From 357bed0bcd3c5d7c4a8caad451754a9a172aca3e Mon Sep 17 00:00:00 2001 From: Brandt Bucher Date: Mon, 22 May 2023 12:34:34 -0700 Subject: [PATCH] GH-104668: Don't call PyOS_* hooks in subinterpreters (GH-104674) --- Doc/c-api/veryhigh.rst | 8 +++++ Doc/whatsnew/3.12.rst | 9 ++++++ ...-05-19-10-22-34.gh-issue-104668.MLX1g9.rst | 5 +++ Parser/myreadline.c | 32 +++++++++++++++---- 4 files changed, 47 insertions(+), 7 deletions(-) create mode 100644 Misc/NEWS.d/next/C API/2023-05-19-10-22-34.gh-issue-104668.MLX1g9.rst diff --git a/Doc/c-api/veryhigh.rst b/Doc/c-api/veryhigh.rst index 513856d8a48..000a2d3d879 100644 --- a/Doc/c-api/veryhigh.rst +++ b/Doc/c-api/veryhigh.rst @@ -167,6 +167,10 @@ the same library that the Python runtime is using. event loops, as done in the :file:`Modules/_tkinter.c` in the Python source code. + .. versionchanged:: 3.12 + This function is only called from the + :ref:`main interpreter `. + .. c:var:: char* (*PyOS_ReadlineFunctionPointer)(FILE *, FILE *, const char *) @@ -187,6 +191,10 @@ the same library that the Python runtime is using. :c:func:`PyMem_RawRealloc`, instead of being allocated by :c:func:`PyMem_Malloc` or :c:func:`PyMem_Realloc`. + .. versionchanged:: 3.12 + This function is only called from the + :ref:`main interpreter `. + .. c:function:: PyObject* PyRun_String(const char *str, int start, PyObject *globals, PyObject *locals) This is a simplified interface to :c:func:`PyRun_StringFlags` below, leaving diff --git a/Doc/whatsnew/3.12.rst b/Doc/whatsnew/3.12.rst index efbd2ca3de1..4ff90664bb7 100644 --- a/Doc/whatsnew/3.12.rst +++ b/Doc/whatsnew/3.12.rst @@ -1476,6 +1476,15 @@ Porting to Python 3.12 Note that :c:func:`PyType_FromMetaclass` (added in Python 3.12) already disallows creating classes whose metaclass overrides ``tp_new``. +* :c:var:`PyOS_InputHook` and :c:var:`PyOS_ReadlineFunctionPointer` are no + longer called in :ref:`subinterpreters `. This is + because clients generally rely on process-wide global state (since these + callbacks have no way of recovering extension module state). + + This also avoids situations where extensions may find themselves running in a + subinterpreter that they don't support (or haven't yet been loaded in). See + :gh:`104668` for more info. + Deprecated ---------- diff --git a/Misc/NEWS.d/next/C API/2023-05-19-10-22-34.gh-issue-104668.MLX1g9.rst b/Misc/NEWS.d/next/C API/2023-05-19-10-22-34.gh-issue-104668.MLX1g9.rst new file mode 100644 index 00000000000..7b882afd7f8 --- /dev/null +++ b/Misc/NEWS.d/next/C API/2023-05-19-10-22-34.gh-issue-104668.MLX1g9.rst @@ -0,0 +1,5 @@ +Don't call :c:var:`PyOS_InputHook` or :c:var:`PyOS_ReadlineFunctionPointer` +in subinterpreters, since it's generally difficult to avoid using global +state in their registered callbacks. This also avoids situations where +extensions may find themselves running in a subinterpreter they don't +support (or haven't yet been loaded in). diff --git a/Parser/myreadline.c b/Parser/myreadline.c index 3f0e29f051a..7074aba74b7 100644 --- a/Parser/myreadline.c +++ b/Parser/myreadline.c @@ -45,7 +45,10 @@ my_fgets(PyThreadState* tstate, char *buf, int len, FILE *fp) #endif while (1) { - if (PyOS_InputHook != NULL) { + if (PyOS_InputHook != NULL && + // GH-104668: See PyOS_ReadlineFunctionPointer's comment below... + _Py_IsMainInterpreter(tstate->interp)) + { (void)(PyOS_InputHook)(); } @@ -131,7 +134,10 @@ _PyOS_WindowsConsoleReadline(PyThreadState *tstate, HANDLE hStdIn) wbuf = wbuf_local; wbuflen = sizeof(wbuf_local) / sizeof(wbuf_local[0]) - 1; while (1) { - if (PyOS_InputHook != NULL) { + if (PyOS_InputHook != NULL && + // GH-104668: See PyOS_ReadlineFunctionPointer's comment below... + _Py_IsMainInterpreter(tstate->interp)) + { (void)(PyOS_InputHook)(); } if (!ReadConsoleW(hStdIn, &wbuf[total_read], wbuflen - total_read, &n_read, NULL)) { @@ -389,11 +395,23 @@ PyOS_Readline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt) * a tty. This can happen, for example if python is run like * this: python -i < test1.py */ - if (!isatty (fileno (sys_stdin)) || !isatty (fileno (sys_stdout))) - rv = PyOS_StdioReadline (sys_stdin, sys_stdout, prompt); - else - rv = (*PyOS_ReadlineFunctionPointer)(sys_stdin, sys_stdout, - prompt); + if (!isatty(fileno(sys_stdin)) || !isatty(fileno(sys_stdout)) || + // GH-104668: Don't call global callbacks like PyOS_InputHook or + // PyOS_ReadlineFunctionPointer from subinterpreters, since it seems + // like there's no good way for users (like readline and tkinter) to + // avoid using global state to manage them. Plus, we generally don't + // want to cause trouble for libraries that don't know/care about + // subinterpreter support. If libraries really need better APIs that + // work per-interpreter and have ways to access module state, we can + // certainly add them later (but for now we'll cross our fingers and + // hope that nobody actually cares): + !_Py_IsMainInterpreter(tstate->interp)) + { + rv = PyOS_StdioReadline(sys_stdin, sys_stdout, prompt); + } + else { + rv = (*PyOS_ReadlineFunctionPointer)(sys_stdin, sys_stdout, prompt); + } Py_END_ALLOW_THREADS PyThread_release_lock(_PyOS_ReadlineLock);