PR libstdc++/85632 fix wraparound in filesystem::space

On 32-bit targets any values over 4GB would wrap and produce the wrong
result.

	PR libstdc++/85632 use uintmax_t for arithmetic
	* src/filesystem/ops.cc (experimental::filesystem::space): Perform
	arithmetic in result type.
	* src/filesystem/std-ops.cc (filesystem::space): Likewise.
	* testsuite/27_io/filesystem/operations/space.cc: Check total capacity
	is greater than free space.
	* testsuite/experimental/filesystem/operations/space.cc: New.

From-SVN: r259901

libstdc++-v3/ChangeLog

 2018-05-03  Jonathan Wakely  <jwakely@redhat.com>
 
+	PR libstdc++/85632 use uintmax_t for arithmetic
+	* src/filesystem/ops.cc (experimental::filesystem::space): Perform
+	arithmetic in result type.
+	* src/filesystem/std-ops.cc (filesystem::space): Likewise.
+	* testsuite/27_io/filesystem/operations/space.cc: Check total capacity
+	is greater than free space.
+	* testsuite/experimental/filesystem/operations/space.cc: New.
+
 	* testsuite/20_util/remove_cvref/requirements/alias_decl.cc: New.
 	* testsuite/20_util/remove_cvref/requirements/explicit_instantiation.cc:
 	New.

libstdc++-v3/src/filesystem/ops.cc

@@ -1132,10 +1132,11 @@ fs::space(const path& p, error_code& ec) noexcept
       ec.assign(errno, std::generic_category());
   else
     {
+      uintmax_t fragment_size = f.f_frsize;
       info = space_info{
-	f.f_blocks * f.f_frsize,
-	f.f_bfree * f.f_frsize,
-	f.f_bavail * f.f_frsize
+	f.f_blocks * fragment_size,
+	f.f_bfree * fragment_size,
+	f.f_bavail * fragment_size
       };
       ec.clear();
     }

libstdc++-v3/src/filesystem/std-ops.cc

@@ -1378,10 +1378,11 @@ fs::space(const path& p, error_code& ec) noexcept
       ec.assign(errno, std::generic_category());
   else
     {
+      uintmax_t fragment_size = f.f_frsize;
       info = space_info{
-	f.f_blocks * f.f_frsize,
-	f.f_bfree * f.f_frsize,
-	f.f_bavail * f.f_frsize
+	f.f_blocks * fragment_size,
+	f.f_bfree * fragment_size,
+	f.f_bavail * fragment_size
       };
       ec.clear();
     }

libstdc++-v3/testsuite/27_io/filesystem/operations/space.cc

@@ -32,6 +32,7 @@ test01()
   std::error_code ec = make_error_code(std::errc::invalid_argument);
   s = std::filesystem::space("/", ec);
   VERIFY( !ec );
+
   s = std::filesystem::space(__gnu_test::nonexistent_path(), ec);
   VERIFY( ec );
   VERIFY( s.capacity ==  static_cast<uintmax_t>(-1) );
@@ -39,8 +40,16 @@ test01()
   VERIFY( s.available ==  static_cast<uintmax_t>(-1) );
 }
 
+void
+test02()
+{
+  std::filesystem::space_info s = std::filesystem::space(".");
+  VERIFY( s.capacity >= s.free );
+}
+
 int
 main()
 {
   test01();
+  test02();
 }

libstdc++-v3/testsuite/experimental/filesystem/operations/space.cc

+// Copyright (C) 2017-2018 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
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, 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 COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-DUSE_FILESYSTEM_TS -lstdc++fs" }
+// { dg-do run { target c++11 } }
+// { dg-require-filesystem-ts "" }
+
+// 30.10.14.3 Permissions [fs.op.space]
+
+#include <experimental/filesystem>
+#include <testsuite_fs.h>
+#include <testsuite_hooks.h>
+
+namespace fs = std::experimental::filesystem;
+
+void
+test01()
+{
+  fs::space_info s = fs::space("/");
+  std::error_code ec = make_error_code(std::errc::invalid_argument);
+  s = fs::space("/", ec);
+  VERIFY( !ec );
+
+  s = fs::space(__gnu_test::nonexistent_path(), ec);
+  VERIFY( ec );
+  VERIFY( s.capacity ==  static_cast<uintmax_t>(-1) );
+  VERIFY( s.free ==  static_cast<uintmax_t>(-1) );
+  VERIFY( s.available ==  static_cast<uintmax_t>(-1) );
+}
+
+void
+test02()
+{
+  fs::space_info s = fs::space(".");
+  VERIFY( s.capacity >= s.free );
+}
+
+int
+main()
+{
+  test01();
+  test02();
+}