Grow lua stack instead of creating it at maximum size

 Also double the default size

src/main/java/org/squiddev/cobalt/ErrorFactory.java

@@ -26,7 +26,7 @@
 package org.squiddev.cobalt;
 
 import org.squiddev.cobalt.debug.DebugHandler;
-import org.squiddev.cobalt.debug.DebugInfo;
+import org.squiddev.cobalt.debug.DebugFrame;
 import org.squiddev.cobalt.lib.DebugLib;
 
 /**
@@ -104,7 +104,7 @@ public static LuaError operandError(LuaState state, LuaValue operand, String ver
 		String type = operand.typeName();
 		LuaString[] kind = null;
 		if (stack >= 0) {
-			DebugInfo info = DebugHandler.getDebugState(state.getCurrentThread()).getDebugInfo();
+			DebugFrame info = DebugHandler.getDebugState(state.getCurrentThread()).getStack();
 			if (info != null && info.closure != null) {
 				if (stack < info.closure.getPrototype().maxstacksize) {
 					kind = DebugLib.getobjname(info, stack);

src/main/java/org/squiddev/cobalt/LuaThread.java

@@ -25,7 +25,7 @@
 package org.squiddev.cobalt;
 
 import org.squiddev.cobalt.debug.DebugHandler;
-import org.squiddev.cobalt.debug.DebugInfo;
+import org.squiddev.cobalt.debug.DebugFrame;
 import org.squiddev.cobalt.debug.DebugState;
 import org.squiddev.cobalt.function.LuaFunction;
 import org.squiddev.cobalt.lib.CoroutineLib;
@@ -92,8 +92,6 @@ public class LuaThread extends LuaValue {
 	 */
 	public LuaValue err;
 
-	public static final int MAX_CALLSTACK = 256;
-
 	public final LuaState luaState;
 
 	/**
@@ -186,7 +184,7 @@ public boolean isAlive() {
 	 * @return LuaFunction on the call stack, or null if outside of range of active stack
 	 */
 	public static LuaFunction getCallstackFunction(LuaState state, int level) {
-		DebugInfo info = DebugHandler.getDebugState(state.currentThread).getDebugInfo(level);
+		DebugFrame info = DebugHandler.getDebugState(state.currentThread).getDebugInfo(level);
 		return info == null ? null : info.func;
 	}
 
@@ -271,8 +269,10 @@ public synchronized void run() {
 				result = function.invoke(state, a);
 			} catch (LuaError e) {
 				error = e.value;
+			} catch (StackOverflowError e) {
+				error = valueOf("stack overflow");
 			} catch (Throwable t) {
-				error = valueOf(t.getMessage());
+				error = valueOf("vm error: " + t.toString());
 			} finally {
 				markDead();
 				notify();

src/main/java/org/squiddev/cobalt/debug/DebugInfo.java → src/main/java/org/squiddev/cobalt/debug/DebugFrame.java

@@ -36,7 +36,7 @@
  * Each thread will get a DebugState attached to it by the debug library
  * which will track function calls, hook functions, etc.
  */
-public final class DebugInfo {
+public final class DebugFrame {
 	/**
 	 * The debug info's function
 	 */
@@ -52,18 +52,18 @@ public final class DebugInfo {
 	 */
 	public LuaValue[] stack;
 
-	public final DebugInfo previous;
+	public final DebugFrame previous;
 
 
 	public Varargs varargs, extras;
 	public int pc, top;
 
-	public DebugInfo(DebugInfo previous) {
+	public DebugFrame(DebugFrame previous) {
 		this.previous = previous;
 		func = null;
 	}
 
-	public DebugInfo(LuaFunction func) {
+	public DebugFrame(LuaFunction func) {
 		pc = -1;
 		previous = null;
 		setFunction(func);

src/main/java/org/squiddev/cobalt/debug/DebugHandler.java

@@ -64,7 +64,7 @@ public final DebugState getDebugState() {
 	 * @param func the function called
 	 */
 	public void onCall(DebugState ds, LuaFunction func) {
-		DebugInfo di = ds.pushInfo();
+		DebugFrame di = ds.pushInfo();
 		di.setFunction(func);
 
 		if (!ds.inhook && ds.hookcall) ds.callHookFunc(CALL, NIL);
@@ -79,8 +79,8 @@ public void onCall(DebugState ds, LuaFunction func) {
 	 * @param stack The current lua stack
 	 * @return The pushed info
 	 */
-	public DebugInfo onCall(DebugState ds, LuaClosure func, Varargs args, LuaValue[] stack) {
-		DebugInfo di = ds.pushInfo();
+	public DebugFrame onCall(DebugState ds, LuaClosure func, Varargs args, LuaValue[] stack) {
+		DebugFrame di = ds.pushInfo();
 		di.setFunction(func, args, stack);
 
 		if (!ds.inhook && ds.hookcall) {
@@ -117,7 +117,7 @@ public void onReturn(DebugState ds) {
 	 * @param extras Extra arguments
 	 * @param top    The top of the callstack
 	 */
-	public void onInstruction(DebugState ds, DebugInfo di, int pc, Varargs extras, int top) {
+	public void onInstruction(DebugState ds, DebugFrame di, int pc, Varargs extras, int top) {
 		Prototype prototype = ds.inhook || di.closure == null ? null : di.closure.getPrototype();
 		int oldPc = di.pc;
 

src/main/java/org/squiddev/cobalt/debug/DebugState.java

@@ -35,6 +35,12 @@
  * DebugState is associated with a Thread
  */
 public final class DebugState {
+	public static final int MAX_SIZE = 512;
+
+	public static final int DEFAULT_SIZE = 8;
+
+	private static final DebugFrame[] EMPTY = new DebugFrame[0];
+
 	/**
 	 * The thread that owns this object
 	 */
@@ -55,7 +61,7 @@ public final class DebugState {
 	/**
 	 * The stack of debug info
 	 */
-	private final DebugInfo[] debugInfo = new DebugInfo[LuaThread.MAX_CALLSTACK];
+	private DebugFrame[] stack = EMPTY;
 
 	/**
 	 * The hook function to call
@@ -83,12 +89,6 @@ public DebugState(LuaThread thread) {
 		this.handler = state.debug;
 	}
 
-	public DebugInfo getInfo(int call) {
-		DebugInfo di = debugInfo[call];
-		if (di == null) debugInfo[call] = di = new DebugInfo(call == 0 ? null : getInfo(call - 1));
-		return di;
-	}
-
 	public void onCall(LuaFunction func) {
 		handler.onCall(this, func);
 	}
@@ -102,19 +102,32 @@ public void onReturn() {
 	 *
 	 * @return The created info
 	 */
-	protected DebugInfo pushInfo() {
+	protected DebugFrame pushInfo() {
 		int top = this.top + 1;
-		if (top >= LuaThread.MAX_CALLSTACK) throw new LuaError("stack overflow");
+
+		DebugFrame[] frames = stack;
+		int length = frames.length;
+		if (top >= length) {
+			if (top >= MAX_SIZE) throw new LuaError("stack overflow");
+
+			int newSize = length == 0 ? DEFAULT_SIZE : length + (length / 2);
+			DebugFrame[] f = new DebugFrame[newSize];
+			System.arraycopy(frames, 0, f, 0, frames.length);
+			for (int i = frames.length; i < newSize; ++i) {
+				f[i] = new DebugFrame(i > 0 ? f[i - 1] : null);
+			}
+			frames = stack = f;
+		}
 
 		this.top = top;
-		return getInfo(top);
+		return frames[top];
 	}
 
 	/**
 	 * Pop a debug info off the stack
 	 */
 	protected void popInfo() {
-		debugInfo[top--].clear();
+		stack[top--].clear();
 	}
 
 	protected void callHookFunc(LuaString type, LuaValue arg) {
@@ -154,8 +167,8 @@ public void setHook(LuaFunction func, boolean call, boolean line, boolean rtrn,
 	 *
 	 * @return The top debug info or {@code null}
 	 */
-	public DebugInfo getDebugInfo() {
-		return top >= 0 ? debugInfo[top] : null;
+	public DebugFrame getStack() {
+		return top >= 0 ? stack[top] : null;
 	}
 
 	/**
@@ -164,8 +177,8 @@ public DebugInfo getDebugInfo() {
 	 * @param level The level to get at
 	 * @return The debug info or {@code null}
 	 */
-	public DebugInfo getDebugInfo(int level) {
-		return level >= 0 && level <= top ? debugInfo[top - level] : null;
+	public DebugFrame getDebugInfo(int level) {
+		return level >= 0 && level <= top ? stack[top - level] : null;
 	}
 
 	/**
@@ -174,13 +187,13 @@ public DebugInfo getDebugInfo(int level) {
 	 * @param func The function to find
 	 * @return The debug info for this function
 	 */
-	public DebugInfo findDebugInfo(LuaFunction func) {
+	public DebugFrame findDebugInfo(LuaFunction func) {
 		for (int i = top - 1; --i >= 0; ) {
-			if (debugInfo[i].func == func) {
-				return debugInfo[i];
+			if (stack[i].func == func) {
+				return stack[i];
 			}
 		}
-		return new DebugInfo(func);
+		return new DebugFrame(func);
 	}
 
 	@Override

src/main/java/org/squiddev/cobalt/function/LuaInterpreter.java

@@ -29,7 +29,7 @@
 import org.squiddev.cobalt.compiler.LoadState;
 import org.squiddev.cobalt.compiler.LuaC;
 import org.squiddev.cobalt.debug.DebugHandler;
-import org.squiddev.cobalt.debug.DebugInfo;
+import org.squiddev.cobalt.debug.DebugFrame;
 import org.squiddev.cobalt.debug.DebugState;
 
 import static org.squiddev.cobalt.Constants.FALSE;
@@ -219,7 +219,7 @@ protected Varargs execute(LuaState state, LuaValue[] stack, Varargs varargs) {
 		// debug wants args to this function
 		DebugHandler handler = state.debug;
 		DebugState ds = handler.getDebugState();
-		DebugInfo di = handler.onCall(ds, this, varargs, stack);
+		DebugFrame di = handler.onCall(ds, this, varargs, stack);
 
 		// process instructions
 		try {

src/main/java/org/squiddev/cobalt/lib/DebugLib.java

@@ -27,7 +27,7 @@
 
 import org.squiddev.cobalt.*;
 import org.squiddev.cobalt.debug.DebugHandler;
-import org.squiddev.cobalt.debug.DebugInfo;
+import org.squiddev.cobalt.debug.DebugFrame;
 import org.squiddev.cobalt.debug.DebugState;
 import org.squiddev.cobalt.function.LibFunction;
 import org.squiddev.cobalt.function.LuaClosure;
@@ -229,10 +229,10 @@ protected static Varargs _getinfo(LuaState state, Varargs args, LuaValue level0f
 
 		// find the stack info
 		DebugState ds = DebugHandler.getDebugState(thread);
-		DebugInfo di;
+		DebugFrame di;
 		if (func.isNumber()) {
 			int level = func.checkInteger();
-			di = level > 0 ? ds.getDebugInfo(level - 1) : new DebugInfo(level0func.checkFunction());
+			di = level > 0 ? ds.getDebugInfo(level - 1) : new DebugFrame(level0func.checkFunction());
 		} else {
 			di = ds.findDebugInfo(func.checkFunction());
 		}
@@ -309,7 +309,7 @@ private static Varargs _getlocal(LuaState state, Varargs args) {
 		int local = args.arg(i).checkInteger();
 
 		DebugState ds = DebugHandler.getDebugState(thread);
-		DebugInfo di = ds.getDebugInfo(level - 1);
+		DebugFrame di = ds.getDebugInfo(level - 1);
 		LuaString name = (di != null ? di.getLocalName(local) : null);
 		if (name != null) {
 			LuaValue value = di.stack[local - 1];
@@ -329,7 +329,7 @@ private static Varargs _setlocal(LuaState state, Varargs args) {
 		LuaValue value = args.arg(a++);
 
 		DebugState ds = DebugHandler.getDebugState(thread);
-		DebugInfo di = ds.getDebugInfo(level - 1);
+		DebugFrame di = ds.getDebugInfo(level - 1);
 		LuaString name = (di != null ? di.getLocalName(local) : null);
 		if (name != null) {
 			di.stack[local - 1] = value;
@@ -444,7 +444,7 @@ public static String traceback(LuaThread thread, int level) {
 		StringBuilder sb = new StringBuilder();
 		DebugState ds = DebugHandler.getDebugState(thread);
 		sb.append("stack traceback:");
-		DebugInfo di = ds.getDebugInfo(level);
+		DebugFrame di = ds.getDebugInfo(level);
 		if (di != null) {
 			sb.append("\n\t");
 			sb.append(di.sourceline());
@@ -470,7 +470,7 @@ public static String traceback(LuaThread thread, int level) {
 	 */
 	public static String fileline(LuaThread thread) {
 		DebugState ds = DebugHandler.getDebugState(thread);
-		DebugInfo di;
+		DebugFrame di;
 		for (int i = 0, n = ds.top; i < n; i++) {
 			di = ds.getDebugInfo(i);
 			if (di != null && di.closure != null) {
@@ -482,7 +482,7 @@ public static String fileline(LuaThread thread) {
 
 	public static String fileline(LuaThread thread, int level) {
 		DebugState ds = DebugHandler.getDebugState(thread);
-		DebugInfo di = ds.getDebugInfo(level);
+		DebugFrame di = ds.getDebugInfo(level);
 		return di != null ? di.sourceline() : null;
 	}
 
@@ -494,7 +494,7 @@ static void lua_assert(boolean x) {
 
 
 	// return StrValue[] { name, namewhat } if found, null if not
-	public static LuaString[] getobjname(DebugInfo di, int stackpos) {
+	public static LuaString[] getobjname(DebugFrame di, int stackpos) {
 		LuaString name;
 		if (di.closure != null) { // a Lua function?
 			Prototype p = di.closure.getPrototype();

src/test/java/org/squiddev/cobalt/ProtectionTest.java

@@ -5,7 +5,7 @@
 import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 import org.squiddev.cobalt.debug.DebugHandler;
-import org.squiddev.cobalt.debug.DebugInfo;
+import org.squiddev.cobalt.debug.DebugFrame;
 import org.squiddev.cobalt.debug.DebugState;
 
 import java.io.IOException;
@@ -51,7 +51,7 @@ public void poll() {
 			}
 
 			@Override
-			public void onInstruction(DebugState ds, DebugInfo di, int pc, Varargs extras, int top) {
+			public void onInstruction(DebugState ds, DebugFrame di, int pc, Varargs extras, int top) {
 				poll();
 				super.onInstruction(ds, di, pc, extras, top);
 			}