From 5ab06bd117a08388e3102fc590e909d59e9a187b Mon Sep 17 00:00:00 2001
From: Gregory Szorc <gps@mozilla.com>
Date: Tue, 3 Sep 2013 19:38:07 -0700
Subject: [PATCH] Bug 911362 - FileCopier support for not removing unreferenced
 files; r=glandium

---
 python/mozbuild/mozpack/copier.py           | 27 ++++++++++++---------
 python/mozbuild/mozpack/test/test_copier.py | 16 ++++++++++++
 2 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/python/mozbuild/mozpack/copier.py b/python/mozbuild/mozpack/copier.py
index f7023aa4870f..1db15ce70e0b 100644
--- a/python/mozbuild/mozpack/copier.py
+++ b/python/mozbuild/mozpack/copier.py
@@ -164,15 +164,17 @@ class FileCopier(FileRegistry):
     FileRegistry with the ability to copy the registered files to a separate
     directory.
     '''
-    def copy(self, destination, skip_if_older=True):
+    def copy(self, destination, skip_if_older=True, remove_unaccounted=True):
         '''
         Copy all registered files to the given destination path. The given
         destination can be an existing directory, or not exist at all. It
         can't be e.g. a file.
         The copy process acts a bit like rsync: files are not copied when they
-        don't need to (see mozpack.files for details on file.copy), and files
-        existing in the destination directory that aren't registered are
-        removed.
+        don't need to (see mozpack.files for details on file.copy).
+
+        By default, files in the destination directory that aren't registered
+        are removed and empty directories are deleted. To disable removing of
+        unregistered files, pass remove_unaccounted=False.
 
         Returns a FileCopyResult that details what changed.
         '''
@@ -195,15 +197,16 @@ class FileCopier(FileRegistry):
             for f in files:
                 actual_dest_files.add(os.path.normpath(os.path.join(root, f)))
 
-        for f in actual_dest_files - dest_files:
-            # Windows requires write access to remove files.
-            if os.name == 'nt' and not os.access(f, os.W_OK):
-                # It doesn't matter what we set the permissions to since we
-                # will remove this file shortly.
-                os.chmod(f, 0600)
+        if remove_unaccounted:
+            for f in actual_dest_files - dest_files:
+                # Windows requires write access to remove files.
+                if os.name == 'nt' and not os.access(f, os.W_OK):
+                    # It doesn't matter what we set the permissions to since we
+                    # will remove this file shortly.
+                    os.chmod(f, 0600)
 
-            os.remove(f)
-            result.removed_files.add(f)
+                os.remove(f)
+                result.removed_files.add(f)
 
         for root, dirs, files in os.walk(destination):
             if files or dirs:
diff --git a/python/mozbuild/mozpack/test/test_copier.py b/python/mozbuild/mozpack/test/test_copier.py
index e8b81d102e98..f9fdbf24e393 100644
--- a/python/mozbuild/mozpack/test/test_copier.py
+++ b/python/mozbuild/mozpack/test/test_copier.py
@@ -155,6 +155,22 @@ class TestFileCopier(TestWithTmpDir):
         self.assertEqual(result.removed_files_count, 1)
         self.assertFalse(os.path.exists(p))
 
+    def test_no_remove(self):
+        copier = FileCopier()
+        copier.add('foo', GeneratedFile('foo'))
+
+        with open(self.tmppath('bar'), 'a'):
+            pass
+
+        os.mkdir(self.tmppath('emptydir'))
+
+        result = copier.copy(self.tmpdir, remove_unaccounted=False)
+
+        self.assertEqual(self.all_files(self.tmpdir), set(['foo', 'bar']))
+        self.assertEqual(result.removed_files, set())
+        self.assertEqual(result.removed_directories,
+            set([self.tmppath('emptydir')]))
+
 
 class TestFilePurger(TestWithTmpDir):
     def test_file_purger(self):