Add archive package

Archive package handles generating and applying diff tar streams
based on the OCI diff tar specification.

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)

archive/time.go

@@ -0,0 +1,38 @@
+package archive
+
+import (
+	"syscall"
+	"time"
+	"unsafe"
+)
+
+var (
+	minTime = time.Unix(0, 0)
+	maxTime time.Time
+)
+
+func init() {
+	if unsafe.Sizeof(syscall.Timespec{}.Nsec) == 8 {
+		// This is a 64 bit timespec
+		// os.Chtimes limits time to the following
+		maxTime = time.Unix(0, 1<<63-1)
+	} else {
+		// This is a 32 bit timespec
+		maxTime = time.Unix(1<<31-1, 0)
+	}
+}
+
+func boundTime(t time.Time) time.Time {
+	if t.Before(minTime) || t.After(maxTime) {
+		return minTime
+	}
+
+	return t
+}
+
+func latestTime(t1, t2 time.Time) time.Time {
+	if t1.Before(t2) {
+		return t2
+	}
+	return t1
+}