[alsa-devel] [PATCH 3/3] ucm: fix inappropriate use of const

[Takashi Iwai]

At Tue, 10 Feb 2015 22:42:34 +0200,
Tanu Kaskinen wrote:
> 
> The caller is expected to free the string returned by
> snd_use_case_get(), but for some reason the string is marked as const,
> so the caller is forced to do type casting to get rid of compiler
> warnings. I don't see any reason for using const in snd_use_case_get(),
> so let's remove that.
> 
> This will cause warnings in application code, if applications
> currently pass const variables to the function, which they very likely
> do. I don't know if that's acceptable. If not, then it's too late to
> fix this bug...

I'm afraid it's too late to change this.


Takashi

> ---
>  include/use-case.h |  2 +-
>  src/ucm/main.c     | 24 ++++++++++++------------
>  2 files changed, 13 insertions(+), 13 deletions(-)
> 
> diff --git a/include/use-case.h b/include/use-case.h
> index f30168f..28d786f 100644
> --- a/include/use-case.h
> +++ b/include/use-case.h
> @@ -286,7 +286,7 @@ int snd_use_case_get_list(snd_use_case_mgr_t *uc_mgr,
>   */
>  int snd_use_case_get(snd_use_case_mgr_t *uc_mgr,
>                       const char *identifier,
> -                     const char **value);
> +                     char **value);
>  
>  /**
>   * \brief Get current - integer
> diff --git a/src/ucm/main.c b/src/ucm/main.c
> index 62bc374..8fbf94f 100644
> --- a/src/ucm/main.c
> +++ b/src/ucm/main.c
> @@ -40,9 +40,9 @@
>   * misc
>   */
>  
> -static int get_value1(const char **value, struct list_head *value_list,
> +static int get_value1(char **value, struct list_head *value_list,
>                        const char *identifier);
> -static int get_value3(const char **value,
> +static int get_value3(char **value,
>  		      const char *identifier,
>  		      struct list_head *value_list1,
>  		      struct list_head *value_list2,
> @@ -299,7 +299,7 @@ static int execute_sequence(snd_use_case_mgr_t *uc_mgr,
>  		case SEQUENCE_ELEMENT_TYPE_CSET:
>  		case SEQUENCE_ELEMENT_TYPE_CSET_BIN_FILE:
>  			if (cdev == NULL) {
> -				const char *cdev1 = NULL, *cdev2 = NULL;
> +				char *cdev1 = NULL, *cdev2 = NULL;
>  				err = get_value3(&cdev1, "PlaybackCTL",
>  						 value_list1,
>  						 value_list2,
> @@ -313,7 +313,7 @@ static int execute_sequence(snd_use_case_mgr_t *uc_mgr,
>  						 value_list2,
>  						 value_list3);
>  				if (err < 0 && err != ENOENT) {
> -					free((char *)cdev1);
> +					free(cdev1);
>  					uc_error("cdev is not defined!");
>  					return err;
>  				}
> @@ -327,11 +327,11 @@ static int execute_sequence(snd_use_case_mgr_t *uc_mgr,
>                                   * before calling open_ctl()). */
>  				if (cdev1 == NULL || cdev2 == NULL ||
>                                      strcmp(cdev1, cdev2) == 0) {
> -					cdev = (char *)cdev1;
> -					free((char *)cdev2);
> +					cdev = cdev1;
> +					free(cdev2);
>  				} else {
> -					free((char *)cdev1);
> -					free((char *)cdev2);
> +					free(cdev1);
> +					free(cdev2);
>  				}
>  			}
>  			if (ctl == NULL) {
> @@ -1233,7 +1233,7 @@ int snd_use_case_get_list(snd_use_case_mgr_t *uc_mgr,
>  	return err;
>  }
>  
> -static int get_value1(const char **value, struct list_head *value_list,
> +static int get_value1(char **value, struct list_head *value_list,
>                        const char *identifier)
>  {
>          struct ucm_value *val;
> @@ -1254,7 +1254,7 @@ static int get_value1(const char **value, struct list_head *value_list,
>          return -ENOENT;
>  }
>  
> -static int get_value3(const char **value,
> +static int get_value3(char **value,
>  		      const char *identifier,
>  		      struct list_head *value_list1,
>  		      struct list_head *value_list2,
> @@ -1284,7 +1284,7 @@ static int get_value3(const char **value,
>   */
>  static int get_value(snd_use_case_mgr_t *uc_mgr,
>  			const char *identifier,
> -			const char **value,
> +			char **value,
>  			const char *mod_dev_name,
>  			const char *verb_name,
>  			int exact)
> @@ -1354,7 +1354,7 @@ static int get_value(snd_use_case_mgr_t *uc_mgr,
>   */      
>  int snd_use_case_get(snd_use_case_mgr_t *uc_mgr,
>  		     const char *identifier,
> -		     const char **value)
> +		     char **value)
>  {
>  	const char *slash1, *slash2, *mod_dev_after;
>  	const char *ident, *mod_dev, *verb;
> -- 
> 1.9.3
>