Re: [PATCH 4/4] btrfs-progs: change -t option for subvolume list to print a simple space-separated table (making it machine-readable)

[Goffredo Baroncelli <kreijack@libero.it>]

On 2015-10-02 18:41, axel@tty0.ch wrote:
> Old implementation used tabs "\t", and tried to work around problems
> by guessing amount of tabs needed (e.g. "\t\t" after top level", with
> buggy output as soon as empty uuids are printed). This will never work
> correctly, as tab width is a user-defined setting in the terminal.


Why not use string_table() and table_*() functions  ? 

> 
> Keep it simple and don't reimplement the wheel, for nice tabular
> output we have the "column" command from util-linux:
> 
>     btrfs subvolume list -t <path> | column -t
> 
> Signed-off-by: Axel Burri <axel@tty0.ch>
> ---
>  btrfs-list.c | 40 ++++++++++++----------------------------
>  1 file changed, 12 insertions(+), 28 deletions(-)
> 
> diff --git a/btrfs-list.c b/btrfs-list.c
> index f8396e7..c09257a 100644
> --- a/btrfs-list.c
> +++ b/btrfs-list.c
> @@ -45,12 +45,12 @@ struct root_lookup {
>  };
>  
>  static struct {
> -	char	*name;
> +	char	*name;  /* machine-readable column identifier: [a-z_]+ */
>  	char	*column_name;
>  	int	need_print;
>  } btrfs_list_columns[] = {
>  	{
> -		.name		= "ID",
> +		.name		= "id",
>  		.column_name	= "ID",
>  		.need_print	= 0,
>  	},
> @@ -70,7 +70,7 @@ static struct {
>  		.need_print	= 0,
>  	},
>  	{
> -		.name		= "top level",
> +		.name		= "top_level",
>  		.column_name	= "Top Level",
>  		.need_print	= 0,
>  	},
> @@ -1465,13 +1465,10 @@ static void print_single_volume_info_table(struct root_info *subv)
>  		if (!btrfs_list_columns[i].need_print)
>  			continue;
>  
> -		print_subvolume_column(subv, i);
> -
> -		if (i != BTRFS_LIST_PATH)
> -			printf("\t");
> +		if (i != 0)
> +			printf(" ");
>  
> -		if (i == BTRFS_LIST_TOP_LEVEL)
> -			printf("\t");
> +		print_subvolume_column(subv, i);
>  	}
>  	printf("\n");
>  }
> @@ -1496,30 +1493,17 @@ static void print_single_volume_info_default(struct root_info *subv)
>  static void print_all_volume_info_tab_head(void)
>  {
>  	int i;
> -	int len;
> -	char barrier[20];
> -
> -	for (i = 0; i < BTRFS_LIST_ALL; i++) {
> -		if (btrfs_list_columns[i].need_print)
> -			printf("%s\t", btrfs_list_columns[i].name);
> -
> -		if (i == BTRFS_LIST_ALL-1)
> -			printf("\n");
> -	}
>  
>  	for (i = 0; i < BTRFS_LIST_ALL; i++) {
> -		memset(barrier, 0, sizeof(barrier));
> +		if (!btrfs_list_columns[i].need_print)
> +			continue;
>  
> -		if (btrfs_list_columns[i].need_print) {
> -			len = strlen(btrfs_list_columns[i].name);
> -			while (len--)
> -				strcat(barrier, "-");
> +		if (i != 0)
> +			printf(" ");
>  
> -			printf("%s\t", barrier);
> -		}
> -		if (i == BTRFS_LIST_ALL-1)
> -			printf("\n");
> +		printf(btrfs_list_columns[i].name);
>  	}
> +	printf("\n");
>  }
>  
>  static void print_all_volume_info(struct root_lookup *sorted_tree,
> 


-- 
gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D  17B2 0EDA 9B37 8B82 E0B5

-- 
gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D  17B2 0EDA 9B37 8B82 E0B5