gh-81057: Move Signal-Related Globals to _PyRuntimeState (gh-100085)

https://github.com/python/cpython/issues/81057

Include/internal/pycore_signal.h

@@ -10,8 +10,11 @@ extern "C" {
 #  error "this header requires Py_BUILD_CORE define"
 #endif
 
+#include "pycore_atomic.h"         // _Py_atomic_address
+
 #include <signal.h>                // NSIG
 
+
 #ifdef _SIG_MAXSIG
    // gh-91145: On FreeBSD, <signal.h> defines NSIG as 32: it doesn't include
    // realtime signals: [SIGRTMIN,SIGRTMAX]. Use _SIG_MAXSIG instead. For
@@ -29,6 +32,66 @@ extern "C" {
 #  define Py_NSIG 64               // Use a reasonable default value
 #endif
 
+#define INVALID_FD (-1)
+
+struct _signals_runtime_state {
+    volatile struct {
+        _Py_atomic_int tripped;
+        /* func is atomic to ensure that PyErr_SetInterrupt is async-signal-safe
+         * (even though it would probably be otherwise, anyway).
+         */
+        _Py_atomic_address func;
+    } handlers[Py_NSIG];
+
+    volatile struct {
+#ifdef MS_WINDOWS
+        /* This would be "SOCKET fd" if <winsock2.h> were always included.
+           It isn't so we must cast to SOCKET where appropriate. */
+        volatile int fd;
+#elif defined(__VXWORKS__)
+        int fd;
+#else
+        sig_atomic_t fd;
+#endif
+
+        int warn_on_full_buffer;
+#ifdef MS_WINDOWS
+        int use_send;
+#endif
+    } wakeup;
+
+    /* Speed up sigcheck() when none tripped */
+    _Py_atomic_int is_tripped;
+
+    /* These objects necessarily belong to the main interpreter. */
+    PyObject *default_handler;
+    PyObject *ignore_handler;
+
+#ifdef MS_WINDOWS
+    /* This would be "HANDLE sigint_event" if <windows.h> were always included.
+       It isn't so we must cast to HANDLE everywhere "sigint_event" is used. */
+    void *sigint_event;
+#endif
+
+    /* True if the main interpreter thread exited due to an unhandled
+     * KeyboardInterrupt exception, suggesting the user pressed ^C. */
+    int unhandled_keyboard_interrupt;
+};
+
+#ifdef MS_WINDOWS
+# define _signals_WAKEUP_INIT \
+    {.fd = INVALID_FD, .warn_on_full_buffer = 1, .use_send = 0}
+#else
+# define _signals_WAKEUP_INIT \
+    {.fd = INVALID_FD, .warn_on_full_buffer = 1}
+#endif
+
+#define _signals_RUNTIME_INIT \
+    { \
+        .wakeup = _signals_WAKEUP_INIT, \
+    }
+
+
 #ifdef __cplusplus
 }
 #endif