Re: [Qemu-devel] [PATCH 04/14] qemu-nbd: Simplify --partition handling

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

01.12.2018 1:03, Eric Blake wrote:
> Our open-coding of strtol handling forgot to handle overflow
> conditions. What's more, since we insiste on a user-supplied
> partition to be non-zero, we can use 0 rather than -1 for our
> initial value to distinguish when a partition is not being
> served, for slightly more optimal code.
> 
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>   qemu-nbd.c | 14 +++++---------
>   1 file changed, 5 insertions(+), 9 deletions(-)
> 
> diff --git a/qemu-nbd.c b/qemu-nbd.c
> index 55e29bd9a7e..866e64779f1 100644
> --- a/qemu-nbd.c
> +++ b/qemu-nbd.c
> @@ -546,7 +546,7 @@ int main(int argc, char **argv)
>       int opt_ind = 0;
>       char *end;
>       int flags = BDRV_O_RDWR;
> -    int partition = -1;
> +    int partition = 0;
>       int ret = 0;
>       bool seen_cache = false;
>       bool seen_discard = false;
> @@ -685,13 +685,9 @@ int main(int argc, char **argv)
>               flags &= ~BDRV_O_RDWR;
>               break;
>           case 'P':
> -            partition = strtol(optarg, &end, 0);
> -            if (*end) {
> -                error_report("Invalid partition `%s'", optarg);
> -                exit(EXIT_FAILURE);
> -            }
> -            if (partition < 1 || partition > 8) {
> -                error_report("Invalid partition %d", partition);
> +            if (qemu_strtoi(optarg, NULL, 0, &partition) < 0 ||

I decided to look into qemu_strtoi, hmm.

is it possible, that "char *ep" remains uninitialized, and than we access
it in check_strtox_error? I don's see in strtol spec a guarantee of setting
endptr on failure path.


> +                partition < 1 || partition > 8) {

don't you like brace on separate line after multi-line conditions?

> +                error_report("Invalid partition %s", optarg);
>                   exit(EXIT_FAILURE);
>               }
>               break;
> @@ -1004,7 +1000,7 @@ int main(int argc, char **argv)
>       }
>       fd_size -= dev_offset;
> 
> -    if (partition != -1) {
> +    if (partition) {
>           ret = find_partition(blk, partition, &dev_offset, &fd_size);
>           if (ret < 0) {
>               error_report("Could not find partition %d: %s", partition,
> 

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

-- 
Best regards,
Vladimir