Simplify SIGIO usage.

The code that dealt with SIGIO was crufty and confusing, e.g., it
played tricks like "#undef SIGIO" but these tricks were not used
consistently.  Simplify mostly by not #undeffing standard symbols,
e.g., use "defined USABLE_SIGIO" (our symbol, which we can define
or not as we please) rather than "defined SIGIO" (standard symbol
that we probably shouldn't #undef).
* configure.ac (NO_TERMIO, BROKEN_FIONREAD, BROKEN_SIGAIO)
(BROKEN_SIGPOLL, BROKEN_SIGPTY): Remove.
(USABLE_FIONREAD, USABLE_SIGIO): New symbols.  All uses of
'defined SIGIO' replaced with 'defined USABLE_SIGIO', with no need
to #undef SIGIO now (which was error-prone).  Likewise, all uses
of 'defined FIONREAD' replaced with 'defined USABLE_FIONREAD'.
* src/admin/CPP_DEFINES (BROKEN_SIGAIO, BROKEN_SIGIO, BROKEN_SIGPOLL)
(BROKEN_SIGPTY, NO_TERMIO): Remove.
* src/conf_post.h [USG5_4]: Do not include <sys/wait.h> here.
Modules that need it can include it.
[USG5_4 && emacs]: Likewise, do not include the streams stuff here.
* src/dispextern.h (ignore_sigio): New decl.
* src/emacs.c (shut_down_emacs): Invoke unrequest_sigio
unconditionally, since it's now a no-op if !USABLE_SIGIO.
* src/emacs.c (shut_down_emacs):
* src/keyboard.c (kbd_buffer_store_event_hold):
Use ignore_sigio rather than invoking 'signal' directly.
* src/keyboard.c (USABLE_FIONREAD && USG5_4): Include <sys/filio.h>,
for FIONREAD.
(FIONREAD, SIGIO): Do not #undef.
(tty_read_avail_input): Use #error rather than a syntax error.
* src/process.c [USG5_4]: Include <sys/stream.h> and <sys/stropts.h>,
for I_PIPE, used by SETUP_SLAVE_PTY.
(DATAGRAM_SOCKETS): Simplify defn, based on USABLE_FIONREAD.
* src/sysdep.c (croak): Remove; no longer needed.  This bit of
temporary code, with Fred N. Fish's comment that it's temporary,
has been in Emacs since at least 1992!
(init_sigio, reset_sigio, request_sigio, unrequest_sigio):
Arrange for them to be no-ops in all cases when ! USABLE_SIGIO.
* src/syssignal.h (croak): Remove decl.
(SIGIO, SIGPOO, SIGAIO, SIGPTY): Do not #undef; that's too fragile.
* src/systty.h [!NO_TERMIO]: Do not include <termio.h>; no longer needed
now that we're termios-only.
(FIONREAD, ASYNC) [BROKEN_FIONREAD]: Do not #undef.
* src/term.c (dissociate_if_controlling_tty): Use #error rather than
a run-time error.

Fixes: debbugs:12408

1 files changed, 18 insertions, 80 deletions

diff --git a/src/sysdep.c b/src/sysdep.c
index 0f16d1a7645..b8f35e79146 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -107,9 +107,6 @@ extern char *getwd (char *);
 
 static int emacs_get_tty (int, struct emacs_tty *);
 static int emacs_set_tty (int, struct emacs_tty *, int);
-#if defined TIOCNOTTY || defined USG5 || defined CYGWIN
-static _Noreturn void croak (char *);
-#endif
 
 /* ULLONG_MAX is missing on Red Hat Linux 7.3; see Bug#11781.  */
 #ifndef ULLONG_MAX
@@ -513,7 +510,7 @@ sys_subshell (void)
   saved_handlers[0].code = SIGINT;
   saved_handlers[1].code = SIGQUIT;
   saved_handlers[2].code = SIGTERM;
-#ifdef SIGIO
+#ifdef USABLE_SIGIO
   saved_handlers[3].code = SIGIO;
   saved_handlers[4].code = 0;
 #else
@@ -642,121 +639,75 @@ restore_signal_handlers (struct save_signal *saved_handlers)
     }
 }
 
-#ifndef SIGIO
-/* If SIGIO is broken, don't do anything. */
-void
-init_sigio (int fd)
-{
-}
-
-static void
-reset_sigio (int fd)
-{
-}
-
-void
-request_sigio (void)
-{
-}
-
-void
-unrequest_sigio (void)
-{
-}
-
-#else
-#ifdef F_SETFL
-
+#ifdef USABLE_SIGIO
 static int old_fcntl_flags[MAXDESC];
+#endif
 
 void
 init_sigio (int fd)
 {
-#ifdef FASYNC
+#ifdef USABLE_SIGIO
   old_fcntl_flags[fd] = fcntl (fd, F_GETFL, 0) & ~FASYNC;
   fcntl (fd, F_SETFL, old_fcntl_flags[fd] | FASYNC);
-#endif
   interrupts_deferred = 0;
+#endif
 }
 
 static void
 reset_sigio (int fd)
 {
-#ifdef FASYNC
+#ifdef USABLE_SIGIO
   fcntl (fd, F_SETFL, old_fcntl_flags[fd]);
 #endif
 }
 
-#ifdef FASYNC           /* F_SETFL does not imply existence of FASYNC */
-/* XXX Uhm, FASYNC is not used anymore here. */
-/* XXX Yeah, but you need it for SIGIO, don't you? */
-
 void
 request_sigio (void)
 {
+#ifdef USABLE_SIGIO
   sigset_t unblocked;
 
   if (noninteractive)
     return;
 
   sigemptyset (&unblocked);
-#ifdef SIGWINCH
+# ifdef SIGWINCH
   sigaddset (&unblocked, SIGWINCH);
-#endif
+# endif
   sigaddset (&unblocked, SIGIO);
   pthread_sigmask (SIG_UNBLOCK, &unblocked, 0);
 
   interrupts_deferred = 0;
+#endif
 }
 
 void
 unrequest_sigio (void)
 {
+#ifdef USABLE_SIGIO
   sigset_t blocked;
 
   if (noninteractive)
     return;
 
-#if 0 /* XXX What's wrong with blocking SIGIO under X?  */
-  if (x_display_list)
-    return;
-#endif
-
   sigemptyset (&blocked);
-#ifdef SIGWINCH
+# ifdef SIGWINCH
   sigaddset (&blocked, SIGWINCH);
-#endif
+# endif
   sigaddset (&blocked, SIGIO);
   pthread_sigmask (SIG_BLOCK, &blocked, 0);
   interrupts_deferred = 1;
-}
-
-#else /* no FASYNC */
-#ifndef MSDOS
-
-void
-request_sigio (void)
-{
-  if (noninteractive || read_socket_hook)
-    return;
-
-  croak ("request_sigio");
+#endif
 }
 
 void
-unrequest_sigio (void)
+ignore_sigio (void)
 {
-  if (noninteractive || read_socket_hook)
-    return;
-
-  croak ("unrequest_sigio");
+#ifdef USABLE_SIGIO
+  signal (SIGIO, SIG_IGN);
+#endif
 }
 
-#endif /* MSDOS */
-#endif /* FASYNC */
-#endif /* F_SETFL */
-#endif /* SIGIO */
-
 
 /* Getting and setting emacs_tty structures.  */
 
@@ -2051,19 +2002,6 @@ getwd (char *pathname)
 }
 
 #endif /* !defined (HAVE_GETWD) || defined (BROKEN_GETWD) */
-
-/*
- *      This function will go away as soon as all the stubs fixed. (fnf)
- */
-
-void
-croak (char *badfunc)
-{
-  printf ("%s not yet implemented\r\n", badfunc);
-  reset_all_sys_modes ();
-  exit (1);
-}
-
 #endif /* USG */
 
 /* Directory routines for systems that don't have them. */