.com>
Date: Wed, 3 Dec 2014 11:58:04 -0500
Subject: [PATCH] Extended string concatenation code to handle arguments in
 'new StringBuilder()' constructer, ie  'new StringBuilder("str")' or 'new
 StringBuilder(String.valueof(varName))'

---
 .../core/dex/visitors/SimplifyVisitor.java    | 95 ++++++++++++-------
 1 file changed, 60 insertions(+), 35 deletions(-)

diff --git a/jadx-core/src/main/java/jadx/core/dex/visitors/SimplifyVisitor.java b/jadx-core/src/main/java/jadx/core/dex/visitors/SimplifyVisitor.java
index 6ed8d488..030e9b15 100644
--- a/jadx-core/src/main/java/jadx/core/dex/visitors/SimplifyVisitor.java
+++ b/jadx-core/src/main/java/jadx/core/dex/visitors/SimplifyVisitor.java
@@ -5,6 +5,7 @@ import jadx.core.dex.info.FieldInfo;
 import jadx.core.dex.info.MethodInfo;
 import jadx.core.dex.instructions.ArithNode;
 import jadx.core.dex.instructions.ArithOp;
+import jadx.core.dex.instructions.ConstStringNode;
 import jadx.core.dex.instructions.IfNode;
 import jadx.core.dex.instructions.IndexInsnNode;
 import jadx.core.dex.instructions.InsnType;
@@ -86,17 +87,6 @@ public class SimplifyVisitor extends AbstractVisitor {
 				}
 				break;
 
-			case MOVE:
-				InsnArg firstArg = insn.getArg(0);
-				if (firstArg.isLiteral()) {
-					InsnNode constInsn = new InsnNode(InsnType.CONST, 1);
-					constInsn.setResult(insn.getResult());
-					constInsn.addArg(firstArg);
-					constInsn.copyAttributesFrom(insn);
-					return constInsn;
-				}
-				break;
-
 			default:
 				break;
 		}
@@ -134,30 +124,65 @@ public class SimplifyVisitor extends AbstractVisitor {
 	}
 
 	private static InsnNode convertInvoke(MethodNode mth, InsnNode insn) {
-		MethodInfo callMth = ((InvokeNode) insn).getCallMth();
-		if (callMth.getDeclClass().getFullName().equals(Consts.CLASS_STRING_BUILDER)
-				&& callMth.getShortId().equals(Consts.MTH_TOSTRING_SIGNATURE)
-				&& insn.getArg(0).isInsnWrap()) {
-			try {
-				List<InsnNode> chain = flattenInsnChain(insn);
-				if (chain.size() > 1 && chain.get(0).getType() == InsnType.CONSTRUCTOR) {
-					ConstructorInsn constr = (ConstructorInsn) chain.get(0);
-					if (constr.getClassType().getFullName().equals(Consts.CLASS_STRING_BUILDER)
-							&& constr.getArgsCount() == 0) {
-						int len = chain.size();
-						InsnNode concatInsn = new InsnNode(InsnType.STR_CONCAT, len - 1);
-						for (int i = 1; i < len; i++) {
-							concatInsn.addArg(chain.get(i).getArg(1));
-						}
-						concatInsn.setResult(insn.getResult());
-						return concatInsn;
-					}
-				}
-			} catch (Throwable e) {
-				LOG.debug("Can't convert string concatenation: {} insn: {}", mth, insn, e);
-			}
-		}
-		return null;
+	  MethodInfo callMth = ((InvokeNode) insn).getCallMth();
+
+          // If this is a 'new StringBuilder(xxx).append(yyy).append(zzz).toString(), 
+          // convert it to STRING_CONCAT pseudo instruction.
+	  if (callMth.getDeclClass().getFullName().equals(Consts.CLASS_STRING_BUILDER)
+	      && callMth.getShortId().equals(Consts.MTH_TOSTRING_SIGNATURE)
+	      && insn.getArg(0).isInsnWrap()) {
+	    try {
+	      List<InsnNode> chain = flattenInsnChain(insn);
+	      int constrIndex = -1;  //RAF
+	      // Case where new StringBuilder() is called with NO args (the entire
+	      // string is created using .append() calls:
+	      if (chain.size()>1 && chain.get(0).getType()==InsnType.CONSTRUCTOR) {
+	        constrIndex = 0;
+	      } else if (chain.size()>2 && chain.get(1).getType()==InsnType.CONSTRUCTOR) {
+	        //RAF Case where the first string element is String arg to the 
+	        // new StringBuilder("xxx") constructor
+	        constrIndex = 1;
+	      } else if (chain.size()>3 && chain.get(2).getType()==InsnType.CONSTRUCTOR) {
+	        //RAF Case where the first string element is String.valueOf() arg 
+	        // to the new StringBuilder(String.valueOf(zzz)) constructor
+	        constrIndex = 2;
+	      }
+
+	      if (constrIndex != -1) {  // If we found a CONSTRUCTOR, is it a StringBuilder?
+	        ConstructorInsn constr = (ConstructorInsn) chain.get(constrIndex);
+	        if (constr.getClassType().getFullName().equals(Consts.CLASS_STRING_BUILDER)) {
+	          int len = chain.size(),  argInd = 1;
+	          InsnNode concatInsn = new InsnNode(InsnType.STR_CONCAT, len-1);
+	          InsnNode argInsn;
+	          if (constrIndex > 0) {  // There was an arg to the StringBuilder constr
+	            InsnWrapArg iwa;
+	            if (constrIndex==2 
+	                && (argInsn = chain.get(1)).getType()==InsnType.INVOKE
+	                && ((InvokeNode)argInsn).getCallMth().getName().compareTo("valueOf")==0) {
+	              // The argument of new StringBuilder() is a String.valueOf(chainElement0)
+	              iwa = (InsnWrapArg)argInsn.getArg(0);
+	              argInd = 3;  // Cause for loop below to skip to after the constructor
+	            } else {
+	              ConstStringNode csn = (ConstStringNode)chain.get(0);
+	              iwa = new InsnWrapArg(csn);
+	              argInd = 2;  // Cause for loop below to skip to after the constructor
+	            }
+	            concatInsn.addArg(iwa);
+	          }
+
+	          for (; argInd < len; argInd++) {  // Add the .append(xxx) arg string to concat 
+	            concatInsn.addArg(chain.get(argInd).getArg(1));
+	          }
+	          concatInsn.setResult(insn.getResult());
+	          return concatInsn;
+	        } // end of if constructor is for StringBuilder
+	      } // end of if we found a constructor early in the chain
+
+	    } catch (Throwable e) {
+	      LOG.debug("Can't convert string concatenation: {} insn: {}", mth, insn, e);
+	    }
+	  }
+	  return null;
 	}
 
 	private static InsnNode simplifyArith(InsnNode insn) {
-- 
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