[Libguestfs] sscanf/stroul (was: Re: [PATCH nbdkit v3 2/3] Add new retry filter.)
On Thu, Sep 19, 2019 at 11:32:47AM -0500, Eric Blake wrote:
> +static int
> +retry_config (nbdkit_next_config *next, void *nxdata,
> + const char *key, const char *value)
> +{
> + int r;
> +
> + if (strcmp (key, "retries") == 0) {
> + if (sscanf (value, "%d", &retries) != 1 || retries < 0) {
> + nbdkit_error ("cannot parse retries: %s", value);
> + return -1;
> + }
> + }
> + else if (strcmp (key, "retry-delay") == 0) {
> + if (sscanf (value, "%d", &initial_delay) != 1 || initial_delay
<= 0) {
sscanf("%d") cannot detect overflow; should this use strtol with errno
checking instead?
AIUI glibc does detect overflow, but it's the C17/POSIX standards
which don't mandate it?
I had a longer email here where I was going to suggest replacing all
use of sscanf/strtoul with new nbdkit_parse_* functions, but we would
need a lot of them and they still wouldn't cover all the clever uses
we make of sscanf, eg:
https://github.com/libguestfs/nbdkit/blob/cfbbe17ee21a9a47a96a5ac7f4321d2...
So I still think the right way to solve this is to fix C2x / POSIX so
it mandates what is possibly already the glibc behaviour.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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