re PR libstdc++/20806 (basic_filebuf::xsgetn() fails with text mode and DOS…

re PR libstdc++/20806 (basic_filebuf::xsgetn()  fails with text mode and DOS line endings and large buffers)

2005-04-08  Danny Smith  <dannysmith@users.sourceforge.net>
	    Paolo Carlini  <pcarlini@suse.de>

	PR libstdc++/20806
	* config/os/mingw32/os_defines.h: Define
	_GLIBCXX_HAVE_DOS_BASED_FILESYSTEM.
	* config/os/newlib/os_defines.h: Likewise, for __CYGWIN__.
	* include/bits/fstream.tcc (basic_filebuf<>::showmanyc()):
	Use it.
	(basic_filebuf<>::xsgetn(_CharT*, streamsize)): Likewise.

Co-Authored-By: Paolo Carlini <pcarlini@suse.de>

From-SVN: r97842

libstdc++-v3/ChangeLog

+2005-04-08  Danny Smith  <dannysmith@users.sourceforge.net>
+	    Paolo Carlini  <pcarlini@suse.de>
+	    		
+	PR libstdc++/20806
+	* config/os/mingw32/os_defines.h: Define
+	_GLIBCXX_HAVE_DOS_BASED_FILESYSTEM.
+	* config/os/newlib/os_defines.h: Likewise, for __CYGWIN__.
+	* include/bits/fstream.tcc (basic_filebuf<>::showmanyc()):
+	Use it.
+	(basic_filebuf<>::xsgetn(_CharT*, streamsize)): Likewise.
+
 2005-04-08  Kelley Cook  <kcook@gcc.gnu.org>
 
 	* acconfig.h: Sort the bottom section.

libstdc++-v3/config/os/mingw32/os_defines.h

 // Specific definitions for generic platforms  -*- C++ -*-
 
-// Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
+// Copyright (C) 2000, 2001, 2002, 2003, 2005 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
@@ -45,4 +45,7 @@
 #undef NOMINMAX
 #define NOMINMAX 1
 
+// See libstdc++/20806.
+#define _GLIBCXX_HAVE_DOS_BASED_FILESYSTEM 1
+
 #endif

libstdc++-v3/config/os/newlib/os_defines.h

 // Specific definitions for newlib  -*- C++ -*-
 
-// Copyright (C) 2000 Free Software Foundation, Inc.
+// Copyright (C) 2000, 2005 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
@@ -35,6 +35,9 @@
 
 #ifdef __CYGWIN__
 #define _GLIBCXX_GTHREAD_USE_WEAK 0
+
+// See libstdc++/20806.
+#define _GLIBCXX_HAVE_DOS_BASED_FILESYSTEM 1
 #endif
 
 #endif

libstdc++-v3/include/bits/fstream.tcc

@@ -171,7 +171,15 @@ namespace std
 	  // For a stateful encoding (-1) the pending sequence might be just
 	  // shift and unshift prefixes with no actual character.
 	  __ret = this->egptr() - this->gptr();
+
+#if _GLIBCXX_HAVE_DOS_BASED_FILESYSTEM
+	  // About this workaround, see libstdc++/20806.
+	  const bool __testbinary = _M_mode & ios_base::binary;
+	  if (__check_facet(_M_codecvt).encoding() >= 0
+	      && __testbinary)
+#else
 	  if (__check_facet(_M_codecvt).encoding() >= 0)
+#endif
 	    __ret += _M_file.showmanyc() / _M_codecvt->max_length();
 	}
       return __ret;
@@ -521,10 +529,17 @@ namespace std
        // future: when __n > __buflen we read directly instead of using the
        // buffer repeatedly.
        const bool __testin = _M_mode & ios_base::in;
-       const streamsize __buflen = _M_buf_size > 1 ? _M_buf_size - 1
-	                                                 : 1;
+       const streamsize __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
+
+#if _GLIBCXX_HAVE_DOS_BASED_FILESYSTEM
+       // About this workaround, see libstdc++/20806.
+       const bool __testbinary = _M_mode & ios_base::binary;
+       if (__n > __buflen && __check_facet(_M_codecvt).always_noconv()
+	   && __testin && __testbinary && !_M_writing)
+#else
        if (__n > __buflen && __check_facet(_M_codecvt).always_noconv()
 	   && __testin && !_M_writing)
+#endif
 	 {
 	   // First, copy the chars already present in the buffer.
 	   const streamsize __avail = this->egptr() - this->gptr();