1 files changed, 109 insertions, 0 deletions
diff --git a/src/time/tzdata/tzdata.go b/src/time/tzdata/tzdata.go
new file mode 100644
index 0000000..25725bd
--- /dev/null
+++ b/src/time/tzdata/tzdata.go
@@ -0,0 +1,109 @@
+// Copyright 2020 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.
+
+//go:generate go run generate_zipdata.go
+
+// Package tzdata provides an embedded copy of the timezone database.
+// If this package is imported anywhere in the program, then if
+// the time package cannot find tzdata files on the system,
+// it will use this embedded information.
+//
+// Importing this package will increase the size of a program by about
+// 450 KB.
+//
+// This package should normally be imported by a program's main package,
+// not by a library. Libraries normally shouldn't decide whether to
+// include the timezone database in a program.
+//
+// This package will be automatically imported if you build with
+// -tags timetzdata.
+package tzdata
+
+// The test for this package is time/tzdata_test.go.
+
+import (
+	"errors"
+	"syscall"
+	_ "unsafe" // for go:linkname
+)
+
+// registerLoadFromEmbeddedTZData is defined in package time.
+//go:linkname registerLoadFromEmbeddedTZData time.registerLoadFromEmbeddedTZData
+func registerLoadFromEmbeddedTZData(func(string) (string, error))
+
+func init() {
+	registerLoadFromEmbeddedTZData(loadFromEmbeddedTZData)
+}
+
+// get4s returns the little-endian 32-bit value at the start of s.
+func get4s(s string) int {
+	if len(s) < 4 {
+		return 0
+	}
+	return int(s[0]) | int(s[1])<<8 | int(s[2])<<16 | int(s[3])<<24
+}
+
+// get2s returns the little-endian 16-bit value at the start of s.
+func get2s(s string) int {
+	if len(s) < 2 {
+		return 0
+	}
+	return int(s[0]) | int(s[1])<<8
+}
+
+// loadFromEmbeddedTZData returns the contents of the file with the given
+// name in an uncompressed zip file, where the contents of the file can
+// be found in embeddedTzdata.
+// This is similar to time.loadTzinfoFromZip.
+func loadFromEmbeddedTZData(name string) (string, error) {
+	const (
+		zecheader = 0x06054b50
+		zcheader  = 0x02014b50
+		ztailsize = 22
+
+		zheadersize = 30
+		zheader     = 0x04034b50
+	)
+
+	z := zipdata
+
+	idx := len(z) - ztailsize
+	n := get2s(z[idx+10:])
+	idx = get4s(z[idx+16:])
+
+	for i := 0; i < n; i++ {
+		// See time.loadTzinfoFromZip for zip entry layout.
+		if get4s(z[idx:]) != zcheader {
+			break
+		}
+		meth := get2s(z[idx+10:])
+		size := get4s(z[idx+24:])
+		namelen := get2s(z[idx+28:])
+		xlen := get2s(z[idx+30:])
+		fclen := get2s(z[idx+32:])
+		off := get4s(z[idx+42:])
+		zname := z[idx+46 : idx+46+namelen]
+		idx += 46 + namelen + xlen + fclen
+		if zname != name {
+			continue
+		}
+		if meth != 0 {
+			return "", errors.New("unsupported compression for " + name + " in embedded tzdata")
+		}
+
+		// See time.loadTzinfoFromZip for zip per-file header layout.
+		idx = off
+		if get4s(z[idx:]) != zheader ||
+			get2s(z[idx+8:]) != meth ||
+			get2s(z[idx+26:]) != namelen ||
+			z[idx+30:idx+30+namelen] != name {
+			return "", errors.New("corrupt embedded tzdata")
+		}
+		xlen = get2s(z[idx+28:])
+		idx += 30 + namelen + xlen
+		return z[idx : idx+size], nil
+	}
+
+	return "", syscall.ENOENT
+}