Allow size as a percent for torusd. Fixes #175

cmd/torusd/main.go

@@ -5,6 +5,9 @@ import (
 	"net/url"
 	"os"
 	"os/signal"
+	"strings"
+	"strconv"
+	"syscall"
 
 	"github.com/coreos/pkg/capnslog"
 	"github.com/dustin/go-humanize"
@@ -110,10 +113,34 @@ func configureServer(cmd *cobra.Command, args []string) {
 		fmt.Fprintf(os.Stderr, "error parsing read-cache-size: %s\n", err)
 		os.Exit(1)
 	}
-	size, err = humanize.ParseBytes(sizeStr)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "error parsing size: %s\n", err)
-		os.Exit(1)
+	if strings.Contains(sizeStr, "%") {
+		var stat syscall.Statfs_t
+		sizePercent := strings.Split(sizeStr, "%")[0]
+		sizeNumber, err := strconv.Atoi(sizePercent)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "error parsing size: %s\n", err)
+			os.Exit(1)
+		}
+		if sizeNumber < 1 || sizeNumber > 100 {
+			fmt.Fprintf(os.Stderr, "invalid size; must be between 1%% and 100%%\n")
+			os.Exit(1)
+		}
+		directory := dataDir
+		if dataDir == "" {
+			directory, _ = os.Getwd()
+		}
+		err = syscall.Statfs(directory, &stat)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "error getting volume for data-dir: %s\n", directory)
+			os.Exit(1)
+		}
+		size = stat.Blocks * uint64(stat.Bsize) * uint64(sizeNumber) / 100
+	} else {
+		size, err = humanize.ParseBytes(sizeStr)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "error parsing size: %s\n", err)
+			os.Exit(1)
+		}
 	}
 
 	var rl torus.ReadLevel