2010-09-22 David Krauss <potswa@mac.com>

	PR libstdc++/45628
	* include/bits/fstream.tcc (basic_filebuf::underflow): Add state
	transition to avoid modality requiring seekoff(0,ios::cur).
	(basic_filebuf::pbackfail): Likewise.
	(basic_filebuf::overflow): Likewise.
	(basic_filebuf::_M_seek): Avoid minor unnecessary conversion.
	(basic_filebuf::seekoff): Remove code to _M_get_ext_pos; make
	(0, ios::cur) a special case preserving buffer contents.
	(basic_filebuf::_M_get_ext_pos): New function to obtain status
	about codecvt extern_t buffer for overflow and seekoff.
	* include/std/fstream (basic_filebuf::_M_get_ext_pos): Likewise.
	* config/abi/pre/gnu.ver: Export new symbols.
	* testsuite/27_io/basic_filebuf/seekoff/char/45628-1.cc: New,
	verifies that seekoff(0, ios::cur) preserves buffers.
	* testsuite/27_io/basic_filebuf/seekoff/char/45628-2.cc: Likewise.
	for codecvt case. More lenient as it may still flush put area.
	* testsuite/27_io/basic_filebuf/seekoff/char/4.cc: Modify to
	check that seekoff is not required between read and write.
	* testsuite/27_io/basic_filebuf/seekoff/wchar_t/4.cc: Likewise.
	* testsuite/27_io/basic_filebuf/sync/wchar_t/1.cc: Remove.
	* testsuite/27_io/basic_filebuf/sync/wchar_t/1.cc: Likewise.
	* testsuite/util/testsuite_character.h (codecvt::do_length): Comply
	with 22.2.1.5.2/10 "Returns ... the LARGEST value in the range..."


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@164529 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 14 insertions, 6 deletions

diff --git a/libstdc++-v3/testsuite/27_io/basic_filebuf/seekoff/char/4.cc b/libstdc++-v3/testsuite/27_io/basic_filebuf/seekoff/char/4.cc
index 9422f29f0d9..fe21b3a88e2 100644
--- a/libstdc++-v3/testsuite/27_io/basic_filebuf/seekoff/char/4.cc
+++ b/libstdc++-v3/testsuite/27_io/basic_filebuf/seekoff/char/4.cc
@@ -31,7 +31,7 @@ void test01()
   typedef filebuf::pos_type pos_type;
   const char name[] = "tmp_seekoff-4.tst";
 
-  const size_t size = 10;
+  const size_t size = 12;
   char buf[size];
   streamsize n;
 
@@ -46,7 +46,7 @@ void test01()
   VERIFY( n == 3 );
   VERIFY( !memcmp(buf, "abc", 3) );
 
-  fb.pubseekoff(0, ios_base::cur);
+  // Check read => write without pubseekoff(0, ios_base::cur)
 
   n = fb.sputn("ef", 2);
   VERIFY( n == 2 );
@@ -58,9 +58,17 @@ void test01()
   VERIFY( !memcmp(buf, "abcef", 5) );
 
   fb.pubseekoff(0, ios_base::beg);
-  n = fb.sputn("ghijkl", 6);
-  VERIFY( n == 6 );
+  n = fb.sputn("gh", 2);
+  VERIFY( n == 2 );
+  
+  // Check write => read without pubseekoff(0, ios_base::cur)
+
+  n = fb.sgetn( buf, 3 );
+  VERIFY( !memcmp(buf, "cef", 3) );
 
+  n = fb.sputn("ijkl", 4);
+  VERIFY( n == 4 );
+  
   fb.pubseekoff(0, ios_base::beg);
   n = fb.sgetn(buf, 2);
   VERIFY( n == 2 );
@@ -72,8 +80,8 @@ void test01()
 
   fb.pubseekoff(0, ios_base::beg);
   n = fb.sgetn(buf, size);
-  VERIFY( n == 9 );
-  VERIFY( !memcmp(buf, "ghijklmno", 9) );
+  VERIFY( n == 12 );
+  VERIFY( !memcmp(buf, "ghcefijklmno", 12) );
 
   fb.close();
 }