gh-64783: Fix signal.NSIG value on FreeBSD (#91929)

Fix signal.NSIG value on FreeBSD to accept signal numbers greater
than 32, like signal.SIGRTMIN and signal.SIGRTMAX.

* Add Py_NSIG constant.
* Add pycore_signal.h internal header file.
* _Py_Sigset_Converter() now includes the range of valid signals in
  the error message.

1 files changed, 5 insertions, 17 deletions

diff --git a/Modules/faulthandler.c b/Modules/faulthandler.c
index 91f9666..4f709ed 100644
--- a/Modules/faulthandler.c
+++ b/Modules/faulthandler.c
@@ -2,6 +2,7 @@
 #include "pycore_initconfig.h"    // _PyStatus_ERR
 #include "pycore_pyerrors.h"      // _Py_DumpExtensionModules
 #include "pycore_pystate.h"       // _PyThreadState_GET()
+#include "pycore_signal.h"        // Py_NSIG
 #include "pycore_traceback.h"     // _Py_DumpTracebackThreads
 
 #include "frameobject.h"
@@ -115,19 +116,6 @@ typedef struct {
 
 static user_signal_t *user_signals;
 
-/* the following macros come from Python: Modules/signalmodule.c */
-#ifndef NSIG
-# if defined(_NSIG)
-#  define NSIG _NSIG            /* For BSD/SysV */
-# elif defined(_SIGMAX)
-#  define NSIG (_SIGMAX + 1)    /* For QNX */
-# elif defined(SIGMAX)
-#  define NSIG (SIGMAX + 1)     /* For djgpp */
-# else
-#  define NSIG 64               /* Use a reasonable default value */
-# endif
-#endif
-
 static void faulthandler_user(int signum);
 #endif /* FAULTHANDLER_USER */
 
@@ -896,7 +884,7 @@ check_signum(int signum)
             return 0;
         }
     }
-    if (signum < 1 || NSIG <= signum) {
+    if (signum < 1 || Py_NSIG <= signum) {
         PyErr_SetString(PyExc_ValueError, "signal number out of range");
         return 0;
     }
@@ -935,7 +923,7 @@ faulthandler_register_py(PyObject *self,
         return NULL;
 
     if (user_signals == NULL) {
-        user_signals = PyMem_Calloc(NSIG, sizeof(user_signal_t));
+        user_signals = PyMem_Calloc(Py_NSIG, sizeof(user_signal_t));
         if (user_signals == NULL)
             return PyErr_NoMemory();
     }
@@ -1215,7 +1203,7 @@ faulthandler_traverse(PyObject *module, visitproc visit, void *arg)
     Py_VISIT(thread.file);
 #ifdef FAULTHANDLER_USER
     if (user_signals != NULL) {
-        for (size_t signum=0; signum < NSIG; signum++)
+        for (size_t signum=0; signum < Py_NSIG; signum++)
             Py_VISIT(user_signals[signum].file);
     }
 #endif
@@ -1416,7 +1404,7 @@ void _PyFaulthandler_Fini(void)
 #ifdef FAULTHANDLER_USER
     /* user */
     if (user_signals != NULL) {
-        for (size_t signum=0; signum < NSIG; signum++) {
+        for (size_t signum=0; signum < Py_NSIG; signum++) {
             faulthandler_unregister(&user_signals[signum], signum);
         }
         PyMem_Free(user_signals);