Library import 16 (#2433)

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1 files changed, 2692 insertions, 0 deletions

diff --git a/contrib/tools/python3/Modules/_io/bufferedio.c b/contrib/tools/python3/Modules/_io/bufferedio.c
new file mode 100644
index 0000000000..f30d54a5e1
--- /dev/null
+++ b/contrib/tools/python3/Modules/_io/bufferedio.c
@@ -0,0 +1,2692 @@
+/*
+    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
+*/
+
+#define PY_SSIZE_T_CLEAN
+#include "Python.h"
+#include "pycore_call.h"          // _PyObject_CallNoArgs()
+#include "pycore_object.h"
+#include "structmember.h"         // PyMemberDef
+#include "_iomodule.h"
+
+/*[clinic input]
+module _io
+class _io._BufferedIOBase "PyObject *" "clinic_state()->PyBufferedIOBase_Type"
+class _io._Buffered "buffered *" "clinic_state()->PyBufferedIOBase_Type"
+class _io.BufferedReader "buffered *" "clinic_state()->PyBufferedReader_Type"
+class _io.BufferedWriter "buffered *" "clinic_state()->PyBufferedWriter_Type"
+class _io.BufferedRWPair "rwpair *" "clinic_state()->PyBufferedRWPair_Type"
+class _io.BufferedRandom "buffered *" "clinic_state()->PyBufferedRandom_Type"
+[clinic start generated code]*/
+/*[clinic end generated code: output=da39a3ee5e6b4b0d input=3b3ef9cbbbad4590]*/
+
+/*
+ * BufferedIOBase class, inherits from IOBase.
+ */
+PyDoc_STRVAR(bufferediobase_doc,
+    "Base class for buffered IO objects.\n"
+    "\n"
+    "The main difference with RawIOBase is that the read() method\n"
+    "supports omitting the size argument, and does not have a default\n"
+    "implementation that defers to readinto().\n"
+    "\n"
+    "In addition, read(), readinto() and write() may raise\n"
+    "BlockingIOError if the underlying raw stream is in non-blocking\n"
+    "mode and not ready; unlike their raw counterparts, they will never\n"
+    "return None.\n"
+    "\n"
+    "A typical implementation should not inherit from a RawIOBase\n"
+    "implementation, but wrap one.\n"
+    );
+
+static PyObject *
+_bufferediobase_readinto_generic(PyObject *self, Py_buffer *buffer, char readinto1)
+{
+    Py_ssize_t len;
+    PyObject *data;
+
+    PyObject *attr = readinto1
+        ? &_Py_ID(read1)
+        : &_Py_ID(read);
+    data = _PyObject_CallMethod(self, attr, "n", buffer->len);
+    if (data == NULL)
+        return NULL;
+
+    if (!PyBytes_Check(data)) {
+        Py_DECREF(data);
+        PyErr_SetString(PyExc_TypeError, "read() should return bytes");
+        return NULL;
+    }
+
+    len = PyBytes_GET_SIZE(data);
+    if (len > buffer->len) {
+        PyErr_Format(PyExc_ValueError,
+                     "read() returned too much data: "
+                     "%zd bytes requested, %zd returned",
+                     buffer->len, len);
+        Py_DECREF(data);
+        return NULL;
+    }
+    memcpy(buffer->buf, PyBytes_AS_STRING(data), len);
+
+    Py_DECREF(data);
+
+    return PyLong_FromSsize_t(len);
+}
+
+/*[clinic input]
+_io._BufferedIOBase.readinto
+    buffer: Py_buffer(accept={rwbuffer})
+    /
+[clinic start generated code]*/
+
+static PyObject *
+_io__BufferedIOBase_readinto_impl(PyObject *self, Py_buffer *buffer)
+/*[clinic end generated code: output=8c8cda6684af8038 input=00a6b9a38f29830a]*/
+{
+    return _bufferediobase_readinto_generic(self, buffer, 0);
+}
+
+/*[clinic input]
+_io._BufferedIOBase.readinto1
+    buffer: Py_buffer(accept={rwbuffer})
+    /
+[clinic start generated code]*/
+
+static PyObject *
+_io__BufferedIOBase_readinto1_impl(PyObject *self, Py_buffer *buffer)
+/*[clinic end generated code: output=358623e4fd2b69d3 input=ebad75b4aadfb9be]*/
+{
+    return _bufferediobase_readinto_generic(self, buffer, 1);
+}
+
+static PyObject *
+bufferediobase_unsupported(_PyIO_State *state, const char *message)
+{
+    PyErr_SetString(state->unsupported_operation, message);
+    return NULL;
+}
+
+/*[clinic input]
+_io._BufferedIOBase.detach
+
+    cls: defining_class
+    /
+
+Disconnect this buffer from its underlying raw stream and return it.
+
+After the raw stream has been detached, the buffer is in an unusable
+state.
+[clinic start generated code]*/
+
+static PyObject *
+_io__BufferedIOBase_detach_impl(PyObject *self, PyTypeObject *cls)
+/*[clinic end generated code: output=b87b135d67cd4448 input=0b61a7b4357c1ea7]*/
+{
+    _PyIO_State *state = get_io_state_by_cls(cls);
+    return bufferediobase_unsupported(state, "detach");
+}
+
+/*[clinic input]
+_io._BufferedIOBase.read
+
+    cls: defining_class
+    size: int(unused=True) = -1
+    /
+
+Read and return up to n bytes.
+
+If the size argument is omitted, None, or negative, read and
+return all data until EOF.
+
+If the size argument is positive, and the underlying raw stream is
+not 'interactive', multiple raw reads may be issued to satisfy
+the byte count (unless EOF is reached first).
+However, for interactive raw streams (as well as sockets and pipes),
+at most one raw read will be issued, and a short result does not
+imply that EOF is imminent.
+
+Return an empty bytes object on EOF.
+
+Return None if the underlying raw stream was open in non-blocking
+mode and no data is available at the moment.
+[clinic start generated code]*/
+
+static PyObject *
+_io__BufferedIOBase_read_impl(PyObject *self, PyTypeObject *cls,
+                              int Py_UNUSED(size))
+/*[clinic end generated code: output=aceb2765587b0a29 input=824f6f910465e61a]*/
+{
+    _PyIO_State *state = get_io_state_by_cls(cls);
+    return bufferediobase_unsupported(state, "read");
+}
+
+/*[clinic input]
+_io._BufferedIOBase.read1
+
+    cls: defining_class
+    size: int(unused=True) = -1
+    /
+
+Read and return up to size bytes, with at most one read() call to the underlying raw stream.
+
+Return an empty bytes object on EOF.
+A short result does not imply that EOF is imminent.
+[clinic start generated code]*/
+
+static PyObject *
+_io__BufferedIOBase_read1_impl(PyObject *self, PyTypeObject *cls,
+                               int Py_UNUSED(size))
+/*[clinic end generated code: output=2e7fc62972487eaa input=af76380e020fd9e6]*/
+{
+    _PyIO_State *state = get_io_state_by_cls(cls);
+    return bufferediobase_unsupported(state, "read1");
+}
+
+/*[clinic input]
+_io._BufferedIOBase.write
+
+    cls: defining_class
+    b: object(unused=True)
+    /
+
+Write buffer b to the IO stream.
+
+Return the number of bytes written, which is always
+the length of b in bytes.
+
+Raise BlockingIOError if the buffer is full and the
+underlying raw stream cannot accept more data at the moment.
+[clinic start generated code]*/
+
+static PyObject *
+_io__BufferedIOBase_write_impl(PyObject *self, PyTypeObject *cls,
+                               PyObject *Py_UNUSED(b))
+/*[clinic end generated code: output=712c635246bf2306 input=9793f5c8f71029ad]*/
+{
+    _PyIO_State *state = get_io_state_by_cls(cls);
+    return bufferediobase_unsupported(state, "write");
+}
+
+
+typedef struct {
+    PyObject_HEAD
+
+    PyObject *raw;
+    int ok;    /* Initialized? */
+    int detached;
+    int readable;
+    int writable;
+    char finalizing;
+
+    /* 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;
+
+    /* Absolute position inside the raw stream (-1 if unknown). */
+    Py_off_t abs_pos;
+
+    /* A static buffer of size `buffer_size` */
+    char *buffer;
+    /* Current logical position in the buffer. */
+    Py_off_t pos;
+    /* Position of the raw stream in the buffer. */
+    Py_off_t raw_pos;
+
+    /* Just after the last buffered byte in the buffer, or -1 if the buffer
+       isn't ready for reading. */
+    Py_off_t read_end;
+
+    /* Just after the last byte actually written */
+    Py_off_t write_pos;
+    /* Just after the last byte waiting to be written, or -1 if the buffer
+       isn't ready for writing. */
+    Py_off_t write_end;
+
+    PyThread_type_lock lock;
+    volatile unsigned long owner;
+
+    Py_ssize_t buffer_size;
+    Py_ssize_t buffer_mask;
+
+    PyObject *dict;
+    PyObject *weakreflist;
+} buffered;
+
+/*
+    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)
+    * They also share a single buffer for reading and writing. This enables
+      interleaved reads and writes without flushing. It also makes the logic
+      a bit trickier to get right.
+    * The absolute position of the raw stream is cached, if possible, in the
+      `abs_pos` member. It must be updated every time an operation is done
+      on the raw stream. If not sure, it can be reinitialized by calling
+      _buffered_raw_tell(), which queries the raw stream (_buffered_raw_seek()
+      also does it). To read it, use RAW_TELL().
+    * Three helpers, _bufferedreader_raw_read, _bufferedwriter_raw_write and
+      _bufferedwriter_flush_unlocked do a lot of useful housekeeping.
+
+    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. */
+
+static int
+_enter_buffered_busy(buffered *self)
+{
+    int relax_locking;
+    PyLockStatus st;
+    if (self->owner == PyThread_get_thread_ident()) {
+        PyErr_Format(PyExc_RuntimeError,
+                     "reentrant call inside %R", self);
+        return 0;
+    }
+    PyInterpreterState *interp = PyInterpreterState_Get();
+    relax_locking = _Py_IsInterpreterFinalizing(interp);
+    Py_BEGIN_ALLOW_THREADS
+    if (!relax_locking)
+        st = PyThread_acquire_lock(self->lock, 1);
+    else {
+        /* When finalizing, we don't want a deadlock to happen with daemon
+         * threads abruptly shut down while they owned the lock.
+         * Therefore, only wait for a grace period (1 s.).
+         * Note that non-daemon threads have already exited here, so this
+         * shouldn't affect carefully written threaded I/O code.
+         */
+        st = PyThread_acquire_lock_timed(self->lock, (PY_TIMEOUT_T)1e6, 0);
+    }
+    Py_END_ALLOW_THREADS
+    if (relax_locking && st != PY_LOCK_ACQUIRED) {
+        PyObject *ascii = PyObject_ASCII((PyObject*)self);
+        _Py_FatalErrorFormat(__func__,
+            "could not acquire lock for %s at interpreter "
+            "shutdown, possibly due to daemon threads",
+            ascii ? PyUnicode_AsUTF8(ascii) : "<ascii(self) failed>");
+    }
+    return 1;
+}
+
+#define ENTER_BUFFERED(self) \
+    ( (PyThread_acquire_lock(self->lock, 0) ? \
+       1 : _enter_buffered_busy(self)) \
+     && (self->owner = PyThread_get_thread_ident(), 1) )
+
+#define LEAVE_BUFFERED(self) \
+    do { \
+        self->owner = 0; \
+        PyThread_release_lock(self->lock); \
+    } while(0);
+
+#define CHECK_INITIALIZED(self) \
+    if (self->ok <= 0) { \
+        if (self->detached) { \
+            PyErr_SetString(PyExc_ValueError, \
+                 "raw stream has been detached"); \
+        } else { \
+            PyErr_SetString(PyExc_ValueError, \
+                "I/O operation on uninitialized object"); \
+        } \
+        return NULL; \
+    }
+
+#define CHECK_INITIALIZED_INT(self) \
+    if (self->ok <= 0) { \
+        if (self->detached) { \
+            PyErr_SetString(PyExc_ValueError, \
+                 "raw stream has been detached"); \
+        } else { \
+            PyErr_SetString(PyExc_ValueError, \
+                "I/O operation on uninitialized object"); \
+        } \
+        return -1; \
+    }
+
+#define IS_CLOSED(self) \
+    (!self->buffer || \
+    (self->fast_closed_checks \
+     ? _PyFileIO_closed(self->raw) \
+     : buffered_closed(self)))
+
+#define CHECK_CLOSED(self, error_msg) \
+    if (IS_CLOSED(self) && (Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t) == 0)) { \
+        PyErr_SetString(PyExc_ValueError, error_msg); \
+        return NULL; \
+    } \
+
+#define VALID_READ_BUFFER(self) \
+    (self->readable && self->read_end != -1)
+
+#define VALID_WRITE_BUFFER(self) \
+    (self->writable && self->write_end != -1)
+
+#define ADJUST_POSITION(self, _new_pos) \
+    do { \
+        self->pos = _new_pos; \
+        if (VALID_READ_BUFFER(self) && self->read_end < self->pos) \
+            self->read_end = self->pos; \
+    } while(0)
+
+#define READAHEAD(self) \
+    ((self->readable && VALID_READ_BUFFER(self)) \
+        ? (self->read_end - self->pos) : 0)
+
+#define RAW_OFFSET(self) \
+    (((VALID_READ_BUFFER(self) || VALID_WRITE_BUFFER(self)) \
+        && self->raw_pos >= 0) ? self->raw_pos - self->pos : 0)
+
+#define RAW_TELL(self) \
+    (self->abs_pos != -1 ? self->abs_pos : _buffered_raw_tell(self))
+
+#define MINUS_LAST_BLOCK(self, size) \
+    (self->buffer_mask ? \
+        (size & ~self->buffer_mask) : \
+        (self->buffer_size * (size / self->buffer_size)))
+
+
+static int
+buffered_clear(buffered *self)
+{
+    self->ok = 0;
+    Py_CLEAR(self->raw);
+    Py_CLEAR(self->dict);
+    return 0;
+}
+
+static void
+buffered_dealloc(buffered *self)
+{
+    PyTypeObject *tp = Py_TYPE(self);
+    self->finalizing = 1;
+    if (_PyIOBase_finalize((PyObject *) self) < 0)
+        return;
+    _PyObject_GC_UNTRACK(self);
+    self->ok = 0;
+    if (self->weakreflist != NULL)
+        PyObject_ClearWeakRefs((PyObject *)self);
+    if (self->buffer) {
+        PyMem_Free(self->buffer);
+        self->buffer = NULL;
+    }
+    if (self->lock) {
+        PyThread_free_lock(self->lock);
+        self->lock = NULL;
+    }
+    (void)buffered_clear(self);
+    tp->tp_free((PyObject *)self);
+    Py_DECREF(tp);
+}
+
+/*[clinic input]
+_io._Buffered.__sizeof__
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered___sizeof___impl(buffered *self)
+/*[clinic end generated code: output=0231ef7f5053134e input=753c782d808d34df]*/
+{
+    size_t res = _PyObject_SIZE(Py_TYPE(self));
+    if (self->buffer) {
+        res += (size_t)self->buffer_size;
+    }
+    return PyLong_FromSize_t(res);
+}
+
+static int
+buffered_traverse(buffered *self, visitproc visit, void *arg)
+{
+    Py_VISIT(Py_TYPE(self));
+    Py_VISIT(self->raw);
+    Py_VISIT(self->dict);
+    return 0;
+}
+
+/* Because this can call arbitrary code, it shouldn't be called when
+   the refcount is 0 (that is, not directly from tp_dealloc unless
+   the refcount has been temporarily re-incremented). */
+/*[clinic input]
+_io._Buffered._dealloc_warn
+
+    source: object
+    /
+
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered__dealloc_warn(buffered *self, PyObject *source)
+/*[clinic end generated code: output=690dcc3df8967162 input=8f845f2a4786391c]*/
+{
+    if (self->ok && self->raw) {
+        PyObject *r;
+        r = PyObject_CallMethodOneArg(self->raw, &_Py_ID(_dealloc_warn), source);
+        if (r)
+            Py_DECREF(r);
+        else
+            PyErr_Clear();
+    }
+    Py_RETURN_NONE;
+}
+
+/*
+ * _BufferedIOMixin methods
+ * This is not a class, just a collection of methods that will be reused
+ * by BufferedReader and BufferedWriter
+ */
+
+/* Flush and close */
+/*[clinic input]
+_io._Buffered.flush as _io__Buffered_simple_flush
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_simple_flush_impl(buffered *self)
+/*[clinic end generated code: output=29ebb3820db1bdfd input=f33ef045e7250767]*/
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(flush));
+}
+
+static int
+buffered_closed(buffered *self)
+{
+    int closed;
+    PyObject *res;
+    CHECK_INITIALIZED_INT(self)
+    res = PyObject_GetAttr(self->raw, &_Py_ID(closed));
+    if (res == NULL)
+        return -1;
+    closed = PyObject_IsTrue(res);
+    Py_DECREF(res);
+    return closed;
+}
+
+static PyObject *
+buffered_closed_get(buffered *self, void *context)
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_GetAttr(self->raw, &_Py_ID(closed));
+}
+
+/*[clinic input]
+_io._Buffered.close
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_close_impl(buffered *self)
+/*[clinic end generated code: output=7280b7b42033be0c input=d20b83d1ddd7d805]*/
+{
+    PyObject *res = NULL;
+    int r;
+
+    CHECK_INITIALIZED(self)
+    if (!ENTER_BUFFERED(self)) {
+        return NULL;
+    }
+
+    r = buffered_closed(self);
+    if (r < 0)
+        goto end;
+    if (r > 0) {
+        res = Py_NewRef(Py_None);
+        goto end;
+    }
+
+    if (self->finalizing) {
+        PyObject *r = _io__Buffered__dealloc_warn(self, (PyObject *) self);
+        if (r)
+            Py_DECREF(r);
+        else
+            PyErr_Clear();
+    }
+    /* flush() will most probably re-take the lock, so drop it first */
+    LEAVE_BUFFERED(self)
+    res = PyObject_CallMethodNoArgs((PyObject *)self, &_Py_ID(flush));
+    if (!ENTER_BUFFERED(self)) {
+        return NULL;
+    }
+    PyObject *exc = NULL;
+    if (res == NULL) {
+        exc = PyErr_GetRaisedException();
+    }
+    else {
+        Py_DECREF(res);
+    }
+
+    res = PyObject_CallMethodNoArgs(self->raw, &_Py_ID(close));
+
+    if (self->buffer) {
+        PyMem_Free(self->buffer);
+        self->buffer = NULL;
+    }
+
+    if (exc != NULL) {
+        _PyErr_ChainExceptions1(exc);
+        Py_CLEAR(res);
+    }
+
+    self->read_end = 0;
+    self->pos = 0;
+
+end:
+    LEAVE_BUFFERED(self)
+    return res;
+}
+
+/*[clinic input]
+_io._Buffered.detach
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_detach_impl(buffered *self)
+/*[clinic end generated code: output=dd0fc057b8b779f7 input=482762a345cc9f44]*/
+{
+    PyObject *raw, *res;
+    CHECK_INITIALIZED(self)
+    res = PyObject_CallMethodNoArgs((PyObject *)self, &_Py_ID(flush));
+    if (res == NULL)
+        return NULL;
+    Py_DECREF(res);
+    raw = self->raw;
+    self->raw = NULL;
+    self->detached = 1;
+    self->ok = 0;
+    return raw;
+}
+
+/* Inquiries */
+
+/*[clinic input]
+_io._Buffered.seekable
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_seekable_impl(buffered *self)
+/*[clinic end generated code: output=90172abb5ceb6e8f input=7d35764f5fb5262b]*/
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(seekable));
+}
+
+/*[clinic input]
+_io._Buffered.readable
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_readable_impl(buffered *self)
+/*[clinic end generated code: output=92afa07661ecb698 input=640619addb513b8b]*/
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(readable));
+}
+
+/*[clinic input]
+_io._Buffered.writable
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_writable_impl(buffered *self)
+/*[clinic end generated code: output=4e3eee8d6f9d8552 input=b35ea396b2201554]*/
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(writable));
+}
+
+static PyObject *
+buffered_name_get(buffered *self, void *context)
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_GetAttr(self->raw, &_Py_ID(name));
+}
+
+static PyObject *
+buffered_mode_get(buffered *self, void *context)
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_GetAttr(self->raw, &_Py_ID(mode));
+}
+
+/* Lower-level APIs */
+
+/*[clinic input]
+_io._Buffered.fileno
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_fileno_impl(buffered *self)
+/*[clinic end generated code: output=b717648d58a95ee3 input=768ea30b3f6314a7]*/
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(fileno));
+}
+
+/*[clinic input]
+_io._Buffered.isatty
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_isatty_impl(buffered *self)
+/*[clinic end generated code: output=c20e55caae67baea input=9ea007b11559bee4]*/
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(isatty));
+}
+
+/* Forward decls */
+static PyObject *
+_bufferedwriter_flush_unlocked(buffered *);
+static Py_ssize_t
+_bufferedreader_fill_buffer(buffered *self);
+static void
+_bufferedreader_reset_buf(buffered *self);
+static void
+_bufferedwriter_reset_buf(buffered *self);
+static PyObject *
+_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
+ */
+
+/* Sets the current error to BlockingIOError */
+static void
+_set_BlockingIOError(const char *msg, Py_ssize_t written)
+{
+    PyObject *err;
+    PyErr_Clear();
+    err = PyObject_CallFunction(PyExc_BlockingIOError, "isn",
+                                errno, msg, written);
+    if (err)
+        PyErr_SetObject(PyExc_BlockingIOError, err);
+    Py_XDECREF(err);
+}
+
+/* Returns the address of the `written` member if a BlockingIOError was
+   raised, NULL otherwise. The error is always re-raised. */
+static Py_ssize_t *
+_buffered_check_blocking_error(void)
+{
+    PyObject *exc = PyErr_GetRaisedException();
+    if (exc == NULL || !PyErr_GivenExceptionMatches(exc, PyExc_BlockingIOError)) {
+        PyErr_SetRaisedException(exc);
+        return NULL;
+    }
+    PyOSErrorObject *err = (PyOSErrorObject *)exc;
+    /* TODO: sanity check (err->written >= 0) */
+    PyErr_SetRaisedException(exc);
+    return &err->written;
+}
+
+static Py_off_t
+_buffered_raw_tell(buffered *self)
+{
+    Py_off_t n;
+    PyObject *res;
+    res = PyObject_CallMethodNoArgs(self->raw, &_Py_ID(tell));
+    if (res == NULL)
+        return -1;
+    n = PyNumber_AsOff_t(res, PyExc_ValueError);
+    Py_DECREF(res);
+    if (n < 0) {
+        if (!PyErr_Occurred())
+            PyErr_Format(PyExc_OSError,
+                         "Raw stream returned invalid position %" PY_PRIdOFF,
+                         (PY_OFF_T_COMPAT)n);
+        return -1;
+    }
+    self->abs_pos = n;
+    return n;
+}
+
+static Py_off_t
+_buffered_raw_seek(buffered *self, Py_off_t target, int whence)
+{
+    PyObject *res, *posobj, *whenceobj;
+    Py_off_t n;
+
+    posobj = PyLong_FromOff_t(target);
+    if (posobj == NULL)
+        return -1;
+    whenceobj = PyLong_FromLong(whence);
+    if (whenceobj == NULL) {
+        Py_DECREF(posobj);
+        return -1;
+    }
+    res = PyObject_CallMethodObjArgs(self->raw, &_Py_ID(seek),
+                                     posobj, whenceobj, NULL);
+    Py_DECREF(posobj);
+    Py_DECREF(whenceobj);
+    if (res == NULL)
+        return -1;
+    n = PyNumber_AsOff_t(res, PyExc_ValueError);
+    Py_DECREF(res);
+    if (n < 0) {
+        if (!PyErr_Occurred())
+            PyErr_Format(PyExc_OSError,
+                         "Raw stream returned invalid position %" PY_PRIdOFF,
+                         (PY_OFF_T_COMPAT)n);
+        return -1;
+    }
+    self->abs_pos = n;
+    return n;
+}
+
+static int
+_buffered_init(buffered *self)
+{
+    Py_ssize_t n;
+    if (self->buffer_size <= 0) {
+        PyErr_SetString(PyExc_ValueError,
+            "buffer size must be strictly positive");
+        return -1;
+    }
+    if (self->buffer)
+        PyMem_Free(self->buffer);
+    self->buffer = PyMem_Malloc(self->buffer_size);
+    if (self->buffer == NULL) {
+        PyErr_NoMemory();
+        return -1;
+    }
+    if (self->lock)
+        PyThread_free_lock(self->lock);
+    self->lock = PyThread_allocate_lock();
+    if (self->lock == NULL) {
+        PyErr_SetString(PyExc_RuntimeError, "can't allocate read lock");
+        return -1;
+    }
+    self->owner = 0;
+    /* Find out whether buffer_size is a power of 2 */
+    /* XXX is this optimization useful? */
+    for (n = self->buffer_size - 1; n & 1; n >>= 1)
+        ;
+    if (n == 0)
+        self->buffer_mask = self->buffer_size - 1;
+    else
+        self->buffer_mask = 0;
+    if (_buffered_raw_tell(self) == -1)
+        PyErr_Clear();
+    return 0;
+}
+
+/* Return 1 if an OSError with errno == EINTR is set (and then
+   clears the error indicator), 0 otherwise.
+   Should only be called when PyErr_Occurred() is true.
+*/
+int
+_PyIO_trap_eintr(void)
+{
+    if (!PyErr_ExceptionMatches(PyExc_OSError)) {
+        return 0;
+    }
+    PyObject *exc = PyErr_GetRaisedException();
+    PyOSErrorObject *env_err = (PyOSErrorObject *)exc;
+    assert(env_err != NULL);
+    if (env_err->myerrno != NULL) {
+        assert(EINTR > 0 && EINTR < INT_MAX);
+        assert(PyLong_CheckExact(env_err->myerrno));
+        int overflow;
+        int myerrno = PyLong_AsLongAndOverflow(env_err->myerrno, &overflow);
+        PyErr_Clear();
+        if (myerrno == EINTR) {
+            Py_DECREF(exc);
+            return 1;
+        }
+    }
+    /* This silences any error set by PyObject_RichCompareBool() */
+    PyErr_SetRaisedException(exc);
+    return 0;
+}
+
+/*
+ * Shared methods and wrappers
+ */
+
+static PyObject *
+buffered_flush_and_rewind_unlocked(buffered *self)
+{
+    PyObject *res;
+
+    res = _bufferedwriter_flush_unlocked(self);
+    if (res == NULL)
+        return NULL;
+    Py_DECREF(res);
+
+    if (self->readable) {
+        /* Rewind the raw stream so that its position corresponds to
+           the current logical position. */
+        Py_off_t n;
+        n = _buffered_raw_seek(self, -RAW_OFFSET(self), 1);
+        _bufferedreader_reset_buf(self);
+        if (n == -1)
+            return NULL;
+    }
+    Py_RETURN_NONE;
+}
+
+/*[clinic input]
+_io._Buffered.flush
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_flush_impl(buffered *self)
+/*[clinic end generated code: output=da2674ef1ce71f3a input=fda63444697c6bf4]*/
+{
+    PyObject *res;
+
+    CHECK_INITIALIZED(self)
+    CHECK_CLOSED(self, "flush of closed file")
+
+    if (!ENTER_BUFFERED(self))
+        return NULL;
+    res = buffered_flush_and_rewind_unlocked(self);
+    LEAVE_BUFFERED(self)
+
+    return res;
+}
+
+/*[clinic input]
+_io._Buffered.peek
+    size: Py_ssize_t = 0
+    /
+
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_peek_impl(buffered *self, Py_ssize_t size)
+/*[clinic end generated code: output=ba7a097ca230102b input=37ffb97d06ff4adb]*/
+{
+    PyObject *res = NULL;
+
+    CHECK_INITIALIZED(self)
+    CHECK_CLOSED(self, "peek of closed file")
+
+    if (!ENTER_BUFFERED(self))
+        return NULL;
+
+    if (self->writable) {
+        res = buffered_flush_and_rewind_unlocked(self);
+        if (res == NULL)
+            goto end;
+        Py_CLEAR(res);
+    }
+    res = _bufferedreader_peek_unlocked(self);
+
+end:
+    LEAVE_BUFFERED(self)
+    return res;
+}
+
+/*[clinic input]
+_io._Buffered.read
+    size as n: Py_ssize_t(accept={int, NoneType}) = -1
+    /
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_read_impl(buffered *self, Py_ssize_t n)
+/*[clinic end generated code: output=f41c78bb15b9bbe9 input=7df81e82e08a68a2]*/
+{
+    PyObject *res;
+
+    CHECK_INITIALIZED(self)
+    if (n < -1) {
+        PyErr_SetString(PyExc_ValueError,
+                        "read length must be non-negative or -1");
+        return NULL;
+    }
+
+    CHECK_CLOSED(self, "read of closed file")
+
+    if (n == -1) {
+        /* The number of bytes is unspecified, read until the end of stream */
+        if (!ENTER_BUFFERED(self))
+            return NULL;
+        res = _bufferedreader_read_all(self);
+    }
+    else {
+        res = _bufferedreader_read_fast(self, n);
+        if (res != Py_None)
+            return res;
+        Py_DECREF(res);
+        if (!ENTER_BUFFERED(self))
+            return NULL;
+        res = _bufferedreader_read_generic(self, n);
+    }
+
+    LEAVE_BUFFERED(self)
+    return res;
+}
+
+/*[clinic input]
+_io._Buffered.read1
+    size as n: Py_ssize_t = -1
+    /
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_read1_impl(buffered *self, Py_ssize_t n)
+/*[clinic end generated code: output=bcc4fb4e54d103a3 input=7d22de9630b61774]*/
+{
+    Py_ssize_t have, r;
+    PyObject *res = NULL;
+
+    CHECK_INITIALIZED(self)
+    if (n < 0) {
+        n = self->buffer_size;
+    }
+
+    CHECK_CLOSED(self, "read of closed file")
+
+    if (n == 0)
+        return PyBytes_FromStringAndSize(NULL, 0);
+
+    /* Return up to n bytes.  If at least one byte is buffered, we
+       only return buffered bytes.  Otherwise, we do one raw read. */
+
+    have = Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t);
+    if (have > 0) {
+        n = Py_MIN(have, n);
+        res = _bufferedreader_read_fast(self, n);
+        assert(res != Py_None);
+        return res;
+    }
+    res = PyBytes_FromStringAndSize(NULL, n);
+    if (res == NULL)
+        return NULL;
+    if (!ENTER_BUFFERED(self)) {
+        Py_DECREF(res);
+        return NULL;
+    }
+    _bufferedreader_reset_buf(self);
+    r = _bufferedreader_raw_read(self, PyBytes_AS_STRING(res), n);
+    LEAVE_BUFFERED(self)
+    if (r == -1) {
+        Py_DECREF(res);
+        return NULL;
+    }
+    if (r == -2)
+        r = 0;
+    if (n > r)
+        _PyBytes_Resize(&res, r);
+    return res;
+}
+
+static PyObject *
+_buffered_readinto_generic(buffered *self, Py_buffer *buffer, char readinto1)
+{
+    Py_ssize_t n, written = 0, remaining;
+    PyObject *res = NULL;
+
+    CHECK_INITIALIZED(self)
+    CHECK_CLOSED(self, "readinto of closed file")
+
+    n = Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t);
+    if (n > 0) {
+        if (n >= buffer->len) {
+            memcpy(buffer->buf, self->buffer + self->pos, buffer->len);
+            self->pos += buffer->len;
+            return PyLong_FromSsize_t(buffer->len);
+        }
+        memcpy(buffer->buf, self->buffer + self->pos, n);
+        self->pos += n;
+        written = n;
+    }
+
+    if (!ENTER_BUFFERED(self))
+        return NULL;
+
+    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 = buffer->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 *) buffer->buf + written,
+                                         remaining);
+        }
+
+        /* In readinto1 mode, we do not want to fill the internal
+           buffer if we already have some data to return */
+        else if (!(readinto1 && written)) {
+            n = _bufferedreader_fill_buffer(self);
+            if (n > 0) {
+                if (n > remaining)
+                    n = remaining;
+                memcpy((char *) buffer->buf + written,
+                       self->buffer + self->pos, n);
+                self->pos += n;
+                continue; /* short circuit */
+            }
+        }
+        else
+            n = 0;
+
+        if (n == 0 || (n == -2 && written > 0))
+            break;
+        if (n < 0) {
+            if (n == -2) {
+                res = Py_NewRef(Py_None);
+            }
+            goto end;
+        }
+
+        /* At most one read in readinto1 mode */
+        if (readinto1) {
+            written += n;
+            break;
+        }
+    }
+    res = PyLong_FromSsize_t(written);
+
+end:
+    LEAVE_BUFFERED(self);
+    return res;
+}
+
+/*[clinic input]
+_io._Buffered.readinto
+    buffer: Py_buffer(accept={rwbuffer})
+    /
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_readinto_impl(buffered *self, Py_buffer *buffer)
+/*[clinic end generated code: output=bcb376580b1d8170 input=ed6b98b7a20a3008]*/
+{
+    return _buffered_readinto_generic(self, buffer, 0);
+}
+
+/*[clinic input]
+_io._Buffered.readinto1
+    buffer: Py_buffer(accept={rwbuffer})
+    /
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_readinto1_impl(buffered *self, Py_buffer *buffer)
+/*[clinic end generated code: output=6e5c6ac5868205d6 input=4455c5d55fdf1687]*/
+{
+    return _buffered_readinto_generic(self, buffer, 1);
+}
+
+
+static PyObject *
+_buffered_readline(buffered *self, Py_ssize_t limit)
+{
+    PyObject *res = NULL;
+    PyObject *chunks = NULL;
+    Py_ssize_t n;
+    const char *start, *s, *end;
+
+    CHECK_CLOSED(self, "readline of closed file")
+
+    /* First, try to find a line in the buffer. This can run unlocked because
+       the calls to the C API are simple enough that they can't trigger
+       any thread switch. */
+    n = Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t);
+    if (limit >= 0 && n > limit)
+        n = limit;
+    start = self->buffer + self->pos;
+    s = memchr(start, '\n', n);
+    if (s != NULL) {
+        res = PyBytes_FromStringAndSize(start, s - start + 1);
+        if (res != NULL)
+            self->pos += s - start + 1;
+        goto end_unlocked;
+    }
+    if (n == limit) {
+        res = PyBytes_FromStringAndSize(start, n);
+        if (res != NULL)
+            self->pos += n;
+        goto end_unlocked;
+    }
+
+    if (!ENTER_BUFFERED(self))
+        goto end_unlocked;
+
+    /* Now we try to get some more from the raw stream */
+    chunks = PyList_New(0);
+    if (chunks == NULL)
+        goto end;
+    if (n > 0) {
+        res = PyBytes_FromStringAndSize(start, n);
+        if (res == NULL)
+            goto end;
+        if (PyList_Append(chunks, res) < 0) {
+            Py_CLEAR(res);
+            goto end;
+        }
+        Py_CLEAR(res);
+        self->pos += n;
+        if (limit >= 0)
+            limit -= n;
+    }
+    if (self->writable) {
+        PyObject *r = buffered_flush_and_rewind_unlocked(self);
+        if (r == NULL)
+            goto end;
+        Py_DECREF(r);
+    }
+
+    for (;;) {
+        _bufferedreader_reset_buf(self);
+        n = _bufferedreader_fill_buffer(self);
+        if (n == -1)
+            goto end;
+        if (n <= 0)
+            break;
+        if (limit >= 0 && n > limit)
+            n = limit;
+        start = self->buffer;
+        end = start + n;
+        s = start;
+        while (s < end) {
+            if (*s++ == '\n') {
+                res = PyBytes_FromStringAndSize(start, s - start);
+                if (res == NULL)
+                    goto end;
+                self->pos = s - start;
+                goto found;
+            }
+        }
+        res = PyBytes_FromStringAndSize(start, n);
+        if (res == NULL)
+            goto end;
+        if (n == limit) {
+            self->pos = n;
+            break;
+        }
+        if (PyList_Append(chunks, res) < 0) {
+            Py_CLEAR(res);
+            goto end;
+        }
+        Py_CLEAR(res);
+        if (limit >= 0)
+            limit -= n;
+    }
+found:
+    if (res != NULL && PyList_Append(chunks, res) < 0) {
+        Py_CLEAR(res);
+        goto end;
+    }
+    Py_XSETREF(res, _PyBytes_Join((PyObject *)&_Py_SINGLETON(bytes_empty), chunks));
+
+end:
+    LEAVE_BUFFERED(self)
+end_unlocked:
+    Py_XDECREF(chunks);
+    return res;
+}
+
+/*[clinic input]
+_io._Buffered.readline
+    size: Py_ssize_t(accept={int, NoneType}) = -1
+    /
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_readline_impl(buffered *self, Py_ssize_t size)
+/*[clinic end generated code: output=24dd2aa6e33be83c input=673b6240e315ef8a]*/
+{
+    CHECK_INITIALIZED(self)
+    return _buffered_readline(self, size);
+}
+
+
+/*[clinic input]
+_io._Buffered.tell
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_tell_impl(buffered *self)
+/*[clinic end generated code: output=386972ae84716c1e input=ad61e04a6b349573]*/
+{
+    Py_off_t pos;
+
+    CHECK_INITIALIZED(self)
+    pos = _buffered_raw_tell(self);
+    if (pos == -1)
+        return NULL;
+    pos -= RAW_OFFSET(self);
+    /* TODO: sanity check (pos >= 0) */
+    return PyLong_FromOff_t(pos);
+}
+
+/*[clinic input]
+_io._Buffered.seek
+    target as targetobj: object
+    whence: int = 0
+    /
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_seek_impl(buffered *self, PyObject *targetobj, int whence)
+/*[clinic end generated code: output=7ae0e8dc46efdefb input=a9c4920bfcba6163]*/
+{
+    Py_off_t target, n;
+    PyObject *res = NULL;
+
+    CHECK_INITIALIZED(self)
+
+    /* Do some error checking instead of trusting OS 'seek()'
+    ** error detection, just in case.
+    */
+    if ((whence < 0 || whence >2)
+#ifdef SEEK_HOLE
+        && (whence != SEEK_HOLE)
+#endif
+#ifdef SEEK_DATA
+        && (whence != SEEK_DATA)
+#endif
+        ) {
+        PyErr_Format(PyExc_ValueError,
+                     "whence value %d unsupported", whence);
+        return NULL;
+    }
+
+    CHECK_CLOSED(self, "seek of closed file")
+
+    _PyIO_State *state = find_io_state_by_def(Py_TYPE(self));
+    if (_PyIOBase_check_seekable(state, self->raw, Py_True) == NULL) {
+        return NULL;
+    }
+
+    target = PyNumber_AsOff_t(targetobj, PyExc_ValueError);
+    if (target == -1 && PyErr_Occurred())
+        return NULL;
+
+    /* SEEK_SET and SEEK_CUR are special because we could seek inside the
+       buffer. Other whence values must be managed without this optimization.
+       Some Operating Systems can provide additional values, like
+       SEEK_HOLE/SEEK_DATA. */
+    if (((whence == 0) || (whence == 1)) && self->readable) {
+        Py_off_t current, avail;
+        /* Check if seeking leaves us inside the current buffer,
+           so as to return quickly if possible. Also, we needn't take the
+           lock in this fast path.
+           Don't know how to do that when whence == 2, though. */
+        /* NOTE: RAW_TELL() can release the GIL but the object is in a stable
+           state at this point. */
+        current = RAW_TELL(self);
+        avail = READAHEAD(self);
+        if (avail > 0) {
+            Py_off_t offset;
+            if (whence == 0)
+                offset = target - (current - RAW_OFFSET(self));
+            else
+                offset = target;
+            if (offset >= -self->pos && offset <= avail) {
+                self->pos += offset;
+                return PyLong_FromOff_t(current - avail + offset);
+            }
+        }
+    }
+
+    if (!ENTER_BUFFERED(self))
+        return NULL;
+
+    /* Fallback: invoke raw seek() method and clear buffer */
+    if (self->writable) {
+        res = _bufferedwriter_flush_unlocked(self);
+        if (res == NULL)
+            goto end;
+        Py_CLEAR(res);
+    }
+
+    /* TODO: align on block boundary and read buffer if needed? */
+    if (whence == 1)
+        target -= RAW_OFFSET(self);
+    n = _buffered_raw_seek(self, target, whence);
+    if (n == -1)
+        goto end;
+    self->raw_pos = -1;
+    res = PyLong_FromOff_t(n);
+    if (res != NULL && self->readable)
+        _bufferedreader_reset_buf(self);
+
+end:
+    LEAVE_BUFFERED(self)
+    return res;
+}
+
+/*[clinic input]
+_io._Buffered.truncate
+    cls: defining_class
+    pos: object = None
+    /
+[clinic start generated code]*/
+
+static PyObject *
+_io__Buffered_truncate_impl(buffered *self, PyTypeObject *cls, PyObject *pos)
+/*[clinic end generated code: output=fe3882fbffe79f1a input=f5b737d97d76303f]*/
+{
+    PyObject *res = NULL;
+
+    CHECK_INITIALIZED(self)
+    CHECK_CLOSED(self, "truncate of closed file")
+    if (!self->writable) {
+        _PyIO_State *state = get_io_state_by_cls(cls);
+        return bufferediobase_unsupported(state, "truncate");
+    }
+    if (!ENTER_BUFFERED(self))
+        return NULL;
+
+    res = buffered_flush_and_rewind_unlocked(self);
+    if (res == NULL) {
+        goto end;
+    }
+    Py_CLEAR(res);
+
+    res = PyObject_CallMethodOneArg(self->raw, &_Py_ID(truncate), pos);
+    if (res == NULL)
+        goto end;
+    /* Reset cached position */
+    if (_buffered_raw_tell(self) == -1)
+        PyErr_Clear();
+
+end:
+    LEAVE_BUFFERED(self)
+    return res;
+}
+
+static PyObject *
+buffered_iternext(buffered *self)
+{
+    PyObject *line;
+    PyTypeObject *tp;
+
+    CHECK_INITIALIZED(self);
+
+    _PyIO_State *state = find_io_state_by_def(Py_TYPE(self));
+    tp = Py_TYPE(self);
+    if (Py_IS_TYPE(tp, state->PyBufferedReader_Type) ||
+        Py_IS_TYPE(tp, state->PyBufferedRandom_Type))
+    {
+        /* Skip method call overhead for speed */
+        line = _buffered_readline(self, -1);
+    }
+    else {
+        line = PyObject_CallMethodNoArgs((PyObject *)self,
+                                             &_Py_ID(readline));
+        if (line && !PyBytes_Check(line)) {
+            PyErr_Format(PyExc_OSError,
+                         "readline() should have returned a bytes object, "
+                         "not '%.200s'", Py_TYPE(line)->tp_name);
+            Py_DECREF(line);
+            return NULL;
+        }
+    }
+
+    if (line == NULL)
+        return NULL;
+
+    if (PyBytes_GET_SIZE(line) == 0) {
+        /* Reached EOF or would have blocked */
+        Py_DECREF(line);
+        return NULL;
+    }
+
+    return line;
+}
+
+static PyObject *
+buffered_repr(buffered *self)
+{
+    PyObject *nameobj, *res;
+
+    if (_PyObject_LookupAttr((PyObject *) self, &_Py_ID(name), &nameobj) < 0) {
+        if (!PyErr_ExceptionMatches(PyExc_ValueError)) {
+            return NULL;
+        }
+        /* Ignore ValueError raised if the underlying stream was detached */
+        PyErr_Clear();
+    }
+    if (nameobj == NULL) {
+        res = PyUnicode_FromFormat("<%s>", Py_TYPE(self)->tp_name);
+    }
+    else {
+        int status = Py_ReprEnter((PyObject *)self);
+        res = NULL;
+        if (status == 0) {
+            res = PyUnicode_FromFormat("<%s name=%R>",
+                                       Py_TYPE(self)->tp_name, nameobj);
+            Py_ReprLeave((PyObject *)self);
+        }
+        else if (status > 0) {
+            PyErr_Format(PyExc_RuntimeError,
+                         "reentrant call inside %s.__repr__",
+                         Py_TYPE(self)->tp_name);
+        }
+        Py_DECREF(nameobj);
+    }
+    return res;
+}
+
+/*
+ * class BufferedReader
+ */
+
+static void _bufferedreader_reset_buf(buffered *self)
+{
+    self->read_end = -1;
+}
+
+/*[clinic input]
+_io.BufferedReader.__init__
+    raw: object
+    buffer_size: Py_ssize_t(c_default="DEFAULT_BUFFER_SIZE") = DEFAULT_BUFFER_SIZE
+
+Create a new buffered reader using the given readable raw IO object.
+[clinic start generated code]*/
+
+static int
+_io_BufferedReader___init___impl(buffered *self, PyObject *raw,
+                                 Py_ssize_t buffer_size)
+/*[clinic end generated code: output=cddcfefa0ed294c4 input=fb887e06f11b4e48]*/
+{
+    self->ok = 0;
+    self->detached = 0;
+
+    _PyIO_State *state = find_io_state_by_def(Py_TYPE(self));
+    if (_PyIOBase_check_readable(state, raw, Py_True) == NULL) {
+        return -1;
+    }
+
+    Py_XSETREF(self->raw, Py_NewRef(raw));
+    self->buffer_size = buffer_size;
+    self->readable = 1;
+    self->writable = 0;
+
+    if (_buffered_init(self) < 0)
+        return -1;
+    _bufferedreader_reset_buf(self);
+
+    self->fast_closed_checks = (
+        Py_IS_TYPE(self, state->PyBufferedReader_Type) &&
+        Py_IS_TYPE(raw, state->PyFileIO_Type)
+    );
+
+    self->ok = 1;
+    return 0;
+}
+
+static Py_ssize_t
+_bufferedreader_raw_read(buffered *self, char *start, Py_ssize_t len)
+{
+    Py_buffer buf;
+    PyObject *memobj, *res;
+    Py_ssize_t n;
+    /* NOTE: the buffer needn't be released as its object is NULL. */
+    if (PyBuffer_FillInfo(&buf, NULL, start, len, 0, PyBUF_CONTIG) == -1)
+        return -1;
+    memobj = PyMemoryView_FromBuffer(&buf);
+    if (memobj == NULL)
+        return -1;
+    /* NOTE: PyErr_SetFromErrno() calls PyErr_CheckSignals() when EINTR
+       occurs so we needn't do it ourselves.
+       We then retry reading, ignoring the signal if no handler has
+       raised (see issue #10956).
+    */
+    do {
+        res = PyObject_CallMethodOneArg(self->raw, &_Py_ID(readinto), memobj);
+    } while (res == NULL && _PyIO_trap_eintr());
+    Py_DECREF(memobj);
+    if (res == NULL)
+        return -1;
+    if (res == Py_None) {
+        /* Non-blocking stream would have blocked. Special return code! */
+        Py_DECREF(res);
+        return -2;
+    }
+    n = PyNumber_AsSsize_t(res, PyExc_ValueError);
+    Py_DECREF(res);
+
+    if (n == -1 && PyErr_Occurred()) {
+        _PyErr_FormatFromCause(
+            PyExc_OSError,
+            "raw readinto() failed"
+        );
+        return -1;
+    }
+
+    if (n < 0 || n > len) {
+        PyErr_Format(PyExc_OSError,
+                     "raw readinto() returned invalid length %zd "
+                     "(should have been between 0 and %zd)", n, len);
+        return -1;
+    }
+    if (n > 0 && self->abs_pos != -1)
+        self->abs_pos += n;
+    return n;
+}
+
+static Py_ssize_t
+_bufferedreader_fill_buffer(buffered *self)
+{
+    Py_ssize_t start, len, n;
+    if (VALID_READ_BUFFER(self))
+        start = Py_SAFE_DOWNCAST(self->read_end, Py_off_t, Py_ssize_t);
+    else
+        start = 0;
+    len = self->buffer_size - start;
+    n = _bufferedreader_raw_read(self, self->buffer + start, len);
+    if (n <= 0)
+        return n;
+    self->read_end = start + n;
+    self->raw_pos = start + n;
+    return n;
+}
+
+static PyObject *
+_bufferedreader_read_all(buffered *self)
+{
+    Py_ssize_t current_size;
+    PyObject *res = NULL, *data = NULL, *tmp = NULL, *chunks = NULL, *readall;
+
+    /* 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)
+            return NULL;
+        self->pos += current_size;
+    }
+    /* We're going past the buffer's bounds, flush it */
+    if (self->writable) {
+        tmp = buffered_flush_and_rewind_unlocked(self);
+        if (tmp == NULL)
+            goto cleanup;
+        Py_CLEAR(tmp);
+    }
+    _bufferedreader_reset_buf(self);
+
+    if (_PyObject_LookupAttr(self->raw, &_Py_ID(readall), &readall) < 0) {
+        goto cleanup;
+    }
+    if (readall) {
+        tmp = _PyObject_CallNoArgs(readall);
+        Py_DECREF(readall);
+        if (tmp == NULL)
+            goto cleanup;
+        if (tmp != Py_None && !PyBytes_Check(tmp)) {
+            PyErr_SetString(PyExc_TypeError, "readall() should return bytes");
+            goto cleanup;
+        }
+        if (current_size == 0) {
+            res = tmp;
+        } else {
+            if (tmp != Py_None) {
+                PyBytes_Concat(&data, tmp);
+            }
+            res = data;
+        }
+        goto cleanup;
+    }
+
+    chunks = PyList_New(0);
+    if (chunks == NULL)
+        goto cleanup;
+
+    while (1) {
+        if (data) {
+            if (PyList_Append(chunks, data) < 0)
+                goto cleanup;
+            Py_CLEAR(data);
+        }
+
+        /* Read until EOF or until read() would block. */
+        data = PyObject_CallMethodNoArgs(self->raw, &_Py_ID(read));
+        if (data == NULL)
+            goto cleanup;
+        if (data != Py_None && !PyBytes_Check(data)) {
+            PyErr_SetString(PyExc_TypeError, "read() should return bytes");
+            goto cleanup;
+        }
+        if (data == Py_None || PyBytes_GET_SIZE(data) == 0) {
+            if (current_size == 0) {
+                res = data;
+                goto cleanup;
+            }
+            else {
+                tmp = _PyBytes_Join((PyObject *)&_Py_SINGLETON(bytes_empty), chunks);
+                res = tmp;
+                goto cleanup;
+            }
+        }
+        current_size += PyBytes_GET_SIZE(data);
+        if (self->abs_pos != -1)
+            self->abs_pos += PyBytes_GET_SIZE(data);
+    }
+cleanup:
+    /* res is either NULL or a borrowed ref */
+    Py_XINCREF(res);
+    Py_XDECREF(data);
+    Py_XDECREF(tmp);
+    Py_XDECREF(chunks);
+    return res;
+}
+
+/* Read n bytes from the buffer if it can, otherwise return None.
+   This function is simple enough that it can run unlocked. */
+static PyObject *
+_bufferedreader_read_fast(buffered *self, Py_ssize_t n)
+{
+    Py_ssize_t current_size;
+
+    current_size = Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t);
+    if (n <= current_size) {
+        /* Fast path: the data to read is fully buffered. */
+        PyObject *res = PyBytes_FromStringAndSize(self->buffer + self->pos, n);
+        if (res != NULL)
+            self->pos += n;
+        return res;
+    }
+    Py_RETURN_NONE;
+}
+
+/* Generic read function: read from the stream until enough bytes are read,
+ * or until an EOF occurs or until read() would block.
+ */
+static PyObject *
+_bufferedreader_read_generic(buffered *self, Py_ssize_t n)
+{
+    PyObject *res = NULL;
+    Py_ssize_t current_size, remaining, written;
+    char *out;
+
+    current_size = Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t);
+    if (n <= current_size)
+        return _bufferedreader_read_fast(self, n);
+
+    res = PyBytes_FromStringAndSize(NULL, n);
+    if (res == NULL)
+        goto error;
+    out = PyBytes_AS_STRING(res);
+    remaining = n;
+    written = 0;
+    if (current_size > 0) {
+        memcpy(out, self->buffer + self->pos, current_size);
+        remaining -= current_size;
+        written += current_size;
+        self->pos += current_size;
+    }
+    /* Flush the write buffer if necessary */
+    if (self->writable) {
+        PyObject *r = buffered_flush_and_rewind_unlocked(self);
+        if (r == NULL)
+            goto error;
+        Py_DECREF(r);
+    }
+    _bufferedreader_reset_buf(self);
+    while (remaining > 0) {
+        /* We want to read a whole block at the end into buffer.
+           If we had readv() we could do this in one pass. */
+        Py_ssize_t r = MINUS_LAST_BLOCK(self, remaining);
+        if (r == 0)
+            break;
+        r = _bufferedreader_raw_read(self, out + written, r);
+        if (r == -1)
+            goto error;
+        if (r == 0 || r == -2) {
+            /* EOF occurred or read() would block. */
+            if (r == 0 || written > 0) {
+                if (_PyBytes_Resize(&res, written))
+                    goto error;
+                return res;
+            }
+            Py_DECREF(res);
+            Py_RETURN_NONE;
+        }
+        remaining -= r;
+        written += r;
+    }
+    assert(remaining <= self->buffer_size);
+    self->pos = 0;
+    self->raw_pos = 0;
+    self->read_end = 0;
+    /* NOTE: when the read is satisfied, we avoid issuing any additional
+       reads, which could block indefinitely (e.g. on a socket).
+       See issue #9550. */
+    while (remaining > 0 && self->read_end < self->buffer_size) {
+        Py_ssize_t r = _bufferedreader_fill_buffer(self);
+        if (r == -1)
+            goto error;
+        if (r == 0 || r == -2) {
+            /* EOF occurred or read() would block. */
+            if (r == 0 || written > 0) {
+                if (_PyBytes_Resize(&res, written))
+                    goto error;
+                return res;
+            }
+            Py_DECREF(res);
+            Py_RETURN_NONE;
+        }
+        if (remaining > r) {
+            memcpy(out + written, self->buffer + self->pos, r);
+            written += r;
+            self->pos += r;
+            remaining -= r;
+        }
+        else if (remaining > 0) {
+            memcpy(out + written, self->buffer + self->pos, remaining);
+            written += remaining;
+            self->pos += remaining;
+            remaining = 0;
+        }
+        if (remaining == 0)
+            break;
+    }
+
+    return res;
+
+error:
+    Py_XDECREF(res);
+    return NULL;
+}
+
+static PyObject *
+_bufferedreader_peek_unlocked(buffered *self)
+{
+    Py_ssize_t have, r;
+
+    have = Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t);
+    /* Constraints:
+       1. we don't want to advance the file position.
+       2. we don't want to lose block alignment, so we can't shift the buffer
+          to make some place.
+       Therefore, we either return `have` bytes (if > 0), or a full buffer.
+    */
+    if (have > 0) {
+        return PyBytes_FromStringAndSize(self->buffer + self->pos, have);
+    }
+
+    /* Fill the buffer from the raw stream, and copy it to the result. */
+    _bufferedreader_reset_buf(self);
+    r = _bufferedreader_fill_buffer(self);
+    if (r == -1)
+        return NULL;
+    if (r == -2)
+        r = 0;
+    self->pos = 0;
+    return PyBytes_FromStringAndSize(self->buffer, r);
+}
+
+
+/*
+ * class BufferedWriter
+ */
+static void
+_bufferedwriter_reset_buf(buffered *self)
+{
+    self->write_pos = 0;
+    self->write_end = -1;
+}
+
+/*[clinic input]
+_io.BufferedWriter.__init__
+    raw: object
+    buffer_size: Py_ssize_t(c_default="DEFAULT_BUFFER_SIZE") = DEFAULT_BUFFER_SIZE
+
+A buffer for a writeable sequential RawIO object.
+
+The constructor creates a BufferedWriter for the given writeable raw
+stream. If the buffer_size is not given, it defaults to
+DEFAULT_BUFFER_SIZE.
+[clinic start generated code]*/
+
+static int
+_io_BufferedWriter___init___impl(buffered *self, PyObject *raw,
+                                 Py_ssize_t buffer_size)
+/*[clinic end generated code: output=c8942a020c0dee64 input=914be9b95e16007b]*/
+{
+    self->ok = 0;
+    self->detached = 0;
+
+    _PyIO_State *state = find_io_state_by_def(Py_TYPE(self));
+    if (_PyIOBase_check_writable(state, raw, Py_True) == NULL) {
+        return -1;
+    }
+
+    Py_INCREF(raw);
+    Py_XSETREF(self->raw, raw);
+    self->readable = 0;
+    self->writable = 1;
+
+    self->buffer_size = buffer_size;
+    if (_buffered_init(self) < 0)
+        return -1;
+    _bufferedwriter_reset_buf(self);
+    self->pos = 0;
+
+    self->fast_closed_checks = (
+        Py_IS_TYPE(self, state->PyBufferedWriter_Type) &&
+        Py_IS_TYPE(raw, state->PyFileIO_Type)
+    );
+
+    self->ok = 1;
+    return 0;
+}
+
+static Py_ssize_t
+_bufferedwriter_raw_write(buffered *self, char *start, Py_ssize_t len)
+{
+    Py_buffer buf;
+    PyObject *memobj, *res;
+    Py_ssize_t n;
+    int errnum;
+    /* NOTE: the buffer needn't be released as its object is NULL. */
+    if (PyBuffer_FillInfo(&buf, NULL, start, len, 1, PyBUF_CONTIG_RO) == -1)
+        return -1;
+    memobj = PyMemoryView_FromBuffer(&buf);
+    if (memobj == NULL)
+        return -1;
+    /* NOTE: PyErr_SetFromErrno() calls PyErr_CheckSignals() when EINTR
+       occurs so we needn't do it ourselves.
+       We then retry writing, ignoring the signal if no handler has
+       raised (see issue #10956).
+    */
+    do {
+        errno = 0;
+        res = PyObject_CallMethodOneArg(self->raw, &_Py_ID(write), memobj);
+        errnum = errno;
+    } while (res == NULL && _PyIO_trap_eintr());
+    Py_DECREF(memobj);
+    if (res == NULL)
+        return -1;
+    if (res == Py_None) {
+        /* Non-blocking stream would have blocked. Special return code!
+           Being paranoid we reset errno in case it is changed by code
+           triggered by a decref.  errno is used by _set_BlockingIOError(). */
+        Py_DECREF(res);
+        errno = errnum;
+        return -2;
+    }
+    n = PyNumber_AsSsize_t(res, PyExc_ValueError);
+    Py_DECREF(res);
+    if (n < 0 || n > len) {
+        PyErr_Format(PyExc_OSError,
+                     "raw write() returned invalid length %zd "
+                     "(should have been between 0 and %zd)", n, len);
+        return -1;
+    }
+    if (n > 0 && self->abs_pos != -1)
+        self->abs_pos += n;
+    return n;
+}
+
+static PyObject *
+_bufferedwriter_flush_unlocked(buffered *self)
+{
+    Py_off_t n, rewind;
+
+    if (!VALID_WRITE_BUFFER(self) || self->write_pos == self->write_end)
+        goto end;
+    /* First, rewind */
+    rewind = RAW_OFFSET(self) + (self->pos - self->write_pos);
+    if (rewind != 0) {
+        n = _buffered_raw_seek(self, -rewind, 1);
+        if (n < 0) {
+            goto error;
+        }
+        self->raw_pos -= rewind;
+    }
+    while (self->write_pos < self->write_end) {
+        n = _bufferedwriter_raw_write(self,
+            self->buffer + self->write_pos,
+            Py_SAFE_DOWNCAST(self->write_end - self->write_pos,
+                             Py_off_t, Py_ssize_t));
+        if (n == -1) {
+            goto error;
+        }
+        else if (n == -2) {
+            _set_BlockingIOError("write could not complete without blocking",
+                                 0);
+            goto error;
+        }
+        self->write_pos += n;
+        self->raw_pos = self->write_pos;
+        /* Partial writes can return successfully when interrupted by a
+           signal (see write(2)).  We must run signal handlers before
+           blocking another time, possibly indefinitely. */
+        if (PyErr_CheckSignals() < 0)
+            goto error;
+    }
+
+
+end:
+    /* This ensures that after return from this function,
+       VALID_WRITE_BUFFER(self) returns false.
+
+       This is a required condition because when a tell() is called
+       after flushing and if VALID_READ_BUFFER(self) is false, we need
+       VALID_WRITE_BUFFER(self) to be false to have
+       RAW_OFFSET(self) == 0.
+
+       Issue: https://bugs.python.org/issue32228 */
+    _bufferedwriter_reset_buf(self);
+    Py_RETURN_NONE;
+
+error:
+    return NULL;
+}
+
+/*[clinic input]
+_io.BufferedWriter.write
+    buffer: Py_buffer
+    /
+[clinic start generated code]*/
+
+static PyObject *
+_io_BufferedWriter_write_impl(buffered *self, Py_buffer *buffer)
+/*[clinic end generated code: output=7f8d1365759bfc6b input=dd87dd85fc7f8850]*/
+{
+    PyObject *res = NULL;
+    Py_ssize_t written, avail, remaining;
+    Py_off_t offset;
+
+    CHECK_INITIALIZED(self)
+
+    if (!ENTER_BUFFERED(self))
+        return NULL;
+
+    /* Issue #31976: Check for closed file after acquiring the lock. Another
+       thread could be holding the lock while closing the file. */
+    if (IS_CLOSED(self)) {
+        PyErr_SetString(PyExc_ValueError, "write to closed file");
+        goto error;
+    }
+
+    /* Fast path: the data to write can be fully buffered. */
+    if (!VALID_READ_BUFFER(self) && !VALID_WRITE_BUFFER(self)) {
+        self->pos = 0;
+        self->raw_pos = 0;
+    }
+    avail = Py_SAFE_DOWNCAST(self->buffer_size - self->pos, Py_off_t, Py_ssize_t);
+    if (buffer->len <= avail) {
+        memcpy(self->buffer + self->pos, buffer->buf, buffer->len);
+        if (!VALID_WRITE_BUFFER(self) || self->write_pos > self->pos) {
+            self->write_pos = self->pos;
+        }
+        ADJUST_POSITION(self, self->pos + buffer->len);
+        if (self->pos > self->write_end)
+            self->write_end = self->pos;
+        written = buffer->len;
+        goto end;
+    }
+
+    /* First write the current buffer */
+    res = _bufferedwriter_flush_unlocked(self);
+    if (res == NULL) {
+        Py_ssize_t *w = _buffered_check_blocking_error();
+        if (w == NULL)
+            goto error;
+        if (self->readable)
+            _bufferedreader_reset_buf(self);
+        /* Make some place by shifting the buffer. */
+        assert(VALID_WRITE_BUFFER(self));
+        memmove(self->buffer, self->buffer + self->write_pos,
+                Py_SAFE_DOWNCAST(self->write_end - self->write_pos,
+                                 Py_off_t, Py_ssize_t));
+        self->write_end -= self->write_pos;
+        self->raw_pos -= self->write_pos;
+        self->pos -= self->write_pos;
+        self->write_pos = 0;
+        avail = Py_SAFE_DOWNCAST(self->buffer_size - self->write_end,
+                                 Py_off_t, Py_ssize_t);
+        if (buffer->len <= avail) {
+            /* Everything can be buffered */
+            PyErr_Clear();
+            memcpy(self->buffer + self->write_end, buffer->buf, buffer->len);
+            self->write_end += buffer->len;
+            self->pos += buffer->len;
+            written = buffer->len;
+            goto end;
+        }
+        /* Buffer as much as possible. */
+        memcpy(self->buffer + self->write_end, buffer->buf, avail);
+        self->write_end += avail;
+        self->pos += avail;
+        /* XXX Modifying the existing exception e using the pointer w
+           will change e.characters_written but not e.args[2].
+           Therefore we just replace with a new error. */
+        _set_BlockingIOError("write could not complete without blocking",
+                             avail);
+        goto error;
+    }
+    Py_CLEAR(res);
+
+    /* Adjust the raw stream position if it is away from the logical stream
+       position. This happens if the read buffer has been filled but not
+       modified (and therefore _bufferedwriter_flush_unlocked() didn't rewind
+       the raw stream by itself).
+       Fixes issue #6629.
+    */
+    offset = RAW_OFFSET(self);
+    if (offset != 0) {
+        if (_buffered_raw_seek(self, -offset, 1) < 0)
+            goto error;
+        self->raw_pos -= offset;
+    }
+
+    /* Then write buf itself. At this point the buffer has been emptied. */
+    remaining = buffer->len;
+    written = 0;
+    while (remaining > self->buffer_size) {
+        Py_ssize_t n = _bufferedwriter_raw_write(
+            self, (char *) buffer->buf + written, buffer->len - written);
+        if (n == -1) {
+            goto error;
+        } else if (n == -2) {
+            /* Write failed because raw file is non-blocking */
+            if (remaining > self->buffer_size) {
+                /* Can't buffer everything, still buffer as much as possible */
+                memcpy(self->buffer,
+                       (char *) buffer->buf + written, self->buffer_size);
+                self->raw_pos = 0;
+                ADJUST_POSITION(self, self->buffer_size);
+                self->write_end = self->buffer_size;
+                written += self->buffer_size;
+                _set_BlockingIOError("write could not complete without "
+                                     "blocking", written);
+                goto error;
+            }
+            PyErr_Clear();
+            break;
+        }
+        written += n;
+        remaining -= n;
+        /* Partial writes can return successfully when interrupted by a
+           signal (see write(2)).  We must run signal handlers before
+           blocking another time, possibly indefinitely. */
+        if (PyErr_CheckSignals() < 0)
+            goto error;
+    }
+    if (self->readable)
+        _bufferedreader_reset_buf(self);
+    if (remaining > 0) {
+        memcpy(self->buffer, (char *) buffer->buf + written, remaining);
+        written += remaining;
+    }
+    self->write_pos = 0;
+    /* TODO: sanity check (remaining >= 0) */
+    self->write_end = remaining;
+    ADJUST_POSITION(self, remaining);
+    self->raw_pos = 0;
+
+end:
+    res = PyLong_FromSsize_t(written);
+
+error:
+    LEAVE_BUFFERED(self)
+    return res;
+}
+
+
+/*
+ * BufferedRWPair
+ */
+
+/* XXX The usefulness of this (compared to having two separate IO objects) is
+ * questionable.
+ */
+
+typedef struct {
+    PyObject_HEAD
+    buffered *reader;
+    buffered *writer;
+    PyObject *dict;
+    PyObject *weakreflist;
+} rwpair;
+
+/*[clinic input]
+_io.BufferedRWPair.__init__
+    reader: object
+    writer: object
+    buffer_size: Py_ssize_t(c_default="DEFAULT_BUFFER_SIZE") = DEFAULT_BUFFER_SIZE
+    /
+
+A buffered reader and writer object together.
+
+A buffered reader object and buffered writer object put together to
+form a sequential IO object that can read and write. This is typically
+used with a socket or two-way pipe.
+
+reader and writer are RawIOBase objects that are readable and
+writeable respectively. If the buffer_size is omitted it defaults to
+DEFAULT_BUFFER_SIZE.
+[clinic start generated code]*/
+
+static int
+_io_BufferedRWPair___init___impl(rwpair *self, PyObject *reader,
+                                 PyObject *writer, Py_ssize_t buffer_size)
+/*[clinic end generated code: output=327e73d1aee8f984 input=620d42d71f33a031]*/
+{
+    _PyIO_State *state = find_io_state_by_def(Py_TYPE(self));
+    if (_PyIOBase_check_readable(state, reader, Py_True) == NULL) {
+        return -1;
+    }
+    if (_PyIOBase_check_writable(state, writer, Py_True) == NULL) {
+        return -1;
+    }
+
+    self->reader = (buffered *) PyObject_CallFunction(
+            (PyObject *)state->PyBufferedReader_Type,
+            "On", reader, buffer_size);
+    if (self->reader == NULL)
+        return -1;
+
+    self->writer = (buffered *) PyObject_CallFunction(
+            (PyObject *)state->PyBufferedWriter_Type,
+            "On", writer, buffer_size);
+    if (self->writer == NULL) {
+        Py_CLEAR(self->reader);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int
+bufferedrwpair_traverse(rwpair *self, visitproc visit, void *arg)
+{
+    Py_VISIT(Py_TYPE(self));
+    Py_VISIT(self->dict);
+    Py_VISIT(self->reader);
+    Py_VISIT(self->writer);
+    return 0;
+}
+
+static int
+bufferedrwpair_clear(rwpair *self)
+{
+    Py_CLEAR(self->reader);
+    Py_CLEAR(self->writer);
+    Py_CLEAR(self->dict);
+    return 0;
+}
+
+static void
+bufferedrwpair_dealloc(rwpair *self)
+{
+    PyTypeObject *tp = Py_TYPE(self);
+    _PyObject_GC_UNTRACK(self);
+    if (self->weakreflist != NULL)
+        PyObject_ClearWeakRefs((PyObject *)self);
+    (void)bufferedrwpair_clear(self);
+    tp->tp_free((PyObject *) self);
+    Py_DECREF(tp);
+}
+
+static PyObject *
+_forward_call(buffered *self, PyObject *name, PyObject *args)
+{
+    PyObject *func, *ret;
+    if (self == NULL) {
+        PyErr_SetString(PyExc_ValueError,
+                        "I/O operation on uninitialized object");
+        return NULL;
+    }
+
+    func = PyObject_GetAttr((PyObject *)self, name);
+    if (func == NULL) {
+        PyErr_SetObject(PyExc_AttributeError, name);
+        return NULL;
+    }
+
+    ret = PyObject_CallObject(func, args);
+    Py_DECREF(func);
+    return ret;
+}
+
+static PyObject *
+bufferedrwpair_read(rwpair *self, PyObject *args)
+{
+    return _forward_call(self->reader, &_Py_ID(read), args);
+}
+
+static PyObject *
+bufferedrwpair_peek(rwpair *self, PyObject *args)
+{
+    return _forward_call(self->reader, &_Py_ID(peek), args);
+}
+
+static PyObject *
+bufferedrwpair_read1(rwpair *self, PyObject *args)
+{
+    return _forward_call(self->reader, &_Py_ID(read1), args);
+}
+
+static PyObject *
+bufferedrwpair_readinto(rwpair *self, PyObject *args)
+{
+    return _forward_call(self->reader, &_Py_ID(readinto), args);
+}
+
+static PyObject *
+bufferedrwpair_readinto1(rwpair *self, PyObject *args)
+{
+    return _forward_call(self->reader, &_Py_ID(readinto1), args);
+}
+
+static PyObject *
+bufferedrwpair_write(rwpair *self, PyObject *args)
+{
+    return _forward_call(self->writer, &_Py_ID(write), args);
+}
+
+static PyObject *
+bufferedrwpair_flush(rwpair *self, PyObject *Py_UNUSED(ignored))
+{
+    return _forward_call(self->writer, &_Py_ID(flush), NULL);
+}
+
+static PyObject *
+bufferedrwpair_readable(rwpair *self, PyObject *Py_UNUSED(ignored))
+{
+    return _forward_call(self->reader, &_Py_ID(readable), NULL);
+}
+
+static PyObject *
+bufferedrwpair_writable(rwpair *self, PyObject *Py_UNUSED(ignored))
+{
+    return _forward_call(self->writer, &_Py_ID(writable), NULL);
+}
+
+static PyObject *
+bufferedrwpair_close(rwpair *self, PyObject *Py_UNUSED(ignored))
+{
+    PyObject *exc = NULL;
+    PyObject *ret = _forward_call(self->writer, &_Py_ID(close), NULL);
+    if (ret == NULL) {
+        exc = PyErr_GetRaisedException();
+    }
+    else {
+        Py_DECREF(ret);
+    }
+    ret = _forward_call(self->reader, &_Py_ID(close), NULL);
+    if (exc != NULL) {
+        _PyErr_ChainExceptions1(exc);
+        Py_CLEAR(ret);
+    }
+    return ret;
+}
+
+static PyObject *
+bufferedrwpair_isatty(rwpair *self, PyObject *Py_UNUSED(ignored))
+{
+    PyObject *ret = _forward_call(self->writer, &_Py_ID(isatty), NULL);
+
+    if (ret != Py_False) {
+        /* either True or exception */
+        return ret;
+    }
+    Py_DECREF(ret);
+
+    return _forward_call(self->reader, &_Py_ID(isatty), NULL);
+}
+
+static PyObject *
+bufferedrwpair_closed_get(rwpair *self, void *context)
+{
+    if (self->writer == NULL) {
+        PyErr_SetString(PyExc_RuntimeError,
+                "the BufferedRWPair object is being garbage-collected");
+        return NULL;
+    }
+    return PyObject_GetAttr((PyObject *) self->writer, &_Py_ID(closed));
+}
+
+
+/*
+ * BufferedRandom
+ */
+
+/*[clinic input]
+_io.BufferedRandom.__init__
+    raw: object
+    buffer_size: Py_ssize_t(c_default="DEFAULT_BUFFER_SIZE") = DEFAULT_BUFFER_SIZE
+
+A buffered interface to random access streams.
+
+The constructor creates a reader and writer for a seekable stream,
+raw, given in the first argument. If the buffer_size is omitted it
+defaults to DEFAULT_BUFFER_SIZE.
+[clinic start generated code]*/
+
+static int
+_io_BufferedRandom___init___impl(buffered *self, PyObject *raw,
+                                 Py_ssize_t buffer_size)
+/*[clinic end generated code: output=d3d64eb0f64e64a3 input=a4e818fb86d0e50c]*/
+{
+    self->ok = 0;
+    self->detached = 0;
+
+    _PyIO_State *state = find_io_state_by_def(Py_TYPE(self));
+    if (_PyIOBase_check_seekable(state, raw, Py_True) == NULL) {
+        return -1;
+    }
+    if (_PyIOBase_check_readable(state, raw, Py_True) == NULL) {
+        return -1;
+    }
+    if (_PyIOBase_check_writable(state, raw, Py_True) == NULL) {
+        return -1;
+    }
+
+    Py_INCREF(raw);
+    Py_XSETREF(self->raw, raw);
+    self->buffer_size = buffer_size;
+    self->readable = 1;
+    self->writable = 1;
+
+    if (_buffered_init(self) < 0)
+        return -1;
+    _bufferedreader_reset_buf(self);
+    _bufferedwriter_reset_buf(self);
+    self->pos = 0;
+
+    self->fast_closed_checks = (Py_IS_TYPE(self, state->PyBufferedRandom_Type) &&
+                                Py_IS_TYPE(raw, state->PyFileIO_Type));
+
+    self->ok = 1;
+    return 0;
+}
+
+#define clinic_state() (find_io_state_by_def(Py_TYPE(self)))
+#include "clinic/bufferedio.c.h"
+#undef clinic_state
+
+static PyMethodDef bufferediobase_methods[] = {
+    _IO__BUFFEREDIOBASE_DETACH_METHODDEF
+    _IO__BUFFEREDIOBASE_READ_METHODDEF
+    _IO__BUFFEREDIOBASE_READ1_METHODDEF
+    _IO__BUFFEREDIOBASE_READINTO_METHODDEF
+    _IO__BUFFEREDIOBASE_READINTO1_METHODDEF
+    _IO__BUFFEREDIOBASE_WRITE_METHODDEF
+    {NULL, NULL}
+};
+
+static PyType_Slot bufferediobase_slots[] = {
+    {Py_tp_doc, (void *)bufferediobase_doc},
+    {Py_tp_methods, bufferediobase_methods},
+    {0, NULL},
+};
+
+/* Do not set Py_TPFLAGS_HAVE_GC so that tp_traverse and tp_clear are inherited */
+PyType_Spec bufferediobase_spec = {
+    .name = "_io._BufferedIOBase",
+    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE |
+              Py_TPFLAGS_IMMUTABLETYPE),
+    .slots = bufferediobase_slots,
+};
+
+static PyMethodDef bufferedreader_methods[] = {
+    /* BufferedIOMixin methods */
+    _IO__BUFFERED_DETACH_METHODDEF
+    _IO__BUFFERED_SIMPLE_FLUSH_METHODDEF
+    _IO__BUFFERED_CLOSE_METHODDEF
+    _IO__BUFFERED_SEEKABLE_METHODDEF
+    _IO__BUFFERED_READABLE_METHODDEF
+    _IO__BUFFERED_FILENO_METHODDEF
+    _IO__BUFFERED_ISATTY_METHODDEF
+    _IO__BUFFERED__DEALLOC_WARN_METHODDEF
+
+    _IO__BUFFERED_READ_METHODDEF
+    _IO__BUFFERED_PEEK_METHODDEF
+    _IO__BUFFERED_READ1_METHODDEF
+    _IO__BUFFERED_READINTO_METHODDEF
+    _IO__BUFFERED_READINTO1_METHODDEF
+    _IO__BUFFERED_READLINE_METHODDEF
+    _IO__BUFFERED_SEEK_METHODDEF
+    _IO__BUFFERED_TELL_METHODDEF
+    _IO__BUFFERED_TRUNCATE_METHODDEF
+    _IO__BUFFERED___SIZEOF___METHODDEF
+
+    {"__reduce__", _PyIOBase_cannot_pickle, METH_VARARGS},
+    {"__reduce_ex__", _PyIOBase_cannot_pickle, METH_VARARGS},
+    {NULL, NULL}
+};
+
+static PyMemberDef bufferedreader_members[] = {
+    {"raw", T_OBJECT, offsetof(buffered, raw), READONLY},
+    {"_finalizing", T_BOOL, offsetof(buffered, finalizing), 0},
+    {"__weaklistoffset__", T_PYSSIZET, offsetof(buffered, weakreflist), READONLY},
+    {"__dictoffset__", T_PYSSIZET, offsetof(buffered, dict), READONLY},
+    {NULL}
+};
+
+static PyGetSetDef bufferedreader_getset[] = {
+    {"closed", (getter)buffered_closed_get, NULL, NULL},
+    {"name", (getter)buffered_name_get, NULL, NULL},
+    {"mode", (getter)buffered_mode_get, NULL, NULL},
+    {NULL}
+};
+
+
+static PyType_Slot bufferedreader_slots[] = {
+    {Py_tp_dealloc, buffered_dealloc},
+    {Py_tp_repr, buffered_repr},
+    {Py_tp_doc, (void *)_io_BufferedReader___init____doc__},
+    {Py_tp_traverse, buffered_traverse},
+    {Py_tp_clear, buffered_clear},
+    {Py_tp_iternext, buffered_iternext},
+    {Py_tp_methods, bufferedreader_methods},
+    {Py_tp_members, bufferedreader_members},
+    {Py_tp_getset, bufferedreader_getset},
+    {Py_tp_init, _io_BufferedReader___init__},
+    {0, NULL},
+};
+
+PyType_Spec bufferedreader_spec = {
+    .name = "_io.BufferedReader",
+    .basicsize = sizeof(buffered),
+    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC |
+              Py_TPFLAGS_IMMUTABLETYPE),
+    .slots = bufferedreader_slots,
+};
+
+static PyMethodDef bufferedwriter_methods[] = {
+    /* BufferedIOMixin methods */
+    _IO__BUFFERED_CLOSE_METHODDEF
+    _IO__BUFFERED_DETACH_METHODDEF
+    _IO__BUFFERED_SEEKABLE_METHODDEF
+    _IO__BUFFERED_WRITABLE_METHODDEF
+    _IO__BUFFERED_FILENO_METHODDEF
+    _IO__BUFFERED_ISATTY_METHODDEF
+    _IO__BUFFERED__DEALLOC_WARN_METHODDEF
+
+    _IO_BUFFEREDWRITER_WRITE_METHODDEF
+    _IO__BUFFERED_TRUNCATE_METHODDEF
+    _IO__BUFFERED_FLUSH_METHODDEF
+    _IO__BUFFERED_SEEK_METHODDEF
+    _IO__BUFFERED_TELL_METHODDEF
+    _IO__BUFFERED___SIZEOF___METHODDEF
+
+    {"__reduce__", _PyIOBase_cannot_pickle, METH_VARARGS},
+    {"__reduce_ex__", _PyIOBase_cannot_pickle, METH_VARARGS},
+    {NULL, NULL}
+};
+
+static PyMemberDef bufferedwriter_members[] = {
+    {"raw", T_OBJECT, offsetof(buffered, raw), READONLY},
+    {"_finalizing", T_BOOL, offsetof(buffered, finalizing), 0},
+    {"__weaklistoffset__", T_PYSSIZET, offsetof(buffered, weakreflist), READONLY},
+    {"__dictoffset__", T_PYSSIZET, offsetof(buffered, dict), READONLY},
+    {NULL}
+};
+
+static PyGetSetDef bufferedwriter_getset[] = {
+    {"closed", (getter)buffered_closed_get, NULL, NULL},
+    {"name", (getter)buffered_name_get, NULL, NULL},
+    {"mode", (getter)buffered_mode_get, NULL, NULL},
+    {NULL}
+};
+
+
+static PyType_Slot bufferedwriter_slots[] = {
+    {Py_tp_dealloc, buffered_dealloc},
+    {Py_tp_repr, buffered_repr},
+    {Py_tp_doc, (void *)_io_BufferedWriter___init____doc__},
+    {Py_tp_traverse, buffered_traverse},
+    {Py_tp_clear, buffered_clear},
+    {Py_tp_methods, bufferedwriter_methods},
+    {Py_tp_members, bufferedwriter_members},
+    {Py_tp_getset, bufferedwriter_getset},
+    {Py_tp_init, _io_BufferedWriter___init__},
+    {0, NULL},
+};
+
+PyType_Spec bufferedwriter_spec = {
+    .name = "_io.BufferedWriter",
+    .basicsize = sizeof(buffered),
+    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC |
+              Py_TPFLAGS_IMMUTABLETYPE),
+    .slots = bufferedwriter_slots,
+};
+
+static PyMethodDef bufferedrwpair_methods[] = {
+    {"read", (PyCFunction)bufferedrwpair_read, METH_VARARGS},
+    {"peek", (PyCFunction)bufferedrwpair_peek, METH_VARARGS},
+    {"read1", (PyCFunction)bufferedrwpair_read1, METH_VARARGS},
+    {"readinto", (PyCFunction)bufferedrwpair_readinto, METH_VARARGS},
+    {"readinto1", (PyCFunction)bufferedrwpair_readinto1, METH_VARARGS},
+
+    {"write", (PyCFunction)bufferedrwpair_write, METH_VARARGS},
+    {"flush", (PyCFunction)bufferedrwpair_flush, METH_NOARGS},
+
+    {"readable", (PyCFunction)bufferedrwpair_readable, METH_NOARGS},
+    {"writable", (PyCFunction)bufferedrwpair_writable, METH_NOARGS},
+
+    {"close", (PyCFunction)bufferedrwpair_close, METH_NOARGS},
+    {"isatty", (PyCFunction)bufferedrwpair_isatty, METH_NOARGS},
+
+    {NULL, NULL}
+};
+
+static PyMemberDef bufferedrwpair_members[] = {
+    {"__weaklistoffset__", T_PYSSIZET, offsetof(rwpair, weakreflist), READONLY},
+    {"__dictoffset__", T_PYSSIZET, offsetof(rwpair, dict), READONLY},
+    {NULL}
+};
+
+static PyGetSetDef bufferedrwpair_getset[] = {
+    {"closed", (getter)bufferedrwpair_closed_get, NULL, NULL},
+    {NULL}
+};
+
+static PyType_Slot bufferedrwpair_slots[] = {
+    {Py_tp_dealloc, bufferedrwpair_dealloc},
+    {Py_tp_doc, (void *)_io_BufferedRWPair___init____doc__},
+    {Py_tp_traverse, bufferedrwpair_traverse},
+    {Py_tp_clear, bufferedrwpair_clear},
+    {Py_tp_methods, bufferedrwpair_methods},
+    {Py_tp_members, bufferedrwpair_members},
+    {Py_tp_getset, bufferedrwpair_getset},
+    {Py_tp_init, _io_BufferedRWPair___init__},
+    {0, NULL},
+};
+
+PyType_Spec bufferedrwpair_spec = {
+    .name = "_io.BufferedRWPair",
+    .basicsize = sizeof(rwpair),
+    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC |
+              Py_TPFLAGS_IMMUTABLETYPE),
+    .slots = bufferedrwpair_slots,
+};
+
+
+static PyMethodDef bufferedrandom_methods[] = {
+    /* BufferedIOMixin methods */
+    _IO__BUFFERED_CLOSE_METHODDEF
+    _IO__BUFFERED_DETACH_METHODDEF
+    _IO__BUFFERED_SEEKABLE_METHODDEF
+    _IO__BUFFERED_READABLE_METHODDEF
+    _IO__BUFFERED_WRITABLE_METHODDEF
+    _IO__BUFFERED_FILENO_METHODDEF
+    _IO__BUFFERED_ISATTY_METHODDEF
+    _IO__BUFFERED__DEALLOC_WARN_METHODDEF
+
+    _IO__BUFFERED_FLUSH_METHODDEF
+
+    _IO__BUFFERED_SEEK_METHODDEF
+    _IO__BUFFERED_TELL_METHODDEF
+    _IO__BUFFERED_TRUNCATE_METHODDEF
+    _IO__BUFFERED_READ_METHODDEF
+    _IO__BUFFERED_READ1_METHODDEF
+    _IO__BUFFERED_READINTO_METHODDEF
+    _IO__BUFFERED_READINTO1_METHODDEF
+    _IO__BUFFERED_READLINE_METHODDEF
+    _IO__BUFFERED_PEEK_METHODDEF
+    _IO_BUFFEREDWRITER_WRITE_METHODDEF
+    _IO__BUFFERED___SIZEOF___METHODDEF
+
+    {"__reduce__", _PyIOBase_cannot_pickle, METH_VARARGS},
+    {"__reduce_ex__", _PyIOBase_cannot_pickle, METH_VARARGS},
+    {NULL, NULL}
+};
+
+static PyMemberDef bufferedrandom_members[] = {
+    {"raw", T_OBJECT, offsetof(buffered, raw), READONLY},
+    {"_finalizing", T_BOOL, offsetof(buffered, finalizing), 0},
+    {"__weaklistoffset__", T_PYSSIZET, offsetof(buffered, weakreflist), READONLY},
+    {"__dictoffset__", T_PYSSIZET, offsetof(buffered, dict), READONLY},
+    {NULL}
+};
+
+static PyGetSetDef bufferedrandom_getset[] = {
+    {"closed", (getter)buffered_closed_get, NULL, NULL},
+    {"name", (getter)buffered_name_get, NULL, NULL},
+    {"mode", (getter)buffered_mode_get, NULL, NULL},
+    {NULL}
+};
+
+
+static PyType_Slot bufferedrandom_slots[] = {
+    {Py_tp_dealloc, buffered_dealloc},
+    {Py_tp_repr, buffered_repr},
+    {Py_tp_doc, (void *)_io_BufferedRandom___init____doc__},
+    {Py_tp_traverse, buffered_traverse},
+    {Py_tp_clear, buffered_clear},
+    {Py_tp_iternext, buffered_iternext},
+    {Py_tp_methods, bufferedrandom_methods},
+    {Py_tp_members, bufferedrandom_members},
+    {Py_tp_getset, bufferedrandom_getset},
+    {Py_tp_init, _io_BufferedRandom___init__},
+    {0, NULL},
+};
+
+PyType_Spec bufferedrandom_spec = {
+    .name = "_io.BufferedRandom",
+    .basicsize = sizeof(buffered),
+    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC |
+              Py_TPFLAGS_IMMUTABLETYPE),
+    .slots = bufferedrandom_slots,
+};