code review 12561043: archive/tar: Fix support for long links and improve PAX...

src/pkg/archive/tar/common.go

Index: src/pkg/archive/tar/common.go
===================================================================
--- a/src/pkg/archive/tar/common.go
+++ b/src/pkg/archive/tar/common.go
@@ -13,6 +13,7 @@
 package tar
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
 	"os"
@@ -174,6 +175,23 @@
 	c_ISSOCK = 0140000 // Socket
 )
 
+// Keywords for the PAX Extended Header
+const (
+	paxAtime    = "atime"
+	paxCharset  = "charset"
+	paxComment  = "comment"
+	paxCtime    = "ctime" // please note that ctime is not a valid pax header.
+	paxGid      = "gid"
+	paxGname    = "gname"
+	paxLinkpath = "linkpath"
+	paxMtime    = "mtime"
+	paxPath     = "path"
+	paxSize     = "size"
+	paxUid      = "uid"
+	paxUname    = "uname"
+	paxNone     = ""
+)
+
 // FileInfoHeader creates a partially-populated Header from fi.
 // If fi describes a symlink, FileInfoHeader records link as the link target.
 // If fi describes a directory, a slash is appended to the name.
@@ -257,3 +275,25 @@
 	b, *sp = s[0:n], s[n:]
 	return
 }
+
+func isASCII(s string) bool {
+	for _, c := range s {
+		if c >= 0x80 {
+			return false
+		}
+	}
+	return true
+}
+
+func toASCII(s string) string {
+	if isASCII(s) {
+		return s
+	}
+	var buf bytes.Buffer
+	for _, c := range s {
+		if c < 0x80 {
+			buf.WriteByte(byte(c))
+		}
+	}
+	return buf.String()
+}