Re: [PATCH] Don't close or flush stdio streams on abort

[OndÅej BÃlka <neleai at seznam dot cz>]

On Wed, May 08, 2013 at 11:31:05AM +0200, Andreas Schwab wrote:
> +* The abort function no longer tries to flush or close any stdio streams.
> +  Doing so would run into locking problems because abort is required to be
> +  async-signal-safe, but fflush and fclose cannot be.

I agree with removal at stage 1.

However removal at stage 4 could cause debugging info not be displayed.
Could it be possible to ignore delivery with something like sigprocmask?
Stopping other threads could be possible but probably an overkill.

Ondra.
>  Version 2.17
>  
> diff --git a/stdlib/abort.c b/stdlib/abort.c
> index 72b2d60..4b7df18 100644
> --- a/stdlib/abort.c
> +++ b/stdlib/abort.c
> @@ -30,9 +30,6 @@
>  # define ABORT_INSTRUCTION
>  #endif
>  
> -#include <libio/libioP.h>
> -#define fflush(s) _IO_flush_all_lockp (0)
> -
>  /* Exported variable to locate abort message in core files etc.  */
>  struct abort_msg_s *__abort_msg __attribute__ ((nocommon));
>  libc_hidden_def (__abort_msg)
> @@ -66,16 +63,8 @@ abort (void)
>  	__sigprocmask (SIG_UNBLOCK, &sigs, (sigset_t *) NULL);
>      }
>  
> -  /* Flush all streams.  We cannot close them now because the user
> -     might have registered a handler for SIGABRT.  */
> -  if (stage == 1)
> -    {
> -      ++stage;
> -      fflush (NULL);
> -    }
> -
>    /* Send signal which possibly calls a user handler.  */
> -  if (stage == 2)
> +  if (stage == 1)
>      {
>        /* This stage is special: we must allow repeated calls of
>  	 `abort' when a user defined handler for SIGABRT is installed.
> @@ -93,7 +82,7 @@ abort (void)
>      }
>  
>    /* There was a handler installed.  Now remove it.  */
> -  if (stage == 3)
> +  if (stage == 2)
>      {
>        ++stage;
>        memset (&act, '\0', sizeof (struct sigaction));
> @@ -103,30 +92,22 @@ abort (void)
>        __sigaction (SIGABRT, &act, NULL);
>      }
>  
> -  /* Now close the streams which also flushes the output the user
> -     defined handler might has produced.  */
> -  if (stage == 4)
> -    {
> -      ++stage;
> -      __fcloseall ();
> -    }
> -
>    /* Try again.  */
> -  if (stage == 5)
> +  if (stage == 3)
>      {
>        ++stage;
>        raise (SIGABRT);
>      }
>  
>    /* Now try to abort using the system specific command.  */
> -  if (stage == 6)
> +  if (stage == 4)
>      {
>        ++stage;
>        ABORT_INSTRUCTION;
>      }
>  
>    /* If we can't signal ourselves and the abort instruction failed, exit.  */
> -  if (stage == 7)
> +  if (stage == 5)
>      {
>        ++stage;
>        _exit (127);
> -- 
> 1.8.2.2
> 
> -- 
> Andreas Schwab, SUSE Labs, schwab@suse.de
> GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
> "And now for something completely different."