code review 162062: Robustness fixes for tar/archive.

src/pkg/archive/tar/writer.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):
 // - catch more errors (no first header, write after close, etc.)
 
 import (
@@ skipping 149 matching lines @@
                 return tw.err
         }
 
         _, tw.err = tw.w.Write(header);
 
         return tw.err;
 }
 
 // Write writes to the current entry in the tar archive.
 // Write returns the error ErrWriteTooLong if more than
-// hdr.Size bytes are written after WriteHeader.  Writes
-// after Close will return ErrWriteTooLong.

[rsc, 2009/12/11 20:48:31]

drop this sentence - it's wrong and can be left unsaid.

+// hdr.Size bytes are written after WriteHeader.
 func (tw *Writer) Write(b []byte) (n int, err os.Error) {
         if tw.closed {
                 err = ErrWriteTooLong;
                 return;
         }
         overwrite := false;
         if int64(len(b)) > tw.nb {
                 b = b[0:tw.nb];
                 overwrite = true;
         }
         n, err = tw.w.Write(b);
         tw.nb -= int64(n);
         if err == nil && overwrite {
                 err = ErrWriteTooLong;
                 return;
         }
         tw.err = err;
         return;
 }
 
-// Close finishes writing to the tar archive.  Trailing blocks are

[rsc, 2009/12/11 20:48:31]

// Close closes the tar archive, flushing any unwritten
// data to the underlying writer. 

the rest is implied by the usual meaning of close

-// written out and any further writes will fail.
+// Close closes the tar archive, flushing any unwritten
+// data to the underlying writer.
 func (tw *Writer) Close() os.Error {
         if tw.err != nil || tw.closed {
                 return tw.err
         }
         tw.Flush();
         tw.closed = true;
 
         // trailer: two zero blocks
         for i := 0; i < 2; i++ {
                 _, tw.err = tw.w.Write(zeroBlock);
                 if tw.err != nil {
                         break
                 }
         }
         return tw.err;
 }