TensorFlow: add gfile.Copy implementation and test. Fixes #1102.

Change: 114712488

tensorflow/python/platform/default/_gfile.py

@@ -420,3 +420,21 @@ def Stat(path):   # pylint: disable=invalid-name
   filestat = collections.namedtuple('FileStat', ['mtime'])
   filestat.mtime = statinfo.st_mtime
   return filestat
+
+
+def Copy(oldpath, newpath, overwrite=False):
+  """Copy a file.
+
+  Args:
+    oldpath: string; a pathname of a file.
+    newpath: string; a pathname to which the file will be copied.
+    overwrite: boolean; if false, it is an error for newpath to be
+      occupied by an existing file.
+
+  Raises:
+    OSError: If "newpath" is occupied by an existing file and overwrite=False,
+             or any error thrown by shutil.copy.
+  """
+  if not overwrite and Exists(newpath):
+    raise OSError(errno.EEXIST, os.strerror(errno.EEXIST), newpath)
+  shutil.copy(oldpath, newpath)

tensorflow/python/platform/default/gfile_test.py

@@ -194,5 +194,32 @@ class FunctionTests(_BaseTest, googletest.TestCase):
     gfile.Rename(self.tmp + "dir2", self.tmp + "newdir")
     self.assertTrue(gfile.Exists(self.tmp + "newdir"))
 
+  def testCopy(self):
+    gfile.MkDir(self.tmp + "dir1")
+    gfile.MkDir(self.tmp + "dir2")
+    with gfile.GFile(self.tmp + "dir1/file1", "w"):
+      pass  # Create file
+    with gfile.GFile(self.tmp + "dir2/file2", "w"):
+      pass  # Create file
+
+    # Dest file already exists, overwrite=False (default).
+    self.assertRaises(
+        OSError, lambda: gfile.Copy(self.tmp + "dir1/file1",
+                                    self.tmp + "dir2/file2"))
+    # Overwrite succeeds
+    gfile.Copy(self.tmp + "dir1/file1", self.tmp + "dir2/file2",
+               overwrite=True)
+    self.assertTrue(gfile.Exists(self.tmp + "dir2/file2"))
+
+    # Normal copy.
+    gfile.Rename(self.tmp + "dir1/file1", self.tmp + "dir2/file1")
+    self.assertTrue(gfile.Exists(self.tmp + "dir2/file1"))
+
+    # Normal copy to non-existent dir
+    self.assertRaises(OSError,
+                      lambda: gfile.Rename(self.tmp + "dir1/file1",
+                                           self.tmp + "newdir/file1"))
+
+
 if __name__ == "__main__":
   googletest.main()