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[Patch] Fix seek to beg after grow bug
- From: Paolo Carlini <pcarlini at unitus dot it>
- To: "libstdc++ at gcc dot gnu dot org" <libstdc++ at gcc dot gnu dot org>
- Cc: bkoz <bkoz at redhat dot com>
- Date: Tue, 18 Feb 2003 21:07:21 +0100
- Subject: [Patch] Fix seek to beg after grow bug
Hi,
the below is the fix for the problem noticed by Peter Hrenka today.
We had this code in str():
__size_type __len = _M_string.size();
if (this->_M_out_cur > this->_M_out_beg)
__len = std::max(__size_type(this->_M_out_end
- this->_M_out_beg), __len);
which failed to compute the correct __len when _M_out_cur was
equal to _M_out_beg upon a seek to ios_base::beg.
We must check instead that _M_out_end > _M_out_beg, since
_M_out_end >= _M_out_cur and stores the current string end.
Tested x86-linux. I'd like to apply it to mainline, and, after a
little while of additional testing, 3_3 too.
Ok?
Paolo.
//////////
2003-02-18 Paolo Carlini <pcarlini@unitus.it>
* include/std/std_sstream.h (str()): the size of the
current string may be different from the initial one
whenever _M_out_end > _M_out_beg.
* testsuite/27_io/stringbuf_members.cc (test07): Add.
diff -urN libstdc++-v3-orig/include/std/std_sstream.h libstdc++-v3/include/std/std_sstream.h
--- libstdc++-v3-orig/include/std/std_sstream.h 2003-01-23 19:56:00.000000000 +0100
+++ libstdc++-v3/include/std/std_sstream.h 2003-02-18 14:29:19.000000000 +0100
@@ -140,7 +140,7 @@
// _M_string, and may not be the correct size of the
// current stringbuf internal buffer.
__size_type __len = _M_string.size();
- if (this->_M_out_cur > this->_M_out_beg)
+ if (this->_M_out_end > this->_M_out_beg)
__len = std::max(__size_type(this->_M_out_end
- this->_M_out_beg), __len);
return __string_type(this->_M_out_beg, this->_M_out_beg + __len);
diff -urN libstdc++-v3-orig/testsuite/27_io/stringbuf_members.cc libstdc++-v3/testsuite/27_io/stringbuf_members.cc
--- libstdc++-v3-orig/testsuite/27_io/stringbuf_members.cc 2002-07-26 03:49:36.000000000 +0200
+++ libstdc++-v3/testsuite/27_io/stringbuf_members.cc 2003-02-18 20:31:00.000000000 +0100
@@ -1,6 +1,6 @@
// 981208 bkoz test functionality of basic_stringbuf for char_type == char
-// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002
+// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003
// Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
@@ -473,6 +473,32 @@
return test;
}
+// http://gcc.gnu.org/ml/libstdc++/2003-02/msg00269.html
+// Growing and then seeking to ios_base::beg triggered a bug in str(),
+// which didn't notice the grow.
+bool test07()
+{
+ bool test = true;
+
+ std::stringbuf strb_01;
+ strb_01.sputc('s');
+ strb_01.pubseekoff(0, std::ios_base::beg);
+ VERIFY( strb_01.str() == "s" );
+
+ std::string str("strivi,");
+ std::stringbuf strb_02(str);
+ strb_02.pubseekoff(0, std::ios_base::end);
+ strb_02.sputn(" no better!", 11);
+ strb_02.pubseekoff(0, std::ios_base::beg);
+ VERIFY( strb_02.str() == "strivi, no better!" );
+
+#ifdef DEBUG_ASSERT
+ assert(test);
+#endif
+
+ return test;
+}
+
int main()
{
test01();
@@ -481,6 +507,7 @@
test04();
test05();
test06();
+ test07();
return 0;
}