unprotect: only process symlinks and hardlinks

Fixes #1373

Signed-off-by: Ruslan Kuprieiev <[email protected]>

dvc/project.py

@@ -325,16 +325,21 @@ class Project(object):
     def _unprotect_file(self, path):
         import stat
         import uuid
+        from dvc.system import System
         from dvc.utils import copyfile, move, remove
 
-        self.logger.debug("Unprotecting '{}'".format(path))
+        if System.is_symlink(path) or System.is_hardlink(path):
+            self.logger.debug("Unprotecting '{}'".format(path))
 
-        tmp = os.path.join(os.path.dirname(path), '.' + str(uuid.uuid4()))
-        move(path, tmp)
+            tmp = os.path.join(os.path.dirname(path), '.' + str(uuid.uuid4()))
+            move(path, tmp)
 
-        copyfile(tmp, path)
+            copyfile(tmp, path)
 
-        remove(tmp)
+            remove(tmp)
+        else:
+            self.logger.debug("Skipping copying for '{}', since it is not "
+                              "a symlink or a hardlink.".format(path))
 
         os.chmod(path, os.stat(path).st_mode | stat.S_IWRITE)
 

dvc/system.py

@@ -240,3 +240,22 @@ class System(object):
             return System._wait_for_input_posix(timeout)
         else:
             return System._wait_for_input_windows(timeout)
+
+    @staticmethod
+    def is_symlink(path):
+        if System.is_unix():
+            return os.path.islink(path)
+
+        # https://docs.microsoft.com/en-us/windows/desktop/fileio/
+        # file-attribute-constants
+        FILE_ATTRIBUTE_REPARSE_POINT = 0x400
+        info = System.getdirinfo(path)
+        return info.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT
+
+    @staticmethod
+    def is_hardlink(path):
+        if System.is_unix():
+            return os.stat(path).st_nlink > 1
+
+        info = System.getdirinfo(path)
+        return info.nNumberOfLinks > 1