1 files changed, 59 insertions, 2 deletions
diff --git a/libgo/go/archive/zip/struct.go b/libgo/go/archive/zip/struct.go
index bfe0aae2e9a..1d6e70f105a 100644
--- a/libgo/go/archive/zip/struct.go
+++ b/libgo/go/archive/zip/struct.go
@@ -1,9 +1,32 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+Package zip provides support for reading and writing ZIP archives.
+
+See: http://www.pkware.com/documents/casestudies/APPNOTE.TXT
+
+This package does not support ZIP64 or disk spanning.
+*/
 package zip
 
+import "os"
+import "time"
+
+// Compression methods.
+const (
+	Store   uint16 = 0
+	Deflate uint16 = 8
+)
+
 const (
 	fileHeaderSignature      = 0x04034b50
 	directoryHeaderSignature = 0x02014b50
 	directoryEndSignature    = 0x06054b50
+	fileHeaderLen            = 30 // + filename + extra
+	directoryHeaderLen       = 46 // + filename + extra + comment
+	directoryEndLen          = 22 // + comment
 	dataDescriptorLen        = 12
 )
 
@@ -13,8 +36,8 @@ type FileHeader struct {
 	ReaderVersion    uint16
 	Flags            uint16
 	Method           uint16
-	ModifiedTime     uint16
-	ModifiedDate     uint16
+	ModifiedTime     uint16 // MS-DOS time
+	ModifiedDate     uint16 // MS-DOS date
 	CRC32            uint32
 	CompressedSize   uint32
 	UncompressedSize uint32
@@ -32,3 +55,37 @@ type directoryEnd struct {
 	commentLen         uint16
 	comment            string
 }
+
+func recoverError(err *os.Error) {
+	if e := recover(); e != nil {
+		if osErr, ok := e.(os.Error); ok {
+			*err = osErr
+			return
+		}
+		panic(e)
+	}
+}
+
+// msDosTimeToTime converts an MS-DOS date and time into a time.Time.
+// The resolution is 2s.
+// See: http://msdn.microsoft.com/en-us/library/ms724247(v=VS.85).aspx
+func msDosTimeToTime(dosDate, dosTime uint16) time.Time {
+	return time.Time{
+		// date bits 0-4: day of month; 5-8: month; 9-15: years since 1980
+		Year:  int64(dosDate>>9 + 1980),
+		Month: int(dosDate >> 5 & 0xf),
+		Day:   int(dosDate & 0x1f),
+
+		// time bits 0-4: second/2; 5-10: minute; 11-15: hour
+		Hour:   int(dosTime >> 11),
+		Minute: int(dosTime >> 5 & 0x3f),
+		Second: int(dosTime & 0x1f * 2),
+	}
+}
+
+// Mtime_ns returns the modified time in ns since epoch.
+// The resolution is 2s.
+func (h *FileHeader) Mtime_ns() int64 {
+	t := msDosTimeToTime(h.ModifiedDate, h.ModifiedTime)
+	return t.Seconds() * 1e9
+}