fix

pkg/crontab/parse.go

@@ -0,0 +1,128 @@
+package crontab
+
+import (
+	"fmt"
+	"math"
+	"strconv"
+	"strings"
+)
+
+func getRange(expr string, r bounds) (uint64, error) {
+	var (
+		start, end, step uint
+		rangeAndStep     = strings.Split(expr, "/")
+		lowAndHigh       = strings.Split(rangeAndStep[0], "-")
+		singleDigit      = len(lowAndHigh) == 1
+		err              error
+	)
+
+	var extra uint64
+	if lowAndHigh[0] == "*" || lowAndHigh[0] == "?" {
+		start = r.min
+		end = r.max
+		extra = starBit
+	} else {
+		if lowAndHigh[0] == "L" {
+			return 0, nil
+		}
+		start, err = parseIntOrName(lowAndHigh[0], r.names)
+		if err != nil {
+			return 0, err
+		}
+
+		switch len(lowAndHigh) {
+		case 1:
+			end = start
+		case 2:
+			end, err = parseIntOrName(lowAndHigh[1], r.names)
+			if err != nil {
+				return 0, err
+			}
+		default:
+			return 0, fmt.Errorf("Too many hyphens: %s", expr)
+		}
+	}
+
+	switch len(rangeAndStep) {
+	case 1:
+		step = 1
+	case 2:
+		step, err = mustParseInt(rangeAndStep[1])
+		if err != nil {
+			return 0, err
+		}
+
+		// Special handling: "N/step" means "N-max/step".
+		if singleDigit {
+			end = r.max
+		}
+	default:
+		return 0, fmt.Errorf("Too many slashes: %s", expr)
+	}
+
+	if start < r.min {
+		return 0, fmt.Errorf("Beginning of range (%d) below minimum (%d): %s", start, r.min, expr)
+	}
+	if end > r.max {
+		return 0, fmt.Errorf("End of range (%d) above maximum (%d): %s", end, r.max, expr)
+	}
+	if start > end {
+		return 0, fmt.Errorf("Beginning of range (%d) beyond end of range (%d): %s", start, end, expr)
+	}
+	if step == 0 {
+		return 0, fmt.Errorf("Step of range should be a positive number: %s", expr)
+	}
+
+	return getBits(start, end, step) | extra, nil
+}
+
+func parseIntOrName(expr string, names map[string]uint) (uint, error) {
+	if names != nil {
+		if namedInt, ok := names[strings.ToLower(expr)]; ok {
+			return namedInt, nil
+		}
+	}
+	return mustParseInt(expr)
+}
+
+// mustParseInt parses the given expression as an int or returns an error.
+func mustParseInt(expr string) (uint, error) {
+	num, err := strconv.Atoi(expr)
+	if err != nil {
+		return 0, fmt.Errorf("Failed to parse int from %s: %s", expr, err)
+	}
+	if num < 0 {
+		return 0, fmt.Errorf("Negative number (%d) not allowed: %s", num, expr)
+	}
+
+	return uint(num), nil
+}
+
+// getBits sets all bits in the range [min, max], modulo the given step size.
+func getBits(min, max, step uint) uint64 {
+	var bits uint64
+
+	// If step is 1, use shifts.
+	if step == 1 {
+		return ^(math.MaxUint64 << (max + 1)) & (math.MaxUint64 << min)
+	}
+
+	// Else, use a simple loop.
+	for i := min; i <= max; i += step {
+		bits |= 1 << i
+	}
+	return bits
+}
+
+func getField(field string, r bounds) (uint64, error) {
+	var bits uint64
+	ranges := strings.FieldsFunc(field, func(r rune) bool { return r == ',' })
+	for _, expr := range ranges {
+		bit, err := getRange(expr, r)
+		if err != nil {
+			return bits, err
+		}
+		bits |= bit
+	}
+	return bits, nil
+}