Implement SA_SIGINFO for i386. Thanks to Bruce Evans for much more

than a review, this was a nice puzzle.

This is supposed to be binary and source compatible with older
applications that access the old FreeBSD-style three arguments to a
signal handler.

Except those applications that access hidden signal handler arguments
bejond the documented third one. If you have applications that do,
please let me know so that we take the opportunity to provide the
functionality they need in a documented manner.

Also except application that use 'struct sigframe' directly. You need
to recompile gdb and doscmd. `make world` is recommended.

Example program that demonstrates how SA_SIGINFO and old-style FreeBSD
handlers (with their three args) may be used in the same process is at
http://www3.cons.org/tmp/fbsd-siginfo.c

Programs that use the old FreeBSD-style three arguments are easy to
change to SA_SIGINFO (although they don't need to, since the old style
will still work):

  Old args to signal handler:
    void handler_sn(int sig, int code, struct sigcontext *scp)

  New args:
    void handler_si(int sig, siginfo_t *si, void *third)
  where:
    old:code == new:second->si_code
    old:scp == &(new:si->si_scp)     /* Passed by value! */

The latter is also pointed to by new:third, but accessing via
si->si_scp is preferred because it is type-save.

FreeBSD implementation notes:
- This is just the framework to make the interface POSIX compatible.
  For now, no additional functionality is provided. This is supposed
  to happen now, starting with floating point values.
- We don't use 'sigcontext_t.si_value' for now (POSIX meant it for
  realtime-related values).
- Documentation will be updated when new functionality is added and
  the exact arguments passed are determined. The comments in
  sys/signal.h are meant to be useful.

Reviewed by:	BDE

1 files changed, 59 insertions, 17 deletions

diff --git a/sys/sys/_sigset.h b/sys/sys/_sigset.h
index 39d554e..471baa9 100644
--- a/sys/sys/_sigset.h
+++ b/sys/sys/_sigset.h
@@ -36,7 +36,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)signal.h	8.4 (Berkeley) 5/4/95
- * $Id: signal.h,v 1.13 1998/03/28 11:50:43 dufault Exp $
+ * $Id: signal.h,v 1.14 1998/08/05 09:04:36 dfr Exp $
  */
 
 #ifndef	_SYS_SIGNAL_H_
@@ -113,6 +113,50 @@
  */
 typedef void __sighandler_t __P((int));
 
+#if defined(_P1003_1B_VISIBLE_HISTORICALLY) || \
+	(!defined(_ANSI_SOURCE) && !defined(_POSIX_SOURCE))
+union sigval {
+	/* Members as suggested by Annex C of POSIX 1003.1b. */
+	int   sigval_int;
+	void *sigval_ptr;
+};
+#endif /* !_ANSI_SOURCE && _P1003_1B_VISIBLE_HISTORICALLY */
+
+#if !defined(_ANSI_SOURCE) && !defined(_POSIX_SOURCE)
+/* POSIX 1003.1b required values. */
+#define SI_USER       0x10001
+#define SI_QUEUE      0x10002
+#define SI_TIMER      0x10003
+#define SI_ASYNCIO    0x10004
+#define SI_MESGQ      0x10005
+
+/* Additional FreeBSD values. */
+#define SI_UNDEFINED  0
+
+struct __siginfo {
+	struct sigcontext si_sc;
+	int               si_signo;              /* signal number */
+
+	/* 
+	 * Cause of signal, one of the SI_ macros or signal-specific
+	 * values, i.e. one of the FPE_... values for SIGFPE. This
+	 * value is equivalent to the second argument to an old-style
+	 * FreeBSD signal handler.
+	 */
+	int               si_code;
+
+	union sigval      si_value;
+};
+#else /* ! _ANSI_SOURCE && ! _POSIX_SOURCE */
+struct __siginfo;
+#endif /* ! _ANSI_SOURCE && ! _POSIX_SOURCE */
+
+typedef struct __siginfo siginfo_t;
+
+#if !defined(_ANSI_SOURCE) && !defined(_POSIX_SOURCE)
+typedef void __siginfohandler_t __P((int, siginfo_t *, void *));
+#endif /* ! _ANSI_SOURCE && ! _POSIX_SOURCE */
+
 #define	SIG_DFL		((__sighandler_t *)0)
 #define	SIG_IGN		((__sighandler_t *)1)
 #define	SIG_ERR		((__sighandler_t *)-1)
@@ -124,16 +168,26 @@ typedef unsigned int sigset_t;
  * Signal vector "template" used in sigaction call.
  */
 struct	sigaction {
-	__sighandler_t *sa_handler;	/* signal handler */
+	union {
+		void    (*__sa_handler) __P((int));
+		void    (*__sa_sigaction) __P((int, siginfo_t *, void *));
+	} __sigaction_u;		/* signal handler */
 	sigset_t sa_mask;		/* signal mask to apply */
 	int	sa_flags;		/* see signal options below */
 };
+/* if SA_SIGINFO is set, sa_sigaction is to be used instead of sa_handler. */
+#define	sa_handler	__sigaction_u.__sa_handler
+#ifndef _POSIX_SOURCE
+#define	sa_sigaction	__sigaction_u.__sa_sigaction
+#endif
+
 #ifndef _POSIX_SOURCE
 #define SA_ONSTACK	0x0001	/* take signal on signal stack */
 #define SA_RESTART	0x0002	/* restart system call on signal return */
 #define	SA_RESETHAND	0x0004	/* reset to SIG_DFL when taking signal */
 #define	SA_NODEFER	0x0010	/* don't mask the signal we're delivering */
 #define	SA_NOCLDWAIT	0x0020	/* don't keep zombies around */
+#define	SA_SIGINFO	0x0040	/* signal handler with SA_SIGINFO args */
 #ifdef COMPAT_SUNOS
 #define	SA_USERTRAMP	0x0100	/* do not bounce off kernel's sigtramp */
 #endif
@@ -183,6 +237,7 @@ struct	sigvec {
 #define SV_RESETHAND	SA_RESETHAND
 #define SV_NODEFER	SA_NODEFER
 #define SV_NOCLDSTOP	SA_NOCLDSTOP
+#define SV_SIGINFO	SA_SIGINFO
 #define sv_onstack sv_flags	/* isn't compatibility wonderful! */
 
 /*
@@ -204,20 +259,7 @@ struct	sigstack {
 #endif	/* !_POSIX_SOURCE */
 #endif	/* !_ANSI_SOURCE */
 
-#ifdef _P1003_1B_VISIBLE_HISTORICALLY
-
-/* sys/aio.h unconditionally defined these */
-
-union sigval {
-	int	sival_int;		/* Integer signal value */
-	void	*sival_ptr;		/* Pointer signal value */
-};
-
-typedef struct siginfo {
-	int	si_signo;		/* Signal number */
-	int	si_code;		/* Cause of the signal */
-	union sigval si_value;		/* Signal value */
-} siginfo_t;
+#if !defined(_ANSI_SOURCE) && defined(_P1003_1B_VISIBLE_HISTORICALLY)
 
 struct sigevent {
 	int	sigev_notify;		/* Notification type */
@@ -228,7 +270,7 @@ struct sigevent {
 #define	SIGEV_NONE	0		/* No async notification */
 #define	SIGEV_SIGNAL	1		/* Generate a queued signal */
 
-#endif
+#endif /* ! _ANSI_SOURCE && _P1003_1B_VISIBLE_HISTORICALLY */
 
 /*
  * For historical reasons; programs expect signal's return value to be