GH-104668: Don't call PyOS_* hooks in subinterpreters (GH-104674)

1 files changed, 25 insertions, 7 deletions

diff --git a/Parser/myreadline.c b/Parser/myreadline.c
index 3f0e29f..7074aba 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);