On Fri, May 09, 2014 at 01:58:06PM +0200, Arturo Borrero Gonzalez wrote:
> We need to store in 'offset' the complete amount of characters as returned
> from _snprintf. The value means how many characters long needs the buffer to be
> in order to store the corresponding string expansion.
>
> Before this patch, in cases where the buffer is smaller than the
> expansion, then ret > len, and therefore ret = len.
> So when incrementing offset, we do it with a wrong value.
>
> All previous versions of libnftnl are unable to handle this situations: small
> buffers (or long string expansion).
>
> BTW, if a caller must reallocate a buffer to the returned value of snprintf, it
> should be ret + 1.
Thanks for looking into this.
> Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@xxxxxxxxx>
> ---
> src/internal.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/internal.h b/src/internal.h
> index 6595e70..43d61ca 100644
> --- a/src/internal.h
> +++ b/src/internal.h
> @@ -184,9 +184,9 @@ struct nft_set_elem {
>
> #define SNPRINTF_BUFFER_SIZE(ret, size, len, offset) \
We should also check if (ret < 0) here in first place, in that case
return ret.
> size += ret; \
You have to move this line above where offset += len was previously.
> + offset += ret; \
> if (ret > len) \
> ret = len; \
> - offset += ret; \
> len -= ret;
After those changes, this macro looks good to me.
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