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, 6 insertions, 6 deletions

diff --git a/src/sound.c b/src/sound.c
index 5729d704b6a..fe48bb277b2 100644
--- a/src/sound.c
+++ b/src/sound.c
@@ -314,7 +314,7 @@ sound_perror (const char *msg)
   int saved_errno = errno;
 
   turn_on_atimers (1);
-#ifdef SIGIO
+#ifdef USABLE_SIGIO
   {
     sigset_t unblocked;
     sigemptyset (&unblocked);
@@ -732,7 +732,7 @@ static void
 vox_configure (struct sound_device *sd)
 {
   int val;
-#ifdef SIGIO
+#ifdef USABLE_SIGIO
   sigset_t blocked;
 #endif
 
@@ -742,7 +742,7 @@ vox_configure (struct sound_device *sd)
      interrupted by a signal.  Block the ones we know to cause
      troubles.  */
   turn_on_atimers (0);
-#ifdef SIGIO
+#ifdef USABLE_SIGIO
   sigemptyset (&blocked);
   sigaddset (&blocked, SIGIO);
   pthread_sigmask (SIG_BLOCK, &blocked, 0);
@@ -778,7 +778,7 @@ vox_configure (struct sound_device *sd)
     }
 
   turn_on_atimers (1);
-#ifdef SIGIO
+#ifdef USABLE_SIGIO
   pthread_sigmask (SIG_UNBLOCK, &blocked, 0);
 #endif
 }
@@ -794,7 +794,7 @@ vox_close (struct sound_device *sd)
       /* On GNU/Linux, it seems that the device driver doesn't like to
 	 be interrupted by a signal.  Block the ones we know to cause
 	 troubles.  */
-#ifdef SIGIO
+#ifdef USABLE_SIGIO
       sigset_t blocked;
       sigemptyset (&blocked);
       sigaddset (&blocked, SIGIO);
@@ -806,7 +806,7 @@ vox_close (struct sound_device *sd)
       ioctl (sd->fd, SNDCTL_DSP_SYNC, NULL);
 
       turn_on_atimers (1);
-#ifdef SIGIO
+#ifdef USABLE_SIGIO
       pthread_sigmask (SIG_UNBLOCK, &blocked, 0);
 #endif