cygwin: unify reparse point checking code into single function

So far we had two functions checking the content of a reparse point,
readdir_check_reparse_point in fhandler_disk_file.cc for the sake of
readdir, and symlink_info::check_reparse_point for the sake of
generic path checking.

* Rename check_reparse_point_target helper to check_reparse_point_string
  and convert to static function.
* Create new check_reparse_point_target helper containing the core
  reparse point checking code
* Just call check_reparse_point_target from readdir_check_reparse_point
  and symlink_info::check_reparse_point and only perform the unique
  task in those functions.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

1 files changed, 15 insertions, 52 deletions

diff --git a/winsup/cygwin/fhandler_disk_file.cc b/winsup/cygwin/fhandler_disk_file.cc
index 6cc081d98..2144a4cdc 100644
--- a/winsup/cygwin/fhandler_disk_file.cc
+++ b/winsup/cygwin/fhandler_disk_file.cc
@@ -161,62 +161,25 @@ path_conv::isgood_inode (ino_t ino) const
   return true;
 }
 
-/* Check reparse point to determine if it should be treated as a posix symlink
-   or as a normal file/directory. Mount points are treated as normal directories
-   to match behavior of other systems. Unknown reparse tags are used for
-   things other than links (HSM, compression, dedup), and generally should be
-   treated as a normal file/directory. Native symlinks and mount points are
-   treated as posix symlinks, depending on the prefix of the target name.
-   This logic needs to agree with equivalent logic in path.cc
-   symlink_info::check_reparse_point() .
-   */
+/* Check reparse point to determine if it should be treated as a
+   posix symlink or as a normal file/directory.  Logic is explained
+   in detail in check_reparse_point_target in path.cc. */
 static inline bool
 readdir_check_reparse_point (POBJECT_ATTRIBUTES attr, bool remote)
 {
-  bool ret = false;
-  IO_STATUS_BLOCK io;
+  NTSTATUS status;
   HANDLE reph;
-  UNICODE_STRING subst;
-
-  if (NT_SUCCESS (NtOpenFile (&reph, READ_CONTROL, attr, &io,
-			      FILE_SHARE_VALID_FLAGS,
-			      FILE_OPEN_FOR_BACKUP_INTENT
-			      | FILE_OPEN_REPARSE_POINT)))
-    {
-      PREPARSE_DATA_BUFFER rp = (PREPARSE_DATA_BUFFER)
-		  alloca (MAXIMUM_REPARSE_DATA_BUFFER_SIZE);
-      if (NT_SUCCESS (NtFsControlFile (reph, NULL, NULL, NULL,
-		      &io, FSCTL_GET_REPARSE_POINT, NULL, 0,
-		      (LPVOID) rp, MAXIMUM_REPARSE_DATA_BUFFER_SIZE)))
-	{
-	  /* If reparse point is stored on a remote volume, lstat returns
-	     them as normal files or dirs, not as symlink.  For a description,
-	     see the comment preceeding remote check in
-	     symlink_info::check_reparse_point. */
-	  if (!remote && rp->ReparseTag == IO_REPARSE_TAG_MOUNT_POINT)
-	    {
-	      RtlInitCountedUnicodeString (&subst,
-		  (WCHAR *)((char *)rp->MountPointReparseBuffer.PathBuffer
-			    + rp->MountPointReparseBuffer.SubstituteNameOffset),
-		  rp->MountPointReparseBuffer.SubstituteNameLength);
-	      if (check_reparse_point_target (&subst))
-	        ret = true;
-	    }
-	  else if (rp->ReparseTag == IO_REPARSE_TAG_SYMLINK)
-	    {
-	      if (rp->SymbolicLinkReparseBuffer.Flags & SYMLINK_FLAG_RELATIVE)
-		ret = true;
-	      else
-		{
-		  RtlInitCountedUnicodeString (&subst,
-		      (WCHAR *)((char *)rp->SymbolicLinkReparseBuffer.PathBuffer
-			    + rp->SymbolicLinkReparseBuffer.SubstituteNameOffset),
-		      rp->SymbolicLinkReparseBuffer.SubstituteNameLength);
-		  if (check_reparse_point_target (&subst))
-		    ret = true;
-		}
-	    }
-	}
+  IO_STATUS_BLOCK io;
+  tmp_pathbuf tp;
+  UNICODE_STRING symbuf;
+  bool ret = false;
+
+  status = NtOpenFile (&reph, READ_CONTROL, attr, &io, FILE_SHARE_VALID_FLAGS,
+		       FILE_OPEN_FOR_BACKUP_INTENT | FILE_OPEN_REPARSE_POINT);
+  if (NT_SUCCESS (status))
+    {
+      PREPARSE_DATA_BUFFER rp = (PREPARSE_DATA_BUFFER) tp.c_get ();
+      ret = (check_reparse_point_target (reph, remote, rp, &symbuf) > 0);
       NtClose (reph);
     }
   return ret;