code review 5777064: archive/tar: catch short writes.

src/pkg/archive/tar/reader.go

 // Copyright 2009 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 tar
 
 // TODO(dsymonds):
 //   - pax extensions
 
 import (
         "bytes"
         "errors"
         "io"
         "io/ioutil"
         "os"
         "strconv"
         "time"
 )
 
 var (
-        ErrHeader = errors.New("invalid tar header")
+        ErrHeader = errors.New("archive/tar: invalid tar header")
 )
 
 // A Reader provides sequential access to the contents of a tar archive.
 // A tar archive consists of a sequence of files.
 // The Next method advances to the next file in the archive (including the first),
 // and then it can be treated as an io.Reader to access the file's data.
 //
 // Example:
 //      tr := tar.NewReader(r)
 //      for {
@@ skipping 182 matching lines @@
         }
         n, err = tr.r.Read(b)
         tr.nb -= int64(n)
 
         if err == io.EOF && tr.nb > 0 {
                 err = io.ErrUnexpectedEOF
         }
         tr.err = err
         return
 }