# HG changeset patch
# User Mike Miller <mtmiller@ieee.org>
# Date 1349537035 14400
# Node ID c1c5b3cc29965a88c5629235acd8ee820cc61a4e
# Parent  d174210ce1ec47ce6eb4ecb3c723aa26b62a338e
Avoid inefficient seeks in gzfilebuf (bug #37509)

* src/zfstream.cc (gzfilebuf::seekoff): Avoid calling gzseek and
invalidating buffers when not actually seeking.

diff -r d174210ce1ec -r c1c5b3cc2996 src/zfstream.cc
--- a/src/zfstream.cc	Mon Oct 01 17:18:49 2012 -0400
+++ b/src/zfstream.cc	Sat Oct 06 11:23:55 2012 -0400
@@ -473,6 +473,11 @@
       if ((io_mode & std::ios_base::in) && way == std::ios_base::cur)
         computed_off += this->gptr() - this->egptr();
 
+      // Handle tellg/tellp as a special case up front, no need to seek
+      // or invalidate get/put buffers
+      if (off == 0 && way == std::ios_base::cur)
+        return pos_type (gztell (file) + computed_off);
+
       if (way == std::ios_base::beg)
         ret = pos_type (gzseek (file, computed_off, SEEK_SET));
       else if (way == std::ios_base::cur)