Issue #23735: Add SIGWINCH handler for Readline 6.3+ support, by Eric Price

6 files changed, 87 insertions, 0 deletions

diff --git a/Misc/ACKS b/Misc/ACKS
index 3a9cd6f..01b42f4 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1155,6 +1155,7 @@ Florian Preinstorfer
 Amrit Prem
 Paul Prescod
 Donovan Preston
+Eric Price
 Paul Price
 Iuliia Proskurnia
 Dorian Pula
diff --git a/Misc/NEWS b/Misc/NEWS
index 9682b40..6d43666 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -99,6 +99,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #23735: Handle terminal resizing with Readline 6.3+ by installing our
+  own SIGWINCH handler.  Patch by Eric Price.
+
 - Issue #26586: In http.server, respond with "413 Request header fields too
   large" if there are too many header fields to parse, rather than killing
   the connection and raising an unhandled exception.  Patch by Xiang Zhang.
diff --git a/Modules/readline.c b/Modules/readline.c
index 4013003..82daa52 100644
--- a/Modules/readline.c
+++ b/Modules/readline.c
@@ -928,6 +928,26 @@ on_completion_display_matches_hook(char **matches,
 
 #endif
 
+#ifdef HAVE_RL_RESIZE_TERMINAL
+static volatile sig_atomic_t sigwinch_received;
+static sighandler_t sigwinch_ohandler;
+
+static void
+readline_sigwinch_handler(int signum)
+{
+    sigwinch_received = 1;
+    if (sigwinch_ohandler &&
+            sigwinch_ohandler != SIG_IGN && sigwinch_ohandler != SIG_DFL)
+        sigwinch_ohandler(signum);
+
+#ifndef HAVE_SIGACTION
+    /* If the handler was installed with signal() rather than sigaction(),
+    we need to reinstall it. */
+    PyOS_setsig(SIGWINCH, readline_sigwinch_handler);
+#endif
+}
+#endif
+
 /* C function to call the Python completer. */
 
 static char *
@@ -1033,6 +1053,10 @@ setup_readline(readlinestate *mod_state)
     /* Bind both ESC-TAB and ESC-ESC to the completion function */
     rl_bind_key_in_map ('\t', rl_complete, emacs_meta_keymap);
     rl_bind_key_in_map ('\033', rl_complete, emacs_meta_keymap);
+#ifdef HAVE_RL_RESIZE_TERMINAL
+    /* Set up signal handler for window resize */
+    sigwinch_ohandler = PyOS_setsig(SIGWINCH, readline_sigwinch_handler);
+#endif
     /* Set our hook functions */
     rl_startup_hook = on_startup_hook;
 #ifdef HAVE_RL_PRE_INPUT_HOOK
@@ -1118,6 +1142,13 @@ readline_until_enter_or_signal(const char *prompt, int *signal)
             struct timeval *timeoutp = NULL;
             if (PyOS_InputHook)
                 timeoutp = &timeout;
+#ifdef HAVE_RL_RESIZE_TERMINAL
+            /* Update readline's view of the window size after SIGWINCH */
+            if (sigwinch_received) {
+                sigwinch_received = 0;
+                rl_resize_terminal();
+            }
+#endif
             FD_SET(fileno(rl_instream), &selectset);
             /* select resets selectset if no input was available */
             has_input = select(fileno(rl_instream) + 1, &selectset,
diff --git a/configure b/configure
index 9ff548f..6f26a36 100755
--- a/configure
+++ b/configure
@@ -14929,6 +14929,50 @@ $as_echo "#define HAVE_RL_COMPLETION_DISPLAY_MATCHES_HOOK 1" >>confdefs.h
 fi
 
 
+# also in 4.0, but not in editline
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for rl_resize_terminal in -lreadline" >&5
+$as_echo_n "checking for rl_resize_terminal in -lreadline... " >&6; }
+if ${ac_cv_lib_readline_rl_resize_terminal+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_check_lib_save_LIBS=$LIBS
+LIBS="-lreadline $READLINE_LIBS $LIBS"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char rl_resize_terminal ();
+int
+main ()
+{
+return rl_resize_terminal ();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_lib_readline_rl_resize_terminal=yes
+else
+  ac_cv_lib_readline_rl_resize_terminal=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_readline_rl_resize_terminal" >&5
+$as_echo "$ac_cv_lib_readline_rl_resize_terminal" >&6; }
+if test "x$ac_cv_lib_readline_rl_resize_terminal" = xyes; then :
+
+$as_echo "#define HAVE_RL_RESIZE_TERMINAL 1" >>confdefs.h
+
+fi
+
+
 # check for readline 4.2
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for rl_completion_matches in -lreadline" >&5
 $as_echo_n "checking for rl_completion_matches in -lreadline... " >&6; }
diff --git a/configure.ac b/configure.ac
index 282610a..e7d7bfc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4527,6 +4527,11 @@ AC_CHECK_LIB(readline, rl_completion_display_matches_hook,
 	AC_DEFINE(HAVE_RL_COMPLETION_DISPLAY_MATCHES_HOOK, 1,
         [Define if you have readline 4.0]), ,$READLINE_LIBS)
 
+# also in 4.0, but not in editline
+AC_CHECK_LIB(readline, rl_resize_terminal,
+	AC_DEFINE(HAVE_RL_RESIZE_TERMINAL, 1,
+        [Define if you have readline 4.0]), ,$READLINE_LIBS)
+
 # check for readline 4.2
 AC_CHECK_LIB(readline, rl_completion_matches,
 	AC_DEFINE(HAVE_RL_COMPLETION_MATCHES, 1,
diff --git a/pyconfig.h.in b/pyconfig.h.in
index e017d4e..d432a82 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -735,6 +735,9 @@
 /* Define if you have readline 4.0 */
 #undef HAVE_RL_PRE_INPUT_HOOK
 
+/* Define if you have readline 4.0 */
+#undef HAVE_RL_RESIZE_TERMINAL
+
 /* Define to 1 if you have the `round' function. */
 #undef HAVE_ROUND