Re: [PATCH v2 01/41] lib: Add a way to find the postiion of a trailing number

[Heinrich Schuchardt <heinrich.schuchardt@canonical.com>]

On 10/24/21 01:25, Simon Glass wrote:
> At present it is not possible to find out which part of the string is the
> number part and which is before it. Add a new variant which provides this
> feature, so we can separate the two in the caller.
> 
> Signed-off-by: Simon Glass <sjg@chromium.org>
> ---
> 
> (no changes since v1)
> 
>   include/vsprintf.h | 18 ++++++++++++++++++
>   lib/strto.c        | 14 ++++++++++++--
>   2 files changed, 30 insertions(+), 2 deletions(-)
> 
> diff --git a/include/vsprintf.h b/include/vsprintf.h
> index b4746301462..8230e7a5126 100644
> --- a/include/vsprintf.h
> +++ b/include/vsprintf.h
> @@ -118,6 +118,24 @@ long trailing_strtol(const char *str);
>    */
>   long trailing_strtoln(const char *str, const char *end);
>   
> +/**
> + * trailing_strtoln() - extract a trailing integer from a fixed-length string
> + *
> + * Given a fixed-length string this finds a trailing number on the string
> + * and returns it. For example, "abc123" would return 123. Only the
> + * characters between @str and @end - 1 are examined. If @end is NULL, it is
> + * set to str + strlen(str).

Please, provide a test with as string like 'abc123def456'.

> + *
> + * @str:	String to exxamine
> + * @end:	Pointer to end of string to examine, or NULL to use the
> + *		whole string
> + * @lenp:	If non-NULL, this is set to the number of characters before the
> + *	number starts, e.g. for "mmc0" this would be 3; if no trailing number is
> + *	found, it is set to the length of the whole string
> + * @return training number if found, else -1
> + */
> +long trailing_strtoln_len(const char *str, const char *end, int *lenp);

Usage in a caller would be easier if you would return a pointer to the 
first digit instead of a length.

Best regards

Heinrich

> +
>   /**
>    * panic() - Print a message and reset/hang
>    *
> diff --git a/lib/strto.c b/lib/strto.c
> index 7bba1e3e549..13ae22a87a1 100644
> --- a/lib/strto.c
> +++ b/lib/strto.c
> @@ -183,7 +183,7 @@ long long simple_strtoll(const char *cp, char **endp, unsigned int base)
>   	return simple_strtoull(cp, endp, base);
>   }
>   
> -long trailing_strtoln(const char *str, const char *end)
> +long trailing_strtoln_len(const char *str, const char *end, int *lenp)
>   {
>   	const char *p;
>   
> @@ -191,14 +191,24 @@ long trailing_strtoln(const char *str, const char *end)
>   		end = str + strlen(str);
>   	if (isdigit(end[-1])) {
>   		for (p = end - 1; p > str; p--) {
> -			if (!isdigit(*p))
> +			if (!isdigit(*p)) {
> +				if (lenp)
> +					*lenp = p - str + 1;
>   				return dectoul(p + 1, NULL);
> +			}
>   		}
>   	}
> +	if (lenp)
> +		*lenp = end - str;
>   
>   	return -1;
>   }
>   
> +long trailing_strtoln(const char *str, const char *end)
> +{
> +	return trailing_strtoln_len(str, end, NULL);
> +}
> +
>   long trailing_strtol(const char *str)
>   {
>   	return trailing_strtoln(str, NULL);
>