Re: [PATCH 1/4] Btrfs-progs: new helper to parse string to u64 for btrfs

[Stefan Behrens <sbehrens@giantdisaster.de>]

On Wed, 19 Feb 2014 19:17:51 +0800, Wang Shilong wrote:
> There are many places that need parse string to u64 for btrfs commands,
> in fact, we do such things *too casually*, using atoi/atol/atoll..is not
> right at all, and even we don't check whether it is a valid string.
> 
> Let's do everything more gracefully, we introduce a new helper
> btrfs_strtoull() which will do all the necessary checks.If we fail to
> parse string to u64, we will output message and exit directly, this is
> something like what usage() is doing. It is ok to not return erro to
> it's caller, because this function should be called when parsing arg
> (just like usage!)
> 
> Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
> ---
>  utils.c | 19 +++++++++++++++++++
>  utils.h |  1 +
>  2 files changed, 20 insertions(+)
> 
> diff --git a/utils.c b/utils.c
> index 97e23d5..0698d8d 100644
> --- a/utils.c
> +++ b/utils.c
> @@ -1520,6 +1520,25 @@ scan_again:
>  	return 0;
>  }
>  
> +u64 btrfs_strtoull(char *str, int base)
> +{
> +	u64 value;
> +	char *ptr_parse_end = NULL;
> +	char *ptr_str_end = str + strlen(str);
> +
> +	value = strtoull(str, &ptr_parse_end, base);
> +	if (ptr_parse_end != ptr_str_end) {
> +		fprintf(stderr, "ERROR: %s is not an invalid unsigned long long integer.\n",

"not invalid" :)

> +				str);
> +		exit(1);
> +	}
> +	if (value == ULONG_MAX) {

ULLONG_MAX or {errno = 0; value = strtoull(...); if (errno == ERANGE)...}


> +		fprintf(stderr, "ERROR: %s is out of range.\n", str);
> +		exit(1);
> +	}

base = 0 is best BTW since it is able to read hex and octal numbers as
well. I'd remove the base parameter to btrfs_strtoull() and always use 0.