[PATCH v2 01/61] kvargs: add numeric conversion helpers

[fengchengwen]

On 9/30/2026 12:36 AM, Stephen Hemminger wrote:
> Drivers which take numeric values in devargs each open code the
> conversion from string to integer, and often get it wrong.
> A survey of the tree finds at least fifteen separate
> implementations of "parse an unsigned integer devarg", of which two are
> exported from lib/ and byte for byte identical to each other.
> 
> The recurring bugs are:
> 
>   - atoi() is used, so overflow is undefined and nothing is validated;
>   - errno is checked without being reset first, so an unrelated earlier
>     failure rejects a valid value;
>   - errno is checked but endptr is not, so "foo" is silently accepted
>     as zero;
>   - endptr is checked but errno is not, so an overflowing value is
>     accepted as ULLONG_MAX;
>   - the result is stored into a narrower type with no range check, so
>     nb_desc=65537 silently becomes 1;
>   - strtoul() is used for an unsigned target, so a leading '-' is
>     accepted and wrapped around, and dev_caps_mask=-1 enables
>     everything;
>   - the value is dereferenced without checking for NULL, so a key given
>     with no value segfaults;
>   - base 0 is passed, so a leading zero unexpectedly selects octal.
> 
> Add a set of helpers matching arg_handler_t, so they can be passed
> straight to rte_kvargs_process(), covering the integer types drivers
> actually store into. Each validates the whole string and only writes
> the target on success, so a caller supplied default survives a bad
> argument.
> 
> Add rte_kvargs_handle_bool for on/off style arguments. It accepts the
> word forms which only sfc supports today, and treats a key given
> without a value as true.
> 
> Where a driver needs a range narrower than the target type, expose the
> underlying rte_kvargs_to_uint and rte_kvargs_to_int.
> 
> Octal is deliberately not supported: no driver documents it, and
> reading "010" as eight has been a recurring surprise.
> 
> Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
> ---

...

> +
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice.
> + *
> + * Convert a string to a signed integer, checking it against a range.
> + *
> + * This is the signed counterpart of rte_kvargs_to_uint().
> + *
> + * @param value
> + *   The string to convert. Must be non-NULL and non-empty. See
> + *   rte_kvargs_handle_u8() for the accepted syntax.
> + * @param min
> + *   Smallest acceptable value, inclusive.
> + * @param max
> + *   Largest acceptable value, inclusive.
> + * @param result
> + *   Where to store the converted value. Left unmodified on error.
> + *
> + * @return
> + *   - 0 on success.
> + *   - -EINVAL if the value is missing or malformed, or if @p result is NULL.
> + *   - -ERANGE if the value is outside [@p min, @p max].
> + */
> +__rte_experimental
> +int rte_kvargs_to_int(const char *value, int64_t min, int64_t max,
> +	int64_t *result);

How about rte_kvargs_handle_int_range() ?

> +
>  #ifdef __cplusplus
>  }
>  #endif