From 50e248f0c8dd85a0e1778050d998f4010d87ed46 Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Wed, 1 Nov 2017 17:09:14 +0000
Subject: [PATCH] PR libstdc++/82777 fix path normalization for dot-dot

	PR libstdc++/82777
	* src/filesystem/std-path.cc (path::lexically_normal): Remove dot-dot
	elements correctly.
	* testsuite/27_io/filesystem/path/generation/normal.cc: Add testcase.
	* testsuite/util/testsuite_fs.h (compare_paths): Improve exception
	text.

From-SVN: r254317
---
 libstdc++-v3/ChangeLog                        |  9 +++++
 libstdc++-v3/src/filesystem/std-path.cc       | 33 ++++++++++++++++---
 .../filesystem/path/generation/normal.cc      |  4 +++
 libstdc++-v3/testsuite/util/testsuite_fs.h    |  2 +-
 4 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index b5adbb19dce..9805e4ba664 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,12 @@
+2017-11-01  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/82777
+	* src/filesystem/std-path.cc (path::lexically_normal): Remove dot-dot
+	elements correctly.
+	* testsuite/27_io/filesystem/path/generation/normal.cc: Add testcase.
+	* testsuite/util/testsuite_fs.h (compare_paths): Improve exception
+	text.
+
 2017-10-30  Jonathan Wakely  <jwakely@redhat.com>
 
 	* include/Makefile.am (stamp-bits-sup): Do not create broken symlink
diff --git a/libstdc++-v3/src/filesystem/std-path.cc b/libstdc++-v3/src/filesystem/std-path.cc
index 1e2a8fad584..330aee72b13 100644
--- a/libstdc++-v3/src/filesystem/std-path.cc
+++ b/libstdc++-v3/src/filesystem/std-path.cc
@@ -388,10 +388,35 @@ path::lexically_normal() const
 #endif
       if (is_dotdot(p))
 	{
-	  if (ret.has_filename() && !is_dotdot(ret.filename()))
-	    ret.remove_filename();
-	  else if (ret.has_filename() || !ret.has_root_directory())
-	    ret /= p;
+	  if (ret.has_filename())
+	    {
+	      // remove a non-dot-dot filename immediately followed by /..
+	      if (!is_dotdot(ret.filename()))
+		ret.remove_filename();
+	      else
+		ret /= p;
+	    }
+	  else if (!ret.has_relative_path())
+	    {
+	      if (!ret.is_absolute())
+		ret /= p;
+	    }
+	  else
+	    {
+	      // Got a path with a relative path (i.e. at least one non-root
+	      // element) and no filename at the end (i.e. empty last element),
+	      // so must have a trailing slash. See what is before it.
+	      auto elem = std::prev(ret.end(), 2);
+	      if (elem->has_filename() && !is_dotdot(*elem))
+		{
+		  // Remove the filename before the trailing slash
+		  // (equiv. to ret = ret.parent_path().remove_filename())
+		  ret._M_pathname.erase(elem._M_cur->_M_pos);
+		  ret._M_cmpts.erase(elem._M_cur, ret._M_cmpts.end());
+		}
+	      else // ???
+		ret /= p;
+	    }
 	}
       else if (is_dot(p))
 	ret /= path();
diff --git a/libstdc++-v3/testsuite/27_io/filesystem/path/generation/normal.cc b/libstdc++-v3/testsuite/27_io/filesystem/path/generation/normal.cc
index 789ce186f82..df3b7154ab3 100644
--- a/libstdc++-v3/testsuite/27_io/filesystem/path/generation/normal.cc
+++ b/libstdc++-v3/testsuite/27_io/filesystem/path/generation/normal.cc
@@ -46,6 +46,10 @@ test02()
   compare_paths( path().lexically_normal(), "" );
 
   compare_paths( path("/..").lexically_normal(), "/" );
+
+  // PR libstdc++/82777
+  compare_paths( path("./a/b/c/../.././b/c").lexically_normal(), "a/b/c" );
+  compare_paths( path("/a/b/c/../.././b/c").lexically_normal(), "/a/b/c" );
 }
 
 void
diff --git a/libstdc++-v3/testsuite/util/testsuite_fs.h b/libstdc++-v3/testsuite/util/testsuite_fs.h
index 47f56090b47..c18dae28fcc 100644
--- a/libstdc++-v3/testsuite/util/testsuite_fs.h
+++ b/libstdc++-v3/testsuite/util/testsuite_fs.h
@@ -40,7 +40,7 @@ namespace __gnu_test
 {
 #define PATH_CHK(p1, p2, fn) \
     if ( p1.fn() != p2.fn() ) \
-      throw test_fs::filesystem_error( #fn, p1, p2, \
+      throw test_fs::filesystem_error("comparing '" #fn "' failed", p1, p2, \
 	  std::make_error_code(std::errc::invalid_argument) )
 
   void
-- 
2.30.2