gnu/abc-shell/sigact.c

   1 /* NAME:
   2  *      sigact.c - fake sigaction(2)
   3  *
   4  * SYNOPSIS:
   5  *      #include "sigact.h"
   6  *
   7  *      int sigaction(int sig, struct sigaction *act,
   8  *                      struct sigaction *oact);
   9  *      int sigaddset(sigset_t *mask, int sig);
  10  *      int sigdelset(sigset_t *mask, int sig);
  11  *      int sigemptyset(sigset_t *mask);
  12  *      int sigfillset(sigset_t *mask);
  13  *      int sigismember(sigset_t *mask, int sig);
  14  *      int sigpending(sigset_t *set);
  15  *      int sigprocmask(int how, sigset_t *set, sigset_t *oset);
  16  *      int sigsuspend(sigset_t *mask);
  17  *
  18  *      void (*_Signal(int sig, void (*disp)(int)))(int);
  19  *
  20  * DESCRIPTION:
  21  *      This is a fake sigaction implementation.  It uses
  22  *      sigsetmask(2) et al or sigset(2) and friends if
  23  *      available, otherwise it just uses signal(2).  If it
  24  *      thinks sigaction(2) really exists it compiles to "almost"
  25  *      nothing.
  26  *
  27  *      In any case it provides a _Signal() function that is
  28  *      implemented in terms of sigaction().
  29  *      If not using signal(2) as part of the underlying
  30  *      implementation (USE_SIGNAL or USE_SIGMASK), and
  31  *      NO_SIGNAL is not defined, it also provides a signal()
  32  *      function that calls _Signal().
  33  *
  34  *      The need for all this mucking about is the problems
  35  *      caused by mixing various signal handling mechanisms in
  36  *      the one process.  This module allows for a consistent
  37  *      POSIX compliant interface to whatever is actually
  38  *      available.
  39  *
  40  *      sigaction() allows the caller to examine and/or set the
  41  *      action to be associated with a given signal. "act" and
  42  *      "oact" are pointers to 'sigaction structs':
  43  *.nf
  44  *
  45  *      struct sigaction
  46  *      {
  47  *             void  (*sa_handler)();
  48  *             sigset_t  sa_mask;
  49  *             int       sa_flags;
  50  *      };
  51  *.fi
  52  *
  53  *      void is normally 'void' in the POSIX implementation
  54  *      and for most current systems.  On some older UNIX
  55  *      systems, signal handlers do not return 'void', so
  56  *      this implementation keeps 'sa_handler' inline with the
  57  *      hosts normal signal handling conventions.
  58  *      'sa_mask' controls which signals will be blocked while
  59  *      the selected signal handler is active.  It is not used
  60  *      in this implementation.
  61  *      'sa_flags' controls various semantics such as whether
  62  *      system calls should be automagically restarted
  63  *      (SA_RESTART) etc.  It is not used in this
  64  *      implementation.
  65  *      Either "act" or "oact" may be NULL in which case the
  66  *      appropriate operation is skipped.
  67  *
  68  *      sigaddset() adds "sig" to the sigset_t pointed to by "mask".
  69  *
  70  *      sigdelset() removes "sig" from the sigset_t pointed to
  71  *      by "mask".
  72  *
  73  *      sigemptyset() makes the sigset_t pointed to by "mask" empty.
  74  *
  75  *      sigfillset() makes the sigset_t pointed to by "mask"
  76  *      full ie. match all signals.
  77  *
  78  *      sigismember() returns true if "sig" is found in "*mask".
  79  *
  80  *      sigpending() is supposed to return "set" loaded with the
  81  *      set of signals that are blocked and pending for the
  82  *      calling process.  It does nothing in this impementation.
  83  *
  84  *      sigprocmask() is used to examine and/or change the
  85  *      signal mask for the calling process.  Either "set" or
  86  *      "oset" may be NULL in which case the appropriate
  87  *      operation is skipped.  "how" may be one of SIG_BLOCK,
  88  *      SIG_UNBLOCK or SIG_SETMASK.  If this package is built
  89  *      with USE_SIGNAL, then this routine achieves nothing.
  90  *
  91  *      sigsuspend() sets the signal mask to "*mask" and waits
  92  *      for a signal to be delivered after which the previous
  93  *      mask is restored.
  94  *
  95  *
  96  * RETURN VALUE:
  97  *      0==success, -1==failure
  98  *
  99  * BUGS:
 100  *      Since we fake most of this, don't expect fancy usage to
 101  *      work.
 102  *
 103  * AUTHOR:
 104  *      Simon J. Gerraty <sjg@zen.void.oz.au>
 105  */
 106 /* COPYRIGHT:
 107  *      @(#)Copyright (c) 1992 Simon J. Gerraty
 108  *
 109  *      This is free software.  It comes with NO WARRANTY.
 110  *      Permission to use, modify and distribute this source code
 111  *      is granted subject to the following conditions.
 112  *      1/ that that the above copyright notice and this notice
 113  *      are preserved in all copies and that due credit be given
 114  *      to the author.
 115  *      2/ that any changes to this code are clearly commented
 116  *      as such so that the author does get blamed for bugs
 117  *      other than his own.
 118  *
 119  *      Please send copies of changes and bug-fixes to:
 120  *      sjg@zen.void.oz.au
 121  *
 122  */
 123 /* Changes to sigact.c for pdksh, Michael Rendell <michael@cs.mun.ca>:
 124  *      - sigsuspend(): pass *mask to bsd4.2 sigpause instead of mask.
 125  *      - changed SIG_HDLR to void for use with GNU autoconf
 126  *      - include sh.h instead of signal.h (to get *_SIGNALS macros)
 127  *      - changed if !SA_NOCLDSTOP ... to USE_FAKE_SIGACT to avoid confusion
 128  *      - set the USE_* defines using the *_SIGNALS defines from autoconf
 129  *      - sigaction(): if using BSD signals, use sigvec() (used to use
 130  *        signal()) and set the SV_INTERRUPT flag (POSIX says syscalls
 131  *        are interrupted and pdksh needs this behaviour).
 132  *      - define IS_KSH before including anything; ifdef out routines
 133  *        not used in ksh if IS_KSH is defined (same in sigact.h).
 134  *      - use ARGS() instead of __P()
 135  *      - sigaction(),sigsuspend(),_Signal(),signal(): use handler_t typedef
 136  *        instead of explicit type.
 137  */
 138
 139 /*
 140     #include <signal.h>
 141 */
 142 #define IS_KSH
 143 #include "sh.h"
 144
 145 /*
 146     #ifndef __P
 147     # if defined(__STDC__) || defined(__cplusplus)
 148     #   define  __P(p)  p
 149     # else
 150     #   define  __P(p)  ()
 151     # endif
 152     #endif
 153 */
 154
 155
 156 /*
 157  * some systems have a faulty sigaction() implementation!
 158  * Allow us to bypass it.
 159  * Or they may have installed sigact.h as signal.h which is why
 160  * we have SA_NOCLDSTOP defined.
 161  */
 162
 163 #include "sigact.h"
 164
 165 int
 166 #if defined(__AROS__)
 167 sigaction(int sig, const struct sigaction *act, struct sigaction *oact)
 168 #else
 169 sigaction(int sig, struct sigaction *act, struct sigaction *oact)
 170 #endif
 171 {
 172   handler_t oldh;
 173
 174   if (act)
 175   {
 176     oldh = signal(sig, act->sa_handler);
 177   }
 178   else
 179   {
 180     if (oact)
 181     {
 182       oldh = signal(sig, SIG_IGN);
 183       if (oldh != SIG_IGN && oldh !=  SIG_ERR)
 184       {
 185         (void) signal(sig, oldh);
 186       }
 187     }
 188   }
 189   if (oact)
 190   {
 191     oact->sa_handler = oldh;
 192   }
 193   return 0;                             /* hey we're faking it */
 194 }
 195
 196 #if !defined(NEWLIB) && !defined(__AROS__)
 197 int sigaddset(sigset_t *mask, int sig)
 198 {
 199   *mask |= sigmask(sig);
 200   return 0;
 201 }
 202
 203 int
 204 sigemptyset(sigset_t *mask)
 205 {
 206   *mask = 0;
 207   return 0;
 208 }
 209 #endif
 210
 211 #if !defined(CLIB2) && !defined(__AROS__)
 212 int
 213 sigprocmask(int how, const sigset_t *set, sigset_t *oset)
 214 {
 215   static sigset_t sm;
 216   static int once = 0;
 217
 218   if (!once)
 219   {
 220     /*
 221      * initally we clear sm,
 222      * there after, it represents the last
 223      * thing we did.
 224      */
 225     once++;
 226     sm = 0;
 227   }
 228
 229   if (oset)
 230     *oset = sm;
 231   if (set)
 232   {
 233     switch (how)
 234     {
 235     case SIG_BLOCK:
 236       sm |= *set;
 237       break;
 238     case SIG_UNBLOCK:
 239       sm &= ~(*set);
 240       break;
 241     case SIG_SETMASK:
 242       sm = *set;
 243       break;
 244     }
 245   }
 246   return 0;
 247 }
 248 #endif
 249
 250 #if !defined(void)
 251 # define void void
 252 #endif
 253 #if !defined(SIG_ERR)
 254 # define SIG_ERR        (void (*)())-1
 255 #endif
 256