re PR libstdc++/29354 (Error when seeking on an ostringstream)

2006-10-06  Paolo Carlini  <pcarlini@suse.de>

	PR libstdc++/29354
	* include/bits/sstream.tcc (basic_stringbuf<>::seekpos(pos_type,
	ios_base::openmode)): Allow for seek to pos_type(off_type(0))
	when the stream is empty.
	* testsuite/27_io/basic_stringbuf/seekpos/char/29354.cc: New.
	* testsuite/27_io/basic_stringbuf/seekpos/wchar_t/29354.cc: New.

From-SVN: r117494

4 files changed, 98 insertions, 1 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index b829317..e90d8f8 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,12 @@
+2006-10-06  Paolo Carlini  <pcarlini@suse.de>
+
+	PR libstdc++/29354
+	* include/bits/sstream.tcc (basic_stringbuf<>::seekpos(pos_type,
+	ios_base::openmode)): Allow for seek to pos_type(off_type(0))
+	when the stream is empty.
+	* testsuite/27_io/basic_stringbuf/seekpos/char/29354.cc: New.
+	* testsuite/27_io/basic_stringbuf/seekpos/wchar_t/29354.cc: New.
+
 2006-10-04  Benjamin Kosnik  <bkoz@redhat.com>
 	    Mike Stump  <mrs@apple.com>
 	
diff --git a/libstdc++-v3/include/bits/sstream.tcc b/libstdc++-v3/include/bits/sstream.tcc
index 2c5be33..4de1c81 100644
--- a/libstdc++-v3/include/bits/sstream.tcc
+++ b/libstdc++-v3/include/bits/sstream.tcc
@@ -206,7 +206,7 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
       const bool __testout = (ios_base::out & this->_M_mode & __mode) != 0;
 
       const char_type* __beg = __testin ? this->eback() : this->pbase();
-      if (__beg && (__testin || __testout))
+      if ((__beg || !off_type(__sp)) && (__testin || __testout))
 	{
 	  _M_update_egptr();
 
diff --git a/libstdc++-v3/testsuite/27_io/basic_stringbuf/seekpos/char/29354.cc b/libstdc++-v3/testsuite/27_io/basic_stringbuf/seekpos/char/29354.cc
new file mode 100644
index 0000000..a9337f9
--- /dev/null
+++ b/libstdc++-v3/testsuite/27_io/basic_stringbuf/seekpos/char/29354.cc
@@ -0,0 +1,44 @@
+// Copyright (C) 2006 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 2, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING.  If not, write to the Free
+// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+// USA.
+
+#include <sstream>
+#include <testsuite_hooks.h>
+
+// libstdc++/29354
+void test01()
+{
+  bool test __attribute__((unused)) = true;
+  using namespace std;
+  typedef stringbuf::pos_type pos_type;
+  typedef stringbuf::off_type off_type;
+
+  stringbuf strb_01(ios_base::out);
+
+  pos_type pt_1 = strb_01.pubseekoff(0, ios_base::cur, ios_base::out);
+  VERIFY( pt_1 == pos_type(off_type(0)) );  
+
+  pos_type pt_2 = strb_01.pubseekpos(pt_1, ios_base::out);
+  VERIFY( pt_2 == pos_type(off_type(0)) );
+}
+
+int
+main()
+{
+  test01();
+  return 0;
+}
diff --git a/libstdc++-v3/testsuite/27_io/basic_stringbuf/seekpos/wchar_t/29354.cc b/libstdc++-v3/testsuite/27_io/basic_stringbuf/seekpos/wchar_t/29354.cc
new file mode 100644
index 0000000..1fd8da4
--- /dev/null
+++ b/libstdc++-v3/testsuite/27_io/basic_stringbuf/seekpos/wchar_t/29354.cc
@@ -0,0 +1,44 @@
+// Copyright (C) 2006 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 2, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING.  If not, write to the Free
+// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+// USA.
+
+#include <sstream>
+#include <testsuite_hooks.h>
+
+// libstdc++/29354
+void test01()
+{
+  bool test __attribute__((unused)) = true;
+  using namespace std;
+  typedef stringbuf::pos_type pos_type;
+  typedef stringbuf::off_type off_type;
+
+  wstringbuf strb_01(ios_base::out);
+
+  pos_type pt_1 = strb_01.pubseekoff(0, ios_base::cur, ios_base::out);
+  VERIFY( pt_1 == pos_type(off_type(0)) );  
+
+  pos_type pt_2 = strb_01.pubseekpos(pt_1, ios_base::out);
+  VERIFY( pt_2 == pos_type(off_type(0)) );
+}
+
+int
+main()
+{
+  test01();
+  return 0;
+}