BufferedWriter() was buffering calls that are the exact same size as the buffer. it's a very common case to read/write in blocks of the exact buffer size.
it's pointless to copy a full buffer, it's costing extra memory copy and the full buffer will have to be written in the next call anyway.
Co-authored-by: rmorotti <romain.morotti@man.com>
lseek() always returns 0 for character pseudo-devices like
`/dev/urandom` (for other non-regular files, e.g. `/dev/stdin`, it
always returns -1, to which CPython reacts by raising appropriate
exceptions). They are thus technically seekable despite not having seek
semantics.
When calling read() on e.g. an instance of `io.BufferedReader` that
wraps such a file, `BufferedReader` reads ahead, filling its buffer,
creating a discrepancy between the number of bytes read and the internal
`tell()` always returning 0, which previously resulted in e.g.
`BufferedReader.tell()` or `BufferedReader.seek()` being able to return
positions < 0 even though these are supposed to be always >= 0.
Invariably keep the return value non-negative by returning
max(former_return_value, 0) instead, and add some corresponding tests.
The `@critical_section` directive instructs Argument Clinic to generate calls
to `Py_BEGIN_CRITICAL_SECTION()` and `Py_END_CRITICAL_SECTION()` around the
bound function. In `--disable-gil` builds, these calls will lock and unlock
the `self` object. They are no-ops in the default build.
This is used in one place (`_io._Buffered.close`) as a demonstration.
Subsequent PRs will use it more widely in the `_io.Buffered` bindings.
Move private _PyBytes functions to the internal C API
(pycore_bytesobject.h):
* _PyBytes_DecodeEscape()
* _PyBytes_FormatEx()
* _PyBytes_FromHex()
* _PyBytes_Join()
No longer export these functions.
Remove private pylifecycle.h functions: move them to the internal C
API ( pycore_atexit.h, pycore_pylifecycle.h and pycore_signal.h). No
longer export most of these functions.
Move _testcapi.test_atexit() to _testinternalcapi.
When preparing the _io extension module for isolation, many methods were
adapted to Argument Clinic. Some of these used the '*args: object'
signature, which is incorrect. These are now corrected to an exact
signature, and marked unused, since they are stub methods.
- Replace query with parameter in bufferediobase_unsupported()
- Replace query with parameter in iobase_unsupported()
- Hide delegate: Add method wrapper for _PyIOBase_check_seekable
- Hide delegate: Add method wraper for _PyIOBase_check_readable
- Hide delegate: Add method wraper for _PyIOBase_check_writable
- Replace query with parameter in _PyIOBase_check_seekable()
- Replace query with parameter in _PyIOBase_check_readable()
- Replace query with parameter in _PyIOBase_check_writable()
The implementation of __sizeof__() methods using _PyObject_SIZE() now
use an unsigned type (size_t) to compute the size, rather than a signed
type (Py_ssize_t).
Cast explicitly signed (Py_ssize_t) values to unsigned type
(Py_ssize_t).
We're no longer using _Py_IDENTIFIER() (or _Py_static_string()) in any core CPython code. It is still used in a number of non-builtin stdlib modules.
The replacement is: PyUnicodeObject (not pointer) fields under _PyRuntimeState, statically initialized as part of _PyRuntime. A new _Py_GET_GLOBAL_IDENTIFIER() macro facilitates lookup of the fields (along with _Py_GET_GLOBAL_STRING() for non-identifier strings).
https://bugs.python.org/issue46541#msg411799 explains the rationale for this change.
The core of the change is in:
* (new) Include/internal/pycore_global_strings.h - the declarations for the global strings, along with the macros
* Include/internal/pycore_runtime_init.h - added the static initializers for the global strings
* Include/internal/pycore_global_objects.h - where the struct in pycore_global_strings.h is hooked into _PyRuntimeState
* Tools/scripts/generate_global_objects.py - added generation of the global string declarations and static initializers
I've also added a --check flag to generate_global_objects.py (along with make check-global-objects) to check for unused global strings. That check is added to the PR CI config.
The remainder of this change updates the core code to use _Py_GET_GLOBAL_IDENTIFIER() instead of _Py_IDENTIFIER() and the related _Py*Id functions (likewise for _Py_GET_GLOBAL_STRING() instead of _Py_static_string()). This includes adding a few functions where there wasn't already an alternative to _Py*Id(), replacing the _Py_Identifier * parameter with PyObject *.
The following are not changed (yet):
* stop using _Py_IDENTIFIER() in the stdlib modules
* (maybe) get rid of _Py_IDENTIFIER(), etc. entirely -- this may not be doable as at least one package on PyPI using this (private) API
* (maybe) intern the strings during runtime init
https://bugs.python.org/issue46541
* Move _PyObject_CallNoArgs() to pycore_call.h (internal C API).
* _ssl, _sqlite and _testcapi extensions now call the public
PyObject_CallNoArgs() function, rather than _PyObject_CallNoArgs().
* _lsprof extension is now built with Py_BUILD_CORE_MODULE macro
defined to get access to internal _PyObject_CallNoArgs().
Fix typo in the private _PyObject_CallNoArg() function name: rename
it to _PyObject_CallNoArgs() to be consistent with the public
function PyObject_CallNoArgs().
The truncate() method of io.BufferedReader() should raise
UnsupportedOperation when it is called on a read-only
io.BufferedReader() instance.
https://bugs.python.org/issue35950
Automerge-Triggered-By: @methane
The bulk of this patch was generated automatically with:
for name in \
PyObject_Vectorcall \
Py_TPFLAGS_HAVE_VECTORCALL \
PyObject_VectorcallMethod \
PyVectorcall_Function \
PyObject_CallOneArg \
PyObject_CallMethodNoArgs \
PyObject_CallMethodOneArg \
;
do
echo $name
git grep -lwz _$name | xargs -0 sed -i "s/\b_$name\b/$name/g"
done
old=_PyObject_FastCallDict
new=PyObject_VectorcallDict
git grep -lwz $old | xargs -0 sed -i "s/\b$old\b/$new/g"
and then cleaned up:
- Revert changes to in docs & news
- Revert changes to backcompat defines in headers
- Nudge misaligned comments
When called on a closed object, readinto() segfaults on account
of a write to a freed buffer:
==220553== Process terminating with default action of signal 11 (SIGSEGV): dumping core
==220553== Access not within mapped region at address 0x2A
==220553== at 0x48408A0: memmove (vg_replace_strmem.c:1272)
==220553== by 0x58DB0C: _buffered_readinto_generic (bufferedio.c:972)
==220553== by 0x58DCBA: _io__Buffered_readinto_impl (bufferedio.c:1053)
==220553== by 0x58DCBA: _io__Buffered_readinto (bufferedio.c.h:253)
Reproducer:
reader = open ("/dev/zero", "rb")
_void = reader.read (42)
reader.close ()
reader.readinto (bytearray (42)) ### BANG!
The problem exists since 2012 when commit dc469454ec added code
to free the read buffer on close().
Signed-off-by: Philipp Gesang <philipp.gesang@intra2net.com>
Victor Stinner
Marc Mueller
morotti
Serhiy Storchaka
6t8k
Donghee Na
Mayuresh Kedari
Sam Gross
Inada Naoki
Kumar Aditya
Eric Snow
Erlend E. Aasland
JosephSBoyle
Irit Katriel
Christian Heimes
Benjamin Peterson
AngstyDuck
David Szotten
Andy Lester
Berker Peksag
Petr Viktorin
Philipp Gesang