package units import ( "fmt" "regexp" "strconv" "strings" ) // See: http://en.wikipedia.org/wiki/Binary_prefix const ( // Decimal KB = 1000 MB = 1000 * KB GB = 1000 * MB TB = 1000 * GB PB = 1000 * TB // Binary KiB = 1024 MiB = 1024 * KiB GiB = 1024 * MiB TiB = 1024 * GiB PiB = 1024 * TiB ) type unitMap map[string]int64 var ( decimalMap = unitMap{"k": KB, "m": MB, "g": GB, "t": TB, "p": PB} binaryMap = unitMap{"k": KiB, "m": MiB, "g": GiB, "t": TiB, "p": PiB} sizeRegex = regexp.MustCompile(`^(\d+)([kKmMgGtTpP])?[bB]?$`) ) var unitAbbrs = [...]string{"B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"} // HumanSize returns a human-readable approximation of a size // using SI standard (eg. "44kB", "17MB") func HumanSize(size int64) string { i := 0 sizef := float64(size) for sizef >= 1000.0 { sizef = sizef / 1000.0 i++ } return fmt.Sprintf("%.4g %s", sizef, unitAbbrs[i]) } // FromHumanSize returns an integer from a human-readable specification of a // size using SI standard (eg. "44kB", "17MB") func FromHumanSize(size string) (int64, error) { return parseSize(size, decimalMap) } // Parses a human-readable string representing an amount of RAM // in bytes, kibibytes, mebibytes, gibibytes, or tebibytes and // returns the number of bytes, or -1 if the string is unparseable. // Units are case-insensitive, and the 'b' suffix is optional. func RAMInBytes(size string) (int64, error) { return parseSize(size, binaryMap) } // Parses the human-readable size string into the amount it represents func parseSize(sizeStr string, uMap unitMap) (int64, error) { matches := sizeRegex.FindStringSubmatch(sizeStr) if len(matches) != 3 { return -1, fmt.Errorf("Invalid size: '%s'", sizeStr) } size, err := strconv.ParseInt(matches[1], 10, 0) if err != nil { return -1, err } unitPrefix := strings.ToLower(matches[2]) if mul, ok := uMap[unitPrefix]; ok { size *= mul } return size, nil }