Re: [PATCH V2 1/8] tools lib: adopt str_has_suffix() from bpftool/gen.c

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

On Mon,  8 Apr 2024 11:52:23 +0530
Chaitanya S Prakash <ChaitanyaS.Prakash@arm.com> wrote:

> From: Chaitanya S Prakash <chaitanyas.prakash@arm.com>
> 
> Adopt the definition of str_has_suffix() from tools/bpf/bpftool/gen.c
> and add it to tools/lib/string.c The function is modified to return
> strlen(suffix) on success and 0 on failure.
> 
> Signed-off-by: Chaitanya S Prakash <chaitanyas.prakash@arm.com>
> ---
>  tools/include/linux/string.h |  2 ++
>  tools/lib/string.c           | 26 ++++++++++++++++++++++++++
>  2 files changed, 28 insertions(+)
> 
> diff --git a/tools/include/linux/string.h b/tools/include/linux/string.h
> index db5c99318c79..e43c8f78d63c 100644
> --- a/tools/include/linux/string.h
> +++ b/tools/include/linux/string.h
> @@ -42,6 +42,8 @@ static inline bool strstarts(const char *str, const char *prefix)
>  	return strncmp(str, prefix, strlen(prefix)) == 0;
>  }
>  
> +size_t str_has_suffix(const char *str, const char *suffix);
> +
>  extern char * __must_check skip_spaces(const char *);
>  
>  extern char *strim(char *);
> diff --git a/tools/lib/string.c b/tools/lib/string.c
> index 8b6892f959ab..9cb515048239 100644
> --- a/tools/lib/string.c
> +++ b/tools/lib/string.c
> @@ -226,3 +226,29 @@ void *memchr_inv(const void *start, int c, size_t bytes)
>  
>  	return check_bytes8(start, value, bytes % 8);
>  }
> +
> +/**
> + * str_has_suffix - Test is a string has a given suffix
> + * @str: The string to be tested
> + * @suffix: The string to see if @str ends with
> + *
> + * Returns:
> + * * strlen(@suffix) if @str ends with @suffix
> + * * 0 if @str does not end with @suffix

I think this should return boolean, because user will never check the
return value is strlen(@suffix). (and user always use the return value
as a boolean)

Thank you,

> + */
> +size_t str_has_suffix(const char *str, const char *suffix)
> +{
> +	size_t i;
> +	size_t str_len = strlen(str);
> +	size_t suffix_len = strlen(suffix);
> +
> +	if (str_len < suffix_len)
> +		return 0;
> +
> +	for (i = 0; i < suffix_len ; i++) {
> +		if (str[str_len  - i - 1] != suffix[suffix_len - i - 1])
> +			return 0;
> +	}
> +
> +	return suffix_len;
> +}
> -- 
> 2.30.2
> 
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>