[dpdk-dev] [PATCH] cmdline: fix unchecked return value

[Olivier Matz]

Hi Daniel,

On 04/14/2016 03:01 PM, Daniel Mrzyglod wrote:
> This patch is for checking if error values occurs.
> fix for coverity errors #13209 & #13195
> 
> If the function returns an error value, the error value may be mistaken
> for a normal value.
> 
> In rdline_char_in: Value returned from a function is not checked for errors
> before being used
> 
> Signed-off-by: Daniel Mrzyglod <danielx.t.mrzyglod at intel.com>
> ---
>  lib/librte_cmdline/cmdline_rdline.c | 19 +++++++++++++++----
>  1 file changed, 15 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/librte_cmdline/cmdline_rdline.c b/lib/librte_cmdline/cmdline_rdline.c
> index 1ef2258..e75a556 100644
> --- a/lib/librte_cmdline/cmdline_rdline.c
> +++ b/lib/librte_cmdline/cmdline_rdline.c
> @@ -377,7 +377,10 @@ rdline_char_in(struct rdline *rdl, char c)
>  		case CMDLINE_KEY_CTRL_K:
>  			cirbuf_get_buf_head(&rdl->right, rdl->kill_buf, RDLINE_BUF_SIZE);
>  			rdl->kill_size = CIRBUF_GET_LEN(&rdl->right);
> -			cirbuf_del_buf_head(&rdl->right, rdl->kill_size);
> +
> +			if (cirbuf_del_buf_head(&rdl->right, rdl->kill_size) < 0)
> +					return -EINVAL;
> +
>  			rdline_puts(rdl, vt100_clear_right);
>  			break;
>  

I wonder if a better way to fix wouldn't be to remove the checks
introduced in http://dpdk.org/browse/dpdk/commit/?id=ab971e562860

There is no reason to check that in cirbuf_get_buf_head/tail():
    if (!cbuf || !c)

The function should never fail, it just returns the number of
copied chars. This is the responsibility of the caller to ensure
that the pointer to the circular buffer is not NULL.

Also, rdline_char_in() is not expected to return -EINVAL, but
RDLINE_RES_* instead.

So I think that partially revert ab971e562860 would fix the
coverity warning.

Regards,
Olivier