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Bug 000091

When Created: 06/13/1996 09:51:57
Against DJGPP version: 2.00
By whom: eliz@is.elta.co.il
Abstract: `sigaction' always returns SIG_DFL instead of previous handler
The library function `sigaction' always returns SIG_DFL, even if
a handler has already been installed for its signal argument.  Thus,
if a program needs to temporary uninstall the signal handler and then
reinstall it, and relies on `sigaction' to return the current handler,
it will get SIG_DFL and thus effectively revert the signal handling
to the default state (i.e. the next signal will abort the program).

Solution added: 06/13/1996 09:54:39
By whom: eliz@is.elta.co.il
Apply this patch:
*** posix/signal/sigactio.c~0   Sun Apr  2 01:11:10 1995
--- posix/signal/sigactio.c     Thu Apr  4 19:50:18 1996
***************
*** 1,19 ****
  /* Copyright (C) 1995 DJ Delorie, see COPYING.DJ for details */
  #include <signal.h>

  int
  sigaction(int _sig, const struct sigaction *_act, struct sigaction *_oact)
  {
    if (_oact)
    {
      /* FIXME */
!     _oact->sa_handler = SIG_DFL;
!     sigemptyset(&_oact->sa_mask);
      _oact->sa_flags = 0;
    }
    if (_act)
    {
!     signal(_sig, _act->sa_handler);
    }
!   return 0;
  }
--- 1,35 ----
  /* Copyright (C) 1995 DJ Delorie, see COPYING.DJ for details */
  #include <signal.h>
+ #include <errno.h>

  int
  sigaction(int _sig, const struct sigaction *_act, struct sigaction *_oact)
  {
+   int retval = 0;
+
    if (_oact)
    {
+     void (*installed_sig)(int) = signal (_sig, SIG_IGN);
+
      /* FIXME */
!     if (installed_sig == SIG_ERR)
!     {
!       retval = -1;
!       errno = EINVAL;
!     }
!     else
!       signal (_sig, installed_sig);
!     _oact->sa_handler = installed_sig;
!     retval = sigemptyset(&_oact->sa_mask);
      _oact->sa_flags = 0;
    }
    if (_act)
    {
!     if (signal(_sig, _act->sa_handler) == SIG_ERR)
!     {
!       retval = -1;
!       errno = EINVAL;
!     }
    }
!   return retval;
  }

Fixed in version 2.01 on 07/26/1996 00:28:26
By whom: dj@delorie.com



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