Re: abort() on Windows 2008 Server

[Bruno Haible]

Hi Eric,

Thanks for the forward.

Ramiro Polla wrote:
> > The loop at sigprocmask.c:197 tests signal() on all signals up to NSIG
> > for SIG_ERR. On some version of Windows (I haven't checked which one,
> > but it affects Windows 2008 Server), a new signal has been added. It
> > is the SIGABRT_COMPAT signal, which is the same as SIGABRT [0]. So on
> > that loop, signal() is called twice for the same signal.

To be clear: The value of SIGABRT under native Windows, 22, has not changed.
The visible change is that <signal.h> of newer MSVS contains the line
  #define SIGABRT_COMPAT 6

> > The abort() on sigprocmask.c:218 has the comment:
> > /* The application changed a signal handler while the signal
> >    was blocked, bypassing our rpl_signal replacement.
> >    We don't support this.  */
> >
> > Actually you are changing it yourself. Once for signal 6 (which is the
> > value of SIGABRT_COMPAT), and then again for 22 (SIGABRT).

Thanks for this analysis. The sigset_t datatype introduced by gnulib has
to be adjusted. I propose this patch. Eric, what do you think?


2008-10-18  Bruno Haible  <address@hidden>

        * lib/sigprocmask.c (SIGABRT_COMPAT): New macro.
        (sigismember, sigaddset, sigdelset, sigfillset, rpl_signal): Handle it
        as an alias for SIGABRT.
        * lib/sigaction.c (SIGABRT_COMPAT): New macro.
        (sigaction): Map it to SIGABRT.
        Reported by Ramiro Polla <address@hidden> via Eric Blake.

*** lib/sigprocmask.c.orig      2008-10-18 23:29:26.000000000 +0200
--- lib/sigprocmask.c   2008-10-18 23:24:48.000000000 +0200
***************
*** 43,48 ****
--- 43,56 ----
  # define SIGSTOP (-1)
  #endif
  
+ /* On native Windows, as of 2008, the signal SIGABRT_COMPAT is an alias
+    for the signal SIGABRT.  Only one signal handler is stored for both
+    SIGABRT and SIGABRT_COMPAT.  SIGABRT_COMPAT is not a signal of its own.  */
+ #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+ # undef SIGABRT_COMPAT
+ # define SIGABRT_COMPAT 6
+ #endif
+ 
  typedef void (*handler_t) (int);
  
  /* Handling of gnulib defined signals.  */
***************
*** 74,80 ****
  sigismember (const sigset_t *set, int sig)
  {
    if (sig >= 0 && sig < NSIG)
!     return (*set >> sig) & 1;
    else
      return 0;
  }
--- 82,95 ----
  sigismember (const sigset_t *set, int sig)
  {
    if (sig >= 0 && sig < NSIG)
!     {
!       #ifdef SIGABRT_COMPAT
!       if (sig == SIGABRT_COMPAT)
!       sig = SIGABRT;
!       #endif
! 
!       return (*set >> sig) & 1;
!     }
    else
      return 0;
  }
***************
*** 91,96 ****
--- 106,116 ----
  {
    if (sig >= 0 && sig < NSIG)
      {
+       #ifdef SIGABRT_COMPAT
+       if (sig == SIGABRT_COMPAT)
+       sig = SIGABRT;
+       #endif
+ 
        *set |= 1U << sig;
        return 0;
      }
***************
*** 106,111 ****
--- 126,136 ----
  {
    if (sig >= 0 && sig < NSIG)
      {
+       #ifdef SIGABRT_COMPAT
+       if (sig == SIGABRT_COMPAT)
+       sig = SIGABRT;
+       #endif
+ 
        *set &= ~(1U << sig);
        return 0;
      }
***************
*** 119,125 ****
  int
  sigfillset (sigset_t *set)
  {
!   *set = (2U << (NSIG - 1)) - 1;
    return 0;
  }
  
--- 144,154 ----
  int
  sigfillset (sigset_t *set)
  {
!   *set = ((2U << (NSIG - 1)) - 1)
!        #ifdef SIGABRT_COMPAT
!        & ~(1U << SIGABRT_COMPAT)
!        #endif
!        ;
    return 0;
  }
  
***************
*** 241,246 ****
--- 270,280 ----
    if (sig >= 0 && sig < NSIG && sig != SIGKILL && sig != SIGSTOP
        && handler != SIG_ERR)
      {
+       #ifdef SIGABRT_COMPAT
+       if (sig == SIGABRT_COMPAT)
+       sig = SIGABRT;
+       #endif
+ 
        if (blocked_set & (1U << sig))
        {
          /* POSIX states that sigprocmask and signal are both
*** lib/sigaction.c.orig        2008-10-18 23:29:26.000000000 +0200
--- lib/sigaction.c     2008-10-18 23:27:42.000000000 +0200
***************
*** 64,69 ****
--- 64,77 ----
  # define SIGSTOP (-1)
  #endif
  
+ /* On native Windows, as of 2008, the signal SIGABRT_COMPAT is an alias
+    for the signal SIGABRT.  Only one signal handler is stored for both
+    SIGABRT and SIGABRT_COMPAT.  SIGABRT_COMPAT is not a signal of its own.  */
+ #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+ # undef SIGABRT_COMPAT
+ # define SIGABRT_COMPAT 6
+ #endif
+ 
  /* A signal handler.  */
  typedef void (*handler_t) (int signal);
  
***************
*** 134,139 ****
--- 142,152 ----
        return -1;
      }
  
+   #ifdef SIGABRT_COMPAT
+   if (sig == SIGABRT_COMPAT)
+     sig = SIGABRT;
+   #endif
+ 
    /* POSIX requires sigaction() to be async-signal-safe.  In other
       words, if an asynchronous signal can occur while we are anywhere
       inside this function, the user's handler could then call