Initial directory junction support. See release_history.html

doc/release_history.html

@@ -36,6 +36,19 @@
   </tr>
 </table>
 
+<h2>1.56.1</h2>
+<ul>
+  <li>The Windows implementation now treats NTFS directory junctions (also known 
+  as junctions, also known as mount points) as symlinks. This has the effect of 
+  treating directory junctions as directories, and thus supporting all 
+  operations suitable for directories. This resolves
+  <a href="https://svn.boost.org/trac/boost/ticket/9016">#9016</a>. Directory 
+  junctions are very similar to symlinks, but may have performance or other 
+  advantages in some situations. They can be created from the command line with 
+  &quot;<code>mklink /j link target</code>&quot;. There is no plan for Boost.Filesystem to 
+  be able to create them directly other than by calling <code>std::system()</code>.</li>
+</ul>
+
 <h2>1.56.0</h2>
 <ul>
   <li>Reorganize <code>recursive_directory_iterator::increment</code>, adding an 
@@ -225,7 +238,7 @@
 </ul>
 <hr>
 <p>Revised
-<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan -->22 July, 2014<!--webbot bot="Timestamp" endspan i-checksum="21122" --></p>
+<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan -->25 July, 2014<!--webbot bot="Timestamp" endspan i-checksum="21128" --></p>
 <p>© Copyright Beman Dawes, 2011</p>
 <p> Use, modification, and distribution are subject to the Boost Software 
 License, Version 1.0. See <a href="http://www.boost.org/LICENSE_1_0.txt">

src/operations.cpp

@@ -53,6 +53,7 @@
 #endif
 #include <cerrno>
 
+#define BOOST_FILEYSTEM_INCLUDE_IOSTREAM
 #ifdef BOOST_FILEYSTEM_INCLUDE_IOSTREAM
 # include <iostream>
 #endif
@@ -586,9 +587,18 @@ namespace
     BOOL result = ::DeviceIoControl(h.handle, FSCTL_GET_REPARSE_POINT, NULL, 0, buf.get(),
       MAXIMUM_REPARSE_DATA_BUFFER_SIZE, &dwRetLen, NULL);
     if (!result) return false;
- 
+
-    return reinterpret_cast<const REPARSE_DATA_BUFFER*>(buf.get())
+    return reinterpret_cast<const REPARSE_DATA_BUFFER*>(buf.get())->ReparseTag
-      ->ReparseTag == IO_REPARSE_TAG_SYMLINK;
+        == IO_REPARSE_TAG_SYMLINK
+        // Issue 9016 asked that NTFS directory junctions be recognized as directories.
+        // That is equivalent to recognizing them as symlinks, and then the normal symlink
+        // mechanism will take care of recognizing them as directories.
+        //
+        // Directory junctions are very similar to symlinks, but have some performance
+        // and other advantages over symlinks. They can be created from the command line
+        // with "mklink /j junction-name target-path".
+      || reinterpret_cast<const REPARSE_DATA_BUFFER*>(buf.get())->ReparseTag
+        == IO_REPARSE_TAG_MOUNT_POINT;  // aka "directory junction" or "junction"
   }
 
   inline std::size_t get_full_path_name(

test/operations_test.cpp

@@ -1684,6 +1684,61 @@ namespace
         ==  "c:/foo");
       BOOST_TEST(fs::system_complete(fs::path("//share")).generic_string()
         ==  "//share");
+
+      // Issue 9016 asked that NTFS directory junctions be recognized as directories.
+      // That is equivalent to recognizing them as symlinks, and then the normal symlink
+      // mechanism will take care of recognizing them as directories.
+      //
+      // Directory junctions are very similar to symlinks, but have some performance
+      // and other advantages over symlinks. They can be created from the command line
+      // with "mklink /j junction-name target-path".
+
+      if (create_symlink_ok)  // only if symlinks supported
+      {
+        cout << "  directory junction tests..." << endl;
+        BOOST_TEST(fs::exists(dir));
+        BOOST_TEST(fs::exists(dir / "d1f1"));
+
+        fs::path junc(dir / "junc");
+        std::string cmd = "pushd ";
+        cmd += dir.string();
+        std::system(cmd.c_str());
+        std::system("mklink /j junc d1");
+        std::system("popd");
+
+        BOOST_TEST(fs::exists(junc));
+        BOOST_TEST(fs::is_symlink(junc));
+        BOOST_TEST(fs::is_directory(junc));
+        BOOST_TEST(!fs::is_regular_file(junc));
+        BOOST_TEST(fs::exists(junc / "d1f1"));
+        BOOST_TEST(fs::is_regular_file(junc / "d1f1"));
+
+        int count = 0;
+        for (fs::directory_iterator itr(junc);
+          itr != fs::directory_iterator(); ++itr)
+        {
+          cout << itr->path() << endl;
+          ++count;
+        }
+        BOOST_TEST(count > 0);
+
+        fs::path new_junc(dir / "new-junc");
+        fs::rename(junc, new_junc);
+        BOOST_TEST(!fs::exists(junc));
+        BOOST_TEST(fs::exists(new_junc));
+        BOOST_TEST(fs::is_symlink(new_junc));
+        BOOST_TEST(fs::is_directory(new_junc));
+        BOOST_TEST(!fs::is_regular_file(new_junc));
+        BOOST_TEST(fs::exists(new_junc / "d1f1"));
+        BOOST_TEST(fs::is_regular_file(new_junc / "d1f1"));
+
+        fs::remove(new_junc);
+        BOOST_TEST(!fs::exists(new_junc / "d1f1"));
+        BOOST_TEST(!fs::exists(new_junc));
+        BOOST_TEST(fs::exists(dir));
+        BOOST_TEST(fs::exists(dir / "d1f1"));
+      }
+
     } // Windows
 
     else if (platform == "POSIX")