https://github.com/python/cpython/commit/cc9b9bebb2c09c475cb0f278268cce03c115eaea commit: cc9b9bebb2c09c475cb0f278268cce03c115eaea branch: main author: Cody Maloney <[email protected]> committer: vstinner <[email protected]> date: 2024-10-08T08:50:42+02:00 summary:
gh-90102: Remove isatty call during regular open (#124922) Co-authored-by: Victor Stinner <[email protected]> files: A Misc/NEWS.d/next/Library/2024-10-02-22-53-48.gh-issue-90102.4qX52R.rst M Include/internal/pycore_global_objects_fini_generated.h M Include/internal/pycore_global_strings.h M Include/internal/pycore_runtime_init_generated.h M Include/internal/pycore_unicodeobject_generated.h M Lib/_pyio.py M Modules/_io/_iomodule.c M Modules/_io/fileio.c M Modules/_io/winconsoleio.c diff --git a/Include/internal/pycore_global_objects_fini_generated.h b/Include/internal/pycore_global_objects_fini_generated.h index 28a76c36801b4b..3140a75a47c5ee 100644 --- a/Include/internal/pycore_global_objects_fini_generated.h +++ b/Include/internal/pycore_global_objects_fini_generated.h @@ -757,6 +757,7 @@ _PyStaticObjects_CheckRefcnt(PyInterpreterState *interp) { _PyStaticObject_CheckRefcnt((PyObject *)&_Py_ID(_initializing)); _PyStaticObject_CheckRefcnt((PyObject *)&_Py_ID(_io)); _PyStaticObject_CheckRefcnt((PyObject *)&_Py_ID(_is_text_encoding)); + _PyStaticObject_CheckRefcnt((PyObject *)&_Py_ID(_isatty_open_only)); _PyStaticObject_CheckRefcnt((PyObject *)&_Py_ID(_length_)); _PyStaticObject_CheckRefcnt((PyObject *)&_Py_ID(_limbo)); _PyStaticObject_CheckRefcnt((PyObject *)&_Py_ID(_lock_unlock_module)); diff --git a/Include/internal/pycore_global_strings.h b/Include/internal/pycore_global_strings.h index ac789b06fb8a61..1591cb0a3f114f 100644 --- a/Include/internal/pycore_global_strings.h +++ b/Include/internal/pycore_global_strings.h @@ -246,6 +246,7 @@ struct _Py_global_strings { STRUCT_FOR_ID(_initializing) STRUCT_FOR_ID(_io) STRUCT_FOR_ID(_is_text_encoding) + STRUCT_FOR_ID(_isatty_open_only) STRUCT_FOR_ID(_length_) STRUCT_FOR_ID(_limbo) STRUCT_FOR_ID(_lock_unlock_module) diff --git a/Include/internal/pycore_runtime_init_generated.h b/Include/internal/pycore_runtime_init_generated.h index 7847a5c63ebf3f..c9d20d0b5aacdb 100644 --- a/Include/internal/pycore_runtime_init_generated.h +++ b/Include/internal/pycore_runtime_init_generated.h @@ -755,6 +755,7 @@ extern "C" { INIT_ID(_initializing), \ INIT_ID(_io), \ INIT_ID(_is_text_encoding), \ + INIT_ID(_isatty_open_only), \ INIT_ID(_length_), \ INIT_ID(_limbo), \ INIT_ID(_lock_unlock_module), \ diff --git a/Include/internal/pycore_unicodeobject_generated.h b/Include/internal/pycore_unicodeobject_generated.h index a688f70a2ba36f..d335373e88ee74 100644 --- a/Include/internal/pycore_unicodeobject_generated.h +++ b/Include/internal/pycore_unicodeobject_generated.h @@ -784,6 +784,10 @@ _PyUnicode_InitStaticStrings(PyInterpreterState *interp) { _PyUnicode_InternStatic(interp, &string); assert(_PyUnicode_CheckConsistency(string, 1)); assert(PyUnicode_GET_LENGTH(string) != 1); + string = &_Py_ID(_isatty_open_only); + _PyUnicode_InternStatic(interp, &string); + assert(_PyUnicode_CheckConsistency(string, 1)); + assert(PyUnicode_GET_LENGTH(string) != 1); string = &_Py_ID(_length_); _PyUnicode_InternStatic(interp, &string); assert(_PyUnicode_CheckConsistency(string, 1)); diff --git a/Lib/_pyio.py b/Lib/_pyio.py index 18849b309b8605..2a1d2a33d02960 100644 --- a/Lib/_pyio.py +++ b/Lib/_pyio.py @@ -238,7 +238,7 @@ def open(file, mode="r", buffering=-1, encoding=None, errors=None, result = raw try: line_buffering = False - if buffering == 1 or buffering < 0 and raw.isatty(): + if buffering == 1 or buffering < 0 and raw._isatty_open_only(): buffering = -1 line_buffering = True if buffering < 0: @@ -1794,6 +1794,21 @@ def isatty(self): self._checkClosed() return os.isatty(self._fd) + def _isatty_open_only(self): + """Checks whether the file is a TTY using an open-only optimization. + + TTYs are always character devices. If the interpreter knows a file is + not a character device when it would call ``isatty``, can skip that + call. Inside ``open()`` there is a fresh stat result that contains that + information. Use the stat result to skip a system call. Outside of that + context TOCTOU issues (the fd could be arbitrarily modified by + surrounding code). + """ + if (self._stat_atopen is not None + and not stat.S_ISCHR(self._stat_atopen.st_mode)): + return True + return os.isatty(self._fd) + @property def closefd(self): """True if the file descriptor will be closed by close().""" diff --git a/Misc/NEWS.d/next/Library/2024-10-02-22-53-48.gh-issue-90102.4qX52R.rst b/Misc/NEWS.d/next/Library/2024-10-02-22-53-48.gh-issue-90102.4qX52R.rst new file mode 100644 index 00000000000000..0e708ed11d21b5 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2024-10-02-22-53-48.gh-issue-90102.4qX52R.rst @@ -0,0 +1,3 @@ +Skip the ``isatty`` system call during open() when the file is known to not +be a character device. This provides a slight performance improvement when +reading whole files. diff --git a/Modules/_io/_iomodule.c b/Modules/_io/_iomodule.c index 1238e6074246d0..6622f2cabb908b 100644 --- a/Modules/_io/_iomodule.c +++ b/Modules/_io/_iomodule.c @@ -346,7 +346,7 @@ _io_open_impl(PyObject *module, PyObject *file, const char *mode, /* buffering */ if (buffering < 0) { - PyObject *res = PyObject_CallMethodNoArgs(raw, &_Py_ID(isatty)); + PyObject *res = PyObject_CallMethodNoArgs(raw, &_Py_ID(_isatty_open_only)); if (res == NULL) goto error; isatty = PyObject_IsTrue(res); diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c index d9597f860b9429..f374592eb95967 100644 --- a/Modules/_io/fileio.c +++ b/Modules/_io/fileio.c @@ -12,9 +12,6 @@ #ifdef HAVE_SYS_TYPES_H # include <sys/types.h> #endif -#ifdef HAVE_SYS_STAT_H -# include <sys/stat.h> -#endif #ifdef HAVE_IO_H # include <io.h> #endif @@ -1218,6 +1215,24 @@ _io_FileIO_isatty_impl(fileio *self) return PyBool_FromLong(res); } +/* Checks whether the file is a TTY using an open-only optimization. + + TTYs are always character devices. If the interpreter knows a file is + not a character device when it would call ``isatty``, can skip that + call. Inside ``open()`` there is a fresh stat result that contains that + information. Use the stat result to skip a system call. Outside of that + context TOCTOU issues (the fd could be arbitrarily modified by + surrounding code). */ +static PyObject * +_io_FileIO_isatty_open_only(PyObject *op, PyObject *Py_UNUSED(ignored)) +{ + fileio *self = _PyFileIO_CAST(op); + if (self->stat_atopen != NULL && !S_ISCHR(self->stat_atopen->st_mode)) { + Py_RETURN_FALSE; + } + return _io_FileIO_isatty_impl(self); +} + #include "clinic/fileio.c.h" static PyMethodDef fileio_methods[] = { @@ -1234,6 +1249,7 @@ static PyMethodDef fileio_methods[] = { _IO_FILEIO_WRITABLE_METHODDEF _IO_FILEIO_FILENO_METHODDEF _IO_FILEIO_ISATTY_METHODDEF + {"_isatty_open_only", _io_FileIO_isatty_open_only, METH_NOARGS}, {"_dealloc_warn", fileio_dealloc_warn, METH_O, NULL}, {"__reduce__", _PyIOBase_cannot_pickle, METH_NOARGS}, {"__reduce_ex__", _PyIOBase_cannot_pickle, METH_O}, diff --git a/Modules/_io/winconsoleio.c b/Modules/_io/winconsoleio.c index ec5c298066a587..d7cb5abfdc0abd 100644 --- a/Modules/_io/winconsoleio.c +++ b/Modules/_io/winconsoleio.c @@ -1128,6 +1128,7 @@ static PyMethodDef winconsoleio_methods[] = { _IO__WINDOWSCONSOLEIO_WRITABLE_METHODDEF _IO__WINDOWSCONSOLEIO_FILENO_METHODDEF _IO__WINDOWSCONSOLEIO_ISATTY_METHODDEF + {"_isatty_open_only", (PyCFunction)_io__WindowsConsoleIO_isatty, METH_NOARGS}, {NULL, NULL} /* sentinel */ }; _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3/lists/python-checkins.python.org/ Member address: [email protected]
