Fix bug

[ 1005248 ] new.code() not cleanly checking its arguments

using the result of new.code() can still destroy the sun, but merely
calling the function shouldn't any more.

I also rewrote the existing tests of new.code() to use vastly less
un-bogus arguments, and added tests for the previous insane behaviours.

Lib/test/test_new.py

-from test.test_support import verbose, verify
+from test.test_support import verbose, verify, TestFailed
 import sys
 import new
 
@@ -99,11 +99,67 @@ print 'new.code()'
 # bogus test of new.code()
 # Note: Jython will never have new.code()
 if hasattr(new, 'code'):
-    # XXX should use less criminally bogus arguments!
-    d = new.code(3, 3, 3, 3, codestr, (), (), (),
-                 "<string>", "<name>", 1, "", (), ())
+    def f(a): pass
+    
+    c = f.func_code
+    argcount = c.co_argcount
+    nlocals = c.co_nlocals
+    stacksize = c.co_stacksize
+    flags = c.co_flags
+    codestring = c.co_code
+    constants = c.co_consts
+    names = c.co_names
+    varnames = c.co_varnames
+    filename = c.co_filename
+    name = c.co_name
+    firstlineno = c.co_firstlineno
+    lnotab = c.co_lnotab
+    freevars = c.co_freevars
+    cellvars = c.co_cellvars
+    
+    d = new.code(argcount, nlocals, stacksize, flags, codestring,
+                 constants, names, varnames, filename, name,
+                 firstlineno, lnotab, freevars, cellvars)
+    
     # test backwards-compatibility version with no freevars or cellvars
-    d = new.code(3, 3, 3, 3, codestr, (), (), (),
-                 "<string>", "<name>", 1, "")
+    d = new.code(argcount, nlocals, stacksize, flags, codestring,
+                 constants, names, varnames, filename, name,
+                 firstlineno, lnotab)
+    
+    try: # this used to trigger a SystemError
+        d = new.code(-argcount, nlocals, stacksize, flags, codestring,
+                     constants, names, varnames, filename, name,
+                     firstlineno, lnotab)
+    except ValueError:
+        pass
+    else:
+        raise TestFailed, "negative co_argcount didn't trigger an exception"
+
+    try: # this used to trigger a SystemError
+        d = new.code(argcount, -nlocals, stacksize, flags, codestring,
+                     constants, names, varnames, filename, name,
+                     firstlineno, lnotab)
+    except ValueError:
+        pass
+    else:
+        raise TestFailed, "negative co_nlocals didn't trigger an exception"
+    
+    try: # this used to trigger a Py_FatalError!
+        d = new.code(argcount, nlocals, stacksize, flags, codestring,
+                     constants, (5,), varnames, filename, name,
+                     firstlineno, lnotab)
+    except TypeError:
+        pass
+    else:
+        raise TestFailed, "non-string co_name didn't trigger an exception"
+
+    # new.code used to be a way to mutate a tuple...
+    class S(str): pass
+    t = (S("ab"),)
+    d = new.code(argcount, nlocals, stacksize, flags, codestring,
+                 constants, t, varnames, filename, name,
+                 firstlineno, lnotab)
+    verify(type(t[0]) is S, "eek, tuple changed under us!")
+
     if verbose:
         print d

Python/compile.c

@@ -88,6 +88,50 @@ static PyMemberDef code_memberlist[] = {
 	{NULL}	/* Sentinel */
 };
 
+/* Helper for code_new: return a shallow copy of a tuple that is
+   guaranteed to contain exact strings, by converting string subclasses
+   to exact strings and complaining if a non-string is found. */
+static PyObject*
+validate_and_copy_tuple(PyObject *tup)
+{
+	PyObject *newtuple;
+	PyObject *item;
+	int i, len;
+
+	len = PyTuple_GET_SIZE(tup);
+	newtuple = PyTuple_New(len);
+	if (newtuple == NULL)
+		return NULL;
+
+	for (i = 0; i < len; i++) {
+		item = PyTuple_GET_ITEM(tup, i);
+		if (PyString_CheckExact(item)) {
+			Py_INCREF(item);
+		}
+		else if (!PyString_Check(item)) {
+			PyErr_Format(
+				PyExc_TypeError,
+				"name tuples must contain only "
+				"strings, not '%.500s'",
+				item->ob_type->tp_name);
+			Py_DECREF(newtuple);
+			return NULL;
+		}
+		else {
+			item = PyString_FromStringAndSize(
+				PyString_AS_STRING(item),
+				PyString_GET_SIZE(item));
+			if (item == NULL) {
+				Py_DECREF(newtuple);
+				return NULL;
+			}
+		}
+		PyTuple_SET_ITEM(newtuple, i, item);
+	}
+
+	return newtuple;
+}
+
 PyDoc_STRVAR(code_doc,
 "code(argcount, nlocals, stacksize, flags, codestring, constants, names,\n\
       varnames, filename, name, firstlineno, lnotab[, freevars[, cellvars]])\n\
@@ -101,14 +145,13 @@ code_new(PyTypeObject *type, PyObject *args, PyObject *kw)
 	int nlocals;
 	int stacksize;
 	int flags;
-	PyObject *co;
-	PyObject *empty = NULL;
+	PyObject *co = NULL;;
 	PyObject *code;
 	PyObject *consts;
-	PyObject *names;
-	PyObject *varnames;
-	PyObject *freevars = NULL;
-	PyObject *cellvars = NULL;
+	PyObject *names, *ournames = NULL;
+	PyObject *varnames, *ourvarnames = NULL;
+	PyObject *freevars = NULL, *ourfreevars = NULL;
+	PyObject *cellvars = NULL, *ourcellvars = NULL;
 	PyObject *filename;
 	PyObject *name;
 	int firstlineno;
@@ -126,27 +169,48 @@ code_new(PyTypeObject *type, PyObject *args, PyObject *kw)
 			      &PyTuple_Type, &cellvars))
 		return NULL;
 
-	if (!PyObject_CheckReadBuffer(code)) {
-		PyErr_SetString(PyExc_TypeError,
-		  "bytecode object must be a single-segment read-only buffer");
-		return NULL;
+	if (argcount < 0) {
+		PyErr_SetString(
+			PyExc_ValueError, 
+			"code: argcount must not be negative");
+		goto cleanup;
 	}
 
-	if (freevars == NULL || cellvars == NULL) {
-		empty = PyTuple_New(0);
-		if (empty == NULL)
-			return NULL;
-		if (freevars == NULL)
-			freevars = empty;
-		if (cellvars == NULL)
-			cellvars = empty;
+	if (nlocals < 0) {
+		PyErr_SetString(
+			PyExc_ValueError, 
+			"code: nlocals must not be negative");
+		goto cleanup;
 	}
 
+	ournames = validate_and_copy_tuple(names);
+	if (ournames == NULL)
+		goto cleanup;
+	ourvarnames = validate_and_copy_tuple(varnames);
+	if (ourvarnames == NULL)
+		goto cleanup;
+	if (freevars)
+		ourfreevars = validate_and_copy_tuple(freevars);
+	else
+		ourfreevars = PyTuple_New(0);
+	if (ourfreevars == NULL)
+		goto cleanup;
+	if (cellvars)
+		ourcellvars = validate_and_copy_tuple(cellvars);
+	else
+		ourcellvars = PyTuple_New(0);
+	if (ourcellvars == NULL)
+		goto cleanup;
+
 	co = (PyObject *) PyCode_New(argcount, nlocals, stacksize, flags,
-				      code, consts, names, varnames,
-				      freevars, cellvars, filename, name,
-				      firstlineno, lnotab);
-	Py_XDECREF(empty);
+				     code, consts, ournames, ourvarnames,
+				     ourfreevars, ourcellvars, filename,
+				     name, firstlineno, lnotab);
+  cleanup:
+	Py_XDECREF(ournames);
+	Py_XDECREF(ourvarnames);
+	Py_XDECREF(ourfreevars);
+	Py_XDECREF(ourcellvars);
 	return co;
 }
 
@@ -302,21 +366,18 @@ all_name_chars(unsigned char *s)
 	return 1;
 }
 
-static int
+static void
 intern_strings(PyObject *tuple)
 {
 	int i;
 
 	for (i = PyTuple_GET_SIZE(tuple); --i >= 0; ) {
 		PyObject *v = PyTuple_GET_ITEM(tuple, i);
-		if (v == NULL || !PyString_Check(v)) {
+		if (v == NULL || !PyString_CheckExact(v)) {
 			Py_FatalError("non-string found in code slot");
-			PyErr_BadInternalCall();
-			return -1;
 		}
 		PyString_InternInPlace(&PyTuple_GET_ITEM(tuple, i));
 	}
-	return 0;
 }
 
 #define GETARG(arr, i) ((int)((arr[i+2]<<8) + arr[i+1]))