Merge branch 'main' into fix/129640

Author: Mr-Sunglasses

Doc/library/functions.rst

@@ -1405,10 +1405,10 @@ are always available.  They are listed here in alphabetical order.
    :func:`io.TextIOWrapper.reconfigure`. When no *buffering* argument is
    given, the default buffering policy works as follows:
 
-   * Binary files are buffered in fixed-size chunks; the size of the buffer is
-     chosen using a heuristic trying to determine the underlying device's "block
-     size" and falling back on :const:`io.DEFAULT_BUFFER_SIZE`.  On many systems,
-     the buffer will typically be 4096 or 8192 bytes long.
+   * Binary files are buffered in fixed-size chunks; the size of the buffer
+     is ``max(min(blocksize, 8 MiB), DEFAULT_BUFFER_SIZE)``
+     when the device block size is available.
+     On most systems, the buffer will typically be 128 kilobytes long.
 
    * "Interactive" text files (files for which :meth:`~io.IOBase.isatty`
      returns ``True``) use line buffering.  Other text files use the policy

Lib/_pyio.py

@@ -23,8 +23,9 @@
     valid_seek_flags.add(os.SEEK_HOLE)
     valid_seek_flags.add(os.SEEK_DATA)
 
-# open() uses st_blksize whenever we can
-DEFAULT_BUFFER_SIZE = 8 * 1024  # bytes
+# open() uses max(min(blocksize, 8 MiB), DEFAULT_BUFFER_SIZE)
+# when the device block size is available.
+DEFAULT_BUFFER_SIZE = 128 * 1024  # bytes
 
 # NOTE: Base classes defined here are registered with the "official" ABCs
 # defined in io.py. We don't use real inheritance though, because we don't want
@@ -123,10 +124,10 @@ def open(file, mode="r", buffering=-1, encoding=None, errors=None,
     the size of a fixed-size chunk buffer.  When no buffering argument is
     given, the default buffering policy works as follows:
 
-    * Binary files are buffered in fixed-size chunks; the size of the buffer
-      is chosen using a heuristic trying to determine the underlying device's
-      "block size" and falling back on `io.DEFAULT_BUFFER_SIZE`.
-      On many systems, the buffer will typically be 4096 or 8192 bytes long.
+   * Binary files are buffered in fixed-size chunks; the size of the buffer
+     is max(min(blocksize, 8 MiB), DEFAULT_BUFFER_SIZE)
+     when the device block size is available.
+     On most systems, the buffer will typically be 128 kilobytes long.
 
     * "Interactive" text files (files for which isatty() returns True)
       use line buffering.  Other text files use the policy described above
@@ -242,7 +243,7 @@ def open(file, mode="r", buffering=-1, encoding=None, errors=None,
             buffering = -1
             line_buffering = True
         if buffering < 0:
-            buffering = raw._blksize
+            buffering = max(min(raw._blksize, 8192 * 1024), DEFAULT_BUFFER_SIZE)
         if buffering < 0:
             raise ValueError("invalid buffering size")
         if buffering == 0:

Lib/gzip.py

@@ -325,31 +325,41 @@ def _write_raw(self, data):
 
         return length
 
-    def read(self, size=-1):
-        self._check_not_closed()
+    def _check_read(self, caller):
         if self.mode != READ:
             import errno
-            raise OSError(errno.EBADF, "read() on write-only GzipFile object")
+            msg = f"{caller}() on write-only GzipFile object"
+            raise OSError(errno.EBADF, msg)
+
+    def read(self, size=-1):
+        self._check_not_closed()
+        self._check_read("read")
         return self._buffer.read(size)
 
     def read1(self, size=-1):
         """Implements BufferedIOBase.read1()
 
         Reads up to a buffer's worth of data if size is negative."""
         self._check_not_closed()
-        if self.mode != READ:
-            import errno
-            raise OSError(errno.EBADF, "read1() on write-only GzipFile object")
+        self._check_read("read1")
 
         if size < 0:
             size = io.DEFAULT_BUFFER_SIZE
         return self._buffer.read1(size)
 
+    def readinto(self, b):
+        self._check_not_closed()
+        self._check_read("readinto")
+        return self._buffer.readinto(b)
+
+    def readinto1(self, b):
+        self._check_not_closed()
+        self._check_read("readinto1")
+        return self._buffer.readinto1(b)
+
     def peek(self, n):
         self._check_not_closed()
-        if self.mode != READ:
-            import errno
-            raise OSError(errno.EBADF, "peek() on write-only GzipFile object")
+        self._check_read("peek")
         return self._buffer.peek(n)
 
     @property