This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

[v3] Fix a corner-case of istream::ignore


Hi,

this one actually represent a regression from 3.3! I have been
able to notice it, because the current behavior would lead to
integer overflows in some corner-cases...

Tested x86-linux.

Paolo.

/////////////////
2005-01-05  Paolo Carlini  <pcarlini@suse.de>

	* src/istream.cc (basic_istream<char>::ignore(streamsize),
	basic_istream<char>::ignore(streamsize, int_type),
	basic_istream<wchar_t>::ignore(streamsize),
	basic_istream<wchar_t>::ignore(streamsize, int_type)): At the end,
	first check _M_gcount vs __n. 	
	* include/bits/istream.tcc (ignore(streamsize), ignore(streamsize,
	int_type)): Likewise.
	* testsuite/27_io/basic_istream/ignore/char/4.cc: New.
	* testsuite/27_io/basic_istream/ignore/wchar_t/4.cc: Likewise.

diff -urN libstdc++-v3-orig/include/bits/istream.tcc libstdc++-v3/include/bits/istream.tcc
--- libstdc++-v3-orig/include/bits/istream.tcc	2005-01-03 14:45:33.000000000 +0100
+++ libstdc++-v3/include/bits/istream.tcc	2005-01-05 12:00:38.000000000 +0100
@@ -685,6 +685,13 @@
               __streambuf_type* __sb = this->rdbuf();
               int_type __c = __sb->sgetc();
 
+	      // N.B. On LFS-enabled platforms streamsize is still 32 bits
+	      // wide: if we want to implement the standard mandated behavior
+	      // for n == max() (see 27.6.1.3/24) we are at risk of signed
+	      // integer overflow: thus these contortions. Also note that,
+	      // by definition, when more than 2G chars are actually ignored,
+	      // _M_gcount (the return value of gcount, that is) cannot be
+	      // really correct, being unavoidably too small.
 	      while (true)
 		{
 		  while (_M_gcount < __n
@@ -700,7 +707,7 @@
 		    break;
 		}
 
-	      if (traits_type::eq_int_type(__c, __eof))
+	      if (_M_gcount < __n)
                 __err |= ios_base::eofbit;
             }
           catch(...)
@@ -730,6 +737,7 @@
               __streambuf_type* __sb = this->rdbuf();
               int_type __c = __sb->sgetc();
 
+	      // See comment above.
 	      while (true)
 		{
 		  while (_M_gcount < __n
@@ -747,9 +755,11 @@
 		    break;
 		}
 
-              if (traits_type::eq_int_type(__c, __eof))
+	      if (_M_gcount == __n)
+		;
+              else if (traits_type::eq_int_type(__c, __eof))
                 __err |= ios_base::eofbit;
-	      else if (traits_type::eq_int_type(__c, __delim))
+	      else
 		{
 		  ++_M_gcount;
 		  __sb->sbumpc();
diff -urN libstdc++-v3-orig/src/istream.cc libstdc++-v3/src/istream.cc
--- libstdc++-v3-orig/src/istream.cc	2005-01-03 14:46:55.000000000 +0100
+++ libstdc++-v3/src/istream.cc	2005-01-04 23:55:20.000000000 +0100
@@ -123,7 +123,8 @@
 	      const int_type __eof = traits_type::eof();
 	      __streambuf_type* __sb = this->rdbuf();
 	      int_type __c = __sb->sgetc();
-	      
+
+	      // See comment in istream.tcc.
 	      while (true)
 		{
 		  while (_M_gcount < __n
@@ -151,7 +152,7 @@
 		    break;
 		}
 
-	      if (traits_type::eq_int_type(__c, __eof))
+	      if (_M_gcount < __n)
 		__err |= ios_base::eofbit;
 	    }
 	  catch(...)
@@ -216,9 +217,11 @@
 		    break;
 		}
 
-	      if (traits_type::eq_int_type(__c, __eof))
+	      if (_M_gcount == __n)
+		;
+	      else if (traits_type::eq_int_type(__c, __eof))
 		__err |= ios_base::eofbit;
-	      else if (traits_type::eq_int_type(__c, __delim))
+	      else
 		{
 		  ++_M_gcount;
 		  __sb->sbumpc();
@@ -429,7 +432,7 @@
 		    break;
 		}
 
-	      if (traits_type::eq_int_type(__c, __eof))
+	      if (_M_gcount < __n)
 		__err |= ios_base::eofbit;
 	    }
 	  catch(...)
@@ -494,9 +497,11 @@
 		    break;
 		}
 
-	      if (traits_type::eq_int_type(__c, __eof))
+	      if (_M_gcount == __n)
+		;
+	      else if (traits_type::eq_int_type(__c, __eof))
 		__err |= ios_base::eofbit;
-	      else if (traits_type::eq_int_type(__c, __delim))
+	      else
 		{
 		  ++_M_gcount;
 		  __sb->sbumpc();
diff -urN libstdc++-v3-orig/testsuite/27_io/basic_istream/ignore/char/4.cc libstdc++-v3/testsuite/27_io/basic_istream/ignore/char/4.cc
--- libstdc++-v3-orig/testsuite/27_io/basic_istream/ignore/char/4.cc	1970-01-01 01:00:00.000000000 +0100
+++ libstdc++-v3/testsuite/27_io/basic_istream/ignore/char/4.cc	2005-01-04 23:59:48.000000000 +0100
@@ -0,0 +1,59 @@
+// 2005-01-05  Paolo Carlini  <pcarlini@suse.de>
+
+// Copyright (C) 2005 Free Software Foundation
+//
+// 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, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+// USA.
+
+// 27.6.1.3 unformatted input functions
+
+#include <istream>
+#include <sstream>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  using namespace std;
+  bool test __attribute__((unused)) = true;
+
+  const string str_01("Gesang der junglinge");
+  ios_base::iostate state1, state2;
+
+  stringbuf isbuf_01(str_01, ios_base::in);
+  istream is_01(&isbuf_01);
+
+  state1 = is_01.rdstate();
+  VERIFY( state1 == ios_base::goodbit );
+
+  is_01.ignore(11, 'j');
+  VERIFY( is_01.gcount() == 11 );
+  state2 = is_01.rdstate();
+  VERIFY( state2 == state1 );
+  VERIFY( is_01.peek() == 'j' );
+
+  is_01.ignore(9);
+  VERIFY( is_01.gcount() == 9 );
+  state2 = is_01.rdstate();
+  VERIFY( state2 == state1 );
+}
+
+int 
+main()
+{
+  test01();
+  return 0;
+}
diff -urN libstdc++-v3-orig/testsuite/27_io/basic_istream/ignore/wchar_t/4.cc libstdc++-v3/testsuite/27_io/basic_istream/ignore/wchar_t/4.cc
--- libstdc++-v3-orig/testsuite/27_io/basic_istream/ignore/wchar_t/4.cc	1970-01-01 01:00:00.000000000 +0100
+++ libstdc++-v3/testsuite/27_io/basic_istream/ignore/wchar_t/4.cc	2005-01-04 23:59:06.000000000 +0100
@@ -0,0 +1,59 @@
+// 2005-01-05  Paolo Carlini  <pcarlini@suse.de>
+
+// Copyright (C) 2005 Free Software Foundation
+//
+// 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, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+// USA.
+
+// 27.6.1.3 unformatted input functions
+
+#include <istream>
+#include <sstream>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  using namespace std;
+  bool test __attribute__((unused)) = true;
+
+  const wstring str_01(L"Gesang der junglinge");
+  ios_base::iostate state1, state2;
+
+  wstringbuf isbuf_01(str_01, ios_base::in);
+  wistream is_01(&isbuf_01);
+
+  state1 = is_01.rdstate();
+  VERIFY( state1 == ios_base::goodbit );
+
+  is_01.ignore(11, L'j');
+  VERIFY( is_01.gcount() == 11 );
+  state2 = is_01.rdstate();
+  VERIFY( state2 == state1 );
+  VERIFY( is_01.peek() == L'j' );
+
+  is_01.ignore(9);
+  VERIFY( is_01.gcount() == 9 );
+  state2 = is_01.rdstate();
+  VERIFY( state2 == state1 );
+}
+
+int 
+main()
+{
+  test01();
+  return 0;
+}

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]