Merge with 3.2.

8 files changed, 606 insertions, 460 deletions

diff --git a/Modules/_io/_iomodule.c b/Modules/_io/_iomodule.c
index 44bdac6b5c..2ad002ecdd 100644
--- a/Modules/_io/_iomodule.c
+++ b/Modules/_io/_iomodule.c
@@ -36,6 +36,7 @@ PyObject *_PyIO_str_nl;
 PyObject *_PyIO_str_read;
 PyObject *_PyIO_str_read1;
 PyObject *_PyIO_str_readable;
+PyObject *_PyIO_str_readall;
 PyObject *_PyIO_str_readinto;
 PyObject *_PyIO_str_readline;
 PyObject *_PyIO_str_reset;
@@ -90,89 +91,6 @@ PyDoc_STRVAR(module_doc,
 
 
 /*
- * BlockingIOError extends IOError
- */
-
-static int
-blockingioerror_init(PyBlockingIOErrorObject *self, PyObject *args,
-                     PyObject *kwds)
-{
-    PyObject *myerrno = NULL, *strerror = NULL;
-    PyObject *baseargs = NULL;
-    Py_ssize_t written = 0;
-
-    assert(PyTuple_Check(args));
-
-    self->written = 0;
-    if (!PyArg_ParseTuple(args, "OO|n:BlockingIOError",
-                          &myerrno, &strerror, &written))
-        return -1;
-
-    baseargs = PyTuple_Pack(2, myerrno, strerror);
-    if (baseargs == NULL)
-        return -1;
-    /* This will take care of initializing of myerrno and strerror members */
-    if (((PyTypeObject *)PyExc_IOError)->tp_init(
-                (PyObject *)self, baseargs, kwds) == -1) {
-        Py_DECREF(baseargs);
-        return -1;
-    }
-    Py_DECREF(baseargs);
-
-    self->written = written;
-    return 0;
-}
-
-static PyMemberDef blockingioerror_members[] = {
-    {"characters_written", T_PYSSIZET, offsetof(PyBlockingIOErrorObject, written), 0},
-    {NULL}  /* Sentinel */
-};
-
-static PyTypeObject _PyExc_BlockingIOError = {
-    PyVarObject_HEAD_INIT(NULL, 0)
-    "BlockingIOError", /*tp_name*/
-    sizeof(PyBlockingIOErrorObject), /*tp_basicsize*/
-    0,                          /*tp_itemsize*/
-    0,                          /*tp_dealloc*/
-    0,                          /*tp_print*/
-    0,                          /*tp_getattr*/
-    0,                          /*tp_setattr*/
-    0,                          /*tp_compare */
-    0,                          /*tp_repr*/
-    0,                          /*tp_as_number*/
-    0,                          /*tp_as_sequence*/
-    0,                          /*tp_as_mapping*/
-    0,                          /*tp_hash */
-    0,                          /*tp_call*/
-    0,                          /*tp_str*/
-    0,                          /*tp_getattro*/
-    0,                          /*tp_setattro*/
-    0,                          /*tp_as_buffer*/
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
-    PyDoc_STR("Exception raised when I/O would block "
-              "on a non-blocking I/O stream"), /* tp_doc */
-    0,                          /* tp_traverse */
-    0,                          /* tp_clear */
-    0,                          /* tp_richcompare */
-    0,                          /* tp_weaklistoffset */
-    0,                          /* tp_iter */
-    0,                          /* tp_iternext */
-    0,                          /* tp_methods */
-    blockingioerror_members,    /* tp_members */
-    0,                          /* tp_getset */
-    0,                          /* tp_base */
-    0,                          /* tp_dict */
-    0,                          /* tp_descr_get */
-    0,                          /* tp_descr_set */
-    0,                          /* tp_dictoffset */
-    (initproc)blockingioerror_init, /* tp_init */
-    0,                          /* tp_alloc */
-    0,                          /* tp_new */
-};
-PyObject *PyExc_BlockingIOError = (PyObject *)&_PyExc_BlockingIOError;
-
-
-/*
  * The main open() function
  */
 PyDoc_STRVAR(open_doc,
@@ -307,6 +225,9 @@ io_open(PyObject *self, PyObject *args, PyObject *kwds)
 
     PyObject *raw, *modeobj = NULL, *buffer = NULL, *wrapper = NULL;
 
+    _Py_IDENTIFIER(isatty);
+    _Py_IDENTIFIER(fileno);
+
     if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|sizzzi:open", kwlist,
                                      &file, &mode, &buffering,
                                      &encoding, &errors, &newline,
@@ -420,7 +341,7 @@ io_open(PyObject *self, PyObject *args, PyObject *kwds)
 
     /* buffering */
     {
-        PyObject *res = PyObject_CallMethod(raw, "isatty", NULL);
+        PyObject *res = _PyObject_CallMethodId(raw, &PyId_isatty, NULL);
         if (res == NULL)
             goto error;
         isatty = PyLong_AsLong(res);
@@ -442,7 +363,7 @@ io_open(PyObject *self, PyObject *args, PyObject *kwds)
         {
             struct stat st;
             long fileno;
-            PyObject *res = PyObject_CallMethod(raw, "fileno", NULL);
+            PyObject *res = _PyObject_CallMethodId(raw, &PyId_fileno, NULL);
             if (res == NULL)
                 goto error;
 
@@ -690,9 +611,11 @@ PyInit__io(void)
                            state->unsupported_operation) < 0)
         goto fail;
 
-    /* BlockingIOError */
-    _PyExc_BlockingIOError.tp_base = (PyTypeObject *) PyExc_IOError;
-    ADD_TYPE(&_PyExc_BlockingIOError, "BlockingIOError");
+    /* BlockingIOError, for compatibility */
+    Py_INCREF(PyExc_BlockingIOError);
+    if (PyModule_AddObject(m, "BlockingIOError",
+                           (PyObject *) PyExc_BlockingIOError) < 0)
+        goto fail;
 
     /* Concrete base types of the IO ABCs.
        (the ABCs themselves are declared through inheritance in io.py)
@@ -767,6 +690,8 @@ PyInit__io(void)
         goto fail;
     if (!(_PyIO_str_readable = PyUnicode_InternFromString("readable")))
         goto fail;
+    if (!(_PyIO_str_readall = PyUnicode_InternFromString("readall")))
+        goto fail;
     if (!(_PyIO_str_readinto = PyUnicode_InternFromString("readinto")))
         goto fail;
     if (!(_PyIO_str_readline = PyUnicode_InternFromString("readline")))
diff --git a/Modules/_io/_iomodule.h b/Modules/_io/_iomodule.h
index 925e4f2cc7..b3a8471bc5 100644
--- a/Modules/_io/_iomodule.h
+++ b/Modules/_io/_iomodule.h
@@ -55,20 +55,11 @@ extern PyObject *_PyIncrementalNewlineDecoder_decode(
    Otherwise, the function will scan further and return garbage. */
 extern Py_ssize_t _PyIO_find_line_ending(
     int translated, int universal, PyObject *readnl,
-    Py_UNICODE *start, Py_UNICODE *end, Py_ssize_t *consumed);
+    int kind, char *start, char *end, Py_ssize_t *consumed);
 
 
 #define DEFAULT_BUFFER_SIZE (8 * 1024)  /* bytes */
 
-typedef struct {
-    PyException_HEAD
-    PyObject *myerrno;
-    PyObject *strerror;
-    PyObject *filename; /* Not used, but part of the IOError object */
-    Py_ssize_t written;
-} PyBlockingIOErrorObject;
-PyAPI_DATA(PyObject *) PyExc_BlockingIOError;
-
 /*
  * Offset type for positioning.
  */
@@ -155,6 +146,7 @@ extern PyObject *_PyIO_str_nl;
 extern PyObject *_PyIO_str_read;
 extern PyObject *_PyIO_str_read1;
 extern PyObject *_PyIO_str_readable;
+extern PyObject *_PyIO_str_readall;
 extern PyObject *_PyIO_str_readinto;
 extern PyObject *_PyIO_str_readline;
 extern PyObject *_PyIO_str_reset;
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index c979ac2336..880ed78d37 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -1,9 +1,9 @@
 /*
     An implementation of Buffered I/O as defined by PEP 3116 - "New I/O"
-    
+
     Classes defined here: BufferedIOBase, BufferedReader, BufferedWriter,
     BufferedRandom.
-    
+
     Written by Amaury Forgeot d'Arc and Antoine Pitrou
 */
 
@@ -13,6 +13,18 @@
 #include "pythread.h"
 #include "_iomodule.h"
 
+_Py_IDENTIFIER(close);
+_Py_IDENTIFIER(_dealloc_warn);
+_Py_IDENTIFIER(flush);
+_Py_IDENTIFIER(isatty);
+_Py_IDENTIFIER(peek);
+_Py_IDENTIFIER(read);
+_Py_IDENTIFIER(read1);
+_Py_IDENTIFIER(readable);
+_Py_IDENTIFIER(readinto);
+_Py_IDENTIFIER(writable);
+_Py_IDENTIFIER(write);
+
 /*
  * BufferedIOBase class, inherits from IOBase.
  */
@@ -38,12 +50,13 @@ bufferediobase_readinto(PyObject *self, PyObject *args)
     Py_buffer buf;
     Py_ssize_t len;
     PyObject *data;
+    _Py_IDENTIFIER(read);
 
     if (!PyArg_ParseTuple(args, "w*:readinto", &buf)) {
         return NULL;
     }
 
-    data = PyObject_CallMethod(self, "read", "n", buf.len);
+    data = _PyObject_CallMethodId(self, &PyId_read, "n", buf.len);
     if (data == NULL)
         goto error;
 
@@ -198,7 +211,7 @@ typedef struct {
     int readable;
     int writable;
     int deallocating;
-    
+
     /* True if this is a vanilla Buffered object (rather than a user derived
        class) *and* the raw stream is a vanilla FileIO object. */
     int fast_closed_checks;
@@ -237,7 +250,7 @@ typedef struct {
 
 /*
     Implementation notes:
-    
+
     * BufferedReader, BufferedWriter and BufferedRandom try to share most
       methods (this is helped by the members `readable` and `writable`, which
       are initialized in the respective constructors)
@@ -255,7 +268,7 @@ typedef struct {
     NOTE: we should try to maintain block alignment of reads and writes to the
     raw stream (according to the buffer size), but for now it is only done
     in read() and friends.
-    
+
 */
 
 /* These macros protect the buffered object against concurrent operations. */
@@ -410,7 +423,7 @@ buffered_dealloc_warn(buffered *self, PyObject *source)
 {
     if (self->ok && self->raw) {
         PyObject *r;
-        r = PyObject_CallMethod(self->raw, "_dealloc_warn", "O", source);
+        r = _PyObject_CallMethodId(self->raw, &PyId__dealloc_warn, "O", source);
         if (r)
             Py_DECREF(r);
         else
@@ -589,14 +602,15 @@ _bufferedreader_reset_buf(buffered *self);
 static void
 _bufferedwriter_reset_buf(buffered *self);
 static PyObject *
-_bufferedreader_peek_unlocked(buffered *self, Py_ssize_t);
+_bufferedreader_peek_unlocked(buffered *self);
 static PyObject *
 _bufferedreader_read_all(buffered *self);
 static PyObject *
 _bufferedreader_read_fast(buffered *self, Py_ssize_t);
 static PyObject *
 _bufferedreader_read_generic(buffered *self, Py_ssize_t);
-
+static Py_ssize_t
+_bufferedreader_raw_read(buffered *self, char *start, Py_ssize_t len);
 
 /*
  * Helpers
@@ -608,14 +622,14 @@ static Py_ssize_t *
 _buffered_check_blocking_error(void)
 {
     PyObject *t, *v, *tb;
-    PyBlockingIOErrorObject *err;
+    PyOSErrorObject *err;
 
     PyErr_Fetch(&t, &v, &tb);
     if (v == NULL || !PyErr_GivenExceptionMatches(v, PyExc_BlockingIOError)) {
         PyErr_Restore(t, v, tb);
         return NULL;
     }
-    err = (PyBlockingIOErrorObject *) v;
+    err = (PyOSErrorObject *) v;
     /* TODO: sanity check (err->written >= 0) */
     PyErr_Restore(t, v, tb);
     return &err->written;
@@ -635,7 +649,7 @@ _buffered_raw_tell(buffered *self)
         if (!PyErr_Occurred())
             PyErr_Format(PyExc_IOError,
                          "Raw stream returned invalid position %" PY_PRIdOFF,
-			 (PY_OFF_T_COMPAT)n);
+                         (PY_OFF_T_COMPAT)n);
         return -1;
     }
     self->abs_pos = n;
@@ -668,7 +682,7 @@ _buffered_raw_seek(buffered *self, Py_off_t target, int whence)
         if (!PyErr_Occurred())
             PyErr_Format(PyExc_IOError,
                          "Raw stream returned invalid position %" PY_PRIdOFF,
-			 (PY_OFF_T_COMPAT)n);
+                         (PY_OFF_T_COMPAT)n);
         return -1;
     }
     self->abs_pos = n;
@@ -809,7 +823,7 @@ buffered_peek(buffered *self, PyObject *args)
             goto end;
         Py_CLEAR(res);
     }
-    res = _bufferedreader_peek_unlocked(self, n);
+    res = _bufferedreader_peek_unlocked(self);
 
 end:
     LEAVE_BUFFERED(self)
@@ -875,7 +889,7 @@ buffered_read1(buffered *self, PyObject *args)
 
     if (!ENTER_BUFFERED(self))
         return NULL;
-    
+
     /* Return up to n bytes.  If at least one byte is buffered, we
        only return buffered bytes.  Otherwise, we do one raw read. */
 
@@ -924,10 +938,78 @@ end:
 static PyObject *
 buffered_readinto(buffered *self, PyObject *args)
 {
+    Py_buffer buf;
+    Py_ssize_t n, written = 0, remaining;
+    PyObject *res = NULL;
+
     CHECK_INITIALIZED(self)
-    
-    /* TODO: use raw.readinto() (or a direct copy from our buffer) instead! */
-    return bufferediobase_readinto((PyObject *)self, args);
+
+    if (!PyArg_ParseTuple(args, "w*:readinto", &buf))
+        return NULL;
+
+    n = Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t);
+    if (n > 0) {
+        if (n >= buf.len) {
+            memcpy(buf.buf, self->buffer + self->pos, buf.len);
+            self->pos += buf.len;
+            res = PyLong_FromSsize_t(buf.len);
+            goto end_unlocked;
+        }
+        memcpy(buf.buf, self->buffer + self->pos, n);
+        self->pos += n;
+        written = n;
+    }
+
+    if (!ENTER_BUFFERED(self))
+        goto end_unlocked;
+
+    if (self->writable) {
+        res = buffered_flush_and_rewind_unlocked(self);
+        if (res == NULL)
+            goto end;
+        Py_CLEAR(res);
+    }
+
+    _bufferedreader_reset_buf(self);
+    self->pos = 0;
+
+    for (remaining = buf.len - written;
+         remaining > 0;
+         written += n, remaining -= n) {
+        /* If remaining bytes is larger than internal buffer size, copy
+         * directly into caller's buffer. */
+        if (remaining > self->buffer_size) {
+            n = _bufferedreader_raw_read(self, (char *) buf.buf + written,
+                                         remaining);
+        }
+        else {
+            n = _bufferedreader_fill_buffer(self);
+            if (n > 0) {
+                if (n > remaining)
+                    n = remaining;
+                memcpy((char *) buf.buf + written,
+                       self->buffer + self->pos, n);
+                self->pos += n;
+                continue; /* short circuit */
+            }
+        }
+        if (n == 0 || (n == -2 && written > 0))
+            break;
+        if (n < 0) {
+            if (n == -2) {
+                Py_INCREF(Py_None);
+                res = Py_None;
+            }
+            goto end;
+        }
+    }
+    res = PyLong_FromSsize_t(written);
+
+end:
+    LEAVE_BUFFERED(self);
+end_unlocked:
+    PyBuffer_Release(&buf);
+    return res;
 }
 
 static PyObject *
@@ -1345,33 +1427,58 @@ static PyObject *
 _bufferedreader_read_all(buffered *self)
 {
     Py_ssize_t current_size;
-    PyObject *res, *data = NULL;
-    PyObject *chunks = PyList_New(0);
-
-    if (chunks == NULL)
-        return NULL;
+    PyObject *res, *data = NULL, *chunk, *chunks;
 
     /* First copy what we have in the current buffer. */
     current_size = Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t);
     if (current_size) {
         data = PyBytes_FromStringAndSize(
             self->buffer + self->pos, current_size);
-        if (data == NULL) {
-            Py_DECREF(chunks);
+        if (data == NULL)
             return NULL;
-        }
         self->pos += current_size;
     }
     /* We're going past the buffer's bounds, flush it */
     if (self->writable) {
         res = buffered_flush_and_rewind_unlocked(self);
-        if (res == NULL) {
-            Py_DECREF(chunks);
+        if (res == NULL)
             return NULL;
-        }
         Py_CLEAR(res);
     }
     _bufferedreader_reset_buf(self);
+
+    if (PyObject_HasAttr(self->raw, _PyIO_str_readall)) {
+        chunk = PyObject_CallMethodObjArgs(self->raw, _PyIO_str_readall, NULL);
+        if (chunk == NULL)
+            return NULL;
+        if (chunk != Py_None && !PyBytes_Check(chunk)) {
+            Py_XDECREF(data);
+            Py_DECREF(chunk);
+            PyErr_SetString(PyExc_TypeError, "readall() should return bytes");
+            return NULL;
+        }
+        if (chunk == Py_None) {
+            if (current_size == 0)
+                return chunk;
+            else {
+                Py_DECREF(chunk);
+                return data;
+            }
+        }
+        else if (current_size) {
+            PyBytes_Concat(&data, chunk);
+            Py_DECREF(chunk);
+            if (data == NULL)
+                return NULL;
+            return data;
+        } else
+            return chunk;
+    }
+
+    chunks = PyList_New(0);
+    if (chunks == NULL)
+        return NULL;
+
     while (1) {
         if (data) {
             if (PyList_Append(chunks, data) < 0) {
@@ -1533,7 +1640,7 @@ error:
 }
 
 static PyObject *
-_bufferedreader_peek_unlocked(buffered *self, Py_ssize_t n)
+_bufferedreader_peek_unlocked(buffered *self)
 {
     Py_ssize_t have, r;
 
@@ -1575,6 +1682,7 @@ static PyMethodDef bufferedreader_methods[] = {
     {"read", (PyCFunction)buffered_read, METH_VARARGS},
     {"peek", (PyCFunction)buffered_peek, METH_VARARGS},
     {"read1", (PyCFunction)buffered_read1, METH_VARARGS},
+    {"readinto", (PyCFunction)buffered_readinto, METH_VARARGS},
     {"readline", (PyCFunction)buffered_readline, METH_VARARGS},
     {"seek", (PyCFunction)buffered_seek, METH_VARARGS},
     {"tell", (PyCFunction)buffered_tell, METH_NOARGS},
@@ -2121,13 +2229,13 @@ bufferedrwpair_dealloc(rwpair *self)
 }
 
 static PyObject *
-_forward_call(buffered *self, const char *name, PyObject *args)
+_forward_call(buffered *self, _Py_Identifier *name, PyObject *args)
 {
-    PyObject *func = PyObject_GetAttrString((PyObject *)self, name);
+    PyObject *func = _PyObject_GetAttrId((PyObject *)self, name);
     PyObject *ret;
 
     if (func == NULL) {
-        PyErr_SetString(PyExc_AttributeError, name);
+        PyErr_SetString(PyExc_AttributeError, name->string);
         return NULL;
     }
 
@@ -2139,66 +2247,66 @@ _forward_call(buffered *self, const char *name, PyObject *args)
 static PyObject *
 bufferedrwpair_read(rwpair *self, PyObject *args)
 {
-    return _forward_call(self->reader, "read", args);
+    return _forward_call(self->reader, &PyId_read, args);
 }
 
 static PyObject *
 bufferedrwpair_peek(rwpair *self, PyObject *args)
 {
-    return _forward_call(self->reader, "peek", args);
+    return _forward_call(self->reader, &PyId_peek, args);
 }
 
 static PyObject *
 bufferedrwpair_read1(rwpair *self, PyObject *args)
 {
-    return _forward_call(self->reader, "read1", args);
+    return _forward_call(self->reader, &PyId_read1, args);
 }
 
 static PyObject *
 bufferedrwpair_readinto(rwpair *self, PyObject *args)
 {
-    return _forward_call(self->reader, "readinto", args);
+    return _forward_call(self->reader, &PyId_readinto, args);
 }
 
 static PyObject *
 bufferedrwpair_write(rwpair *self, PyObject *args)
 {
-    return _forward_call(self->writer, "write", args);
+    return _forward_call(self->writer, &PyId_write, args);
 }
 
 static PyObject *
 bufferedrwpair_flush(rwpair *self, PyObject *args)
 {
-    return _forward_call(self->writer, "flush", args);
+    return _forward_call(self->writer, &PyId_flush, args);
 }
 
 static PyObject *
 bufferedrwpair_readable(rwpair *self, PyObject *args)
 {
-    return _forward_call(self->reader, "readable", args);
+    return _forward_call(self->reader, &PyId_readable, args);
 }
 
 static PyObject *
 bufferedrwpair_writable(rwpair *self, PyObject *args)
 {
-    return _forward_call(self->writer, "writable", args);
+    return _forward_call(self->writer, &PyId_writable, args);
 }
 
 static PyObject *
 bufferedrwpair_close(rwpair *self, PyObject *args)
 {
-    PyObject *ret = _forward_call(self->writer, "close", args);
+    PyObject *ret = _forward_call(self->writer, &PyId_close, args);
     if (ret == NULL)
         return NULL;
     Py_DECREF(ret);
 
-    return _forward_call(self->reader, "close", args);
+    return _forward_call(self->reader, &PyId_close, args);
 }
 
 static PyObject *
 bufferedrwpair_isatty(rwpair *self, PyObject *args)
 {
-    PyObject *ret = _forward_call(self->writer, "isatty", args);
+    PyObject *ret = _forward_call(self->writer, &PyId_isatty, args);
 
     if (ret != Py_False) {
         /* either True or exception */
@@ -2206,7 +2314,7 @@ bufferedrwpair_isatty(rwpair *self, PyObject *args)
     }
     Py_DECREF(ret);
 
-    return _forward_call(self->reader, "isatty", args);
+    return _forward_call(self->reader, &PyId_isatty, args);
 }
 
 static PyObject *
diff --git a/Modules/_io/bytesio.c b/Modules/_io/bytesio.c
index b40513f7a7..65ec93124a 100644
--- a/Modules/_io/bytesio.c
+++ b/Modules/_io/bytesio.c
@@ -938,13 +938,11 @@ static int
 bytesiobuf_getbuffer(bytesiobuf *obj, Py_buffer *view, int flags)
 {
     int ret;
-    void *ptr;
     bytesio *b = (bytesio *) obj->source;
     if (view == NULL) {
         b->exports++;
         return 0;
     }
-    ptr = (void *) obj;
     ret = PyBuffer_FillInfo(view, (PyObject*)obj, b->buf, b->string_size,
                             0, flags);
     if (ret >= 0) {
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index be5c9f8da9..acb0097968 100644
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -122,6 +122,7 @@ internal_close(fileio *self)
 static PyObject *
 fileio_close(fileio *self)
 {
+    _Py_IDENTIFIER(close);
     if (!self->closefd) {
         self->fd = -1;
         Py_RETURN_NONE;
@@ -137,8 +138,8 @@ fileio_close(fileio *self)
     if (errno < 0)
         return NULL;
 
-    return PyObject_CallMethod((PyObject*)&PyRawIOBase_Type,
-                               "close", "O", self);
+    return _PyObject_CallMethodId((PyObject*)&PyRawIOBase_Type,
+                                  &PyId_close, "O", self);
 }
 
 static PyObject *
@@ -253,9 +254,11 @@ fileio_init(PyObject *oself, PyObject *args, PyObject *kwds)
     }
 
 #ifdef MS_WINDOWS
-    if (PyUnicode_Check(nameobj))
-        widename = PyUnicode_AS_UNICODE(nameobj);
-    if (widename == NULL)
+    if (PyUnicode_Check(nameobj)) {
+        widename = PyUnicode_AsUnicode(nameobj);
+        if (widename == NULL)
+            return -1;
+    } else
 #endif
     if (fd < 0)
     {
@@ -372,7 +375,7 @@ fileio_init(PyObject *oself, PyObject *args, PyObject *kwds)
         if (self->fd < 0) {
 #ifdef MS_WINDOWS
             if (widename != NULL)
-                PyErr_SetFromErrnoWithUnicodeFilename(PyExc_IOError, widename);
+                PyErr_SetFromErrnoWithFilenameObject(PyExc_IOError, nameobj);
             else
 #endif
                 PyErr_SetFromErrnoWithFilename(PyExc_IOError, name);
@@ -541,21 +544,25 @@ fileio_readinto(fileio *self, PyObject *args)
 }
 
 static size_t
-new_buffersize(fileio *self, size_t currentsize)
+new_buffersize(fileio *self, size_t currentsize
+#ifdef HAVE_FSTAT
+               , Py_off_t pos, Py_off_t end
+#endif
+               )
 {
 #ifdef HAVE_FSTAT
-    off_t pos, end;
-    struct stat st;
-    if (fstat(self->fd, &st) == 0) {
-        end = st.st_size;
-        pos = lseek(self->fd, 0L, SEEK_CUR);
+    if (end != (Py_off_t)-1) {
         /* Files claiming a size smaller than SMALLCHUNK may
            actually be streaming pseudo-files. In this case, we
            apply the more aggressive algorithm below.
         */
         if (end >= SMALLCHUNK && end >= pos && pos >= 0) {
             /* Add 1 so if the file were to grow we'd notice. */
-            return currentsize + end - pos + 1;
+            Py_off_t bufsize = currentsize + end - pos + 1;
+            if (bufsize < PY_SSIZE_T_MAX)
+                return (size_t)bufsize;
+            else
+                return PY_SSIZE_T_MAX;
         }
     }
 #endif
@@ -568,9 +575,14 @@ new_buffersize(fileio *self, size_t currentsize)
 static PyObject *
 fileio_readall(fileio *self)
 {
+#ifdef HAVE_FSTAT
+    struct stat st;
+    Py_off_t pos, end;
+#endif
     PyObject *result;
     Py_ssize_t total = 0;
     int n;
+    size_t newsize;
 
     if (self->fd < 0)
         return err_closed();
@@ -581,8 +593,23 @@ fileio_readall(fileio *self)
     if (result == NULL)
         return NULL;
 
+#ifdef HAVE_FSTAT
+#if defined(MS_WIN64) || defined(MS_WINDOWS)
+    pos = _lseeki64(self->fd, 0L, SEEK_CUR);
+#else
+    pos = lseek(self->fd, 0L, SEEK_CUR);
+#endif
+    if (fstat(self->fd, &st) == 0)
+        end = st.st_size;
+    else
+        end = (Py_off_t)-1;
+#endif
     while (1) {
-        size_t newsize = new_buffersize(self, total);
+#ifdef HAVE_FSTAT
+        newsize = new_buffersize(self, total, pos, end);
+#else
+        newsize = new_buffersize(self, total);
+#endif
         if (newsize > PY_SSIZE_T_MAX || newsize <= 0) {
             PyErr_SetString(PyExc_OverflowError,
                 "unbounded read returned more bytes "
@@ -621,6 +648,9 @@ fileio_readall(fileio *self)
             return NULL;
         }
         total += n;
+#ifdef HAVE_FSTAT
+        pos += n;
+#endif
     }
 
     if (PyBytes_GET_SIZE(result) > total) {
diff --git a/Modules/_io/iobase.c b/Modules/_io/iobase.c
index 35c7cdd480..52f6aa0a40 100644
--- a/Modules/_io/iobase.c
+++ b/Modules/_io/iobase.c
@@ -97,7 +97,9 @@ PyDoc_STRVAR(iobase_tell_doc,
 static PyObject *
 iobase_tell(PyObject *self, PyObject *args)
 {
-    return PyObject_CallMethod(self, "seek", "ii", 0, 1);
+    _Py_IDENTIFIER(seek);
+
+    return _PyObject_CallMethodId(self, &PyId_seek, "ii", 0, 1);
 }
 
 PyDoc_STRVAR(iobase_truncate_doc,
@@ -464,6 +466,7 @@ iobase_readline(PyObject *self, PyObject *args)
     int has_peek = 0;
     PyObject *buffer, *result;
     Py_ssize_t old_size = -1;
+    _Py_IDENTIFIER(read);
 
     if (!PyArg_ParseTuple(args, "|O&:readline", &_PyIO_ConvertSsize_t, &limit)) {
         return NULL;
@@ -481,7 +484,9 @@ iobase_readline(PyObject *self, PyObject *args)
         PyObject *b;
 
         if (has_peek) {
-            PyObject *readahead = PyObject_CallMethod(self, "peek", "i", 1);
+            _Py_IDENTIFIER(peek);
+            PyObject *readahead = _PyObject_CallMethodId(self, &PyId_peek, "i", 1);
+
             if (readahead == NULL)
                 goto fail;
             if (!PyBytes_Check(readahead)) {
@@ -515,7 +520,7 @@ iobase_readline(PyObject *self, PyObject *args)
             Py_DECREF(readahead);
         }
 
-        b = PyObject_CallMethod(self, "read", "n", nreadahead);
+        b = _PyObject_CallMethodId(self, &PyId_read, "n", nreadahead);
         if (b == NULL)
             goto fail;
         if (!PyBytes_Check(b)) {
@@ -601,7 +606,9 @@ iobase_readlines(PyObject *self, PyObject *args)
         /* XXX special-casing this made sense in the Python version in order
            to remove the bytecode interpretation overhead, but it could
            probably be removed here. */
-        PyObject *ret = PyObject_CallMethod(result, "extend", "O", self);
+        _Py_IDENTIFIER(extend);
+        PyObject *ret = _PyObject_CallMethodId(result, &PyId_extend, "O", self);
+
         if (ret == NULL) {
             Py_DECREF(result);
             return NULL;
@@ -781,8 +788,11 @@ rawiobase_read(PyObject *self, PyObject *args)
         return NULL;
     }
 
-    if (n < 0)
-        return PyObject_CallMethod(self, "readall", NULL);
+    if (n < 0) {
+        _Py_IDENTIFIER(readall);
+
+        return _PyObject_CallMethodId(self, &PyId_readall, NULL);
+    }
 
     /* TODO: allocate a bytes object directly instead and manually construct
        a writable memoryview pointing to it. */
@@ -823,8 +833,9 @@ rawiobase_readall(PyObject *self, PyObject *args)
         return NULL;
 
     while (1) {
-        PyObject *data = PyObject_CallMethod(self, "read",
-                                             "i", DEFAULT_BUFFER_SIZE);
+        _Py_IDENTIFIER(read);
+        PyObject *data = _PyObject_CallMethodId(self, &PyId_read,
+                                                "i", DEFAULT_BUFFER_SIZE);
         if (!data) {
             Py_DECREF(chunks);
             return NULL;
diff --git a/Modules/_io/stringio.c b/Modules/_io/stringio.c
index c9d14b114b..83a2465d4d 100644
--- a/Modules/_io/stringio.c
+++ b/Modules/_io/stringio.c
@@ -9,7 +9,7 @@
 
 typedef struct {
     PyObject_HEAD
-    Py_UNICODE *buf;
+    Py_UCS4 *buf;
     Py_ssize_t pos;
     Py_ssize_t string_size;
     size_t buf_size;
@@ -21,7 +21,7 @@ typedef struct {
     PyObject *decoder;
     PyObject *readnl;
     PyObject *writenl;
-    
+
     PyObject *dict;
     PyObject *weakreflist;
 } stringio;
@@ -56,7 +56,7 @@ resize_buffer(stringio *self, size_t size)
     /* Here, unsigned types are used to avoid dealing with signed integer
        overflow, which is undefined in C. */
     size_t alloc = self->buf_size;
-    Py_UNICODE *new_buf = NULL;
+    Py_UCS4 *new_buf = NULL;
 
     assert(self->buf != NULL);
 
@@ -84,10 +84,9 @@ resize_buffer(stringio *self, size_t size)
         alloc = size + 1;
     }
 
-    if (alloc > ((size_t)-1) / sizeof(Py_UNICODE))
+    if (alloc > PY_SIZE_MAX / sizeof(Py_UCS4))
         goto overflow;
-    new_buf = (Py_UNICODE *)PyMem_Realloc(self->buf,
-                                          alloc * sizeof(Py_UNICODE));
+    new_buf = (Py_UCS4 *)PyMem_Realloc(self->buf, alloc * sizeof(Py_UCS4));
     if (new_buf == NULL) {
         PyErr_NoMemory();
         return -1;
@@ -108,9 +107,9 @@ resize_buffer(stringio *self, size_t size)
 static Py_ssize_t
 write_str(stringio *self, PyObject *obj)
 {
-    Py_UNICODE *str;
     Py_ssize_t len;
     PyObject *decoded = NULL;
+
     assert(self->buf != NULL);
     assert(self->pos >= 0);
 
@@ -132,8 +131,11 @@ write_str(stringio *self, PyObject *obj)
         return -1;
 
     assert(PyUnicode_Check(decoded));
-    str = PyUnicode_AS_UNICODE(decoded);
-    len = PyUnicode_GET_SIZE(decoded);
+    if (PyUnicode_READY(decoded)) {
+        Py_DECREF(decoded);
+        return -1;
+    }
+    len = PyUnicode_GET_LENGTH(decoded);
 
     assert(len >= 0);
 
@@ -161,18 +163,21 @@ write_str(stringio *self, PyObject *obj)
 
         */
         memset(self->buf + self->string_size, '\0',
-               (self->pos - self->string_size) * sizeof(Py_UNICODE));
+               (self->pos - self->string_size) * sizeof(Py_UCS4));
     }
 
     /* Copy the data to the internal buffer, overwriting some of the
        existing data if self->pos < self->string_size. */
-    memcpy(self->buf + self->pos, str, len * sizeof(Py_UNICODE));
-    self->pos += len;
+    if (!PyUnicode_AsUCS4(decoded,
+                          self->buf + self->pos,
+                          self->buf_size - self->pos,
+                          0))
+        goto fail;
 
     /* Set the new length of the internal string if it has changed. */
-    if (self->string_size < self->pos) {
+    self->pos += len;
+    if (self->string_size < self->pos)
         self->string_size = self->pos;
-    }
 
     Py_DECREF(decoded);
     return 0;
@@ -190,7 +195,8 @@ stringio_getvalue(stringio *self)
 {
     CHECK_INITIALIZED(self);
     CHECK_CLOSED(self);
-    return PyUnicode_FromUnicode(self->buf, self->string_size);
+    return PyUnicode_FromKindAndData(PyUnicode_4BYTE_KIND, self->buf,
+                                     self->string_size);
 }
 
 PyDoc_STRVAR(stringio_tell_doc,
@@ -214,7 +220,7 @@ static PyObject *
 stringio_read(stringio *self, PyObject *args)
 {
     Py_ssize_t size, n;
-    Py_UNICODE *output;
+    Py_UCS4 *output;
     PyObject *arg = Py_None;
 
     CHECK_INITIALIZED(self);
@@ -247,19 +253,19 @@ stringio_read(stringio *self, PyObject *args)
 
     output = self->buf + self->pos;
     self->pos += size;
-    return PyUnicode_FromUnicode(output, size);
+    return PyUnicode_FromKindAndData(PyUnicode_4BYTE_KIND, output, size);
 }
 
 /* Internal helper, used by stringio_readline and stringio_iternext */
 static PyObject *
 _stringio_readline(stringio *self, Py_ssize_t limit)
 {
-    Py_UNICODE *start, *end, old_char;
+    Py_UCS4 *start, *end, old_char;
     Py_ssize_t len, consumed;
 
     /* In case of overseek, return the empty string */
     if (self->pos >= self->string_size)
-        return PyUnicode_FromString("");
+        return PyUnicode_New(0, 0);
 
     start = self->buf + self->pos;
     if (limit < 0 || limit > self->string_size - self->pos)
@@ -270,14 +276,14 @@ _stringio_readline(stringio *self, Py_ssize_t limit)
     *end = '\0';
     len = _PyIO_find_line_ending(
         self->readtranslate, self->readuniversal, self->readnl,
-        start, end, &consumed);
+        PyUnicode_4BYTE_KIND, (char*)start, (char*)end, &consumed);
     *end = old_char;
     /* If we haven't found any line ending, we just return everything
        (`consumed` is ignored). */
     if (len < 0)
         len = limit;
     self->pos += len;
-    return PyUnicode_FromUnicode(start, len);
+    return PyUnicode_FromKindAndData(PyUnicode_4BYTE_KIND, start, len);
 }
 
 PyDoc_STRVAR(stringio_readline_doc,
@@ -337,7 +343,7 @@ stringio_iternext(stringio *self)
     if (line == NULL)
         return NULL;
 
-    if (PyUnicode_GET_SIZE(line) == 0) {
+    if (PyUnicode_GET_LENGTH(line) == 0) {
         /* Reached EOF */
         Py_DECREF(line);
         return NULL;
@@ -462,8 +468,10 @@ stringio_write(stringio *self, PyObject *obj)
                      Py_TYPE(obj)->tp_name);
         return NULL;
     }
+    if (PyUnicode_READY(obj))
+        return NULL;
     CHECK_CLOSED(self);
-    size = PyUnicode_GET_SIZE(obj);
+    size = PyUnicode_GET_LENGTH(obj);
 
     if (size > 0 && write_str(self, obj) < 0)
         return NULL;
@@ -535,7 +543,7 @@ stringio_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
     /* tp_alloc initializes all the fields to zero. So we don't have to
        initialize them here. */
 
-    self->buf = (Py_UNICODE *)PyMem_Malloc(0);
+    self->buf = (Py_UCS4 *)PyMem_Malloc(0);
     if (self->buf == NULL) {
         Py_DECREF(self);
         return PyErr_NoMemory();
@@ -747,11 +755,22 @@ stringio_setstate(stringio *self, PyObject *state)
        once by __init__. So we do not take any chance and replace object's
        buffer completely. */
     {
-        Py_UNICODE *buf = PyUnicode_AS_UNICODE(PyTuple_GET_ITEM(state, 0));
-        Py_ssize_t bufsize = PyUnicode_GET_SIZE(PyTuple_GET_ITEM(state, 0));
-        if (resize_buffer(self, bufsize) < 0)
+        PyObject *item;
+        Py_UCS4 *buf;
+        Py_ssize_t bufsize;
+
+        item = PyTuple_GET_ITEM(state, 0);
+        buf = PyUnicode_AsUCS4Copy(item);
+        if (buf == NULL)
             return NULL;
-        memcpy(self->buf, buf, bufsize * sizeof(Py_UNICODE));
+        bufsize = PyUnicode_GET_LENGTH(item);
+
+        if (resize_buffer(self, bufsize) < 0) {
+            PyMem_Free(buf);
+            return NULL;
+        }
+        memcpy(self->buf, buf, bufsize * sizeof(Py_UCS4));
+        PyMem_Free(buf);
         self->string_size = bufsize;
     }
 
diff --git a/Modules/_io/textio.c b/Modules/_io/textio.c
index 9c5f4416d1..c63c3c7b8a 100644
--- a/Modules/_io/textio.c
+++ b/Modules/_io/textio.c
@@ -11,6 +11,24 @@
 #include "structmember.h"
 #include "_iomodule.h"
 
+_Py_IDENTIFIER(close);
+_Py_IDENTIFIER(_dealloc_warn);
+_Py_IDENTIFIER(decode);
+_Py_IDENTIFIER(device_encoding);
+_Py_IDENTIFIER(fileno);
+_Py_IDENTIFIER(flush);
+_Py_IDENTIFIER(getpreferredencoding);
+_Py_IDENTIFIER(isatty);
+_Py_IDENTIFIER(read);
+_Py_IDENTIFIER(readable);
+_Py_IDENTIFIER(replace);
+_Py_IDENTIFIER(reset);
+_Py_IDENTIFIER(seek);
+_Py_IDENTIFIER(seekable);
+_Py_IDENTIFIER(setstate);
+_Py_IDENTIFIER(tell);
+_Py_IDENTIFIER(writable);
+
 /* TextIOBase */
 
 PyDoc_STRVAR(textiobase_doc,
@@ -274,18 +292,26 @@ _PyIncrementalNewlineDecoder_decode(PyObject *_self,
         goto error;
     }
 
-    output_len = PyUnicode_GET_SIZE(output);
+    if (PyUnicode_READY(output) == -1)
+        goto error;
+
+    output_len = PyUnicode_GET_LENGTH(output);
     if (self->pendingcr && (final || output_len > 0)) {
-        Py_UNICODE *out;
-        PyObject *modified = PyUnicode_FromUnicode(NULL, output_len + 1);
+        /* Prefix output with CR */
+        int kind;
+        PyObject *modified;
+        char *out;
+
+        modified = PyUnicode_New(output_len + 1,
+                                 PyUnicode_MAX_CHAR_VALUE(output));
         if (modified == NULL)
             goto error;
-        out = PyUnicode_AS_UNICODE(modified);
-        out[0] = '\r';
-        memcpy(out + 1, PyUnicode_AS_UNICODE(output),
-               output_len * sizeof(Py_UNICODE));
+        kind = PyUnicode_KIND(modified);
+        out = PyUnicode_DATA(modified);
+        PyUnicode_WRITE(kind, PyUnicode_DATA(modified), 0, '\r');
+        memcpy(out + kind, PyUnicode_DATA(output), kind * output_len);
         Py_DECREF(output);
-        output = modified;
+        output = modified; /* output remains ready */
         self->pendingcr = 0;
         output_len++;
     }
@@ -295,21 +321,13 @@ _PyIncrementalNewlineDecoder_decode(PyObject *_self,
      */
     if (!final) {
         if (output_len > 0
-            && PyUnicode_AS_UNICODE(output)[output_len - 1] == '\r') {
-
-            if (Py_REFCNT(output) == 1) {
-                if (PyUnicode_Resize(&output, output_len - 1) < 0)
-                    goto error;
-            }
-            else {
-                PyObject *modified = PyUnicode_FromUnicode(
-                    PyUnicode_AS_UNICODE(output),
-                    output_len - 1);
-                if (modified == NULL)
-                    goto error;
-                Py_DECREF(output);
-                output = modified;
-            }
+            && PyUnicode_READ_CHAR(output, output_len - 1) == '\r')
+        {
+            PyObject *modified = PyUnicode_Substring(output, 0, output_len -1);
+            if (modified == NULL)
+                goto error;
+            Py_DECREF(output);
+            output = modified;
             self->pendingcr = 1;
         }
     }
@@ -317,13 +335,15 @@ _PyIncrementalNewlineDecoder_decode(PyObject *_self,
     /* Record which newlines are read and do newline translation if desired,
        all in one pass. */
     {
-        Py_UNICODE *in_str;
+        void *in_str;
         Py_ssize_t len;
         int seennl = self->seennl;
         int only_lf = 0;
+        int kind;
 
-        in_str = PyUnicode_AS_UNICODE(output);
-        len = PyUnicode_GET_SIZE(output);
+        in_str = PyUnicode_DATA(output);
+        len = PyUnicode_GET_LENGTH(output);
+        kind = PyUnicode_KIND(output);
 
         if (len == 0)
             return output;
@@ -332,7 +352,7 @@ _PyIncrementalNewlineDecoder_decode(PyObject *_self,
            for the \r *byte* with the libc's optimized memchr.
            */
         if (seennl == SEEN_LF || seennl == 0) {
-            only_lf = (memchr(in_str, '\r', len * sizeof(Py_UNICODE)) == NULL);
+            only_lf = (memchr(in_str, '\r', kind * len) == NULL);
         }
 
         if (only_lf) {
@@ -340,21 +360,19 @@ _PyIncrementalNewlineDecoder_decode(PyObject *_self,
                (there's nothing else to be done, even when in translation mode)
             */
             if (seennl == 0 &&
-                memchr(in_str, '\n', len * sizeof(Py_UNICODE)) != NULL) {
-                Py_UNICODE *s, *end;
-                s = in_str;
-                end = in_str + len;
+                memchr(in_str, '\n', kind * len) != NULL) {
+                Py_ssize_t i = 0;
                 for (;;) {
-                    Py_UNICODE c;
+                    Py_UCS4 c;
                     /* Fast loop for non-control characters */
-                    while (*s > '\n')
-                        s++;
-                    c = *s++;
+                    while (PyUnicode_READ(kind, in_str, i) > '\n')
+                        i++;
+                    c = PyUnicode_READ(kind, in_str, i++);
                     if (c == '\n') {
                         seennl |= SEEN_LF;
                         break;
                     }
-                    if (s > end)
+                    if (i >= len)
                         break;
                 }
             }
@@ -362,29 +380,27 @@ _PyIncrementalNewlineDecoder_decode(PyObject *_self,
                need translating */
         }
         else if (!self->translate) {
-            Py_UNICODE *s, *end;
+            Py_ssize_t i = 0;
             /* We have already seen all newline types, no need to scan again */
             if (seennl == SEEN_ALL)
                 goto endscan;
-            s = in_str;
-            end = in_str + len;
             for (;;) {
-                Py_UNICODE c;
+                Py_UCS4 c;
                 /* Fast loop for non-control characters */
-                while (*s > '\r')
-                    s++;
-                c = *s++;
+                while (PyUnicode_READ(kind, in_str, i) > '\r')
+                    i++;
+                c = PyUnicode_READ(kind, in_str, i++);
                 if (c == '\n')
                     seennl |= SEEN_LF;
                 else if (c == '\r') {
-                    if (*s == '\n') {
+                    if (PyUnicode_READ(kind, in_str, i) == '\n') {
                         seennl |= SEEN_CRLF;
-                        s++;
+                        i++;
                     }
                     else
                         seennl |= SEEN_CR;
                 }
-                if (s > end)
+                if (i >= len)
                     break;
                 if (seennl == SEEN_ALL)
                     break;
@@ -393,61 +409,50 @@ _PyIncrementalNewlineDecoder_decode(PyObject *_self,
             ;
         }
         else {
-            PyObject *translated = NULL;
-            Py_UNICODE *out_str;
-            Py_UNICODE *in, *out, *end;
-            if (Py_REFCNT(output) != 1) {
-                /* We could try to optimize this so that we only do a copy
-                   when there is something to translate. On the other hand,
-                   most decoders should only output non-shared strings, i.e.
-                   translation is done in place. */
-                translated = PyUnicode_FromUnicode(NULL, len);
-                if (translated == NULL)
-                    goto error;
-                assert(Py_REFCNT(translated) == 1);
-                memcpy(PyUnicode_AS_UNICODE(translated),
-                       PyUnicode_AS_UNICODE(output),
-                       len * sizeof(Py_UNICODE));
-            }
-            else {
-                translated = output;
+            void *translated;
+            int kind = PyUnicode_KIND(output);
+            void *in_str = PyUnicode_DATA(output);
+            Py_ssize_t in, out;
+            /* XXX: Previous in-place translation here is disabled as
+               resizing is not possible anymore */
+            /* We could try to optimize this so that we only do a copy
+               when there is something to translate. On the other hand,
+               we already know there is a \r byte, so chances are high
+               that something needs to be done. */
+            translated = PyMem_Malloc(kind * len);
+            if (translated == NULL) {
+                PyErr_NoMemory();
+                goto error;
             }
-            out_str = PyUnicode_AS_UNICODE(translated);
-            in = in_str;
-            out = out_str;
-            end = in_str + len;
+            in = out = 0;
             for (;;) {
-                Py_UNICODE c;
+                Py_UCS4 c;
                 /* Fast loop for non-control characters */
-                while ((c = *in++) > '\r')
-                    *out++ = c;
+                while ((c = PyUnicode_READ(kind, in_str, in++)) > '\r')
+                    PyUnicode_WRITE(kind, translated, out++, c);
                 if (c == '\n') {
-                    *out++ = c;
+                    PyUnicode_WRITE(kind, translated, out++, c);
                     seennl |= SEEN_LF;
                     continue;
                 }
                 if (c == '\r') {
-                    if (*in == '\n') {
+                    if (PyUnicode_READ(kind, in_str, in) == '\n') {
                         in++;
                         seennl |= SEEN_CRLF;
                     }
                     else
                         seennl |= SEEN_CR;
-                    *out++ = '\n';
+                    PyUnicode_WRITE(kind, translated, out++, '\n');
                     continue;
                 }
-                if (in > end)
+                if (in > len)
                     break;
-                *out++ = c;
-            }
-            if (translated != output) {
-                Py_DECREF(output);
-                output = translated;
-            }
-            if (out - out_str != len) {
-                if (PyUnicode_Resize(&output, out - out_str) < 0)
-                    goto error;
+                PyUnicode_WRITE(kind, translated, out++, c);
             }
+            Py_DECREF(output);
+            output = PyUnicode_FromKindAndData(kind, translated, out);
+            if (!output)
+                goto error;
         }
         self->seennl |= seennl;
     }
@@ -514,8 +519,8 @@ incrementalnewlinedecoder_setstate(nldecoder_object *self, PyObject *state)
     flag >>= 1;
 
     if (self->decoder != Py_None)
-        return PyObject_CallMethod(self->decoder,
-                                   "setstate", "((OK))", buffer, flag);
+        return _PyObject_CallMethodId(self->decoder,
+                                      &PyId_setstate, "((OK))", buffer, flag);
     else
         Py_RETURN_NONE;
 }
@@ -680,12 +685,16 @@ typedef struct
     PyObject *pending_bytes;       /* list of bytes objects waiting to be
                                       written, or NULL */
     Py_ssize_t pending_bytes_count;
-    PyObject *snapshot;
+
     /* snapshot is either None, or a tuple (dec_flags, next_input) where
      * dec_flags is the second (integer) item of the decoder state and
      * next_input is the chunk of input bytes that comes next after the
      * snapshot point.  We use this to reconstruct decoder states in tell().
      */
+    PyObject *snapshot;
+    /* Bytes-to-characters ratio for the current chunk. Serves as input for
+       the heuristic in tell(). */
+    double b2cratio;
 
     /* Cache raw object if it's a FileIO object */
     PyObject *raw;
@@ -701,9 +710,7 @@ typedef struct
 static PyObject *
 ascii_encode(textio *self, PyObject *text)
 {
-    return PyUnicode_EncodeASCII(PyUnicode_AS_UNICODE(text),
-                                 PyUnicode_GET_SIZE(text),
-                                 PyBytes_AS_STRING(self->errors));
+    return _PyUnicode_AsASCIIString(text, PyBytes_AS_STRING(self->errors));
 }
 
 static PyObject *
@@ -773,17 +780,13 @@ utf32_encode(textio *self, PyObject *text)
 static PyObject *
 utf8_encode(textio *self, PyObject *text)
 {
-    return PyUnicode_EncodeUTF8(PyUnicode_AS_UNICODE(text),
-                                PyUnicode_GET_SIZE(text),
-                                PyBytes_AS_STRING(self->errors));
+    return _PyUnicode_AsUTF8String(text, PyBytes_AS_STRING(self->errors));
 }
 
 static PyObject *
 latin1_encode(textio *self, PyObject *text)
 {
-    return PyUnicode_EncodeLatin1(PyUnicode_AS_UNICODE(text),
-                                  PyUnicode_GET_SIZE(text),
-                                  PyBytes_AS_STRING(self->errors));
+    return _PyUnicode_AsLatin1String(text, PyBytes_AS_STRING(self->errors));
 }
 
 /* Map normalized encoding names onto the specialized encoding funcs */
@@ -852,11 +855,12 @@ textiowrapper_init(textio *self, PyObject *args, PyObject *kwds)
     self->decoded_chars_used = 0;
     self->pending_bytes_count = 0;
     self->encodefunc = NULL;
+    self->b2cratio = 0.0;
 
     if (encoding == NULL) {
         /* Try os.device_encoding(fileno) */
         PyObject *fileno;
-        fileno = PyObject_CallMethod(buffer, "fileno", NULL);
+        fileno = _PyObject_CallMethodId(buffer, &PyId_fileno, NULL);
         /* Ignore only AttributeError and UnsupportedOperation */
         if (fileno == NULL) {
             if (PyErr_ExceptionMatches(PyExc_AttributeError) ||
@@ -868,9 +872,9 @@ textiowrapper_init(textio *self, PyObject *args, PyObject *kwds)
             }
         }
         else {
-            self->encoding = PyObject_CallMethod(state->os_module,
-                                                 "device_encoding",
-                                                 "N", fileno);
+            self->encoding = _PyObject_CallMethodId(state->os_module,
+                                                    &PyId_device_encoding,
+                                                    "N", fileno);
             if (self->encoding == NULL)
                 goto error;
             else if (!PyUnicode_Check(self->encoding))
@@ -887,8 +891,8 @@ textiowrapper_init(textio *self, PyObject *args, PyObject *kwds)
         }
         else {
           use_locale:
-            self->encoding = PyObject_CallMethod(
-                state->locale_module, "getpreferredencoding", NULL);
+            self->encoding = _PyObject_CallMethodId(
+                state->locale_module, &PyId_getpreferredencoding, NULL);
             if (self->encoding == NULL) {
               catch_ImportError:
                 /*
@@ -953,7 +957,7 @@ textiowrapper_init(textio *self, PyObject *args, PyObject *kwds)
 #endif
 
     /* Build the decoder object */
-    res = PyObject_CallMethod(buffer, "readable", NULL);
+    res = _PyObject_CallMethodId(buffer, &PyId_readable, NULL);
     if (res == NULL)
         goto error;
     r = PyObject_IsTrue(res);
@@ -978,7 +982,7 @@ textiowrapper_init(textio *self, PyObject *args, PyObject *kwds)
     }
 
     /* Build the encoder object */
-    res = PyObject_CallMethod(buffer, "writable", NULL);
+    res = _PyObject_CallMethodId(buffer, &PyId_writable, NULL);
     if (res == NULL)
         goto error;
     r = PyObject_IsTrue(res);
@@ -1036,7 +1040,7 @@ textiowrapper_init(textio *self, PyObject *args, PyObject *kwds)
             Py_DECREF(raw);
     }
 
-    res = PyObject_CallMethod(buffer, "seekable", NULL);
+    res = _PyObject_CallMethodId(buffer, &PyId_seekable, NULL);
     if (res == NULL)
         goto error;
     self->seekable = self->telling = PyObject_IsTrue(res);
@@ -1208,18 +1212,6 @@ textiowrapper_detach(textio *self)
     return buffer;
 }
 
-Py_LOCAL_INLINE(const Py_UNICODE *)
-findchar(const Py_UNICODE *s, Py_ssize_t size, Py_UNICODE ch)
-{
-    /* like wcschr, but doesn't stop at NULL characters */
-    while (size-- > 0) {
-        if (*s == ch)
-            return s;
-        s++;
-    }
-    return NULL;
-}
-
 /* Flush the internal write buffer. This doesn't explicitly flush the
    underlying buffered object, though. */
 static int
@@ -1264,6 +1256,9 @@ textiowrapper_write(textio *self, PyObject *args)
         return NULL;
     }
 
+    if (PyUnicode_READY(text) == -1)
+        return NULL;
+
     CHECK_CLOSED(self);
 
     if (self->encoder == NULL)
@@ -1271,16 +1266,15 @@ textiowrapper_write(textio *self, PyObject *args)
 
     Py_INCREF(text);
 
-    textlen = PyUnicode_GetSize(text);
+    textlen = PyUnicode_GET_LENGTH(text);
 
     if ((self->writetranslate && self->writenl != NULL) || self->line_buffering)
-        if (findchar(PyUnicode_AS_UNICODE(text),
-                     PyUnicode_GET_SIZE(text), '\n'))
+        if (PyUnicode_FindChar(text, '\n', 0, PyUnicode_GET_LENGTH(text), 1) != -1)
             haslf = 1;
 
     if (haslf && self->writetranslate && self->writenl != NULL) {
-        PyObject *newtext = PyObject_CallMethod(
-            text, "replace", "ss", "\n", self->writenl);
+        PyObject *newtext = _PyObject_CallMethodId(
+            text, &PyId_replace, "ss", "\n", self->writenl);
         Py_DECREF(text);
         if (newtext == NULL)
             return NULL;
@@ -1291,8 +1285,7 @@ textiowrapper_write(textio *self, PyObject *args)
         needflush = 1;
     else if (self->line_buffering &&
         (haslf ||
-         findchar(PyUnicode_AS_UNICODE(text),
-                  PyUnicode_GET_SIZE(text), '\r')))
+         PyUnicode_FindChar(text, '\r', 0, PyUnicode_GET_LENGTH(text), 1) != -1))
         needflush = 1;
 
     /* XXX What if we were just reading? */
@@ -1336,7 +1329,7 @@ textiowrapper_write(textio *self, PyObject *args)
     Py_CLEAR(self->snapshot);
 
     if (self->decoder) {
-        ret = PyObject_CallMethod(self->decoder, "reset", NULL);
+        ret = _PyObject_CallMethodId(self->decoder, &PyId_reset, NULL);
         if (ret == NULL)
             return NULL;
         Py_DECREF(ret);
@@ -1364,7 +1357,8 @@ textiowrapper_get_decoded_chars(textio *self, Py_ssize_t n)
     if (self->decoded_chars == NULL)
         return PyUnicode_FromStringAndSize(NULL, 0);
 
-    avail = (PyUnicode_GET_SIZE(self->decoded_chars)
+    /* decoded_chars is guaranteed to be "ready". */
+    avail = (PyUnicode_GET_LENGTH(self->decoded_chars)
              - self->decoded_chars_used);
 
     assert(avail >= 0);
@@ -1373,9 +1367,9 @@ textiowrapper_get_decoded_chars(textio *self, Py_ssize_t n)
         n = avail;
 
     if (self->decoded_chars_used > 0 || n < avail) {
-        chars = PyUnicode_FromUnicode(
-            PyUnicode_AS_UNICODE(self->decoded_chars)
-            + self->decoded_chars_used, n);
+        chars = PyUnicode_Substring(self->decoded_chars,
+                                    self->decoded_chars_used,
+                                    self->decoded_chars_used + n);
         if (chars == NULL)
             return NULL;
     }
@@ -1397,6 +1391,7 @@ textiowrapper_read_chunk(textio *self)
     PyObject *dec_flags = NULL;
     PyObject *input_chunk = NULL;
     PyObject *decoded_chars, *chunk_size;
+    Py_ssize_t nbytes, nchars;
     int eof;
 
     /* The return value is True unless EOF was reached.  The decoded string is
@@ -1443,7 +1438,8 @@ textiowrapper_read_chunk(textio *self)
         goto fail;
     assert(PyBytes_Check(input_chunk));
 
-    eof = (PyBytes_Size(input_chunk) == 0);
+    nbytes = PyBytes_Size(input_chunk);
+    eof = (nbytes == 0);
 
     if (Py_TYPE(self->decoder) == &PyIncrementalNewlineDecoder_Type) {
         decoded_chars = _PyIncrementalNewlineDecoder_decode(
@@ -1457,8 +1453,15 @@ textiowrapper_read_chunk(textio *self)
     /* TODO sanity check: isinstance(decoded_chars, unicode) */
     if (decoded_chars == NULL)
         goto fail;
+    if (PyUnicode_READY(decoded_chars) == -1)
+        goto fail;
     textiowrapper_set_decoded_chars(self, decoded_chars);
-    if (PyUnicode_GET_SIZE(decoded_chars) > 0)
+    nchars = PyUnicode_GET_LENGTH(decoded_chars);
+    if (nchars > 0)
+        self->b2cratio = (double) nbytes / nchars;
+    else
+        self->b2cratio = 0.0;
+    if (nchars > 0)
         eof = 0;
 
     if (self->telling) {
@@ -1505,12 +1508,17 @@ textiowrapper_read(textio *self, PyObject *args)
 
     if (n < 0) {
         /* Read everything */
-        PyObject *bytes = PyObject_CallMethod(self->buffer, "read", NULL);
+        PyObject *bytes = _PyObject_CallMethodId(self->buffer, &PyId_read, NULL);
         PyObject *decoded;
         if (bytes == NULL)
             goto fail;
-        decoded = PyObject_CallMethodObjArgs(self->decoder, _PyIO_str_decode,
-                                             bytes, Py_True, NULL);
+
+        if (Py_TYPE(self->decoder) == &PyIncrementalNewlineDecoder_Type)
+            decoded = _PyIncrementalNewlineDecoder_decode(self->decoder,
+                                                          bytes, 1);
+        else
+            decoded = PyObject_CallMethodObjArgs(
+                self->decoder, _PyIO_str_decode, bytes, Py_True, NULL);
         Py_DECREF(bytes);
         if (decoded == NULL)
             goto fail;
@@ -1536,7 +1544,9 @@ textiowrapper_read(textio *self, PyObject *args)
         result = textiowrapper_get_decoded_chars(self, n);
         if (result == NULL)
             goto fail;
-        remaining -= PyUnicode_GET_SIZE(result);
+        if (PyUnicode_READY(result) == -1)
+            goto fail;
+        remaining -= PyUnicode_GET_LENGTH(result);
 
         /* Keep reading chunks until we have n characters to return */
         while (remaining > 0) {
@@ -1556,7 +1566,7 @@ textiowrapper_read(textio *self, PyObject *args)
             result = textiowrapper_get_decoded_chars(self, remaining);
             if (result == NULL)
                 goto fail;
-            remaining -= PyUnicode_GET_SIZE(result);
+            remaining -= PyUnicode_GET_LENGTH(result);
         }
         if (chunks != NULL) {
             if (result != NULL && PyList_Append(chunks, result) < 0)
@@ -1576,36 +1586,35 @@ textiowrapper_read(textio *self, PyObject *args)
 }
 
 
-/* NOTE: `end` must point to the real end of the Py_UNICODE storage,
+/* NOTE: `end` must point to the real end of the Py_UCS4 storage,
    that is to the NUL character. Otherwise the function will produce
    incorrect results. */
-static Py_UNICODE *
-find_control_char(Py_UNICODE *start, Py_UNICODE *end, Py_UNICODE ch)
+static char *
+find_control_char(int kind, char *s, char *end, Py_UCS4 ch)
 {
-    Py_UNICODE *s = start;
     for (;;) {
-        while (*s > ch)
-            s++;
-        if (*s == ch)
+        while (PyUnicode_READ(kind, s, 0) > ch)
+            s += kind;
+        if (PyUnicode_READ(kind, s, 0) == ch)
             return s;
         if (s == end)
             return NULL;
-        s++;
+        s += kind;
     }
 }
 
 Py_ssize_t
 _PyIO_find_line_ending(
     int translated, int universal, PyObject *readnl,
-    Py_UNICODE *start, Py_UNICODE *end, Py_ssize_t *consumed)
+    int kind, char *start, char *end, Py_ssize_t *consumed)
 {
-    Py_ssize_t len = end - start;
+    Py_ssize_t len = ((char*)end - (char*)start)/kind;
 
     if (translated) {
         /* Newlines are already translated, only search for \n */
-        Py_UNICODE *pos = find_control_char(start, end, '\n');
+        char *pos = find_control_char(kind, start, end, '\n');
         if (pos != NULL)
-            return pos - start + 1;
+            return (pos - start)/kind + 1;
         else {
             *consumed = len;
             return -1;
@@ -1615,63 +1624,66 @@ _PyIO_find_line_ending(
         /* Universal newline search. Find any of \r, \r\n, \n
          * The decoder ensures that \r\n are not split in two pieces
          */
-        Py_UNICODE *s = start;
+        char *s = start;
         for (;;) {
-            Py_UNICODE ch;
+            Py_UCS4 ch;
             /* Fast path for non-control chars. The loop always ends
-               since the Py_UNICODE storage is NUL-terminated. */
-            while (*s > '\r')
-                s++;
+               since the Unicode string is NUL-terminated. */
+            while (PyUnicode_READ(kind, s, 0) > '\r')
+                s += kind;
             if (s >= end) {
                 *consumed = len;
                 return -1;
             }
-            ch = *s++;
+            ch = PyUnicode_READ(kind, s, 0);
+            s += kind;
             if (ch == '\n')
-                return s - start;
+                return (s - start)/kind;
             if (ch == '\r') {
-                if (*s == '\n')
-                    return s - start + 1;
+                if (PyUnicode_READ(kind, s, 0) == '\n')
+                    return (s - start)/kind + 1;
                 else
-                    return s - start;
+                    return (s - start)/kind;
             }
         }
     }
     else {
         /* Non-universal mode. */
-        Py_ssize_t readnl_len = PyUnicode_GET_SIZE(readnl);
-        Py_UNICODE *nl = PyUnicode_AS_UNICODE(readnl);
+        Py_ssize_t readnl_len = PyUnicode_GET_LENGTH(readnl);
+        char *nl = PyUnicode_DATA(readnl);
+        /* Assume that readnl is an ASCII character. */
+        assert(PyUnicode_KIND(readnl) == PyUnicode_1BYTE_KIND);
         if (readnl_len == 1) {
-            Py_UNICODE *pos = find_control_char(start, end, nl[0]);
+            char *pos = find_control_char(kind, start, end, nl[0]);
             if (pos != NULL)
-                return pos - start + 1;
+                return (pos - start)/kind + 1;
             *consumed = len;
             return -1;
         }
         else {
-            Py_UNICODE *s = start;
-            Py_UNICODE *e = end - readnl_len + 1;
-            Py_UNICODE *pos;
+            char *s = start;
+            char *e = end - (readnl_len - 1)*kind;
+            char *pos;
             if (e < s)
                 e = s;
             while (s < e) {
                 Py_ssize_t i;
-                Py_UNICODE *pos = find_control_char(s, end, nl[0]);
+                char *pos = find_control_char(kind, s, end, nl[0]);
                 if (pos == NULL || pos >= e)
                     break;
                 for (i = 1; i < readnl_len; i++) {
-                    if (pos[i] != nl[i])
+                    if (PyUnicode_READ(kind, pos, i) != nl[i])
                         break;
                 }
                 if (i == readnl_len)
-                    return pos - start + readnl_len;
-                s = pos + 1;
+                    return (pos - start)/kind + readnl_len;
+                s = pos + kind;
             }
-            pos = find_control_char(e, end, nl[0]);
+            pos = find_control_char(kind, e, end, nl[0]);
             if (pos == NULL)
                 *consumed = len;
             else
-                *consumed = pos - start;
+                *consumed = (pos - start)/kind;
             return -1;
         }
     }
@@ -1692,14 +1704,15 @@ _textiowrapper_readline(textio *self, Py_ssize_t limit)
     chunked = 0;
 
     while (1) {
-        Py_UNICODE *ptr;
+        char *ptr;
         Py_ssize_t line_len;
+        int kind;
         Py_ssize_t consumed = 0;
 
         /* First, get some data if necessary */
         res = 1;
         while (!self->decoded_chars ||
-               !PyUnicode_GET_SIZE(self->decoded_chars)) {
+               !PyUnicode_GET_LENGTH(self->decoded_chars)) {
             res = textiowrapper_read_chunk(self);
             if (res < 0)
                 goto error;
@@ -1724,18 +1737,24 @@ _textiowrapper_readline(textio *self, Py_ssize_t limit)
             assert(self->decoded_chars_used == 0);
             line = PyUnicode_Concat(remaining, self->decoded_chars);
             start = 0;
-            offset_to_buffer = PyUnicode_GET_SIZE(remaining);
+            offset_to_buffer = PyUnicode_GET_LENGTH(remaining);
             Py_CLEAR(remaining);
             if (line == NULL)
                 goto error;
+            if (PyUnicode_READY(line) == -1)
+                goto error;
         }
 
-        ptr = PyUnicode_AS_UNICODE(line);
-        line_len = PyUnicode_GET_SIZE(line);
+        ptr = PyUnicode_DATA(line);
+        line_len = PyUnicode_GET_LENGTH(line);
+        kind = PyUnicode_KIND(line);
 
         endpos = _PyIO_find_line_ending(
             self->readtranslate, self->readuniversal, self->readnl,
-            ptr + start, ptr + line_len, &consumed);
+            kind,
+            ptr + kind * start,
+            ptr + kind * line_len,
+            &consumed);
         if (endpos >= 0) {
             endpos += start;
             if (limit >= 0 && (endpos - start) + chunked >= limit)
@@ -1759,21 +1778,20 @@ _textiowrapper_readline(textio *self, Py_ssize_t limit)
                 if (chunks == NULL)
                     goto error;
             }
-            s = PyUnicode_FromUnicode(ptr + start, endpos - start);
+            s = PyUnicode_Substring(line, start, endpos);
             if (s == NULL)
                 goto error;
             if (PyList_Append(chunks, s) < 0) {
                 Py_DECREF(s);
                 goto error;
             }
-            chunked += PyUnicode_GET_SIZE(s);
+            chunked += PyUnicode_GET_LENGTH(s);
             Py_DECREF(s);
         }
         /* There may be some remaining bytes we'll have to prepend to the
            next chunk of data */
         if (endpos < line_len) {
-            remaining = PyUnicode_FromUnicode(
-                    ptr + endpos, line_len - endpos);
+            remaining = PyUnicode_Substring(line, endpos, line_len);
             if (remaining == NULL)
                 goto error;
         }
@@ -1785,19 +1803,12 @@ _textiowrapper_readline(textio *self, Py_ssize_t limit)
     if (line != NULL) {
         /* Our line ends in the current buffer */
         self->decoded_chars_used = endpos - offset_to_buffer;
-        if (start > 0 || endpos < PyUnicode_GET_SIZE(line)) {
-            if (start == 0 && Py_REFCNT(line) == 1) {
-                if (PyUnicode_Resize(&line, endpos) < 0)
-                    goto error;
-            }
-            else {
-                PyObject *s = PyUnicode_FromUnicode(
-                        PyUnicode_AS_UNICODE(line) + start, endpos - start);
-                Py_CLEAR(line);
-                if (s == NULL)
-                    goto error;
-                line = s;
-            }
+        if (start > 0 || endpos < PyUnicode_GET_LENGTH(line)) {
+            PyObject *s = PyUnicode_Substring(line, start, endpos);
+            Py_CLEAR(line);
+            if (s == NULL)
+                goto error;
+            line = s;
         }
     }
     if (remaining != NULL) {
@@ -1811,16 +1822,20 @@ _textiowrapper_readline(textio *self, Py_ssize_t limit)
         Py_CLEAR(remaining);
     }
     if (chunks != NULL) {
-        if (line != NULL && PyList_Append(chunks, line) < 0)
-            goto error;
-        Py_CLEAR(line);
+        if (line != NULL) {
+            if (PyList_Append(chunks, line) < 0)
+                goto error;
+            Py_DECREF(line);
+        }
         line = PyUnicode_Join(_PyIO_empty_str, chunks);
         if (line == NULL)
             goto error;
-        Py_DECREF(chunks);
+        Py_CLEAR(chunks);
+    }
+    if (line == NULL) {
+        Py_INCREF(_PyIO_empty_str);
+        line = _PyIO_empty_str;
     }
-    if (line == NULL)
-        line = PyUnicode_FromStringAndSize(NULL, 0);
 
     return line;
 
@@ -1943,8 +1958,8 @@ _textiowrapper_decoder_setstate(textio *self, cookie_type *cookie)
     if (cookie->start_pos == 0 && cookie->dec_flags == 0)
         res = PyObject_CallMethodObjArgs(self->decoder, _PyIO_str_reset, NULL);
     else
-        res = PyObject_CallMethod(self->decoder, "setstate",
-                                  "((yi))", "", cookie->dec_flags);
+        res = _PyObject_CallMethodId(self->decoder, &PyId_setstate,
+                                     "((yi))", "", cookie->dec_flags);
     if (res == NULL)
         return -1;
     Py_DECREF(res);
@@ -2008,13 +2023,12 @@ textiowrapper_seek(textio *self, PyObject *args)
          * sync the underlying buffer with the current position.
          */
         Py_DECREF(cookieObj);
-        cookieObj = PyObject_CallMethod((PyObject *)self, "tell", NULL);
+        cookieObj = _PyObject_CallMethodId((PyObject *)self, &PyId_tell, NULL);
         if (cookieObj == NULL)
             goto fail;
     }
     else if (whence == 2) {
         /* seek relative to end of file */
-
         cmp = PyObject_RichCompareBool(cookieObj, _PyIO_zero, Py_EQ);
         if (cmp < 0)
             goto fail;
@@ -2024,7 +2038,7 @@ textiowrapper_seek(textio *self, PyObject *args)
             goto fail;
         }
 
-        res = PyObject_CallMethod((PyObject *)self, "flush", NULL);
+        res = _PyObject_CallMethodId((PyObject *)self, &PyId_flush, NULL);
         if (res == NULL)
             goto fail;
         Py_DECREF(res);
@@ -2032,13 +2046,13 @@ textiowrapper_seek(textio *self, PyObject *args)
         textiowrapper_set_decoded_chars(self, NULL);
         Py_CLEAR(self->snapshot);
         if (self->decoder) {
-            res = PyObject_CallMethod(self->decoder, "reset", NULL);
+            res = _PyObject_CallMethodId(self->decoder, &PyId_reset, NULL);
             if (res == NULL)
                 goto fail;
             Py_DECREF(res);
         }
 
-        res = PyObject_CallMethod(self->buffer, "seek", "ii", 0, 2);
+        res = _PyObject_CallMethodId(self->buffer, &PyId_seek, "ii", 0, 2);
         Py_XDECREF(cookieObj);
         return res;
     }
@@ -2091,8 +2105,8 @@ textiowrapper_seek(textio *self, PyObject *args)
 
     if (cookie.chars_to_skip) {
         /* Just like _read_chunk, feed the decoder and save a snapshot. */
-        PyObject *input_chunk = PyObject_CallMethod(
-            self->buffer, "read", "i", cookie.bytes_to_feed);
+        PyObject *input_chunk = _PyObject_CallMethodId(
+            self->buffer, &PyId_read, "i", cookie.bytes_to_feed);
         PyObject *decoded;
 
         if (input_chunk == NULL)
@@ -2106,11 +2120,15 @@ textiowrapper_seek(textio *self, PyObject *args)
             goto fail;
         }
 
-        decoded = PyObject_CallMethod(self->decoder, "decode",
-                                      "Oi", input_chunk, (int)cookie.need_eof);
+        decoded = _PyObject_CallMethodId(self->decoder, &PyId_decode,
+            "Oi", input_chunk, (int)cookie.need_eof);
 
         if (decoded == NULL)
             goto fail;
+        if (PyUnicode_READY(decoded) == -1) {
+            Py_DECREF(decoded);
+            goto fail;
+        }
 
         textiowrapper_set_decoded_chars(self, decoded);
 
@@ -2147,8 +2165,12 @@ textiowrapper_tell(textio *self, PyObject *args)
     cookie_type cookie = {0,0,0,0,0};
     PyObject *next_input;
     Py_ssize_t chars_to_skip, chars_decoded;
+    Py_ssize_t skip_bytes, skip_back;
     PyObject *saved_state = NULL;
     char *input, *input_end;
+    char *dec_buffer;
+    Py_ssize_t dec_buffer_len;
+    int dec_flags;
 
     CHECK_INITIALIZED(self);
     CHECK_CLOSED(self);
@@ -2165,12 +2187,12 @@ textiowrapper_tell(textio *self, PyObject *args)
 
     if (_textiowrapper_writeflush(self) < 0)
         return NULL;
-    res = PyObject_CallMethod((PyObject *)self, "flush", NULL);
+    res = _PyObject_CallMethodId((PyObject *)self, &PyId_flush, NULL);
     if (res == NULL)
         goto fail;
     Py_DECREF(res);
 
-    posobj = PyObject_CallMethod(self->buffer, "tell", NULL);
+    posobj = _PyObject_CallMethodId(self->buffer, &PyId_tell, NULL);
     if (posobj == NULL)
         goto fail;
 
@@ -2184,6 +2206,7 @@ textiowrapper_tell(textio *self, PyObject *args)
 #else
     cookie.start_pos = PyLong_AsLong(posobj);
 #endif
+    Py_DECREF(posobj);
     if (PyErr_Occurred())
         goto fail;
 
@@ -2198,57 +2221,99 @@ textiowrapper_tell(textio *self, PyObject *args)
     /* How many decoded characters have been used up since the snapshot? */
     if (self->decoded_chars_used == 0)  {
         /* We haven't moved from the snapshot point. */
-        Py_DECREF(posobj);
         return textiowrapper_build_cookie(&cookie);
     }
 
     chars_to_skip = self->decoded_chars_used;
 
-    /* Starting from the snapshot position, we will walk the decoder
-     * forward until it gives us enough decoded characters.
-     */
+    /* Decoder state will be restored at the end */
     saved_state = PyObject_CallMethodObjArgs(self->decoder,
                                              _PyIO_str_getstate, NULL);
     if (saved_state == NULL)
         goto fail;
 
-    /* Note our initial start point. */
-    if (_textiowrapper_decoder_setstate(self, &cookie) < 0)
-        goto fail;
+#define DECODER_GETSTATE() do { \
+        PyObject *_state = PyObject_CallMethodObjArgs(self->decoder, \
+            _PyIO_str_getstate, NULL); \
+        if (_state == NULL) \
+            goto fail; \
+        if (!PyArg_Parse(_state, "(y#i)", &dec_buffer, &dec_buffer_len, &dec_flags)) { \
+            Py_DECREF(_state); \
+            goto fail; \
+        } \
+        Py_DECREF(_state); \
+    } while (0)
+
+    /* TODO: replace assert with exception */
+#define DECODER_DECODE(start, len, res) do { \
+        PyObject *_decoded = _PyObject_CallMethodId( \
+            self->decoder, &PyId_decode, "y#", start, len); \
+        if (_decoded == NULL) \
+            goto fail; \
+        assert (PyUnicode_Check(_decoded)); \
+        res = PyUnicode_GET_LENGTH(_decoded); \
+        Py_DECREF(_decoded); \
+    } while (0)
 
-    /* Feed the decoder one byte at a time.  As we go, note the
-     * nearest "safe start point" before the current location
-     * (a point where the decoder has nothing buffered, so seek()
+    /* Fast search for an acceptable start point, close to our
+       current pos */
+    skip_bytes = (Py_ssize_t) (self->b2cratio * chars_to_skip);
+    skip_back = 1;
+    assert(skip_back <= PyBytes_GET_SIZE(next_input));
+    input = PyBytes_AS_STRING(next_input);
+    while (skip_bytes > 0) {
+        /* Decode up to temptative start point */
+        if (_textiowrapper_decoder_setstate(self, &cookie) < 0)
+            goto fail;
+        DECODER_DECODE(input, skip_bytes, chars_decoded);
+        if (chars_decoded <= chars_to_skip) {
+            DECODER_GETSTATE();
+            if (dec_buffer_len == 0) {
+                /* Before pos and no bytes buffered in decoder => OK */
+                cookie.dec_flags = dec_flags;
+                chars_to_skip -= chars_decoded;
+                break;
+            }
+            /* Skip back by buffered amount and reset heuristic */
+            skip_bytes -= dec_buffer_len;
+            skip_back = 1;
+        }
+        else {
+            /* We're too far ahead, skip back a bit */
+            skip_bytes -= skip_back;
+            skip_back *= 2;
+        }
+    }
+    if (skip_bytes <= 0) {
+        skip_bytes = 0;
+        if (_textiowrapper_decoder_setstate(self, &cookie) < 0)
+            goto fail;
+    }
+
+    /* Note our initial start point. */
+    cookie.start_pos += skip_bytes;
+    cookie.chars_to_skip = chars_to_skip;
+    if (chars_to_skip == 0)
+        goto finally;
+
+    /* We should be close to the desired position.  Now feed the decoder one
+     * byte at a time until we reach the `chars_to_skip` target.
+     * As we go, note the nearest "safe start point" before the current
+     * location (a point where the decoder has nothing buffered, so seek()
      * can safely start from there and advance to this location).
      */
     chars_decoded = 0;
     input = PyBytes_AS_STRING(next_input);
     input_end = input + PyBytes_GET_SIZE(next_input);
+    input += skip_bytes;
     while (input < input_end) {
-        PyObject *state;
-        char *dec_buffer;
-        Py_ssize_t dec_buffer_len;
-        int dec_flags;
-
-        PyObject *decoded = PyObject_CallMethod(
-            self->decoder, "decode", "y#", input, 1);
-        if (decoded == NULL)
-            goto fail;
-        assert (PyUnicode_Check(decoded));
-        chars_decoded += PyUnicode_GET_SIZE(decoded);
-        Py_DECREF(decoded);
+        Py_ssize_t n;
 
+        DECODER_DECODE(input, 1, n);
+        /* We got n chars for 1 byte */
+        chars_decoded += n;
         cookie.bytes_to_feed += 1;
-
-        state = PyObject_CallMethodObjArgs(self->decoder,
-                                           _PyIO_str_getstate, NULL);
-        if (state == NULL)
-            goto fail;
-        if (!PyArg_Parse(state, "(y#i)", &dec_buffer, &dec_buffer_len, &dec_flags)) {
-            Py_DECREF(state);
-            goto fail;
-        }
-        Py_DECREF(state);
+        DECODER_GETSTATE();
 
         if (dec_buffer_len == 0 && chars_decoded <= chars_to_skip) {
             /* Decoder buffer is empty, so this is a safe start point. */
@@ -2264,12 +2329,12 @@ textiowrapper_tell(textio *self, PyObject *args)
     }
     if (input == input_end) {
         /* We didn't get enough decoded data; signal EOF to get more. */
-        PyObject *decoded = PyObject_CallMethod(
-            self->decoder, "decode", "yi", "", /* final = */ 1);
+        PyObject *decoded = _PyObject_CallMethodId(
+            self->decoder, &PyId_decode, "yi", "", /* final = */ 1);
         if (decoded == NULL)
             goto fail;
         assert (PyUnicode_Check(decoded));
-        chars_decoded += PyUnicode_GET_SIZE(decoded);
+        chars_decoded += PyUnicode_GET_LENGTH(decoded);
         Py_DECREF(decoded);
         cookie.need_eof = 1;
 
@@ -2280,9 +2345,8 @@ textiowrapper_tell(textio *self, PyObject *args)
         }
     }
 
-    /* finally */
-    Py_XDECREF(posobj);
-    res = PyObject_CallMethod(self->decoder, "setstate", "(O)", saved_state);
+finally:
+    res = _PyObject_CallMethodId(self->decoder, &PyId_setstate, "(O)", saved_state);
     Py_DECREF(saved_state);
     if (res == NULL)
         return NULL;
@@ -2292,13 +2356,12 @@ textiowrapper_tell(textio *self, PyObject *args)
     cookie.chars_to_skip = Py_SAFE_DOWNCAST(chars_to_skip, Py_ssize_t, int);
     return textiowrapper_build_cookie(&cookie);
 
-  fail:
-    Py_XDECREF(posobj);
+fail:
     if (saved_state) {
         PyObject *type, *value, *traceback;
         PyErr_Fetch(&type, &value, &traceback);
 
-        res = PyObject_CallMethod(self->decoder, "setstate", "(O)", saved_state);
+        res = _PyObject_CallMethodId(self->decoder, &PyId_setstate, "(O)", saved_state);
         Py_DECREF(saved_state);
         if (res == NULL)
             return NULL;
@@ -2386,35 +2449,35 @@ static PyObject *
 textiowrapper_fileno(textio *self, PyObject *args)
 {
     CHECK_INITIALIZED(self);
-    return PyObject_CallMethod(self->buffer, "fileno", NULL);
+    return _PyObject_CallMethodId(self->buffer, &PyId_fileno, NULL);
 }
 
 static PyObject *
 textiowrapper_seekable(textio *self, PyObject *args)
 {
     CHECK_INITIALIZED(self);
-    return PyObject_CallMethod(self->buffer, "seekable", NULL);
+    return _PyObject_CallMethodId(self->buffer, &PyId_seekable, NULL);
 }
 
 static PyObject *
 textiowrapper_readable(textio *self, PyObject *args)
 {
     CHECK_INITIALIZED(self);
-    return PyObject_CallMethod(self->buffer, "readable", NULL);
+    return _PyObject_CallMethodId(self->buffer, &PyId_readable, NULL);
 }
 
 static PyObject *
 textiowrapper_writable(textio *self, PyObject *args)
 {
     CHECK_INITIALIZED(self);
-    return PyObject_CallMethod(self->buffer, "writable", NULL);
+    return _PyObject_CallMethodId(self->buffer, &PyId_writable, NULL);
 }
 
 static PyObject *
 textiowrapper_isatty(textio *self, PyObject *args)
 {
     CHECK_INITIALIZED(self);
-    return PyObject_CallMethod(self->buffer, "isatty", NULL);
+    return _PyObject_CallMethodId(self->buffer, &PyId_isatty, NULL);
 }
 
 static PyObject *
@@ -2433,7 +2496,7 @@ textiowrapper_flush(textio *self, PyObject *args)
     self->telling = self->seekable;
     if (_textiowrapper_writeflush(self) < 0)
         return NULL;
-    return PyObject_CallMethod(self->buffer, "flush", NULL);
+    return _PyObject_CallMethodId(self->buffer, &PyId_flush, NULL);
 }
 
 static PyObject *
@@ -2456,20 +2519,20 @@ textiowrapper_close(textio *self, PyObject *args)
     }
     else {
         if (self->deallocating) {
-            res = PyObject_CallMethod(self->buffer, "_dealloc_warn", "O", self);
+            res = _PyObject_CallMethodId(self->buffer, &PyId__dealloc_warn, "O", self);
             if (res)
                 Py_DECREF(res);
             else
                 PyErr_Clear();
         }
-        res = PyObject_CallMethod((PyObject *)self, "flush", NULL);
+        res = _PyObject_CallMethodId((PyObject *)self, &PyId_flush, NULL);
         if (res == NULL) {
             return NULL;
         }
         else
             Py_DECREF(res);
 
-        return PyObject_CallMethod(self->buffer, "close", NULL);
+        return _PyObject_CallMethodId(self->buffer, &PyId_close, NULL);
     }
 }
 
@@ -2497,10 +2560,10 @@ textiowrapper_iternext(textio *self)
         }
     }
 
-    if (line == NULL)
+    if (line == NULL || PyUnicode_READY(line) == -1)
         return NULL;
 
-    if (PyUnicode_GET_SIZE(line) == 0) {
+    if (PyUnicode_GET_LENGTH(line) == 0) {
         /* Reached EOF or would have blocked */
         Py_DECREF(line);
         Py_CLEAR(self->snapshot);