Added a new "base" type, IOobject for which most of the
operations are defined.  This will, hopefully clarify
some of the logic.

Added close test to raise proper error when operations
are performed on closed StringIOs.

Added a position argument to the truncate method.

Added a size argument to readline.

Added PyArg_Parse calls for methods that don't take arguments to
make sure they don't take arguments.
diff --git a/Modules/cStringIO.c b/Modules/cStringIO.c
index 4341a8f..1cb40ea 100644
--- a/Modules/cStringIO.c
+++ b/Modules/cStringIO.c
@@ -85,170 +85,205 @@
 #include "import.h"
 #include "cStringIO.h"
 
-#define UNLESS(E) if(!(E))
+#define UNLESS(E) if (!(E))
 
-/* Declarations for objects of type StringO */
 
-typedef struct {
-  PyObject_HEAD
-  char *buf;
-  int pos, string_size, buf_size, softspace;
-} Oobject;
+/* Declaration for file-like objects that manage data as strings 
 
-/* Declarations for objects of type StringI */
+   The IOobject type should be though of as a common base type for
+   Iobjects, which provide input (read-only) StringIO objects and
+   Oobjects, which provide read-write objects.  Most of the methods
+   depend only on common data.
+*/
 
 typedef struct {
   PyObject_HEAD
   char *buf;
   int pos, string_size;
+} IOobject;
+
+#define IOOOBJECT(O) ((IOobject*)(O))
+
+/* Declarations for objects of type StringO */
+
+typedef struct { /* Subtype of IOobject */
+  PyObject_HEAD
+  char *buf;
+  int pos, string_size;
+
+  int buf_size, softspace;
+} Oobject;
+
+/* Declarations for objects of type StringI */
+
+typedef struct { /* Subtype of IOobject */
+  PyObject_HEAD
+  char *buf;
+  int pos, string_size;
+
   PyObject *pbuf;
 } Iobject;
 
-static char O_reset__doc__[] = 
-"reset() -- Reset the file position to the beginning"
+/* IOobject (common) methods */
+
+static char IO_flush__doc__[] = "flush(): does nothing.";
+
+static int
+IO__opencheck(IOobject *self) {
+        UNLESS (self->buf) {
+                PyErr_SetString(PyExc_ValueError,
+                                "I/O operation on closed file");
+                return 0;
+        }
+        return 1;
+}
+
+static PyObject *
+IO_flush(IOobject *self, PyObject *args) {
+
+        UNLESS (IO__opencheck(self)) return NULL;
+        UNLESS (PyArg_ParseTuple(args, ":flush")) return NULL;
+
+        Py_INCREF(Py_None);
+        return Py_None;
+}
+
+static char IO_getval__doc__[] = 
+   "getvalue([use_pos]) -- Get the string value."
+   "\n"
+   "If use_pos is specified and is a true value, then the string returned\n"
+   "will include only the text up to the current file position.\n"
 ;
 
 static PyObject *
-O_reset(Oobject *self, PyObject *args) {
-  self->pos = 0;
-
-  Py_INCREF(Py_None);
-  return Py_None;
+IO_cgetval(PyObject *self) {
+        UNLESS (IO__opencheck(IOOOBJECT(self))) return NULL;
+        return PyString_FromStringAndSize(((IOobject*)self)->buf,
+                                          ((IOobject*)self)->pos);
 }
 
-
-static char O_tell__doc__[] =
-"tell() -- get the current position.";
-
 static PyObject *
-O_tell(Oobject *self, PyObject *args) {
-  return PyInt_FromLong(self->pos);
+IO_getval(IOobject *self, PyObject *args) {
+        PyObject *use_pos=Py_None;
+        int s;
+
+        UNLESS (IO__opencheck(self)) return NULL;
+        UNLESS (PyArg_ParseTuple(args,"|O:getval",&use_pos)) return NULL;
+
+        if (PyObject_IsTrue(use_pos)) {
+                  s=self->pos;
+                  if (s > self->string_size) s=self->string_size;
+        }
+        else
+                  s=self->string_size;
+        return PyString_FromStringAndSize(self->buf, s);
 }
 
-
-static char O_seek__doc__[] =
-"seek(position)       -- set the current position\n"
-"seek(position, mode) -- mode 0: absolute; 1: relative; 2: relative to EOF";
+static char IO_isatty__doc__[] = "isatty(): always returns 0";
 
 static PyObject *
-O_seek(Oobject *self, PyObject *args) {
-  int position, mode = 0;
+IO_isatty(IOobject *self, PyObject *args) {
 
-  UNLESS(PyArg_ParseTuple(args, "i|i:seek", &position, &mode)) {
-    return NULL;
-  }
+        UNLESS (PyArg_ParseTuple(args, ":isatty")) return NULL;
 
-  if (mode == 2) {
-    position += self->string_size;
-  }
-  else if (mode == 1) {
-    position += self->pos;
-  }
-
-  if (position > self->buf_size) {
-      self->buf_size*=2;
-      if(self->buf_size <= position) self->buf_size=position+1;
-      UNLESS(self->buf=(char*)realloc(self->buf,self->buf_size*sizeof(char))) {
-	  self->buf_size=self->pos=0;
-	  return PyErr_NoMemory();
-	}
-    }
-  else if(position < 0) position=0;
-  
-  self->pos=position;
-
-  while(--position >= self->string_size) self->buf[position]=0;
-
-  Py_INCREF(Py_None);
-  return Py_None;
+        return PyInt_FromLong(0);
 }
 
-static char O_read__doc__[] = 
+static char IO_read__doc__[] = 
 "read([s]) -- Read s characters, or the rest of the string"
 ;
 
 static int
-O_cread(PyObject *self, char **output, int  n) {
-  int l;
+IO_cread(PyObject *self, char **output, int  n) {
+        int l;
 
-  l = ((Oobject*)self)->string_size - ((Oobject*)self)->pos;  
-  if (n < 0 || n > l) {
-    n = l;
-    if (n < 0) n=0;
-  }
+        UNLESS (IO__opencheck(IOOOBJECT(self))) return -1;
+        l = ((IOobject*)self)->string_size - ((IOobject*)self)->pos;  
+        if (n < 0 || n > l) {
+                n = l;
+                if (n < 0) n=0;
+        }
 
-  *output=((Oobject*)self)->buf + ((Oobject*)self)->pos;
-  ((Oobject*)self)->pos += n;
-  return n;
+        *output=((IOobject*)self)->buf + ((IOobject*)self)->pos;
+        ((IOobject*)self)->pos += n;
+        return n;
 }
 
 static PyObject *
-O_read(Oobject *self, PyObject *args) {
-  int n = -1;
-  char *output;
+IO_read(IOobject *self, PyObject *args) {
+        int n = -1;
+        char *output;
 
-  UNLESS(PyArg_ParseTuple(args, "|i:read", &n)) return NULL;
+        UNLESS (PyArg_ParseTuple(args, "|i:read", &n)) return NULL;
 
-  n=O_cread((PyObject*)self,&output,n);
+        if ( (n=IO_cread((PyObject*)self,&output,n)) < 0) return NULL;
 
-  return PyString_FromStringAndSize(output, n);
+        return PyString_FromStringAndSize(output, n);
 }
 
-
-static char O_readline__doc__[] = 
+static char IO_readline__doc__[] = 
 "readline() -- Read one line"
 ;
 
 static int
-O_creadline(PyObject *self, char **output) {
-  char *n, *s;
-  int l;
+IO_creadline(PyObject *self, char **output) {
+        char *n, *s;
+        int l;
 
-  for (n = ((Oobject*)self)->buf + ((Oobject*)self)->pos,
-	 s = ((Oobject*)self)->buf + ((Oobject*)self)->string_size; 
-       n < s && *n != '\n'; n++);
-  if (n < s) n++;
- 
-  *output=((Oobject*)self)->buf + ((Oobject*)self)->pos;
-  l = n - ((Oobject*)self)->buf - ((Oobject*)self)->pos;
-  ((Oobject*)self)->pos += l;
-  return l;
+        UNLESS (IO__opencheck(IOOOBJECT(self))) return -1;
+
+        for (n = ((IOobject*)self)->buf + ((IOobject*)self)->pos,
+               s = ((IOobject*)self)->buf + ((IOobject*)self)->string_size; 
+             n < s && *n != '\n'; n++);
+        if (n < s) n++;
+
+        *output=((IOobject*)self)->buf + ((IOobject*)self)->pos;
+        l = n - ((IOobject*)self)->buf - ((IOobject*)self)->pos;
+        ((IOobject*)self)->pos += l;
+        return l;
 }
 
 static PyObject *
-O_readline(Oobject *self, PyObject *args) {
-  int n;
-  char *output;
+IO_readline(IOobject *self, PyObject *args) {
+        int n, m=-1;
+        char *output;
 
-  n=O_creadline((PyObject*)self,&output);
-  return PyString_FromStringAndSize(output, n);
+        UNLESS (PyArg_ParseTuple(args, "|i:readline", &m)) return NULL;
+
+        if( (n=IO_creadline((PyObject*)self,&output)) < 0) return NULL;
+        if (m >= 0 && m < n) {
+                m = n - m;
+                n -= m;
+                self->pos -= m;
+        }
+        return PyString_FromStringAndSize(output, n);
 }
 
-static char O_readlines__doc__[] = 
+static char IO_readlines__doc__[] = 
 "readlines() -- Read all lines"
 ;
 
 static PyObject *
-O_readlines(Oobject *self, PyObject *args) {
+IO_readlines(IOobject *self, PyObject *args) {
 	int n;
 	char *output;
 	PyObject *result, *line;
         int hint = 0, length = 0;
 	
-        UNLESS(PyArg_ParseTuple(args, "|i:write", &hint)) return NULL;
+        UNLESS (PyArg_ParseTuple(args, "|i:readlines", &hint)) return NULL;
+
 	result = PyList_New(0);
 	if (!result)
 		return NULL;
 
-	while(1){
-		n = O_creadline((PyObject*)self,&output);
+	while (1){
+		if ( (n = IO_creadline((PyObject*)self,&output)) < 0)
+                        goto err;
 		if (n == 0)
 			break;
 		line = PyString_FromStringAndSize (output, n);
-		if (!line){
-			Py_DECREF (result);
-			return NULL;
-		}
+		if (!line) 
+                        goto err;
 		PyList_Append (result, line);
 		Py_DECREF (line);
                 length += n;
@@ -256,6 +291,97 @@
 			break;
 	}
 	return result;
+ err:
+        Py_DECREF(result);
+        return NULL;
+}
+
+static char IO_reset__doc__[] = 
+"reset() -- Reset the file position to the beginning"
+;
+
+static PyObject *
+IO_reset(IOobject *self, PyObject *args) {
+
+        UNLESS (IO__opencheck(self)) return NULL;
+        UNLESS (PyArg_ParseTuple(args, ":reset")) return NULL;
+
+        self->pos = 0;
+
+        Py_INCREF(Py_None);
+        return Py_None;
+}
+
+static char IO_tell__doc__[] =
+"tell() -- get the current position.";
+
+static PyObject *
+IO_tell(IOobject *self, PyObject *args) {
+
+        UNLESS (IO__opencheck(self)) return NULL;
+        UNLESS (PyArg_ParseTuple(args, ":tell")) return NULL;
+
+        return PyInt_FromLong(self->pos);
+}
+
+static char IO_truncate__doc__[] = 
+"truncate(): truncate the file at the current position.";
+
+static PyObject *
+IO_truncate(IOobject *self, PyObject *args) {
+        int pos = -1;
+	
+        UNLESS (IO__opencheck(self)) return NULL;
+        UNLESS (PyArg_ParseTuple(args, "|i:truncate", &pos)) return NULL;
+        if (pos < 0) pos = self->pos;
+
+        if (self->string_size > pos) self->string_size = pos;
+
+        Py_INCREF(Py_None);
+        return Py_None;
+}
+
+
+
+
+/* Read-write object methods */
+
+static char O_seek__doc__[] =
+"seek(position)       -- set the current position\n"
+"seek(position, mode) -- mode 0: absolute; 1: relative; 2: relative to EOF";
+
+static PyObject *
+O_seek(Oobject *self, PyObject *args) {
+        int position, mode = 0;
+
+        UNLESS (IO__opencheck(IOOOBJECT(self))) return NULL;
+        UNLESS (PyArg_ParseTuple(args, "i|i:seek", &position, &mode)) 
+                return NULL;
+
+        if (mode == 2) {
+                position += self->string_size;
+        }
+        else if (mode == 1) {
+                position += self->pos;
+        }
+
+        if (position > self->buf_size) {
+                  self->buf_size*=2;
+                  if (self->buf_size <= position) self->buf_size=position+1;
+                  UNLESS (self->buf=(char*)
+                          realloc(self->buf,self->buf_size*sizeof(char))) {
+                      self->buf_size=self->pos=0;
+                      return PyErr_NoMemory();
+                    }
+          }
+        else if (position < 0) position=0;
+
+        self->pos=position;
+
+        while (--position >= self->string_size) self->buf[position]=0;
+
+        Py_INCREF(Py_None);
+        return Py_None;
 }
 
 static char O_write__doc__[] = 
@@ -266,114 +392,66 @@
 
 static int
 O_cwrite(PyObject *self, char *c, int  l) {
-  int newl;
+        int newl;
 
-  newl=((Oobject*)self)->pos+l;
-  if(newl >= ((Oobject*)self)->buf_size) {
-      ((Oobject*)self)->buf_size*=2;
-      if(((Oobject*)self)->buf_size <= newl) ((Oobject*)self)->buf_size=newl+1;
-      UNLESS(((Oobject*)self)->buf=
-	     (char*)realloc(((Oobject*)self)->buf,
-			    (((Oobject*)self)->buf_size) *sizeof(char))) {
-	  PyErr_SetString(PyExc_MemoryError,"out of memory");
-	  ((Oobject*)self)->buf_size=((Oobject*)self)->pos=0;
-	  return -1;
-	}
-    }
+        UNLESS (IO__opencheck(IOOOBJECT(self))) return -1;
 
-  memcpy(((Oobject*)((Oobject*)self))->buf+((Oobject*)self)->pos,c,l);
+        newl=((Oobject*)self)->pos+l;
+        if (newl >= ((Oobject*)self)->buf_size) {
+            ((Oobject*)self)->buf_size*=2;
+            if (((Oobject*)self)->buf_size <= newl) 
+                    ((Oobject*)self)->buf_size=newl+1;
+            UNLESS (((Oobject*)self)->buf=
+                   (char*)realloc(
+                        ((Oobject*)self)->buf,
+                        (((Oobject*)self)->buf_size) *sizeof(char))) {
+                    PyErr_SetString(PyExc_MemoryError,"out of memory");
+                    ((Oobject*)self)->buf_size=((Oobject*)self)->pos=0;
+                    return -1;
+              }
+          }
 
-  ((Oobject*)self)->pos += l;
+        memcpy(((Oobject*)((Oobject*)self))->buf+((Oobject*)self)->pos,c,l);
 
-  if (((Oobject*)self)->string_size < ((Oobject*)self)->pos) {
-      ((Oobject*)self)->string_size = ((Oobject*)self)->pos;
-    }
+        ((Oobject*)self)->pos += l;
 
-  return l;
+        if (((Oobject*)self)->string_size < ((Oobject*)self)->pos) {
+            ((Oobject*)self)->string_size = ((Oobject*)self)->pos;
+          }
+
+        return l;
 }
 
 static PyObject *
 O_write(Oobject *self, PyObject *args) {
-  PyObject *s;
-  char *c;
-  int l;
+        PyObject *s;
+        char *c;
+        int l;
 
-  UNLESS(PyArg_ParseTuple(args, "O:write", &s)) return NULL;
-  UNLESS(-1 != (l=PyString_Size(s))) return NULL;
-  UNLESS(c=PyString_AsString(s)) return NULL;
-  UNLESS(-1 != O_cwrite((PyObject*)self,c,l)) return NULL;
+        UNLESS (PyArg_ParseTuple(args, "O:write", &s)) return NULL;
 
-  Py_INCREF(Py_None);
-  return Py_None;
-}
+        UNLESS (-1 != (l=PyString_Size(s))) return NULL;
+        UNLESS (c=PyString_AsString(s)) return NULL;
+        if (O_cwrite((PyObject*)self,c,l) < 0) return NULL;
 
-static char O_getval__doc__[] = 
-   "getvalue([use_pos]) -- Get the string value."
-   "\n"
-   "If use_pos is specified and is a true value, then the string returned\n"
-   "will include only the text up to the current file position.\n"
-;
-
-static PyObject *
-O_getval(Oobject *self, PyObject *args) {
-  PyObject *use_pos=Py_None;
-  int s;
-
-  use_pos=Py_None;
-  UNLESS(PyArg_ParseTuple(args,"|O:getval",&use_pos)) return NULL;
-  if(PyObject_IsTrue(use_pos)) {
-      s=self->pos;
-      if (s > self->string_size) s=self->string_size;
-  }
-  else
-      s=self->string_size;
-  return PyString_FromStringAndSize(self->buf, s);
-}
-
-static PyObject *
-O_cgetval(PyObject *self) {
-  return PyString_FromStringAndSize(((Oobject*)self)->buf,
-				    ((Oobject*)self)->pos);
-}
-
-static char O_truncate__doc__[] = 
-"truncate(): truncate the file at the current position.";
-
-static PyObject *
-O_truncate(Oobject *self, PyObject *args) {
-  if (self->string_size > self->pos)
-      self->string_size = self->pos;
-  Py_INCREF(Py_None);
-  return Py_None;
-}
-
-static char O_isatty__doc__[] = "isatty(): always returns 0";
-
-static PyObject *
-O_isatty(Oobject *self, PyObject *args) {
-  return PyInt_FromLong(0);
+        Py_INCREF(Py_None);
+        return Py_None;
 }
 
 static char O_close__doc__[] = "close(): explicitly release resources held.";
 
 static PyObject *
 O_close(Oobject *self, PyObject *args) {
-  if (self->buf != NULL)
-    free(self->buf);
-  self->buf = NULL;
 
-  self->pos = self->string_size = self->buf_size = 0;
+        UNLESS (PyArg_ParseTuple(args, ":close")) return NULL;
 
-  Py_INCREF(Py_None);
-  return Py_None;
-}
+        if (self->buf != NULL) free(self->buf);
+        self->buf = NULL;
 
-static char O_flush__doc__[] = "flush(): does nothing.";
+        self->pos = self->string_size = self->buf_size = 0;
 
-static PyObject *
-O_flush(Oobject *self, PyObject *args) {
-  Py_INCREF(Py_None);
-  return Py_None;
+        Py_INCREF(Py_None);
+        return Py_None;
 }
 
 
@@ -381,76 +459,65 @@
 "writelines(sequence_of_strings): write each string";
 static PyObject *
 O_writelines(Oobject *self, PyObject *args) {
-  PyObject *string_module = 0;
-  static PyObject *string_joinfields = 0;
+        PyObject *tmp = 0;
+        static PyObject *string_joinfields = 0;
 
-  UNLESS(PyArg_ParseTuple(args, "O:writelines", &args)) {
-    return NULL;
-  }
+        UNLESS (PyArg_ParseTuple(args, "O:writelines", &args)) return NULL;
 
-  if (!string_joinfields) {
-    UNLESS(string_module = PyImport_ImportModule("string")) {
-      return NULL;
-    }
+        if (!string_joinfields) {
+                UNLESS (tmp = PyImport_ImportModule("string")) return NULL;
+                string_joinfields=PyObject_GetAttrString(tmp, "joinfields");
+                Py_DECREF(tmp);
+                UNLESS (string_joinfields) return NULL;
+        }
 
-    UNLESS(string_joinfields=
-        PyObject_GetAttrString(string_module, "joinfields")) {
-      return NULL;
-    }
+        if (PyObject_Size(args) < 0) return NULL;
 
-    Py_DECREF(string_module);
-  }
+        tmp = PyObject_CallFunction(string_joinfields, "Os", args, "");
+        UNLESS (tmp) return NULL;
 
-  if (PyObject_Size(args) == -1) {
-    return NULL;
-  }
+        args = Py_BuildValue("(O)", tmp);
+        Py_DECREF(tmp);
+        UNLESS (args) return NULL;
 
-  {
-	  PyObject *x = PyObject_CallFunction(string_joinfields,
-					      "Os", args, "");
-	  if (x == NULL)
-		  return NULL;
-	  args = Py_BuildValue("(O)", x);
-	  Py_DECREF(x);
-	  if (args == NULL)
-		  return NULL;
-	  x = O_write(self, args);
-	  Py_DECREF(args);
-	  return x;
-  }
+        tmp = O_write(self, args);
+        Py_DECREF(args);
+        return tmp;
 }
 
 static struct PyMethodDef O_methods[] = {
-  {"write",	 (PyCFunction)O_write,      METH_VARARGS, O_write__doc__},
-  {"read",       (PyCFunction)O_read,       METH_VARARGS, O_read__doc__},
-  {"readline",   (PyCFunction)O_readline,   METH_VARARGS, O_readline__doc__},
-  {"readlines",  (PyCFunction)O_readlines,  METH_VARARGS, O_readlines__doc__},
-  {"reset",      (PyCFunction)O_reset,      METH_VARARGS, O_reset__doc__},
-  {"seek",       (PyCFunction)O_seek,       METH_VARARGS, O_seek__doc__},
-  {"tell",       (PyCFunction)O_tell,       METH_VARARGS, O_tell__doc__},
-  {"getvalue",   (PyCFunction)O_getval,     METH_VARARGS, O_getval__doc__},
-  {"truncate",   (PyCFunction)O_truncate,   METH_VARARGS, O_truncate__doc__},
-  {"isatty",     (PyCFunction)O_isatty,     METH_VARARGS, O_isatty__doc__},
+  /* Common methods: */
+  {"flush",     (PyCFunction)IO_flush,    METH_VARARGS, IO_flush__doc__},
+  {"getvalue",  (PyCFunction)IO_getval,   METH_VARARGS, IO_getval__doc__},
+  {"isatty",    (PyCFunction)IO_isatty,   METH_VARARGS, IO_isatty__doc__},
+  {"read",	(PyCFunction)IO_read,     METH_VARARGS, IO_read__doc__},
+  {"readline",	(PyCFunction)IO_readline, METH_VARARGS, IO_readline__doc__},
+  {"readlines",	(PyCFunction)IO_readlines,METH_VARARGS, IO_readlines__doc__},
+  {"reset",	(PyCFunction)IO_reset,	  METH_VARARGS, IO_reset__doc__},
+  {"tell",      (PyCFunction)IO_tell,     METH_VARARGS, IO_tell__doc__},
+  {"truncate",  (PyCFunction)IO_truncate, METH_VARARGS, IO_truncate__doc__},
+
+  /* Read-write StringIO specific  methods: */
   {"close",      (PyCFunction)O_close,      METH_VARARGS, O_close__doc__},
-  {"flush",      (PyCFunction)O_flush,      METH_VARARGS, O_flush__doc__},
+  {"seek",       (PyCFunction)O_seek,       METH_VARARGS, O_seek__doc__},
+  {"write",	 (PyCFunction)O_write,      METH_VARARGS, O_write__doc__},
   {"writelines", (PyCFunction)O_writelines, METH_VARARGS, O_writelines__doc__},
   {NULL,	 NULL}		/* sentinel */
 };
 
-
 static void
 O_dealloc(Oobject *self) {
-  if (self->buf != NULL)
-    free(self->buf);
-  PyObject_Del(self);
+        if (self->buf != NULL)
+                free(self->buf);
+        PyObject_Del(self);
 }
 
 static PyObject *
 O_getattr(Oobject *self, char *name) {
-  if (strcmp(name, "softspace") == 0) {
-	  return PyInt_FromLong(self->softspace);
-  }
-  return Py_FindMethod(O_methods, (PyObject *)self, name);
+        if (strcmp(name, "softspace") == 0) {
+                return PyInt_FromLong(self->softspace);
+        }
+        return Py_FindMethod(O_methods, (PyObject *)self, name);
 }
 
 static int
@@ -461,7 +528,7 @@
 		return -1;
 	}
 	x = PyInt_AsLong(value);
-	if (x == -1 && PyErr_Occurred())
+	if (x < 0 && PyErr_Occurred())
 		return -1;
 	self->softspace = x;
 	return 0;
@@ -498,23 +565,23 @@
 
 static PyObject *
 newOobject(int  size) {
-  Oobject *self;
-	
-  self = PyObject_New(Oobject, &Otype);
-  if (self == NULL)
-    return NULL;
-  self->pos=0;
-  self->string_size = 0;
-  self->softspace = 0;
+        Oobject *self;
 
-  UNLESS(self->buf=malloc(size*sizeof(char))) {
-      PyErr_SetString(PyExc_MemoryError,"out of memory");
-      self->buf_size = 0;
-      return NULL;
-    }
+        self = PyObject_New(Oobject, &Otype);
+        if (self == NULL)
+                return NULL;
+        self->pos=0;
+        self->string_size = 0;
+        self->softspace = 0;
 
-  self->buf_size=size;
-  return (PyObject*)self;
+        UNLESS (self->buf=malloc(size*sizeof(char))) {
+                  PyErr_SetString(PyExc_MemoryError,"out of memory");
+                  self->buf_size = 0;
+                  return NULL;
+          }
+
+        self->buf_size=size;
+        return (PyObject*)self;
 }
 
 /* End of code for StringO objects */
@@ -522,50 +589,53 @@
 
 static PyObject *
 I_close(Iobject *self, PyObject *args) {
-  Py_XDECREF(self->pbuf);
-  self->pbuf = NULL;
 
-  self->pos = self->string_size = 0;
+        UNLESS (PyArg_ParseTuple(args, ":close")) return NULL;
 
-  Py_INCREF(Py_None);
-  return Py_None;
+        Py_XDECREF(self->pbuf);
+        self->pbuf = NULL;
+        self->buf = NULL;
+
+        self->pos = self->string_size = 0;
+
+        Py_INCREF(Py_None);
+        return Py_None;
 }
 
 static PyObject *
-I_seek(Oobject *self, PyObject *args) {
-  int position, mode = 0;
+I_seek(Iobject *self, PyObject *args) {
+        int position, mode = 0;
 
-  UNLESS(PyArg_ParseTuple(args, "i|i:seek", &position, &mode)) {
-    return NULL;
-  }
+        UNLESS (IO__opencheck(IOOOBJECT(self))) return NULL;
+        UNLESS (PyArg_ParseTuple(args, "i|i:seek", &position, &mode)) 
+                return NULL;
 
-  if (mode == 2) {
-    position += self->string_size;
-  }
-  else if (mode == 1) {
-    position += self->pos;
-  }
+        if (mode == 2) position += self->string_size;
+        else if (mode == 1) position += self->pos;
 
-  if(position < 0) position=0;
-  
-  self->pos=position;
+        if (position < 0) position=0;
 
-  Py_INCREF(Py_None);
-  return Py_None;
+        self->pos=position;
+
+        Py_INCREF(Py_None);
+        return Py_None;
 }
 
 static struct PyMethodDef I_methods[] = {
-  {"read",	(PyCFunction)O_read,     METH_VARARGS, O_read__doc__},
-  {"readline",	(PyCFunction)O_readline, METH_VARARGS, O_readline__doc__},
-  {"readlines",	(PyCFunction)O_readlines,METH_VARARGS, O_readlines__doc__},
-  {"reset",	(PyCFunction)O_reset,	 METH_VARARGS, O_reset__doc__},
-  {"seek",      (PyCFunction)I_seek,     METH_VARARGS, O_seek__doc__},  
-  {"tell",      (PyCFunction)O_tell,     METH_VARARGS, O_tell__doc__},
-  {"getvalue",  (PyCFunction)O_getval,   METH_VARARGS, O_getval__doc__},
-  {"truncate",  (PyCFunction)O_truncate, METH_VARARGS, O_truncate__doc__},
-  {"isatty",    (PyCFunction)O_isatty,   METH_VARARGS, O_isatty__doc__},
+  /* Common methods: */
+  {"flush",     (PyCFunction)IO_flush,    METH_VARARGS, IO_flush__doc__},
+  {"getvalue",  (PyCFunction)IO_getval,   METH_VARARGS, IO_getval__doc__},
+  {"isatty",    (PyCFunction)IO_isatty,   METH_VARARGS, IO_isatty__doc__},
+  {"read",	(PyCFunction)IO_read,     METH_VARARGS, IO_read__doc__},
+  {"readline",	(PyCFunction)IO_readline, METH_VARARGS, IO_readline__doc__},
+  {"readlines",	(PyCFunction)IO_readlines,METH_VARARGS, IO_readlines__doc__},
+  {"reset",	(PyCFunction)IO_reset,	  METH_VARARGS, IO_reset__doc__},
+  {"tell",      (PyCFunction)IO_tell,     METH_VARARGS, IO_tell__doc__},
+  {"truncate",  (PyCFunction)IO_truncate, METH_VARARGS, IO_truncate__doc__},
+
+  /* Read-only StringIO specific  methods: */
   {"close",     (PyCFunction)I_close,    METH_VARARGS, O_close__doc__},
-  {"flush",     (PyCFunction)O_flush,    METH_VARARGS, O_flush__doc__},
+  {"seek",      (PyCFunction)I_seek,     METH_VARARGS, O_seek__doc__},  
   {NULL,	NULL}
 };
 
@@ -622,7 +692,7 @@
   }
   buf = PyString_AS_STRING(s);
   size = PyString_GET_SIZE(s);
-  UNLESS(self = PyObject_New(Iobject, &Itype)) return NULL;
+  UNLESS (self = PyObject_New(Iobject, &Itype)) return NULL;
   Py_INCREF(s);
   self->buf=buf;
   self->string_size=size;
@@ -644,9 +714,9 @@
 IO_StringIO(PyObject *self, PyObject *args) {
   PyObject *s=0;
 
-  if (!PyArg_ParseTuple(args, "|O:StringIO", &s))
-      return NULL;
-  if(s) return newIobject(s);
+  if (!PyArg_ParseTuple(args, "|O:StringIO", &s)) return NULL;
+
+  if (s) return newIobject(s);
   return newOobject(128);
 }
 
@@ -662,10 +732,10 @@
 /* Initialization function for the module (*must* be called initcStringIO) */
 
 static struct PycStringIO_CAPI CAPI = {
-  O_cread,
-  O_creadline,
+  IO_cread,
+  IO_creadline,
   O_cwrite,
-  O_cgetval,
+  IO_cgetval,
   newOobject,
   newIobject,
   &Itype,
@@ -700,5 +770,5 @@
   PyDict_SetItemString(d,"OutputType", (PyObject*)&Otype);
 
   /* Maybe make certain warnings go away */
-  if(0) PycString_IMPORT;
+  if (0) PycString_IMPORT;
 }