linux-kernel - Re: [PATCH] kconfig: remove 'const' from the return type of sym_escape

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Message-ID: <YVLol5WyUCrKu7tY@deb-nschier.ads.avm.de>
Date:   Tue, 28 Sep 2021 12:04:07 +0200
From:   Nicolas Schier <n.schier@....de>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kconfig: remove 'const' from the return type of
 sym_escape_string()

On Mon, Sep 27, 2021 at 09:59:44PM +0900, Masahiro Yamada wrote:
> sym_escape_string() returns a malloc'ed memory, so it must be freed
> when it is done.
> 
> Currently, sym_escape_string() returns the malloc'ed memory as
> (const char *), then it is casted to (void *) when it is passed to
> free(). This is odd.
> 
> The return type of sym_escape_string() should be (char *).
> 
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>

Reviewed-by: Nicolas Schier <n.schier@....de>

> ---
> 
>  scripts/kconfig/conf.c      | 10 +++++-----
>  scripts/kconfig/confdata.c  |  8 ++++----
>  scripts/kconfig/lkc_proto.h |  2 +-
>  scripts/kconfig/symbol.c    |  3 ++-
>  4 files changed, 12 insertions(+), 11 deletions(-)
> 
> diff --git a/scripts/kconfig/conf.c b/scripts/kconfig/conf.c
> index a6dad4a2e7a2..d8e1994bfed0 100644
> --- a/scripts/kconfig/conf.c
> +++ b/scripts/kconfig/conf.c
> @@ -647,15 +647,15 @@ static void check_conf(struct menu *menu)
>  		switch (input_mode) {
>  		case listnewconfig:
>  			if (sym->name) {
> -				const char *str;
> -
>  				if (sym->type == S_STRING) {
> +					char *str;
> +
>  					str = sym_escape_string(sym);
>  					printf("%s%s=%s\n", CONFIG_, sym->name, str);
> -					free((void *)str);
> +					free(str);
>  				} else {
> -					str = sym_get_string_value(sym);
> -					printf("%s%s=%s\n", CONFIG_, sym->name, str);
> +					printf("%s%s=%s\n", CONFIG_, sym->name,
> +					       sym_get_string_value(sym));
>  				}
>  			}
>  			break;
> diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
> index 4e053f2477f9..f7eac4beb128 100644
> --- a/scripts/kconfig/confdata.c
> +++ b/scripts/kconfig/confdata.c
> @@ -728,7 +728,7 @@ static struct conf_printer header_printer_cb =
>  static void conf_write_symbol(FILE *fp, struct symbol *sym,
>  			      struct conf_printer *printer, void *printer_arg)
>  {
> -	const char *str;
> +	char *str;
>  
>  	switch (sym->type) {
>  	case S_UNKNOWN:
> @@ -736,11 +736,11 @@ static void conf_write_symbol(FILE *fp, struct symbol *sym,
>  	case S_STRING:
>  		str = sym_escape_string(sym);
>  		printer->print_symbol(fp, sym, str, printer_arg);
> -		free((void *)str);
> +		free(str);
>  		break;
>  	default:
> -		str = sym_get_string_value(sym);
> -		printer->print_symbol(fp, sym, str, printer_arg);
> +		printer->print_symbol(fp, sym, sym_get_string_value(sym),
> +				      printer_arg);
>  	}
>  }
>  
> diff --git a/scripts/kconfig/lkc_proto.h b/scripts/kconfig/lkc_proto.h
> index 035cc522808b..7ce4b666bba8 100644
> --- a/scripts/kconfig/lkc_proto.h
> +++ b/scripts/kconfig/lkc_proto.h
> @@ -18,7 +18,7 @@ extern struct symbol * symbol_hash[SYMBOL_HASHSIZE];
>  
>  struct symbol * sym_lookup(const char *name, int flags);
>  struct symbol * sym_find(const char *name);
> -const char * sym_escape_string(struct symbol *sym);
> +char *sym_escape_string(struct symbol *sym);
>  struct symbol ** sym_re_search(const char *pattern);
>  const char * sym_type_name(enum symbol_type type);
>  void sym_calc_value(struct symbol *sym);
> diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
> index 4a31bb943f79..57189a1ad797 100644
> --- a/scripts/kconfig/symbol.c
> +++ b/scripts/kconfig/symbol.c
> @@ -871,7 +871,8 @@ struct symbol *sym_find(const char *name)
>  	return symbol;
>  }
>  
> -const char *sym_escape_string(struct symbol *sym)
> +/* the returned pointer must be freed on the caller side */
> +char *sym_escape_string(struct symbol *sym)
>  {
>  	const char *in, *p;
>  	size_t reslen;
> -- 
> 2.30.2
>