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, 43 insertions, 17 deletions

diff --git a/configure.ac b/configure.ac
index ed1849514c1..3761d814364 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3271,10 +3271,6 @@ esac
 
 
 case $opsys in
-  darwin | gnu | hpux* | *bsd )
-    AC_DEFINE(NO_TERMIO, 1, [Define if termio.h should not be included.])
-    ;;
-
   irix6-5 | sol2* | unixware )
     dnl Some SVr4s don't define NSIG in sys/signal.h for ANSI environments;
     dnl instead, there's a system variable _sys_nsig.  Unfortunately, we
@@ -3284,26 +3280,16 @@ case $opsys in
     ;;
 esac
 
+emacs_broken_SIGIO=no
 
 case $opsys in
   dnl SIGIO exists, but the feature doesn't work in the way Emacs needs.
   dnl See eg <http://article.gmane.org/gmane.os.openbsd.ports/46831>.
   hpux* | irix6-5 | openbsd | sol2* | unixware )
-    AC_DEFINE(BROKEN_SIGIO, 1, [Define if SIGIO should not be used.])
+    emacs_broken_SIGIO=yes
     ;;
 
   aix4-2)
-    dnl BUILD 9008 - FIONREAD problem still exists in X-Windows.
-    AC_DEFINE(BROKEN_FIONREAD, 1, [Define if FIONREAD should not be used.])
-    dnl As we define BROKEN_FIONREAD, SIGIO will be undefined in systty.h.
-    dnl But, on AIX, SIGAIO, SIGPTY, and SIGPOLL are defined as SIGIO,
-    dnl which causes compilation error at init_signals in sysdep.c.
-    dnl So, we define these macros so that syssignal.h detects them
-    dnl and undefine SIGAIO, SIGPTY and SIGPOLL.
-    AC_DEFINE(BROKEN_SIGAIO, 1, [Define if SIGAIO should not be used.])
-    AC_DEFINE(BROKEN_SIGPOLL,1, [Define if SIGPOLL should not be used.])
-    AC_DEFINE(BROKEN_SIGPTY, 1, [Define if SIGPTY should not be used.])
-
     dnl On AIX Emacs uses the gmalloc.c malloc implementation.  But given
     dnl the way this system works, libc functions that return malloced
     dnl memory use the libc malloc implementation. Calling xfree or
@@ -3379,7 +3365,7 @@ dnl The choice is controlled by the variable interrupt_input.
 dnl
 dnl Define INTERRUPT_INPUT to make interrupt_input = 1 the default (use SIGIO)
 dnl
-dnl Emacs uses the presence or absence of the SIGIO and BROKEN_SIGIO macros
+dnl Emacs uses the presence of the USABLE_SIGIO macro
 dnl to indicate whether or not signal-driven I/O is possible.  It uses
 dnl INTERRUPT_INPUT to decide whether to use it by default.
 dnl
@@ -3900,6 +3886,46 @@ case $opsys in
     ;;
 esac
 
+AC_CACHE_CHECK([for usable FIONREAD], [emacs_cv_usable_FIONREAD],
+  [case $opsys in
+     aix4-2)
+       dnl BUILD 9008 - FIONREAD problem still exists in X-Windows.
+       emacs_cv_usable_FIONREAD=no
+       ;;
+
+     *)
+       AC_COMPILE_IFELSE(
+	 [AC_LANG_PROGRAM([[#include <sys/types.h>
+			    #include <sys/ioctl.h>
+			    #ifdef USG5_4
+			    # include <sys/filio.h>
+			    #endif
+			  ]],
+			  [[int foo = ioctl (0, FIONREAD, &foo);]])],
+	 [emacs_cv_usable_FIONREAD=yes],
+	 [emacs_cv_usable_FIONREAD=no])
+       ;;
+   esac])
+if test $emacs_cv_usable_FIONREAD = yes; then
+  AC_DEFINE([USABLE_FIONREAD], [1], [Define to 1 if FIONREAD is usable.])
+
+  if test $emacs_broken_SIGIO = no; then
+    AC_CACHE_CHECK([for usable SIGIO], [emacs_cv_usable_SIGIO],
+      [AC_COMPILE_IFELSE(
+	 [AC_LANG_PROGRAM([[#include <fcntl.h>
+			    #include <signal.h>
+			  ]],
+			  [[int foo = SIGIO | F_SETFL | FASYNC;]])],
+	 [emacs_cv_usable_SIGIO=yes],
+	 [emacs_cv_usable_SIGIO=no])],
+      [emacs_cv_usable_SIGIO=yes],
+      [emacs_cv_usable_SIGIO=no])
+    if test $emacs_cv_usable_SIGIO = yes; then
+      AC_DEFINE([USABLE_SIGIO], [1], [Define to 1 if SIGIO is usable.])
+    fi
+  fi
+fi
+
 
 case $opsys in
   dnl Emacs supplies its own malloc, but glib (part of Gtk+) calls