Fix arg check and behavior of xpcall() to leave stack intact.

README.html

@@ -17,7 +17,7 @@
 Getting Started with LuaJ
 
 </h1>
-James Roseborough, Ian Farmer, Version 1.0
+James Roseborough, Ian Farmer, Version 1.0.1
 <p>
 <small>
 Copyright &copy; 2007-2009 Luaj.org.
@@ -36,6 +36,8 @@ Freely available under the terms of the
 <a href="#4">building</a>
 &middot;
 <a href="#5">downloads</a>
+&middot;
+<a href="#6">release notes</a>
 
 <!-- ====================================================================== -->
 <p>
@@ -334,3 +336,10 @@ and LuaForge:
 	<a href="http://luaforge.net/frs/?group_id=457">LuaForge Luaj Project Area</a>
 </pre>
 
+<h1>6 - <a name="6">Release Notes</a></h1>
+
+Main changes by version:
+<table cellspacing="10"><tr><td><table cellspacing="4">
+<tr><td>&nbsp;&nbsp;<b>1.0</b></td><td>Initial publicly supported release.</td></tr>
+<tr><td>&nbsp;&nbsp;<b>1.0.1</b></td><td>Fix arg check and behavior of xpcall() to leave stack intact.</td></tr>
+</table></td></tr></table>

src/core/org/luaj/lib/BaseLib.java

@@ -198,7 +198,7 @@ public class BaseLib extends LFunction {
 		case PCALL: {
 			vm.checkany(1);
 			int n = vm.gettop();
-			int s = vm.pcall( n-1, Lua.LUA_MULTRET, 0 );
+			int s = vm.pcall( n-1, Lua.LUA_MULTRET );
 			if ( s == 0 ) { // success, results are on stack
 				vm.pushboolean( true );
 				vm.insert( 1 );
@@ -210,26 +210,17 @@ public class BaseLib extends LFunction {
 			}
 		}
 		case XPCALL: {
-			LValue errfun = vm.checkany(3);
+			LValue errfun = vm.checkany(2);
 			vm.settop(1);
-			int s = vm.pcall( 0, Lua.LUA_MULTRET, 0 );
+			int s = vm.xpcall( 0, Lua.LUA_MULTRET, errfun );
 			if ( s == 0 ) { // success, results are on stack
 				vm.pushboolean( true );
 				vm.insert( 1 );
 				return -1;
 			} else { // error, error message is on the stack
-				vm.pushlvalue( errfun );
+				vm.pushboolean( false );
 				vm.insert( 1 );
-				s = vm.pcall( vm.gettop()-1, 1, 0 );
-				if ( s == 0 ) {
-					vm.pushboolean( false );
-					vm.insert( 1 );
-					return -1;
-				} else { // error in error handler
-					vm.pushboolean(false);
-					vm.pushstring("error in error handling");
-					return 2;
-				}
+				return 2;
 			}
 		}
 		case ERROR: {
@@ -489,7 +480,7 @@ public class BaseLib extends LFunction {
 		try {
 			while ( true ) {
 				setResult(vm,c);
-				if ( 0 != vm.pcall(0, 1, 0) ) {
+				if ( 0 != vm.pcall(0, 1) ) {
 					setErrorResult(vm, vm.tostring(2));
 					return false;
 				}

src/core/org/luaj/vm/LuaErrorException.java

@@ -74,14 +74,18 @@ public class LuaErrorException extends RuntimeException {
 	 * @return
 	 */
 	private static String addLineInfo(LuaState vm, String message, int level) {
-		if ( level == 0 || message == null )
-			return message;
+		// add position information
 		if ( vm == null ) {
 			if ( LThread.running != null )
 				vm = LThread.running.vm;
 			else
 				vm = LuaState.mainState;
+			if ( vm == null )
+				return message;
 		}
-		return vm != null? vm.getFileLine(level) + ": " + message: message;
+		if ( level > 0 ) {
+			message = vm.getFileLine(level);
+		}
+		return vm.luaV_call_errfunc( message );
 	}
 }

src/core/org/luaj/vm/LuaState.java

@@ -98,7 +98,7 @@ public class LuaState extends Lua {
     public int cc = -1;
     public CallInfo[] calls = new CallInfo[LUA_MINCALLS];
     protected Stack upvals = new Stack();
-	protected LFunction panic;
+	protected LValue errfunc;
     
 	static LuaState mainState;
     public LTable _G;
@@ -362,24 +362,6 @@ public class LuaState extends Lua {
 	 * <a href="#lua_pcall"><code>lua_pcall</code></a> always removes the
 	 * function and its arguments from the stack.
 	 * 
-	 * 
-	 * <p>
-	 * If <code>errfunc</code> is 0, then the error message returned on the
-	 * stack is exactly the original error message. Otherwise,
-	 * <code>errfunc</code> is the stack index of an
-	 * <em>error handler function</em>. (In the current implementation, this
-	 * index cannot be a pseudo-index.) In case of runtime errors, this function
-	 * will be called with the error message and its return value will be the
-	 * message returned on the stack by <a href="#lua_pcall"><code>lua_pcall</code></a>.
-	 * 
-	 * 
-	 * <p>
-	 * Typically, the error handler function is used to add more debug
-	 * information to the error message, such as a stack traceback. Such
-	 * information cannot be gathered after the return of <a href="#lua_pcall"><code>lua_pcall</code></a>,
-	 * since by then the stack has unwound.
-	 * 
-	 * 
 	 * <p>
 	 * The <a href="#lua_pcall"><code>lua_pcall</code></a> function returns
 	 * 0 in case of success or one of the following error codes (defined in
@@ -399,7 +381,7 @@ public class LuaState extends Lua {
 	 * 
 	 * </ul>
 	 */
-    public int pcall( int nargs, int nreturns, int errfunc ) {
+    public int pcall( int nargs, int nreturns ) {
         // save stack state
         int oldtop = top;
         int oldbase = base;
@@ -446,6 +428,46 @@ public class LuaState extends Lua {
         }
     }
 
+
+	/**
+	 * Calls a function in protected mode with an error function. 
+	 * <span class="apii">[-(nargs + 1), +(nresults|1), <em>-</em>]</span>
+	 * 
+	 * 
+	 * <p>
+	 * Both <code>nargs</code> and <code>nresults</code> have the same
+	 * meaning as in <a href="#lua_call"><code>lua_call</code></a>. If there
+	 * are no errors during the call, <a href="#lua_xpcall"><code>lua_xpcall</code></a>
+	 * behaves exactly like <a href="#lua_call"><code>lua_call</code></a>.
+	 * However, if there is any error, <a href="#lua_xpcall"><code>lua_xpcall</code></a>
+	 * catches it, pushes a single value on the stack (the error message), and
+	 * tries to call the supplied error function. 
+	 * 
+	 * <p>In case of runtime errors, this function
+	 * will be called with the error message and its return value will be the
+	 * message returned on the stack by <a href="#lua_pcall"><code>lua_pcall</code></a>.
+	 * 
+	 * <p>
+	 * Typically, the error handler function is used to add more debug
+	 * information to the error message, such as a stack traceback. Such
+	 * information cannot be gathered after the return of <a href="#lua_pcall"><code>lua_pcall</code></a>,
+	 * since by then the stack has unwound.
+	 * 
+	 * <p>
+	 * The return values for 
+	 * <a href="#lua_xpcall"><code>lua_xpcall</code></a> are the same as those for 
+	 * <a href="#lua_pcall"><code>lua_pcall</code></a>
+	 */
+    public int xpcall( int nargs, int nreturns, LValue errfunc ) {
+    	LValue preverrfunc = this.errfunc;
+    	try {
+    		this.errfunc = errfunc;
+    		return pcall( nargs, nreturns );
+    	} finally {
+    		this.errfunc = preverrfunc;
+    	}
+    }
+
 	/**
 	 * Loads a Lua chunk. <span class="apii">[-0, +1, <em>-</em>]</span>
 	 * 
@@ -2361,6 +2383,40 @@ public class LuaState extends Lua {
         }
 	}
 
+    
+    /** 
+     * Call the error function, if any, to possibly modify the message 
+     */
+	public String luaV_call_errfunc(String message) {
+		
+		// error function is run at most once
+		if ( errfunc == null )
+			return message;
+
+		// run the error function
+		int oldtop = top;
+    	int oldmask = hookmask;
+		LValue olderr = errfunc;
+        try {
+	    	hookmask = 0;
+			errfunc = null;		
+        	if ( cc >= 0 )
+        		top = base + this.calls[cc].closure.p.maxstacksize;
+  	    	pushlvalue(olderr);
+    		pushstring(message);
+   	    	call(1,1);
+        	return poplvalue().toJavaString();
+	        
+    	} catch ( Throwable t ) {
+    		return "error in error handling: "+t.getMessage();
+        	
+        } finally {
+        	top = oldtop;
+    		hookmask = oldmask;
+    		errfunc = olderr;
+        }
+	}
+	
 	
 	// ===========================================================================
 	// Debug hooks.  

src/j2se/lua.java

@@ -159,7 +159,7 @@ public class lua {
 			// load via "require"
 			vm.getglobal("require");
 			vm.pushstring(libname);
-			int status = vm.pcall(1, 0, 0);
+			int status = vm.pcall(1, 0);
 			if ( status == 0 )
 				return;
 

src/test/res/pcalls.lua

@@ -58,3 +58,18 @@ for i = 0,4 do
 	print( 'pcall(ge,i)', i, pcall(ge,i) )
 end
 
+-- xpcall tests
+local function goodfunction()	return 'from good function' end
+local function badfunction()	error( 'from bad function') end
+local function goodhandler(msg)	return '-->'..msg..'<--'    end
+local function badhandler(msg)	error( 'from bad handler' ) end
+print( 'xpcall(error,goodhandler)', ( xpcall(error,goodhandler) ) )
+print( 'xpcall(goodfunction,goodhandler)', ( xpcall(goodfunction,goodhandler) ) )
+print( 'xpcall(badfunction,goodhandler)', ( xpcall(badfunction,goodhandler) ) )
+print( 'xpcall(goodfunction,badhandler)', ( xpcall(goodfunction,badhandler) ) )
+print( 'xpcall(badfunction,badhandler)', ( xpcall(badfunction,badhandler) ) )
+print( 'xpcall(goodfunction,nil)', ( xpcall(goodfunction,nil) ) )
+print( 'xpcall(badfunction,nil)', ( xpcall(badfunction,nil) ) )
+print( 'xpcall(goodfunction)', ( pcall( function() return xpcall(goodfunction) end ) ) )
+print( 'xpcall(badfunction)', ( pcall( function() return xpcall(badfunction) end ) ) )
+

version.properties

@@ -1 +1 @@
-version: 1.0
+version: 1.0.1