Date:	Thu, 1 Oct 1998 21:07:27 +0300 (IDT)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender:	eliz AT is
To:	djgpp-workers AT delorie DOT com
cc:	DJ Delorie <dj AT delorie DOT com>
Subject:	Unhook the timer at exit
Message-ID:	<Pine.SUN.3.91.981001210618.18395I-100000@is>
MIME-Version:	1.0

Here's a patch that makes sure we don't leave the timer tick interrupt 
pointing into the void.

*** src/libc/go32/dpmiexcp.c~0	Sun Aug 23 14:23:44 1998
--- src/libc/go32/dpmiexcp.c	Tue Sep 29 11:39:14 1998
*************** extern void __djgpp_cbrk_hdlr(void);
*** 39,44 ****
--- 39,45 ----
  extern int __djgpp_hw_lock_start, __djgpp_hw_lock_end;
  extern __dpmi_paddr __djgpp_old_kbd;
  extern unsigned djgpp_exception_stack __asm__("exception_stack");
+ extern __dpmi_paddr __djgpp_old_timer;
  
  static void
  itox(int v, int len)
*************** __djgpp_exception_processor(void)
*** 385,390 ****
--- 386,392 ----
  static __dpmi_paddr except_ori[EXCEPTION_COUNT];
  static __dpmi_paddr kbd_ori;
  static __dpmi_paddr npx_ori;
+ static __dpmi_paddr timer_ori;
  static __dpmi_raddr cbrk_ori,cbrk_rmcb;
  static char cbrk_hooked = 0;
  static __dpmi_regs cbrk_regs;
*************** __djgpp_exception_toggle(void)
*** 420,425 ****
--- 422,444 ----
      __dpmi_set_real_mode_interrupt_vector(cbrk_vect, &cbrk_rmcb);
      cbrk_hooked = 1;
    }
+   /* If the timer interrupt is hooked, toggle it as well.  This is so
+      programs which use SIGALRM or itimer, and don't unhook the timer before
+      they exit, won't leave the system with timer pointing into the void.  */
+   if (__djgpp_old_timer.selector != 0 && __djgpp_old_timer.offset32 != 0)
+   {
+     if (timer_ori.selector == __djgpp_old_timer.selector
+ 	&& timer_ori.offset32 == __djgpp_old_timer.offset32)
+     {
+       __dpmi_get_protected_mode_interrupt_vector(8, &timer_ori);
+       __dpmi_set_protected_mode_interrupt_vector(8, &__djgpp_old_timer);
+     }
+     else
+     {
+       __dpmi_set_protected_mode_interrupt_vector(8, &timer_ori);
+       timer_ori = __djgpp_old_timer;
+     }
+   }
  }
  
  #define RSHIFT 1
*************** __djgpp_exception_setup(void)
*** 532,537 ****
--- 551,557 ----
    __dpmi_set_protected_mode_interrupt_vector(0x24, &except);
  
    __dpmi_get_protected_mode_interrupt_vector(9, &__djgpp_old_kbd);
+   __dpmi_get_protected_mode_interrupt_vector(8, &timer_ori);
    __djgpp_exception_toggle();	/* Set new values & save old values */
  
    /* get original video mode and save */
*** src/docs/kb/wc202.t~0	Sun Jul 26 13:34:04 1998
--- src/docs/kb/wc202.txi	Tue Sep 29 11:51:12 1998
***************
*** 447,449 ****
--- 447,461 ----
  interrupted or crashed, and reports the run time with millisecond
  resolution.
  @cindex redir
+ 
+ The exit code now makes sure the timer interrupt is left pointing to its
+ original handler, even if the program is aborted, or exits without
+ disabling timers.  @code{__djgpp_exception_toggle} now toggles the timer
+ interrupt handler as well, if it was hooked by SIGALRM/SIGPROF handler
+ or by @code{setitimer}.  Thus, timers, periodic alarms, and profiling
+ will be disabled inside blocks that call @code{__djgpp_exception_toggle}.
+ @findex __djgpp_exception_toggle
+ @findex setitimer
+ @cindex SIGALRM
+ @cindex SIGPROF
+ @cindex profiling

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