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| author | Cody Maloney <cmaloney@users.noreply.github.com> | 2024-10-08 06:50:42 (GMT) |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2024-10-08 06:50:42 (GMT) |
| commit | cc9b9bebb2c09c475cb0f278268cce03c115eaea (patch) | |
| tree | 0eef6d302bcf6922b4664e1feb3e4aa41161c8b5 /Modules/_io/fileio.c | |
| parent | 6e3c70c61bf961e55e9912a31ca11f61c8e2cd0c (diff) | |
| download | cpython-cc9b9bebb2c09c475cb0f278268cce03c115eaea.zip cpython-cc9b9bebb2c09c475cb0f278268cce03c115eaea.tar.gz cpython-cc9b9bebb2c09c475cb0f278268cce03c115eaea.tar.bz2 | |
gh-90102: Remove isatty call during regular open (#124922)
Co-authored-by: Victor Stinner <vstinner@python.org>
Diffstat (limited to 'Modules/_io/fileio.c')
| -rw-r--r-- | Modules/_io/fileio.c | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c index d9597f8..f374592 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}, |