Re: [PATCH] Speed up gets

[Jeff Johnston <jjohnstn at redhat dot com>]

Corinna Vinschen wrote:
> Hi,
>
> I'd like to propose the below patch.  The current code implements
> gets/_gets_r in terms of _getchar_r calls.  That means, for every single
> character of input the following sequence of functions is called:
>
>   for each char
>     _getchar_r
>       _getc_r
>         _flockfile
> 	_sgetc_r
> 	_funlockfile
>
> It should be much quicker to move the locking up into gets itself and to
> call __sgetc_r right there, as FreeBSD does as well:
>
>   _flockfile
>   for each char
>     _sgetc_r
>   _funlockfile
>
> That doesn't change the fact that gets is inherently unsecure, of
> course :)
>
> Ok to apply?
>
>   
Yes, please go ahead.

-- Jeff J.
> Thanks,
> Corinna
>
>
> 	* libc/stdio/gets.c (_gets_r): Lock stdin here and call
> 	__sgetc_r instead of _getchar_r.
>
>
> Index: libc/stdio/gets.c
> ===================================================================
> RCS file: /cvs/src/src/newlib/libc/stdio/gets.c,v
> retrieving revision 1.2
> diff -u -p -r1.2 gets.c
> --- libc/stdio/gets.c	23 Apr 2004 20:01:55 -0000	1.2
> +++ libc/stdio/gets.c	24 Nov 2008 17:25:27 -0000
> @@ -79,15 +79,20 @@ _DEFUN(_gets_r, (ptr, buf),
>    register int c;
>    register char *s = buf;
>  
> -  while ((c = _getchar_r (ptr)) != '\n')
> +  _flockfile (stdin);
> +  while ((c = __sgetc_r (ptr, stdin)) != '\n')
>      if (c == EOF)
>        if (s == buf)
> -	return NULL;
> +	{
> +	  _funlockfile (stdin);
> +	  return NULL;
> +	}
>        else
>  	break;
>      else
>        *s++ = c;
>    *s = 0;
> +  _funlockfile (stdin);
>    return buf;
>  }
>  
>
>