[PATCH 1/3] Add support for different unit.

[Goffredo Baroncelli <kreijack@gmail.com>]

From: Goffredo Baroncelli <kreijack@inwind.it>

The function pretty_sizes() returns a string containing the passed
number. It add a suffix depending by the number: eg KiB, MiB.
This change replace the old SI suffix (KB, MB..) by the IEC
ones (KiB, MiB..). Moreover a space is added between the suffix
and the number.

Setting opprtunately the enviroment variable BTRFS_UNIT, it is
possible to:
BTRFS_UNIT=SI the suffix is KB for 1000bytes, MB for 10^6 bytes...
BTRFS_UNIT=IEC the suffix is KiB for 1024bytes, MiB for 1024 KiB ...
BTRFS_UNIT=COMPACT the suffix is KB for 1024 bytes, MB for 1024 KiB;
                   no space between the number and the suffix.

See http://en.wikipedia.org/wiki/Byte for further information about
the different suffix.
---
 utils.c |   70 +++++++++++++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 61 insertions(+), 9 deletions(-)

diff --git a/utils.c b/utils.c
index 205e667..8528cc1 100644
--- a/utils.c
+++ b/utils.c
@@ -1085,33 +1085,85 @@ out:
 	return ret;
 }
 
-static char *size_strs[] = { "", "KB", "MB", "GB", "TB",
+static char *size_strs_inf[] = { "", "KiB", "MiB", "GiB", "TiB",
+			    "PiB", "EiB", "ZiB", "YiB"};
+static char *size_strs_dec[] = { "", "KB", "MB", "GB", "TB",
 			    "PB", "EB", "ZB", "YB"};
+
+static int which_unit( ){
+	static int unit=-1;
+	char	*u;
+
+	if( unit != -1 )
+		return unit;
+
+	unit = 0;
+
+	u =getenv("BTRFS_UNIT");
+	if(!u) return 0;
+
+	if( !strcmp(u,"SI") )
+		unit = 1;
+	else if( !strcmp(u, "COMPACT") )
+		unit = 2;
+	else if( !strcmp(u, "IEC") )
+		unit = 0;
+	/* else
+		Shall we raise an error ? 
+	*/
+		
+	return unit;
+
+}
+
+
 char *pretty_sizes(u64 size)
 {
 	int num_divs = 0;
-        int pretty_len = 16;
+        int pretty_len = 20;
 	float fraction;
-	char *pretty;
+	char *pretty, *space;
+	int  shift = 1024;
+	char **size_strs;
+
+	if( which_unit() == 1 ){		/* SI */
+		shift = 1000;
+		size_strs = size_strs_dec;
+		space = " ";
+	} else if( which_unit() == 2 ){		/* Old method:
+						   SI suffix, but 
+						   multiply of 1024 */
+		shift = 1024;
+		size_strs = size_strs_dec;
+		space = "";
+	}else{
+		shift = 1024;			/* IEC */
+		size_strs = size_strs_inf;
+		space = " ";
+	}
 
-	if( size < 1024 ){
+	if( size < shift ){
 		fraction = size;
 		num_divs = 0;
 	} else {
 		u64 last_size = size;
 		num_divs = 0;
-		while(size >= 1024){
+		while(size >= shift){
 			last_size = size;
-			size /= 1024;
+			size /= shift;
 			num_divs ++;
 		}
 
-		if (num_divs > ARRAY_SIZE(size_strs))
+		if (num_divs > ARRAY_SIZE(size_strs_inf))
 			return NULL;
-		fraction = (float)last_size / 1024;
+		fraction = (float)last_size / shift;
 	}
 	pretty = malloc(pretty_len);
-	snprintf(pretty, pretty_len, "%.2f%s", fraction, size_strs[num_divs]);
+
+	snprintf(pretty, pretty_len, "%.2f%s%s", 
+		fraction, 
+		space,
+		size_strs[num_divs]);
 	return pretty;
 }
 
-- 
1.7.10.4