From 45ab4741a5ace18e77b027a2f7e318327c33d4b7 Mon Sep 17 00:00:00 2001
From: Cliff Click <cliffc@acm.org>
Date: Mon, 30 Sep 2024 09:15:12 -0700
Subject: Tests for negative array size and runtime OOB

---
 .../main/java/com/seaofnodes/simple/Parser.java    |  2 ++
 .../com/seaofnodes/simple/node/ReturnNode.java     |  3 ++-
 .../java/com/seaofnodes/simple/Chapter15Test.java  | 28 ++++++++++++++++++++++
 .../com/seaofnodes/simple/evaluator/Evaluator.java |  4 +++-
 4 files changed, 35 insertions(+), 2 deletions(-)

(limited to 'chapter15/src')

diff --git a/chapter15/src/main/java/com/seaofnodes/simple/Parser.java b/chapter15/src/main/java/com/seaofnodes/simple/Parser.java
index d9726d28..ec040b4f 100644
--- a/chapter15/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter15/src/main/java/com/seaofnodes/simple/Parser.java
@@ -711,6 +711,8 @@ public class Parser {
 
     private Node newArray(Type t) {
         Node len = parseExpression().keep();
+        if( !(len._type instanceof TypeInteger) )
+            throw error("Cannot allocate an array with length "+len._type);
         TypeStruct ary = (TypeStruct)TYPES.get("[]"+t.str());
         if( ary == null ) {
             TYPES.put("[]"+t.str(), ary = TypeStruct.makeAry(TypeInteger.BOT,ALIAS++,t,ALIAS++));
diff --git a/chapter15/src/main/java/com/seaofnodes/simple/node/ReturnNode.java b/chapter15/src/main/java/com/seaofnodes/simple/node/ReturnNode.java
index 444b76a8..e12f1fef 100644
--- a/chapter15/src/main/java/com/seaofnodes/simple/node/ReturnNode.java
+++ b/chapter15/src/main/java/com/seaofnodes/simple/node/ReturnNode.java
@@ -17,7 +17,8 @@ public class ReturnNode extends CFGNode {
 
     public ReturnNode(Node ctrl, Node data, ScopeNode scope) {
         super(ctrl, data);
-        // We lookup memory slices by the naming convention that they start with $
+        // Add memory slices to Return, so all memory updates are live-on-exit.
+        // We look up memory slices by the naming convention that they start with $.
         // We could also use implicit knowledge that all memory projects are at offset >= 2
         if( scope != null ) {
             String[] names = scope.reverseNames();
diff --git a/chapter15/src/test/java/com/seaofnodes/simple/Chapter15Test.java b/chapter15/src/test/java/com/seaofnodes/simple/Chapter15Test.java
index 2955361a..a3dd48d0 100644
--- a/chapter15/src/test/java/com/seaofnodes/simple/Chapter15Test.java
+++ b/chapter15/src/test/java/com/seaofnodes/simple/Chapter15Test.java
@@ -89,4 +89,32 @@ int is = new int[2];
         try { parser.parse(false).iterate(false); fail(); }
         catch( Exception e ) { assertEquals("Type *[]int is not of declared type int",e.getMessage()); }
     }
+
+    @Test
+    public void testBad2() {
+        Parser parser = new Parser(
+"""
+int[] is = new int[3.14];
+return is[1];
+""");
+        try { parser.parse(false).iterate(false); fail(); }
+        catch( Exception e ) { assertEquals("Cannot allocate an array with length 3.14",e.getMessage()); }
+    }
+
+    @Test
+    public void testBad3() {
+        Parser parser = new Parser(
+"""
+int[] is = new int[arg];
+return is[1];
+""");
+        StopNode stop = parser.parse(false).iterate(false);
+        assertEquals("return 0;", stop.toString());
+        assertEquals(0L, Evaluator.evaluate(stop,  4));
+        try { Evaluator.evaluate(stop,0); }
+        catch( ArrayIndexOutOfBoundsException e ) { assertEquals("Array index 1 out of bounds for array length 0",e.getMessage()); }
+        try { Evaluator.evaluate(stop,-1); }
+        catch( NegativeArraySizeException e ) { assertEquals("-1",e.getMessage()); }
+    }
+
 }
diff --git a/chapter15/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java b/chapter15/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java
index 40d73b19..e59017e7 100644
--- a/chapter15/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java
+++ b/chapter15/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java
@@ -91,6 +91,8 @@ public class Evaluator {
             int base  = alloc._ptr._obj.aryBase();
             int scale = alloc._ptr._obj.aryScale();
             long n = (sz-base)>>scale;
+            if( n < 0 )
+                throw new NegativeArraySizeException(""+n);
             body = new Object[(int)n+1]; // Array body
             body[0] = n;                 // Array length
         } else {
@@ -113,7 +115,7 @@ public class Evaluator {
             int scale = from.struct.aryScale();
             long i = ((Long)off - base)>>scale;
             if( i < 0 || i >= len )
-                throw new RuntimeException("Array index out of bounds " + off + " <= " + len);
+                throw new ArrayIndexOutOfBoundsException("Array index out of bounds " + off + " <= " + len);
             return from.fields[(int)i+1];
 
         } else
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