fix #782 (bring vendor into the main tree)

vendor/code.cloudfoundry.org/bytefmt/bytes.go

@@ -0,0 +1,121 @@
+// Package bytefmt contains helper methods and constants for converting to and from a human-readable byte format.
+//
+//	bytefmt.ByteSize(100.5*bytefmt.MEGABYTE) // "100.5M"
+//	bytefmt.ByteSize(uint64(1024)) // "1K"
+//
+package bytefmt
+
+import (
+	"errors"
+	"strconv"
+	"strings"
+	"unicode"
+)
+
+const (
+	BYTE = 1 << (10 * iota)
+	KILOBYTE
+	MEGABYTE
+	GIGABYTE
+	TERABYTE
+	PETABYTE
+	EXABYTE
+)
+
+var invalidByteQuantityError = errors.New("byte quantity must be a positive integer with a unit of measurement like M, MB, MiB, G, GiB, or GB")
+
+// ByteSize returns a human-readable byte string of the form 10M, 12.5K, and so forth.  The following units are available:
+//	E: Exabyte
+//	P: Petabyte
+//	T: Terabyte
+//	G: Gigabyte
+//	M: Megabyte
+//	K: Kilobyte
+//	B: Byte
+// The unit that results in the smallest number greater than or equal to 1 is always chosen.
+func ByteSize(bytes uint64) string {
+	unit := ""
+	value := float64(bytes)
+
+	switch {
+	case bytes >= EXABYTE:
+		unit = "E"
+		value = value / EXABYTE
+	case bytes >= PETABYTE:
+		unit = "P"
+		value = value / PETABYTE
+	case bytes >= TERABYTE:
+		unit = "T"
+		value = value / TERABYTE
+	case bytes >= GIGABYTE:
+		unit = "G"
+		value = value / GIGABYTE
+	case bytes >= MEGABYTE:
+		unit = "M"
+		value = value / MEGABYTE
+	case bytes >= KILOBYTE:
+		unit = "K"
+		value = value / KILOBYTE
+	case bytes >= BYTE:
+		unit = "B"
+	case bytes == 0:
+		return "0B"
+	}
+
+	result := strconv.FormatFloat(value, 'f', 1, 64)
+	result = strings.TrimSuffix(result, ".0")
+	return result + unit
+}
+
+// ToMegabytes parses a string formatted by ByteSize as megabytes.
+func ToMegabytes(s string) (uint64, error) {
+	bytes, err := ToBytes(s)
+	if err != nil {
+		return 0, err
+	}
+
+	return bytes / MEGABYTE, nil
+}
+
+// ToBytes parses a string formatted by ByteSize as bytes. Note binary-prefixed and SI prefixed units both mean a base-2 units
+// KB = K = KiB	= 1024
+// MB = M = MiB = 1024 * K
+// GB = G = GiB = 1024 * M
+// TB = T = TiB = 1024 * G
+// PB = P = PiB = 1024 * T
+// EB = E = EiB = 1024 * P
+func ToBytes(s string) (uint64, error) {
+	s = strings.TrimSpace(s)
+	s = strings.ToUpper(s)
+
+	i := strings.IndexFunc(s, unicode.IsLetter)
+
+	if i == -1 {
+		return 0, invalidByteQuantityError
+	}
+
+	bytesString, multiple := s[:i], s[i:]
+	bytes, err := strconv.ParseFloat(bytesString, 64)
+	if err != nil || bytes < 0 {
+		return 0, invalidByteQuantityError
+	}
+
+	switch multiple {
+	case "E", "EB", "EIB":
+		return uint64(bytes * EXABYTE), nil
+	case "P", "PB", "PIB":
+		return uint64(bytes * PETABYTE), nil
+	case "T", "TB", "TIB":
+		return uint64(bytes * TERABYTE), nil
+	case "G", "GB", "GIB":
+		return uint64(bytes * GIGABYTE), nil
+	case "M", "MB", "MIB":
+		return uint64(bytes * MEGABYTE), nil
+	case "K", "KB", "KIB":
+		return uint64(bytes * KILOBYTE), nil
+	case "B":
+		return uint64(bytes), nil
+	default:
+		return 0, invalidByteQuantityError
+	}
+}