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, 15 insertions, 14 deletions

diff --git a/src/process.c b/src/process.c
index f80b5e80c76..b4b05a4b2e2 100644
--- a/src/process.c
+++ b/src/process.c
@@ -75,6 +75,11 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include <bsdtty.h>
 #endif
 
+#ifdef USG5_4
+# include <sys/stream.h>
+# include <sys/stropts.h>
+#endif
+
 #ifdef HAVE_RES_INIT
 #include <netinet/in.h>
 #include <arpa/nameser.h>
@@ -212,17 +217,13 @@ static EMACS_INT update_tick;
    "non-destructive" select.  So we require either native select,
    or emulation of select using FIONREAD.  */
 
-#ifdef BROKEN_DATAGRAM_SOCKETS
-#undef DATAGRAM_SOCKETS
-#else
-#ifndef DATAGRAM_SOCKETS
-#if defined (HAVE_SELECT) || defined (FIONREAD)
-#if defined (HAVE_SENDTO) && defined (HAVE_RECVFROM) && defined (EMSGSIZE)
-#define DATAGRAM_SOCKETS
-#endif /* HAVE_SENDTO && HAVE_RECVFROM && EMSGSIZE */
-#endif /* HAVE_SELECT || FIONREAD */
-#endif /* DATAGRAM_SOCKETS */
-#endif /* BROKEN_DATAGRAM_SOCKETS */
+#ifndef BROKEN_DATAGRAM_SOCKETS
+# if defined HAVE_SELECT || defined USABLE_FIONREAD
+#  if defined HAVE_SENDTO && defined HAVE_RECVFROM && defined EMSGSIZE
+#   define DATAGRAM_SOCKETS
+#  endif
+# endif
+#endif
 
 #if defined HAVE_LOCAL_SOCKETS && defined DATAGRAM_SOCKETS
 # define HAVE_SEQPACKET
@@ -251,7 +252,7 @@ static int process_output_skip;
 #endif
 
 static void create_process (Lisp_Object, char **, Lisp_Object);
-#ifdef SIGIO
+#ifdef USABLE_SIGIO
 static int keyboard_bit_set (SELECT_TYPE *);
 #endif
 static void deactivate_process (Lisp_Object);
@@ -4836,7 +4837,7 @@ wait_reading_process_output (intmax_t time_limit, int nsecs, int read_kbd,
       if (! NILP (wait_for_cell) && ! NILP (XCAR (wait_for_cell)))
         break;
 
-#ifdef SIGIO
+#ifdef USABLE_SIGIO
       /* If we think we have keyboard input waiting, but didn't get SIGIO,
          go read it.  This can happen with X on BSD after logging out.
          In that case, there really is no input and no SIGIO,
@@ -6853,7 +6854,7 @@ delete_gpm_wait_descriptor (int desc)
 
 # endif
 
-# ifdef SIGIO
+# ifdef USABLE_SIGIO
 
 /* Return nonzero if *MASK has a bit set
    that corresponds to one of the keyboard input descriptors.  */