update upstart version check logic

version.go

@@ -0,0 +1,57 @@
+package service
+
+import (
+	"errors"
+	"strconv"
+	"strings"
+)
+
+// versionAtMost will return true if the provided version is less than or equal to max
+func versionAtMost(version, max []int) (bool, error) {
+	if comp, err := versionCompare(version, max); err != nil {
+		return false, err
+	} else if comp == 1 {
+		return false, nil
+	}
+	return true, nil
+}
+
+// versionCompare take to versions split into integer arrays and attempts to compare them
+// An error will be returned if there is an array length mismatch.
+// Return values are as follows
+// -1 - v1 is less than v2
+// 0  - v1 is equal to v2
+// 1  - v1 is greater than v2
+func versionCompare(v1, v2 []int) (int, error) {
+	if len(v1) != len(v2) {
+		return 0, errors.New("version length mismatch")
+	}
+
+	for idx, v2S := range v2 {
+		v1S := v1[idx]
+		if v1S > v2S {
+			return 1, nil
+		}
+
+		if v1S < v2S {
+			return -1, nil
+		}
+	}
+	return 0, nil
+}
+
+// parseVersion will parse any integer type version seperated by periods.
+// This does not fully support semver style versions.
+func parseVersion(v string) []int {
+	version := make([]int, 3)
+
+	for idx, vStr := range strings.Split(v, ".") {
+		vS, err := strconv.Atoi(vStr)
+		if err != nil {
+			return nil
+		}
+		version[idx] = vS
+	}
+
+	return version
+}