Add RepositoryInterface.validate_chunk_content method

5 files changed, 52 insertions, 6 deletions

diff --git a/obnamlib/plugins/restore_plugin.py b/obnamlib/plugins/restore_plugin.py
index bc8b42d3..bdbcfed5 100644
--- a/obnamlib/plugins/restore_plugin.py
+++ b/obnamlib/plugins/restore_plugin.py
@@ -302,10 +302,7 @@ class RestorePlugin(obnamlib.ObnamPlugin):
                 f.write('\0')
 
     def verify_chunk_checksum(self, data, chunkid):
-        # FIXME: The RepositoryInterface does not currently have
-        # a way to do this, so at this time this is a no-op, to be
-        # fixed later.
-        pass
+        self.repo.validate_chunk_content(chunkid)
 
     def restore_fifo(self, gen, filename, metadata):
         logging.debug('restoring fifo %s' % filename)
diff --git a/obnamlib/repo_dummy.py b/obnamlib/repo_dummy.py
index 078bed6b..61800593 100644
--- a/obnamlib/repo_dummy.py
+++ b/obnamlib/repo_dummy.py
@@ -659,6 +659,8 @@ class RepositoryFormatDummy(obnamlib.RepositoryInterface):
     def remove_chunk_from_indexes(self, chunk_id, client_id):
         return self._chunk_indexes.remove_chunk(chunk_id, client_id)
 
+    def validate_chunk_content(self, chunk_id):
+        return None
+
     def get_fsck_work_item(self):
         return 'this pretends to be a work item'
-
diff --git a/obnamlib/repo_fmt_6.py b/obnamlib/repo_fmt_6.py
index 9288805b..920b5d04 100644
--- a/obnamlib/repo_fmt_6.py
+++ b/obnamlib/repo_fmt_6.py
@@ -685,6 +685,15 @@ class RepositoryFormat6(obnamlib.RepositoryInterface):
                 return chunk_id
         raise obnamlib.RepositoryChunkContentNotInIndexes()
 
+    def validate_chunk_content(self, chunk_id):
+        try:
+            content = self.get_chunk_content(chunk_id)
+        except obnamlib.RepositoryChunkDoesNotExist:
+            return False
+        actual_checksum = self._checksum(content)
+        expected_checksum = self._chunklist.get_checksum(chunk_id)
+        return actual_checksum == expected_checksum
+
     # Individual files in a generation.
 
     def _setup_file_keys(self):
diff --git a/obnamlib/repo_interface.py b/obnamlib/repo_interface.py
index 38f33b61..6fc02034 100644
--- a/obnamlib/repo_interface.py
+++ b/obnamlib/repo_interface.py
@@ -709,6 +709,26 @@ class RepositoryInterface(object):
         '''
         raise NotImplementedError()
 
+    def validate_chunk_content(self, chunk_id):
+        '''Make sure the content of a chunk is valid.
+
+        This is (presumably) done by storing a checksum of the chunk
+        data in the chunk indexes, and then verifying that. However,
+        it could be done by error checking codes. It could also not be
+        done at all: if a repository format does not have chunk
+        indexes in any form, it can just return None for all
+        validation.
+
+        If a chunk is missing, it should be treated as an invalid
+        chunk (return False or None, depending).
+
+        Return True if content is valid, False if it is invalid, and
+        None if it is not known either way.
+
+        '''
+
+        raise NotImplementedError()
+
     # Fsck.
 
     def get_fsck_work_item(self):
@@ -1757,8 +1777,26 @@ class RepositoryInterfaceTests(unittest.TestCase): # pragma: no cover
         self.repo.force_chunk_indexes_lock()
         self.assertEqual(self.repo.lock_chunk_indexes(), None)
 
+    def test_validate_chunk_content_returns_True_or_None(self):
+        self.setup_client()
+        chunk_id = self.repo.put_chunk_content('foochunk')
+        self.repo.lock_chunk_indexes()
+        self.repo.put_chunk_into_indexes(chunk_id, 'foochunk', 'fooclient')
+        self.repo.commit_chunk_indexes()
+        ret = self.repo.validate_chunk_content(chunk_id)
+        self.assertTrue(ret is True or ret is None)
+
+    def test_validate_chunk_content_returns_False_or_None_if_corrupted(self):
+        self.setup_client()
+        chunk_id = self.repo.put_chunk_content('foochunk')
+        self.repo.lock_chunk_indexes()
+        self.repo.put_chunk_into_indexes(chunk_id, 'foochunk', 'fooclient')
+        self.repo.commit_chunk_indexes()
+        self.repo.remove_chunk(chunk_id)
+        ret = self.repo.validate_chunk_content(chunk_id)
+        self.assertTrue(ret is False or ret is None)
+
     # Fsck.
 
     def test_returns_fsck_work_item(self):
         self.assertNotEqual(self.repo.get_fsck_work_item(), None)
-
diff --git a/test-gpghome/random_seed b/test-gpghome/random_seed
index 2a075662..3a3a9272 100644
--- a/test-gpghome/random_seed
+++ b/test-gpghome/random_seed