std_fstream.h (basic_filebuf::sync): Hoist unconditional flush on lower-layer handle to here...

	* include/std/std_fstream.h (basic_filebuf::sync): Hoist
	unconditional flush on lower-layer handle to here...
	* include/bits/fstream.tcc (basic_filebuf::_M_really_overflow):
	...from here.  Optimize remaining _M_file.sync() call pattern.
	* testsuite/27_io/narrow_stream_objects.cc (test04): New test.
	(test05): Likewise.

From-SVN: r52699

4 files changed, 56 insertions, 7 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index bc89207..3e4eb3e 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,12 @@
+2002-04-23  Loren J. Rittle <ljrittle@acm.org>
+
+	* include/std/std_fstream.h (basic_filebuf::sync): Hoist
+	unconditional flush on lower-layer handle to here...
+	* include/bits/fstream.tcc (basic_filebuf::_M_really_overflow):
+	...from here.  Optimize remaining _M_file.sync() call pattern.
+	* testsuite/27_io/narrow_stream_objects.cc (test04): New test.
+	(test05): Likewise.
+
 2002-04-23  Jason Merrill  <jason@redhat.com>
 
 	* include/bits/fstream.tcc (basic_filebuf::seekoff): Fix for
diff --git a/libstdc++-v3/include/bits/fstream.tcc b/libstdc++-v3/include/bits/fstream.tcc
index 6019cd1..740d5e2 100644
--- a/libstdc++-v3/include/bits/fstream.tcc
+++ b/libstdc++-v3/include/bits/fstream.tcc
@@ -476,16 +476,20 @@ namespace std
 				   __elen, __plen);
 
 	  // Convert pending sequence to external representation, output.
+	  // If eof, then just attempt sync.
 	  if (!traits_type::eq_int_type(__c, traits_type::eof()))
 	    {
 	      char_type __pending = traits_type::to_char_type(__c);
 	      _M_convert_to_external(&__pending, 1, __elen, __plen);
-	    }
 
-	  // Last, sync internal and external buffers.
-	  // NB: Need this so that external byte sequence reflects
-	  // internal buffer plus pending sequence.
-	  if (__elen == __plen && !_M_file.sync())
+	      // User code must flush when switching modes (thus don't sync).
+	      if (__elen == __plen)
+		{
+		  _M_set_indeterminate();
+		  __ret = traits_type::not_eof(__c);
+		}
+	    }
+	  else if (!_M_file.sync())
 	    {
 	      _M_set_indeterminate();
 	      __ret = traits_type::not_eof(__c);
diff --git a/libstdc++-v3/include/std/std_fstream.h b/libstdc++-v3/include/std/std_fstream.h
index 0b20df1..ce3a48e 100644
--- a/libstdc++-v3/include/std/std_fstream.h
+++ b/libstdc++-v3/include/std/std_fstream.h
@@ -204,14 +204,16 @@ namespace std
 
 	// Make sure that the internal buffer resyncs its idea of
 	// the file position with the external file.
-	if (__testput && !_M_file.sync())
+	if (__testput)
 	  {
 	    // Need to restore current position after the write.
 	    off_type __off = _M_out_cur - _M_out_end;
-	    _M_really_overflow();
+	    _M_really_overflow(); // _M_file.sync() will be called within
 	    if (__off)
 	      _M_file.seekoff(__off, ios_base::cur);
 	  }
+	else
+	  _M_file.sync();
 	_M_last_overflowed = false;
 	return 0;
       }
diff --git a/libstdc++-v3/testsuite/27_io/narrow_stream_objects.cc b/libstdc++-v3/testsuite/27_io/narrow_stream_objects.cc
index c420449..3abcb07 100644
--- a/libstdc++-v3/testsuite/27_io/narrow_stream_objects.cc
+++ b/libstdc++-v3/testsuite/27_io/narrow_stream_objects.cc
@@ -113,6 +113,38 @@ void test03()
   cout << "i == " << i << endl;
 }
 
+// Interactive test, to be exercised as follows:
+// assign stderr to stdout in shell command line,
+// pipe stdout to cat process and/or redirect stdout to file.
+// "hello fine world\n" should be written to stdout in proper order.
+// This is a version of the scott snyder test taken from:
+// http://gcc.gnu.org/ml/libstdc++/1999-q4/msg00108.html
+void test04()
+{
+  using namespace std;
+
+  cout << "hello ";
+  cout.flush ();
+  cerr << "fine ";
+  cerr.flush ();
+  cout << "world" << endl;
+  cout.flush ();
+}
+
+// Interactive test, to be exercised as follows:
+// run test under truss(1) or strace(1).  Look at
+// size and pattern of write system calls.
+// Should be 2 or 3 write(1,[...]) calls when run interactively
+// depending upon buffering mode enforced.
+void test05()
+{
+  std::cout << "hello" << ' ' << "world" <<std::endl;
+  std::cout << "Enter your name: ";
+  std::string s;
+  std::cin >> s;
+  std::cout << "hello " << s << std::endl;
+}
+
 int 
 main()
 {
@@ -120,5 +152,7 @@ main()
 
   // test02();
   // test03();
+  // test04();
+  // test05();
   return 0;
 }