svn commit: r197752 - head/lib/libc/stdio

[Max Laier]

On Sunday 04 October 2009 21:43:36 David Schultz wrote:
> Author: das
> Date: Sun Oct  4 19:43:36 2009
> New Revision: 197752
> URL: http://svn.freebsd.org/changeset/base/197752
> 
> Log:
>   Better glibc compatibility for getline/getdelim:
> 
>   - Tolerate applications that pass a NULL pointer for the buffer and
>     claim that the capacity of the buffer is nonzero.
> 
>   - If an application passes in a non-NULL buffer pointer and claims the
>     buffer has zero capacity, we should free (well, realloc) it
>     anyway. It could have been obtained from malloc(0), so failing to
>     free it would be a small memory leak.
> 
>   MFC After:	2 weeks
>   Reported by:	naddy
>   PR:		ports/138320
> 
> Modified:
>   head/lib/libc/stdio/getdelim.c
> 
> Modified: head/lib/libc/stdio/getdelim.c
> ===========================================================================
> === --- head/lib/libc/stdio/getdelim.c	Sun Oct  4 19:03:32 2009	(r197751)
>  +++ head/lib/libc/stdio/getdelim.c	Sun Oct  4 19:43:36 2009	(r197752) @@
>  -120,8 +120,8 @@ getdelim(char ** __restrict linep, size_
>  		goto error;
>  	}
> 
> -	if (*linecapp == 0)
> -		*linep = NULL;
> +	if (*linep == NULL)
> +		*linecapp = 0;
> 
>  	if (fp->_r <= 0 && __srefill(fp)) {
>  		/* If fp is at EOF already, we just need space for the NUL. */

I think we should have kept the original if case here, as well.  Otherwise 
something like this might fail:

	char *line;				/* note uninitialized */
	size_t len = 0;
	getline(&line, &len, fd);

and I think it is a reasonable thing to pass in an uninitialized pointer if 
you tell that there is no space associated with it, yet.

I don't know if there are many (ab)uses of getline like this, but I was just 
bitten by it.

--
  Max