C-g does not interrupt lisp code (emacs 21.1 on HP-UX 10.20)

[Klaus Zeitler]

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In GNU Emacs 21.1.4 (hppa2.0-hp-hpux10.20, OSF/Motif Version 1.2.6)
 of 2001-12-06 on nbghs10
configured using `configure  --with-gcc 
--prefix=/vol/freeware/HP-UX-B.10.20/emacs/21.1 
--sharedstatedir=/vol/freeware/HP-UX-B.10.20/emacs/21.1/share 
--with-x-toolkit=motif --x-includes=/usr/include/X11R6:/usr/local/gnu/include 
--x-libraries=/usr/lib/X11R6:/usr/local/gnu/lib --with-pop'
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: C.iso88591
  locale-coding-system: iso-latin-1
  default-enable-multibyte-characters: t

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

A few weeks ago Philippe Waroquiers posted that on HP-UX 11 emacs 21.1
can't be interrupted in an infinite lisp loop.

Under HP-UX 10.20 there's the same problem. C-g doesn't interrupt an
infinite loop in emacs 21.1, but it works with 20.7.  I tried Philippes
suggestions below:

>>>>> "Philippe" == Philippe Waroquiers <wao@gull.sup.cfmu.eurocontrol.be>
>>>>> writes:
    Philippe> 
    Philippe> When defining POSIX_SIGNALS in config.h, C-g is interrupting a
    Philippe> lisp infinite loop.
    Philippe> 
    Philippe> 
    Philippe> Details of what I did:
    Philippe> ----------------------
    Philippe> * first, configure emacs (as previously) and build emacs.
    Philippe> * reproduced the bug (while t) not interruptible.
    Philippe> * edited config.h in src directory, adding 
    Philippe>   #define POSIX_SIGNALS 1
    Philippe>  just after the #define EMACS_CONFIG_H
    Philippe> * make emacs again
    Philippe> * test again => C-g is interrupting.
    Philippe> * tested what the pre-processing was giving.
    Philippe>  The calls to UNBLOCK_ATIMERS are replaced by
    Philippe>  sys_sigunblock ((sys_sigmask (14))) ;
    Philippe> 

The behavior on HP-UX 10.20 is very similar to what Philippe described.
UNBLOCK_ATIMERS is replaced with an empty line.
But defining POSIX_SIGNALS replaces UNBLOCK_ATIMERS with:

  sys_sigunblock ( ({   sigset_t _mask; sigemptyset (&_mask);
        sigaddset (&_mask,  14   );     _mask;  })  )  ;

Unfortunately this doesn't seem to have any effect. Still can't interrupt.

Any hints what and how to investigate further?

Klaus



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