Replaced "string" with "bytes object" in docstrings of binary I/O objects.

6 files changed, 319 insertions, 282 deletions

diff --git a/Modules/_io/_iomodule.c b/Modules/_io/_iomodule.c
index 45c31a550e..e70c4b7611 100644
--- a/Modules/_io/_iomodule.c
+++ b/Modules/_io/_iomodule.c
@@ -237,8 +237,8 @@ io_open(PyObject *self, PyObject *args, PyObject *kwds)
 
     PyObject *raw, *modeobj = NULL, *buffer, *wrapper, *result = NULL;
 
+    _Py_IDENTIFIER(_blksize);
     _Py_IDENTIFIER(isatty);
-    _Py_IDENTIFIER(fileno);
     _Py_IDENTIFIER(mode);
     _Py_IDENTIFIER(close);
 
@@ -380,24 +380,14 @@ io_open(PyObject *self, PyObject *args, PyObject *kwds)
         line_buffering = 0;
 
     if (buffering < 0) {
-        buffering = DEFAULT_BUFFER_SIZE;
-#ifdef HAVE_STRUCT_STAT_ST_BLKSIZE
-        {
-            struct stat st;
-            long fileno;
-            PyObject *res = _PyObject_CallMethodId(raw, &PyId_fileno, NULL);
-            if (res == NULL)
-                goto error;
-
-            fileno = PyLong_AsLong(res);
-            Py_DECREF(res);
-            if (fileno == -1 && PyErr_Occurred())
-                goto error;
-
-            if (fstat(fileno, &st) >= 0 && st.st_blksize > 1)
-                buffering = st.st_blksize;
-        }
-#endif
+        PyObject *blksize_obj;
+        blksize_obj = _PyObject_GetAttrId(raw, &PyId__blksize);
+        if (blksize_obj == NULL)
+            goto error;
+        buffering = PyLong_AsLong(blksize_obj);
+        Py_DECREF(blksize_obj);
+        if (buffering == -1 && PyErr_Occurred())
+            goto error;
     }
     if (buffering < 0) {
         PyErr_SetString(PyExc_ValueError,
diff --git a/Modules/_io/_iomodule.h b/Modules/_io/_iomodule.h
index 8927864e8c..9d5205ec30 100644
--- a/Modules/_io/_iomodule.h
+++ b/Modules/_io/_iomodule.h
@@ -69,7 +69,7 @@ extern int _PyIO_trap_eintr(void);
  * Offset type for positioning.
  */
 
-/* Printing a variable of type off_t (with e.g., PyString_FromFormat)
+/* Printing a variable of type off_t (with e.g., PyUnicode_FromFormat)
    correctly and without producing compiler warnings is surprisingly painful.
    We identify an integer type whose size matches off_t and then: (1) cast the
    off_t to that integer type and (2) use the appropriate conversion
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index 445c8708ad..ea9f5332a4 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -24,6 +24,7 @@ _Py_IDENTIFIER(read);
 _Py_IDENTIFIER(read1);
 _Py_IDENTIFIER(readable);
 _Py_IDENTIFIER(readinto);
+_Py_IDENTIFIER(readinto1);
 _Py_IDENTIFIER(writable);
 _Py_IDENTIFIER(write);
 
@@ -47,17 +48,21 @@ PyDoc_STRVAR(bufferediobase_doc,
     );
 
 static PyObject *
-bufferediobase_readinto(PyObject *self, PyObject *args)
+_bufferediobase_readinto_generic(PyObject *self, PyObject *args, char readinto1)
 {
     Py_buffer buf;
     Py_ssize_t len;
     PyObject *data;
 
-    if (!PyArg_ParseTuple(args, "w*:readinto", &buf)) {
+    if (!PyArg_ParseTuple(args,
+                          readinto1 ? "w*:readinto1" : "w*:readinto",
+                          &buf)) {
         return NULL;
     }
 
-    data = _PyObject_CallMethodId(self, &PyId_read, "n", buf.len);
+    data = _PyObject_CallMethodId(self,
+                                  readinto1 ? &PyId_read1 : &PyId_read,
+                                  "n", buf.len);
     if (data == NULL)
         goto error;
 
@@ -89,6 +94,18 @@ bufferediobase_readinto(PyObject *self, PyObject *args)
 }
 
 static PyObject *
+bufferediobase_readinto(PyObject *self, PyObject *args)
+{
+    return _bufferediobase_readinto_generic(self, args, 0);
+}
+
+static PyObject *
+bufferediobase_readinto1(PyObject *self, PyObject *args)
+{
+    return _bufferediobase_readinto_generic(self, args, 1);
+}
+
+static PyObject *
 bufferediobase_unsupported(const char *message)
 {
     _PyIO_State *state = IO_STATE();
@@ -167,6 +184,7 @@ static PyMethodDef bufferediobase_methods[] = {
     {"read", bufferediobase_read, METH_VARARGS, bufferediobase_read_doc},
     {"read1", bufferediobase_read1, METH_VARARGS, bufferediobase_read1_doc},
     {"readinto", bufferediobase_readinto, METH_VARARGS, NULL},
+    {"readinto1", bufferediobase_readinto1, METH_VARARGS, NULL},
     {"write", bufferediobase_write, METH_VARARGS, bufferediobase_write_doc},
     {NULL, NULL}
 };
@@ -662,11 +680,7 @@ static void
 _set_BlockingIOError(char *msg, Py_ssize_t written)
 {
     PyObject *err;
-#ifdef Py_DEBUG
-    /* in debug mode, PyEval_EvalFrameEx() fails with an assertion error
-       if an exception is set when it is called */
     PyErr_Clear();
-#endif
     err = PyObject_CallFunction(PyExc_BlockingIOError, "isn",
                                 errno, msg, written);
     if (err)
@@ -977,7 +991,7 @@ buffered_read1(buffered *self, PyObject *args)
 }
 
 static PyObject *
-buffered_readinto(buffered *self, PyObject *args)
+_buffered_readinto_generic(buffered *self, PyObject *args, char readinto1)
 {
     Py_buffer buf;
     Py_ssize_t n, written = 0, remaining;
@@ -985,7 +999,9 @@ buffered_readinto(buffered *self, PyObject *args)
 
     CHECK_INITIALIZED(self)
 
-    if (!PyArg_ParseTuple(args, "w*:readinto", &buf))
+    if (!PyArg_ParseTuple(args,
+                          readinto1 ? "w*:readinto1" : "w*:readinto",
+                          &buf))
         return NULL;
 
     n = Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t);
@@ -1023,7 +1039,10 @@ buffered_readinto(buffered *self, PyObject *args)
             n = _bufferedreader_raw_read(self, (char *) buf.buf + written,
                                          remaining);
         }
-        else {
+
+        /* 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)
@@ -1034,6 +1053,9 @@ buffered_readinto(buffered *self, PyObject *args)
                 continue; /* short circuit */
             }
         }
+        else
+            n = 0;
+
         if (n == 0 || (n == -2 && written > 0))
             break;
         if (n < 0) {
@@ -1043,6 +1065,12 @@ buffered_readinto(buffered *self, PyObject *args)
             }
             goto end;
         }
+
+        /* At most one read in readinto1 mode */
+        if (readinto1) {
+            written += n;
+            break;
+        }
     }
     res = PyLong_FromSsize_t(written);
 
@@ -1054,6 +1082,19 @@ end_unlocked:
 }
 
 static PyObject *
+buffered_readinto(buffered *self, PyObject *args)
+{
+    return _buffered_readinto_generic(self, args, 0);
+}
+
+static PyObject *
+buffered_readinto1(buffered *self, PyObject *args)
+{
+    return _buffered_readinto_generic(self, args, 1);
+}
+
+
+static PyObject *
 _buffered_readline(buffered *self, Py_ssize_t limit)
 {
     PyObject *res = NULL;
@@ -1738,6 +1779,7 @@ static PyMethodDef bufferedreader_methods[] = {
     {"peek", (PyCFunction)buffered_peek, METH_VARARGS},
     {"read1", (PyCFunction)buffered_read1, METH_VARARGS},
     {"readinto", (PyCFunction)buffered_readinto, METH_VARARGS},
+    {"readinto1", (PyCFunction)buffered_readinto1, METH_VARARGS},
     {"readline", (PyCFunction)buffered_readline, METH_VARARGS},
     {"seek", (PyCFunction)buffered_seek, METH_VARARGS},
     {"tell", (PyCFunction)buffered_tell, METH_NOARGS},
@@ -2339,6 +2381,12 @@ bufferedrwpair_readinto(rwpair *self, PyObject *args)
 }
 
 static PyObject *
+bufferedrwpair_readinto1(rwpair *self, PyObject *args)
+{
+    return _forward_call(self->reader, &PyId_readinto1, args);
+}
+
+static PyObject *
 bufferedrwpair_write(rwpair *self, PyObject *args)
 {
     return _forward_call(self->writer, &PyId_write, args);
@@ -2409,6 +2457,7 @@ static PyMethodDef bufferedrwpair_methods[] = {
     {"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},
@@ -2557,6 +2606,7 @@ static PyMethodDef bufferedrandom_methods[] = {
     {"read", (PyCFunction)buffered_read, METH_VARARGS},
     {"read1", (PyCFunction)buffered_read1, METH_VARARGS},
     {"readinto", (PyCFunction)buffered_readinto, METH_VARARGS},
+    {"readinto1", (PyCFunction)buffered_readinto1, METH_VARARGS},
     {"readline", (PyCFunction)buffered_readline, METH_VARARGS},
     {"peek", (PyCFunction)buffered_peek, METH_VARARGS},
     {"write", (PyCFunction)bufferedwriter_write, METH_VARARGS},
diff --git a/Modules/_io/bytesio.c b/Modules/_io/bytesio.c
index 4652356f31..974e33ac2a 100644
--- a/Modules/_io/bytesio.c
+++ b/Modules/_io/bytesio.c
@@ -4,10 +4,9 @@
 
 typedef struct {
     PyObject_HEAD
-    char *buf;
+    PyObject *buf;
     Py_ssize_t pos;
     Py_ssize_t string_size;
-    size_t buf_size;
     PyObject *dict;
     PyObject *weakreflist;
     Py_ssize_t exports;
@@ -18,6 +17,12 @@ typedef struct {
     bytesio *source;
 } bytesiobuf;
 
+/* The bytesio object can be in three states:
+  * Py_REFCNT(buf) == 1, exports == 0.
+  * Py_REFCNT(buf) > 1.  exports == 0,
+    first modification or export causes the internal buffer copying.
+  * exports > 0.  Py_REFCNT(buf) == 1, any modifications are forbidden.
+*/
 
 #define CHECK_CLOSED(self)                                  \
     if ((self)->buf == NULL) {                              \
@@ -33,40 +38,60 @@ typedef struct {
         return NULL; \
     }
 
+#define SHARED_BUF(self) (Py_REFCNT((self)->buf) > 1)
+
 
 /* Internal routine to get a line from the buffer of a BytesIO
    object. Returns the length between the current position to the
    next newline character. */
 static Py_ssize_t
-get_line(bytesio *self, char **output)
+scan_eol(bytesio *self, Py_ssize_t len)
 {
-    char *n;
-    const char *str_end;
-    Py_ssize_t len;
+    const char *start, *n;
+    Py_ssize_t maxlen;
 
     assert(self->buf != NULL);
 
     /* Move to the end of the line, up to the end of the string, s. */
-    str_end = self->buf + self->string_size;
-    for (n = self->buf + self->pos;
-         n < str_end && *n != '\n';
-         n++);
-
-    /* Skip the newline character */
-    if (n < str_end)
-        n++;
-
-    /* Get the length from the current position to the end of the line. */
-    len = n - (self->buf + self->pos);
-    *output = self->buf + self->pos;
-
+    start = PyBytes_AS_STRING(self->buf) + self->pos;
+    maxlen = self->string_size - self->pos;
+    if (len < 0 || len > maxlen)
+        len = maxlen;
+
+    if (len) {
+        n = memchr(start, '\n', len);
+        if (n)
+            /* Get the length from the current position to the end of
+               the line. */
+            len = n - start + 1;
+    }
     assert(len >= 0);
     assert(self->pos < PY_SSIZE_T_MAX - len);
-    self->pos += len;
 
     return len;
 }
 
+/* Internal routine for detaching the shared buffer of BytesIO objects.
+   The caller should ensure that the 'size' argument is non-negative and
+   not lesser than self->string_size.  Returns 0 on success, -1 otherwise. */
+static int
+unshare_buffer(bytesio *self, size_t size)
+{
+    PyObject *new_buf, *old_buf;
+    assert(SHARED_BUF(self));
+    assert(self->exports == 0);
+    assert(size >= (size_t)self->string_size);
+    new_buf = PyBytes_FromStringAndSize(NULL, size);
+    if (new_buf == NULL)
+        return -1;
+    memcpy(PyBytes_AS_STRING(new_buf), PyBytes_AS_STRING(self->buf),
+           self->string_size);
+    old_buf = self->buf;
+    self->buf = new_buf;
+    Py_DECREF(old_buf);
+    return 0;
+}
+
 /* Internal routine for changing the size of the buffer of BytesIO objects.
    The caller should ensure that the 'size' argument is non-negative.  Returns
    0 on success, -1 otherwise. */
@@ -75,8 +100,7 @@ resize_buffer(bytesio *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;
-    char *new_buf = NULL;
+    size_t alloc = PyBytes_GET_SIZE(self->buf);
 
     assert(self->buf != NULL);
 
@@ -104,13 +128,15 @@ resize_buffer(bytesio *self, size_t size)
 
     if (alloc > ((size_t)-1) / sizeof(char))
         goto overflow;
-    new_buf = (char *)PyMem_Realloc(self->buf, alloc * sizeof(char));
-    if (new_buf == NULL) {
-        PyErr_NoMemory();
-        return -1;
+
+    if (SHARED_BUF(self)) {
+        if (unshare_buffer(self, alloc) < 0)
+            return -1;
+    }
+    else {
+        if (_PyBytes_Resize(&self->buf, alloc) < 0)
+            return -1;
     }
-    self->buf_size = alloc;
-    self->buf = new_buf;
 
     return 0;
 
@@ -125,12 +151,18 @@ resize_buffer(bytesio *self, size_t size)
 static Py_ssize_t
 write_bytes(bytesio *self, const char *bytes, Py_ssize_t len)
 {
+    size_t endpos;
     assert(self->buf != NULL);
     assert(self->pos >= 0);
     assert(len >= 0);
 
-    if ((size_t)self->pos + len > self->buf_size) {
-        if (resize_buffer(self, (size_t)self->pos + len) < 0)
+    endpos = (size_t)self->pos + len;
+    if (endpos > (size_t)PyBytes_GET_SIZE(self->buf)) {
+        if (resize_buffer(self, endpos) < 0)
+            return -1;
+    }
+    else if (SHARED_BUF(self)) {
+        if (unshare_buffer(self, Py_MAX(endpos, (size_t)self->string_size)) < 0)
             return -1;
     }
 
@@ -143,18 +175,18 @@ write_bytes(bytesio *self, const char *bytes, Py_ssize_t len)
           |   |            <--to pad-->|<---to write--->    |
           0   buf                   position
         */
-        memset(self->buf + self->string_size, '\0',
+        memset(PyBytes_AS_STRING(self->buf) + self->string_size, '\0',
                (self->pos - self->string_size) * sizeof(char));
     }
 
     /* Copy the data to the internal buffer, overwriting some of the existing
        data if self->pos < self->string_size. */
-    memcpy(self->buf + self->pos, bytes, len);
-    self->pos += len;
+    memcpy(PyBytes_AS_STRING(self->buf) + self->pos, bytes, len);
+    self->pos = endpos;
 
     /* Set the new length of the internal string if it has changed. */
-    if (self->string_size < self->pos) {
-        self->string_size = self->pos;
+    if ((size_t)self->string_size < endpos) {
+        self->string_size = endpos;
     }
 
     return len;
@@ -231,7 +263,22 @@ static PyObject *
 bytesio_getvalue(bytesio *self)
 {
     CHECK_CLOSED(self);
-    return PyBytes_FromStringAndSize(self->buf, self->string_size);
+    if (self->string_size <= 1 || self->exports > 0)
+        return PyBytes_FromStringAndSize(PyBytes_AS_STRING(self->buf),
+                                         self->string_size);
+
+    if (self->string_size != PyBytes_GET_SIZE(self->buf)) {
+        if (SHARED_BUF(self)) {
+            if (unshare_buffer(self, self->string_size) < 0)
+                return NULL;
+        }
+        else {
+            if (_PyBytes_Resize(&self->buf, self->string_size) < 0)
+                return NULL;
+        }
+    }
+    Py_INCREF(self->buf);
+    return self->buf;
 }
 
 PyDoc_STRVAR(isatty_doc,
@@ -257,6 +304,26 @@ bytesio_tell(bytesio *self)
     return PyLong_FromSsize_t(self->pos);
 }
 
+static PyObject *
+read_bytes(bytesio *self, Py_ssize_t size)
+{
+    char *output;
+
+    assert(self->buf != NULL);
+    assert(size <= self->string_size);
+    if (size > 1 &&
+        self->pos == 0 && size == PyBytes_GET_SIZE(self->buf) &&
+        self->exports == 0) {
+        self->pos += size;
+        Py_INCREF(self->buf);
+        return self->buf;
+    }
+
+    output = PyBytes_AS_STRING(self->buf) + self->pos;
+    self->pos += size;
+    return PyBytes_FromStringAndSize(output, size);
+}
+
 PyDoc_STRVAR(read_doc,
 "read([size]) -> read at most size bytes, returned as a bytes object.\n"
 "\n"
@@ -267,7 +334,6 @@ static PyObject *
 bytesio_read(bytesio *self, PyObject *args)
 {
     Py_ssize_t size, n;
-    char *output;
     PyObject *arg = Py_None;
 
     CHECK_CLOSED(self);
@@ -298,11 +364,7 @@ bytesio_read(bytesio *self, PyObject *args)
             size = 0;
     }
 
-    assert(self->buf != NULL);
-    output = self->buf + self->pos;
-    self->pos += size;
-
-    return PyBytes_FromStringAndSize(output, size);
+    return read_bytes(self, size);
 }
 
 
@@ -336,7 +398,6 @@ static PyObject *
 bytesio_readline(bytesio *self, PyObject *args)
 {
     Py_ssize_t size, n;
-    char *output;
     PyObject *arg = Py_None;
 
     CHECK_CLOSED(self);
@@ -359,15 +420,9 @@ bytesio_readline(bytesio *self, PyObject *args)
         return NULL;
     }
 
-    n = get_line(self, &output);
-
-    if (size >= 0 && size < n) {
-        size = n - size;
-        n -= size;
-        self->pos -= size;
-    }
+    n = scan_eol(self, size);
 
-    return PyBytes_FromStringAndSize(output, n);
+    return read_bytes(self, n);
 }
 
 PyDoc_STRVAR(readlines_doc,
@@ -410,7 +465,9 @@ bytesio_readlines(bytesio *self, PyObject *args)
     if (!result)
         return NULL;
 
-    while ((n = get_line(self, &output)) != 0) {
+    output = PyBytes_AS_STRING(self->buf) + self->pos;
+    while ((n = scan_eol(self, -1)) != 0) {
+        self->pos += n;
         line = PyBytes_FromStringAndSize(output, n);
         if (!line)
             goto on_error;
@@ -422,6 +479,7 @@ bytesio_readlines(bytesio *self, PyObject *args)
         size += n;
         if (maxsize > 0 && size >= maxsize)
             break;
+        output += n;
     }
     return result;
 
@@ -456,7 +514,7 @@ bytesio_readinto(bytesio *self, PyObject *arg)
             len = 0;
     }
 
-    memcpy(buffer.buf, self->buf + self->pos, len);
+    memcpy(buffer.buf, PyBytes_AS_STRING(self->buf) + self->pos, len);
     assert(self->pos + len < PY_SSIZE_T_MAX);
     assert(len >= 0);
     self->pos += len;
@@ -516,17 +574,16 @@ bytesio_truncate(bytesio *self, PyObject *args)
 static PyObject *
 bytesio_iternext(bytesio *self)
 {
-    char *next;
     Py_ssize_t n;
 
     CHECK_CLOSED(self);
 
-    n = get_line(self, &next);
+    n = scan_eol(self, -1);
 
-    if (!next || n == 0)
+    if (n == 0)
         return NULL;
 
-    return PyBytes_FromStringAndSize(next, n);
+    return read_bytes(self, n);
 }
 
 PyDoc_STRVAR(seek_doc,
@@ -658,10 +715,7 @@ static PyObject *
 bytesio_close(bytesio *self)
 {
     CHECK_EXPORTS(self);
-    if (self->buf != NULL) {
-        PyMem_Free(self->buf);
-        self->buf = NULL;
-    }
+    Py_CLEAR(self->buf);
     Py_RETURN_NONE;
 }
 
@@ -791,10 +845,7 @@ bytesio_dealloc(bytesio *self)
                         "deallocated BytesIO object has exported buffers");
         PyErr_Print();
     }
-    if (self->buf != NULL) {
-        PyMem_Free(self->buf);
-        self->buf = NULL;
-    }
+    Py_CLEAR(self->buf);
     Py_CLEAR(self->dict);
     if (self->weakreflist != NULL)
         PyObject_ClearWeakRefs((PyObject *) self);
@@ -814,7 +865,7 @@ bytesio_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 = (char *)PyMem_Malloc(0);
+    self->buf = PyBytes_FromStringAndSize(NULL, 0);
     if (self->buf == NULL) {
         Py_DECREF(self);
         return PyErr_NoMemory();
@@ -837,13 +888,26 @@ bytesio_init(bytesio *self, PyObject *args, PyObject *kwds)
     self->string_size = 0;
     self->pos = 0;
 
+    if (self->exports > 0) {
+        PyErr_SetString(PyExc_BufferError,
+                        "Existing exports of data: object cannot be re-sized");
+        return -1;
+    }
     if (initvalue && initvalue != Py_None) {
-        PyObject *res;
-        res = bytesio_write(self, initvalue);
-        if (res == NULL)
-            return -1;
-        Py_DECREF(res);
-        self->pos = 0;
+        if (PyBytes_CheckExact(initvalue)) {
+            Py_INCREF(initvalue);
+            Py_XDECREF(self->buf);
+            self->buf = initvalue;
+            self->string_size = PyBytes_GET_SIZE(initvalue);
+        }
+        else {
+            PyObject *res;
+            res = bytesio_write(self, initvalue);
+            if (res == NULL)
+                return -1;
+            Py_DECREF(res);
+            self->pos = 0;
+        }
     }
 
     return 0;
@@ -855,8 +919,8 @@ bytesio_sizeof(bytesio *self, void *unused)
     Py_ssize_t res;
 
     res = sizeof(bytesio);
-    if (self->buf)
-        res += self->buf_size;
+    if (self->buf && !SHARED_BUF(self))
+        res += _PySys_GetSizeOf(self->buf);
     return PyLong_FromSsize_t(res);
 }
 
@@ -964,18 +1028,24 @@ PyTypeObject PyBytesIO_Type = {
 static int
 bytesiobuf_getbuffer(bytesiobuf *obj, Py_buffer *view, int flags)
 {
-    int ret;
     bytesio *b = (bytesio *) obj->source;
+
     if (view == NULL) {
-        b->exports++;
-        return 0;
+        PyErr_SetString(PyExc_BufferError,
+            "bytesiobuf_getbuffer: view==NULL argument is obsolete");
+        return -1;
     }
-    ret = PyBuffer_FillInfo(view, (PyObject*)obj, b->buf, b->string_size,
-                            0, flags);
-    if (ret >= 0) {
-        b->exports++;
+    if (SHARED_BUF(b)) {
+        if (unshare_buffer(b, b->string_size) < 0)
+            return -1;
     }
-    return ret;
+
+    /* cannot fail if view != NULL and readonly == 0 */
+    (void)PyBuffer_FillInfo(view, (PyObject*)obj,
+                            PyBytes_AS_STRING(b->buf), b->string_size,
+                            0, flags);
+    b->exports++;
+    return 0;
 }
 
 static void
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index 23ca31d2d4..eca8bba136 100644
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -53,6 +53,7 @@ typedef struct {
     signed int seekable : 2; /* -1 means unknown */
     unsigned int closefd : 1;
     char finalizing;
+    unsigned int blksize;
     PyObject *weakreflist;
     PyObject *dict;
 } fileio;
@@ -168,6 +169,7 @@ fileio_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
         self->writable = 0;
         self->appending = 0;
         self->seekable = -1;
+        self->blksize = 0;
         self->closefd = 1;
         self->weakreflist = NULL;
     }
@@ -175,44 +177,6 @@ fileio_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
     return (PyObject *) self;
 }
 
-/* On Unix, open will succeed for directories.
-   In Python, there should be no file objects referring to
-   directories, so we need a check.  */
-
-static int
-dircheck(fileio* self, PyObject *nameobj)
-{
-#if defined(HAVE_FSTAT) && defined(S_ISDIR) && defined(EISDIR)
-    struct stat buf;
-    if (self->fd < 0)
-        return 0;
-    if (fstat(self->fd, &buf) == 0 && S_ISDIR(buf.st_mode)) {
-        errno = EISDIR;
-        PyErr_SetFromErrnoWithFilenameObject(PyExc_IOError, nameobj);
-        return -1;
-    }
-#endif
-    return 0;
-}
-
-static int
-check_fd(int fd)
-{
-#if defined(HAVE_FSTAT)
-    struct stat buf;
-    if (!_PyVerify_fd(fd) || (fstat(fd, &buf) < 0 && errno == EBADF)) {
-        PyObject *exc;
-        char *msg = strerror(EBADF);
-        exc = PyObject_CallFunction(PyExc_OSError, "(is)",
-                                    EBADF, msg);
-        PyErr_SetObject(PyExc_OSError, exc);
-        Py_XDECREF(exc);
-        return -1;
-    }
-#endif
-    return 0;
-}
-
 #ifdef O_CLOEXEC
 extern int _Py_open_cloexec_works;
 #endif
@@ -240,6 +204,8 @@ fileio_init(PyObject *oself, PyObject *args, PyObject *kwds)
 #elif !defined(MS_WINDOWS)
     int *atomic_flag_works = NULL;
 #endif
+    struct _Py_stat_struct fdfstat;
+    int async_err = 0;
 
     assert(PyFileIO_Check(oself));
     if (self->fd >= 0) {
@@ -278,7 +244,7 @@ fileio_init(PyObject *oself, PyObject *args, PyObject *kwds)
         int rv = _PyUnicode_HasNULChars(nameobj);
         if (rv) {
             if (rv != -1)
-                PyErr_SetString(PyExc_TypeError, "embedded NUL character");
+                PyErr_SetString(PyExc_ValueError, "embedded null character");
             return -1;
         }
         widename = PyUnicode_AsUnicode(nameobj);
@@ -367,8 +333,6 @@ fileio_init(PyObject *oself, PyObject *args, PyObject *kwds)
 #endif
 
     if (fd >= 0) {
-        if (check_fd(fd))
-            goto error;
         self->fd = fd;
         self->closefd = closefd;
     }
@@ -382,15 +346,20 @@ fileio_init(PyObject *oself, PyObject *args, PyObject *kwds)
 
         errno = 0;
         if (opener == Py_None) {
-            Py_BEGIN_ALLOW_THREADS
+            do {
+                Py_BEGIN_ALLOW_THREADS
 #ifdef MS_WINDOWS
-            if (widename != NULL)
-                self->fd = _wopen(widename, flags, 0666);
-            else
+                if (widename != NULL)
+                    self->fd = _wopen(widename, flags, 0666);
+                else
 #endif
-                self->fd = open(name, flags, 0666);
+                    self->fd = open(name, flags, 0666);
+                Py_END_ALLOW_THREADS
+            } while (self->fd < 0 && errno == EINTR &&
+                     !(async_err = PyErr_CheckSignals()));
 
-            Py_END_ALLOW_THREADS
+            if (async_err)
+                goto error;
         }
         else {
             PyObject *fdobj;
@@ -428,8 +397,24 @@ fileio_init(PyObject *oself, PyObject *args, PyObject *kwds)
             goto error;
 #endif
     }
-    if (dircheck(self, nameobj) < 0)
+
+    self->blksize = DEFAULT_BUFFER_SIZE;
+    if (_Py_fstat(self->fd, &fdfstat) < 0)
+        goto error;
+#if defined(S_ISDIR) && defined(EISDIR)
+    /* On Unix, open will succeed for directories.
+       In Python, there should be no file objects referring to
+       directories, so we need a check.  */
+    if (S_ISDIR(fdfstat.st_mode)) {
+        errno = EISDIR;
+        PyErr_SetFromErrnoWithFilenameObject(PyExc_IOError, nameobj);
         goto error;
+    }
+#endif /* defined(S_ISDIR) */
+#ifdef HAVE_STRUCT_STAT_ST_BLKSIZE
+    if (fdfstat.st_blksize > 1)
+        self->blksize = fdfstat.st_blksize;
+#endif /* HAVE_STRUCT_STAT_ST_BLKSIZE */
 
 #if defined(MS_WINDOWS) || defined(__CYGWIN__)
     /* don't translate newlines (\r\n <=> \n) */
@@ -553,7 +538,7 @@ static PyObject *
 fileio_readinto(fileio *self, PyObject *args)
 {
     Py_buffer pbuf;
-    Py_ssize_t n, len;
+    Py_ssize_t n;
     int err;
 
     if (self->fd < 0)
@@ -564,45 +549,22 @@ fileio_readinto(fileio *self, PyObject *args)
     if (!PyArg_ParseTuple(args, "w*", &pbuf))
         return NULL;
 
-    if (_PyVerify_fd(self->fd)) {
-        len = pbuf.len;
-        Py_BEGIN_ALLOW_THREADS
-        errno = 0;
-#ifdef MS_WINDOWS
-        if (len > INT_MAX)
-            len = INT_MAX;
-        n = read(self->fd, pbuf.buf, (int)len);
-#else
-        n = read(self->fd, pbuf.buf, len);
-#endif
-        Py_END_ALLOW_THREADS
-    } else
-        n = -1;
+    n = _Py_read(self->fd, pbuf.buf, pbuf.len);
+    /* copy errno because PyBuffer_Release() can indirectly modify it */
     err = errno;
     PyBuffer_Release(&pbuf);
-    if (n < 0) {
-        if (err == EAGAIN)
+
+    if (n == -1) {
+        if (err == EAGAIN) {
+            PyErr_Clear();
             Py_RETURN_NONE;
-        errno = err;
-        PyErr_SetFromErrno(PyExc_IOError);
+        }
         return NULL;
     }
 
     return PyLong_FromSsize_t(n);
 }
 
-#ifndef HAVE_FSTAT
-
-static PyObject *
-fileio_readall(fileio *self)
-{
-    _Py_IDENTIFIER(readall);
-    return _PyObject_CallMethodId((PyObject*)&PyRawIOBase_Type,
-                                  &PyId_readall, "O", self);
-}
-
-#else
-
 static size_t
 new_buffersize(fileio *self, size_t currentsize)
 {
@@ -625,7 +587,7 @@ new_buffersize(fileio *self, size_t currentsize)
 static PyObject *
 fileio_readall(fileio *self)
 {
-    struct stat st;
+    struct _Py_stat_struct status;
     Py_off_t pos, end;
     PyObject *result;
     Py_ssize_t bytes_read = 0;
@@ -642,8 +604,8 @@ fileio_readall(fileio *self)
 #else
     pos = lseek(self->fd, 0L, SEEK_CUR);
 #endif
-    if (fstat(self->fd, &st) == 0)
-        end = st.st_size;
+    if (_Py_fstat_noraise(self->fd, &status) == 0)
+        end = status.st_size;
     else
         end = (Py_off_t)-1;
 
@@ -677,35 +639,22 @@ fileio_readall(fileio *self)
                     return NULL;
             }
         }
-        Py_BEGIN_ALLOW_THREADS
-        errno = 0;
-        n = bufsize - bytes_read;
-#ifdef MS_WINDOWS
-        if (n > INT_MAX)
-            n = INT_MAX;
-        n = read(self->fd, PyBytes_AS_STRING(result) + bytes_read, (int)n);
-#else
-        n = read(self->fd, PyBytes_AS_STRING(result) + bytes_read, n);
-#endif
-        Py_END_ALLOW_THREADS
+
+        n = _Py_read(self->fd,
+                     PyBytes_AS_STRING(result) + bytes_read,
+                     bufsize - bytes_read);
+
         if (n == 0)
             break;
-        if (n < 0) {
-            if (errno == EINTR) {
-                if (PyErr_CheckSignals()) {
-                    Py_DECREF(result);
-                    return NULL;
-                }
-                continue;
-            }
+        if (n == -1) {
             if (errno == EAGAIN) {
+                PyErr_Clear();
                 if (bytes_read > 0)
                     break;
                 Py_DECREF(result);
                 Py_RETURN_NONE;
             }
             Py_DECREF(result);
-            PyErr_SetFromErrno(PyExc_IOError);
             return NULL;
         }
         bytes_read += n;
@@ -719,8 +668,6 @@ fileio_readall(fileio *self)
     return result;
 }
 
-#endif /* HAVE_FSTAT */
-
 static PyObject *
 fileio_read(fileio *self, PyObject *args)
 {
@@ -737,38 +684,29 @@ fileio_read(fileio *self, PyObject *args)
     if (!PyArg_ParseTuple(args, "|O&", &_PyIO_ConvertSsize_t, &size))
         return NULL;
 
-    if (size < 0) {
+    if (size < 0)
         return fileio_readall(self);
-    }
 
 #ifdef MS_WINDOWS
+    /* On Windows, the count parameter of read() is an int */
     if (size > INT_MAX)
         size = INT_MAX;
 #endif
+
     bytes = PyBytes_FromStringAndSize(NULL, size);
     if (bytes == NULL)
         return NULL;
     ptr = PyBytes_AS_STRING(bytes);
 
-    if (_PyVerify_fd(self->fd)) {
-        Py_BEGIN_ALLOW_THREADS
-        errno = 0;
-#ifdef MS_WINDOWS
-        n = read(self->fd, ptr, (int)size);
-#else
-        n = read(self->fd, ptr, size);
-#endif
-        Py_END_ALLOW_THREADS
-    } else
-        n = -1;
-
-    if (n < 0) {
+    n = _Py_read(self->fd, ptr, size);
+    if (n == -1) {
+        /* copy errno because Py_DECREF() can indirectly modify it */
         int err = errno;
         Py_DECREF(bytes);
-        if (err == EAGAIN)
+        if (err == EAGAIN) {
+            PyErr_Clear();
             Py_RETURN_NONE;
-        errno = err;
-        PyErr_SetFromErrno(PyExc_IOError);
+        }
         return NULL;
     }
 
@@ -786,7 +724,7 @@ static PyObject *
 fileio_write(fileio *self, PyObject *args)
 {
     Py_buffer pbuf;
-    Py_ssize_t n, len;
+    Py_ssize_t n;
     int err;
 
     if (self->fd < 0)
@@ -797,36 +735,16 @@ fileio_write(fileio *self, PyObject *args)
     if (!PyArg_ParseTuple(args, "y*", &pbuf))
         return NULL;
 
-    if (_PyVerify_fd(self->fd)) {
-        Py_BEGIN_ALLOW_THREADS
-        errno = 0;
-        len = pbuf.len;
-#ifdef MS_WINDOWS
-        if (len > 32767 && isatty(self->fd)) {
-            /* Issue #11395: the Windows console returns an error (12: not
-               enough space error) on writing into stdout if stdout mode is
-               binary and the length is greater than 66,000 bytes (or less,
-               depending on heap usage). */
-            len = 32767;
-        }
-        else if (len > INT_MAX)
-            len = INT_MAX;
-        n = write(self->fd, pbuf.buf, (int)len);
-#else
-        n = write(self->fd, pbuf.buf, len);
-#endif
-        Py_END_ALLOW_THREADS
-    } else
-        n = -1;
+    n = _Py_write(self->fd, pbuf.buf, pbuf.len);
+    /* copy errno because PyBuffer_Release() can indirectly modify it */
     err = errno;
-
     PyBuffer_Release(&pbuf);
 
     if (n < 0) {
-        if (err == EAGAIN)
+        if (err == EAGAIN) {
+            PyErr_Clear();
             Py_RETURN_NONE;
-        errno = err;
-        PyErr_SetFromErrno(PyExc_IOError);
+        }
         return NULL;
     }
 
@@ -1058,12 +976,14 @@ fileio_repr(fileio *self)
             PyErr_Clear();
         else
             return NULL;
-        res = PyUnicode_FromFormat("<_io.FileIO fd=%d mode='%s'>",
-                                   self->fd, mode_string(self));
+        res = PyUnicode_FromFormat(
+            "<_io.FileIO fd=%d mode='%s' closefd=%s>",
+            self->fd, mode_string(self), self->closefd ? "True" : "False");
     }
     else {
-        res = PyUnicode_FromFormat("<_io.FileIO name=%R mode='%s'>",
-                                   nameobj, mode_string(self));
+        res = PyUnicode_FromFormat(
+            "<_io.FileIO name=%R mode='%s' closefd=%s>",
+            nameobj, mode_string(self), self->closefd ? "True" : "False");
         Py_DECREF(nameobj);
     }
     return res;
@@ -1225,6 +1145,7 @@ static PyGetSetDef fileio_getsetlist[] = {
 };
 
 static PyMemberDef fileio_members[] = {
+    {"_blksize", T_UINT, offsetof(fileio, blksize), 0},
     {"_finalizing", T_BOOL, offsetof(fileio, finalizing), 0},
     {NULL}
 };
diff --git a/Modules/_io/textio.c b/Modules/_io/textio.c
index d1c0d01232..af232bf6ed 100644
--- a/Modules/_io/textio.c
+++ b/Modules/_io/textio.c
@@ -224,8 +224,8 @@ typedef struct {
     PyObject_HEAD
     PyObject *decoder;
     PyObject *errors;
-    signed int pendingcr: 1;
-    signed int translate: 1;
+    unsigned int pendingcr: 1;
+    unsigned int translate: 1;
     unsigned int seennl: 3;
 } nldecoder_object;
 
@@ -546,7 +546,7 @@ incrementalnewlinedecoder_setstate(nldecoder_object *self, PyObject *state)
     if (!PyArg_Parse(state, "(OK)", &buffer, &flag))
         return NULL;
 
-    self->pendingcr = (int) flag & 1;
+    self->pendingcr = (int) (flag & 1);
     flag >>= 1;
 
     if (self->decoder != Py_None)
@@ -1441,6 +1441,7 @@ textiowrapper_read_chunk(textio *self, Py_ssize_t size_hint)
     PyObject *dec_buffer = NULL;
     PyObject *dec_flags = NULL;
     PyObject *input_chunk = NULL;
+    Py_buffer input_chunk_buf;
     PyObject *decoded_chars, *chunk_size;
     Py_ssize_t nbytes, nchars;
     int eof;
@@ -1472,6 +1473,15 @@ textiowrapper_read_chunk(textio *self, Py_ssize_t size_hint)
             Py_DECREF(state);
             return -1;
         }
+
+        if (!PyBytes_Check(dec_buffer)) {
+            PyErr_Format(PyExc_TypeError,
+                         "decoder getstate() should have returned a bytes "
+                         "object, not '%.200s'",
+                         Py_TYPE(dec_buffer)->tp_name);
+            Py_DECREF(state);
+            return -1;
+        }
         Py_INCREF(dec_buffer);
         Py_INCREF(dec_flags);
         Py_DECREF(state);
@@ -1484,23 +1494,24 @@ textiowrapper_read_chunk(textio *self, Py_ssize_t size_hint)
     chunk_size = PyLong_FromSsize_t(Py_MAX(self->chunk_size, size_hint));
     if (chunk_size == NULL)
         goto fail;
+
     input_chunk = PyObject_CallMethodObjArgs(self->buffer,
         (self->has_read1 ? _PyIO_str_read1: _PyIO_str_read),
         chunk_size, NULL);
     Py_DECREF(chunk_size);
     if (input_chunk == NULL)
         goto fail;
-    if (!PyBytes_Check(input_chunk)) {
+
+    if (PyObject_GetBuffer(input_chunk, &input_chunk_buf, 0) != 0) {
         PyErr_Format(PyExc_TypeError,
-                     "underlying %s() should have returned a bytes object, "
+                     "underlying %s() should have returned a bytes-like object, "
                      "not '%.200s'", (self->has_read1 ? "read1": "read"),
                      Py_TYPE(input_chunk)->tp_name);
         goto fail;
     }
 
-    nbytes = PyBytes_Size(input_chunk);
+    nbytes = input_chunk_buf.len;
     eof = (nbytes == 0);
-
     if (Py_TYPE(self->decoder) == &PyIncrementalNewlineDecoder_Type) {
         decoded_chars = _PyIncrementalNewlineDecoder_decode(
             self->decoder, input_chunk, eof);
@@ -1509,6 +1520,7 @@ textiowrapper_read_chunk(textio *self, Py_ssize_t size_hint)
         decoded_chars = PyObject_CallMethodObjArgs(self->decoder,
             _PyIO_str_decode, input_chunk, eof ? Py_True : Py_False, NULL);
     }
+    PyBuffer_Release(&input_chunk_buf);
 
     if (check_decoded(decoded_chars) < 0)
         goto fail;
@@ -1525,18 +1537,12 @@ textiowrapper_read_chunk(textio *self, Py_ssize_t size_hint)
         /* At the snapshot point, len(dec_buffer) bytes before the read, the
          * next input to be decoded is dec_buffer + input_chunk.
          */
-        PyObject *next_input = PyNumber_Add(dec_buffer, input_chunk);
-        if (next_input == NULL)
-            goto fail;
-        if (!PyBytes_Check(next_input)) {
-            PyErr_Format(PyExc_TypeError,
-                         "decoder getstate() should have returned a bytes "
-                         "object, not '%.200s'",
-                         Py_TYPE(next_input)->tp_name);
-            Py_DECREF(next_input);
+        PyObject *next_input = dec_buffer;
+        PyBytes_Concat(&next_input, input_chunk);
+        if (next_input == NULL) {
+            dec_buffer = NULL; /* Reference lost to PyBytes_Concat */
             goto fail;
         }
-        Py_DECREF(dec_buffer);
         Py_CLEAR(self->snapshot);
         self->snapshot = Py_BuildValue("NN", dec_flags, next_input);
     }
@@ -1725,7 +1731,7 @@ _PyIO_find_line_ending(
     else {
         /* Non-universal mode. */
         Py_ssize_t readnl_len = PyUnicode_GET_LENGTH(readnl);
-        char *nl = PyUnicode_DATA(readnl);
+        Py_UCS1 *nl = PyUnicode_1BYTE_DATA(readnl);
         /* Assume that readnl is an ASCII character. */
         assert(PyUnicode_KIND(readnl) == PyUnicode_1BYTE_KIND);
         if (readnl_len == 1) {