Simplify formatFileSize

No need to use a loop with divisions and multiplications when we have logarithms.

internal/template/functions.go

@@ -209,11 +209,7 @@ func formatFileSize(b int64) string {
 	if b < unit {
 		return fmt.Sprintf("%d B", b)
 	}
-	div, exp := int64(unit), 0
-	for n := b / unit; n >= unit; n /= unit {
-		div *= unit
-		exp++
-	}
-	return fmt.Sprintf("%.1f %ciB",
-		float64(b)/float64(div), "KMGTPE"[exp])
+	base := math.Log(float64(b)) / math.Log(unit)
+	number := math.Pow(unit, base-math.Floor(base))
+	return fmt.Sprintf("%.1f %ciB", number, "KMGTPE"[int64(base)-1])
 }

internal/template/functions_test.go

@@ -156,6 +156,8 @@ func TestFormatFileSize(t *testing.T) {
 		input    int64
 		expected string
 	}{
+		{0, "0 B"},
+		{1, "1 B"},
 		{500, "500 B"},
 		{1024, "1.0 KiB"},
 		{43520, "42.5 KiB"},