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NetBSD/bin/ksh/sigact.c

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/* $NetBSD: sigact.c,v 1.3 2002/05/25 23:29:17 wiz Exp $ */
/* NAME:
* sigact.c - fake sigaction(2)
*
* SYNOPSIS:
* #include "sigact.h"
*
* int sigaction(int sig, struct sigaction *act,
* struct sigaction *oact);
* int sigaddset(sigset_t *mask, int sig);
* int sigdelset(sigset_t *mask, int sig);
* int sigemptyset(sigset_t *mask);
* int sigfillset(sigset_t *mask);
* int sigismember(sigset_t *mask, int sig);
* int sigpending(sigset_t *set);
* int sigprocmask(int how, sigset_t *set, sigset_t *oset);
* int sigsuspend(sigset_t *mask);
*
* RETSIGTYPE (*Signal(int sig, RETSIGTYPE (*disp)(int)))(int);
*
* DESCRIPTION:
* This is a fake sigaction implementation. It uses
* sigsetmask(2) et al or sigset(2) and friends if
* available, otherwise it just uses signal(2). If it
* thinks sigaction(2) really exists it compiles to "almost"
* nothing.
*
* In any case it provides a Signal() function that is
* implemented in terms of sigaction().
* If not using signal(2) as part of the underlying
* implementation (USE_SIGNAL or USE_SIGMASK), and
* NO_SIGNAL is not defined, it also provides a signal()
* function that calls Signal().
*
* The need for all this mucking about is the problems
* caused by mixing various signal handling mechanisms in
* the one process. This module allows for a consistent
* POSIX compliant interface to whatever is actually
* available.
*
* sigaction() allows the caller to examine and/or set the
* action to be associated with a given signal. "act" and
* "oact" are pointers to 'sigaction structs':
*.nf
*
* struct sigaction
* {
* RETSIGTYPE (*sa_handler)();
* sigset_t sa_mask;
* int sa_flags;
* };
*.fi
*
* RETSIGTYPE is normally 'void' in the POSIX implementation
* and for most current systems. On some older UNIX
* systems, signal handlers do not return 'void', so
* this implementation keeps 'sa_handler' inline with the
* hosts normal signal handling conventions.
* 'sa_mask' controls which signals will be blocked while
* the selected signal handler is active. It is not used
* in this implementation.
* 'sa_flags' controls various semantics such as whether
* system calls should be automagically restarted
* (SA_RESTART) etc. It is not used in this
* implementation.
* Either "act" or "oact" may be NULL in which case the
* appropriate operation is skipped.
*
* sigaddset() adds "sig" to the sigset_t pointed to by "mask".
*
* sigdelset() removes "sig" from the sigset_t pointed to
* by "mask".
*
* sigemptyset() makes the sigset_t pointed to by "mask" empty.
*
* sigfillset() makes the sigset_t pointed to by "mask"
* full ie. match all signals.
*
* sigismember() returns true if "sig" is found in "*mask".
*
* sigpending() is supposed to return "set" loaded with the
* set of signals that are blocked and pending for the
* calling process. It does nothing in this impementation.
*
* sigprocmask() is used to examine and/or change the
* signal mask for the calling process. Either "set" or
* "oset" may be NULL in which case the appropriate
* operation is skipped. "how" may be one of SIG_BLOCK,
* SIG_UNBLOCK or SIG_SETMASK. If this package is built
* with USE_SIGNAL, then this routine achieves nothing.
*
* sigsuspend() sets the signal mask to "*mask" and waits
* for a signal to be delivered after which the previous
* mask is restored.
*
*
* RETURN VALUE:
* 0==success, -1==failure
*
* BUGS:
* Since we fake most of this, don't expect fancy usage to
* work.
*
* AUTHOR:
* Simon J. Gerraty <sjg@zen.void.oz.au>
*/
/* COPYRIGHT:
* @(#)Copyright (c) 1992 Simon J. Gerraty
*
* This is free software. It comes with NO WARRANTY.
* Permission to use, modify and distribute this source code
* is granted subject to the following conditions.
* 1/ that that the above copyright notice and this notice
* are preserved in all copies and that due credit be given
* to the author.
* 2/ that any changes to this code are clearly commented
* as such so that the author does get blamed for bugs
* other than his own.
*
* Please send copies of changes and bug-fixes to:
* sjg@zen.void.oz.au
*
*/
/* Changes to sigact.c for pdksh, Michael Rendell <michael@cs.mun.ca>:
* - sigsuspend(): pass *mask to bsd4.2 sigpause instead of mask.
* - changed SIG_HDLR to RETSIGTYPE for use with GNU autoconf
* - added and used RETSIGVAL
* - include sh.h instead of signal.h (to get *_SIGNALS macros)
* - changed if !SA_NOCLDSTOP ... to USE_FAKE_SIGACT to avoid confusion
* - set the USE_* defines using the *_SIGNALS defines from autoconf
* - sigaction(): if using BSD signals, use sigvec() (used to use
* signal()) and set the SV_INTERRUPT flag (POSIX says syscalls
* are interrupted and pdksh needs this behaviour).
* - define IS_KSH before including anything; ifdef out routines
* not used in ksh if IS_KSH is defined (same in sigact.h).
* - use ARGS() instead of __P()
* - sigaction(),sigsuspend(),Signal(),signal(): use handler_t typedef
* instead of explicit type.
*/
/*
#include <signal.h>
*/
#define IS_KSH
#include "sh.h"
/*
#ifndef __P
# define __P(p) p
#endif
*/
/*
* some systems have a faulty sigaction() implementation!
* Allow us to bypass it.
* Or they may have installed sigact.h as signal.h which is why
* we have SA_NOCLDSTOP defined.
*/
#ifdef USE_FAKE_SIGACT /* let autoconf decide.. */
/* #if !defined(SA_NOCLDSTOP) || defined(_SIGACT_H) || defined(USE_SIGNAL) || defined(USE_SIGSET) || defined(USE_SIGMASK) */
/* Let autoconf decide which to use */
#ifdef BSD42_SIGNALS
# define USE_SIGMASK
#else
# ifdef BSD41_SIGNALS
# define USE_SIGSET
# else
# define USE_SIGNAL
# endif
#endif /* BSD42_SIGNALS */
/*
* if we haven't been told,
* try and guess what we should implement with.
*/
#if !defined(USE_SIGSET) && !defined(USE_SIGMASK) && !defined(USE_SIGNAL)
# if defined(sigmask) || defined(BSD) || defined(_BSD) && !defined(BSD41)
# define USE_SIGMASK
# else
# ifndef NO_SIGSET
# define USE_SIGSET
# else
# define USE_SIGNAL
# endif
# endif
#endif
/*
* if we still don't know, we're in trouble
*/
#if !defined(USE_SIGSET) && !defined(USE_SIGMASK) && !defined(USE_SIGNAL)
error must know what to implement with
#endif
#include "sigact.h"
/*
* in case signal() has been mapped to our Signal().
*/
#undef signal
int
sigaction(sig, act, oact)
int sig;
struct sigaction *act, *oact;
{
handler_t oldh;
if (act)
{
#ifdef USE_SIGSET
oldh = sigset(sig, act->sa_handler);
#else
# ifdef USE_SIGMASK
struct sigvec nsv,osv;
nsv.sv_handler = act->sa_handler;
nsv.sv_mask = 0; /* punt */
nsv.sv_flags = SV_INTERRUPT; /* punt */
sigvec(sig, &nsv, &osv);
oldh = osv.sv_handler;
# else /* USE_SIGMASK */
oldh = signal(sig, act->sa_handler);
# endif /* USE_SIGMASK */
#endif
}
else
{
if (oact)
{
#ifdef USE_SIGSET
oldh = sigset(sig, SIG_IGN);
#else
oldh = signal(sig, SIG_IGN);
#endif
if (oldh != SIG_IGN && oldh != SIG_ERR)
{
#ifdef USE_SIGSET
(void) sigset(sig, oldh);
#else
(void) signal(sig, oldh);
#endif
}
}
}
if (oact)
{
oact->sa_handler = oldh;
}
return 0; /* hey we're faking it */
}
int
sigaddset(mask, sig)
sigset_t *mask;
int sig;
{
*mask |= sigmask(sig);
return 0;
}
#ifndef IS_KSH
int
sigdelset(mask, sig)
sigset_t *mask;
int sig;
{
*mask &= ~(sigmask(sig));
return 0;
}
#endif /* IS_KSH */
int
sigemptyset(mask)
sigset_t *mask;
{
*mask = 0;
return 0;
}
#ifndef IS_KSH
int
sigfillset(mask)
sigset_t *mask;
{
*mask = ~0;
return 0;
}
#endif /* IS_KSH */
#ifndef IS_KSH
int
sigismember(mask, sig)
sigset_t *mask;
int sig;
{
return ((*mask) & sigmask(sig));
}
#endif /* IS_KSH */
#ifndef IS_KSH
int
sigpending(set)
sigset_t *set;
{
return 0; /* faking it! */
}
#endif /* IS_KSH */
int
sigprocmask(how, set, oset)
int how;
sigset_t *set, *oset;
{
#ifdef USE_SIGSET
register int i;
#endif
static sigset_t sm;
static int once = 0;
if (!once)
{
/*
* initally we clear sm,
* there after, it represents the last
* thing we did.
*/
once++;
#ifdef USE_SIGMASK
sm = sigblock(0);
#else
sm = 0;
#endif
}
if (oset)
*oset = sm;
if (set)
{
switch (how)
{
case SIG_BLOCK:
sm |= *set;
break;
case SIG_UNBLOCK:
sm &= ~(*set);
break;
case SIG_SETMASK:
sm = *set;
break;
}
#ifdef USE_SIGMASK
(void) sigsetmask(sm);
#else
# ifdef USE_SIGSET
for (i = 1; i < NSIG; i++)
{
if (how == SIG_UNBLOCK)
{
if (*set & sigmask(i))
sigrelse(i);
}
else
if (sm & sigmask(i))
{
sighold(i);
}
}
# endif
#endif
}
return 0;
}
int
sigsuspend(mask)
sigset_t *mask;
{
#ifdef USE_SIGMASK
sigpause(*mask);
#else
register int i;
# ifdef USE_SIGSET
for (i = 1; i < NSIG; i++)
{
if (*mask & sigmask(i))
{
/* not the same sigpause() as above! */
sigpause(i);
break;
}
}
# else /* signal(2) only */
handler_t oldh;
/*
* make sure that signals in mask will not
* be ignored.
*/
for (i = 1; i < NSIG; i++)
{
if (*mask & sigmask(i))
{
if ((oldh = signal(i, SIG_DFL)) != SIG_ERR &&
oldh != SIG_IGN &&
oldh != SIG_DFL)
(void) signal(i, oldh); /* restore handler */
}
}
pause(); /* wait for a signal */
# endif
#endif
return 0;
}
#endif /* USE_FAKE_SIGACT (was ! SA_NOCLDSTOP) */
#if !defined(RETSIGTYPE)
# define RETSIGTYPE void
# define RETSIGVAL
#endif
#if !defined(SIG_ERR)
# define SIG_ERR (RETSIGTYPE (*)())-1
#endif
/*
* an implementation of signal() using sigaction().
*/
#ifndef IS_KSH
handler_t Signal(sig, handler)
int sig;
handler_t handler;
{
struct sigaction act, oact;
act.sa_handler = handler;
sigemptyset(&act.sa_mask);
act.sa_flags = 0;
if (sigaction(sig, &act, &oact) < 0)
return (SIG_ERR);
return (oact.sa_handler);
}
#endif /* IS_KSH */
#ifndef IS_KSH
#if !defined(USE_SIGNAL) && !defined(USE_SIGMASK) && !defined(NO_SIGNAL)
/*
* ensure we avoid signal mayhem
*/
handler_t signal(sig, handler)
int sig;
handler_t handler;
{
return (Signal(sig, handler));
}
#endif
#endif /* IS_KSH */
/* This lot (for GNU-Emacs) goes at the end of the file. */
/*
* Local Variables:
* version-control:t
* comment-column:40
* End:
*/
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