D7890: nodemapdata: double check the source docket when doing incremental update

[marmoute (Pierre-Yves David)]

marmoute created this revision.
Herald added a subscriber: mercurial-devel.
Herald added a reviewer: hg-reviewers.

REVISION SUMMARY
  In theory, the index will have the information we expect it to have. However by
  security, it seems safer to double check that the incremental data are generated
  from the data currently on disk.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D7890

AFFECTED FILES
  mercurial/pure/parsers.py
  mercurial/revlogutils/nodemap.py

CHANGE DETAILS

diff --git a/mercurial/revlogutils/nodemap.py b/mercurial/revlogutils/nodemap.py
--- a/mercurial/revlogutils/nodemap.py
+++ b/mercurial/revlogutils/nodemap.py
@@ -77,18 +77,27 @@
     can_incremental = util.safehasattr(revlog.index, "nodemap_data_incremental")
     ondisk_docket = revlog._nodemap_docket
 
+    data = None
     # first attemp an incremental update of the data
     if can_incremental and ondisk_docket is not None:
         target_docket = revlog._nodemap_docket.copy()
-        data_changed_count, data = revlog.index.nodemap_data_incremental()
-        datafile = _rawdata_filepath(revlog, target_docket)
-        # EXP-TODO: if this is a cache, this should use a cache vfs, not a
-        # store vfs
-        with revlog.opener(datafile, 'a') as fd:
-            fd.write(data)
-        target_docket.data_length += len(data)
-        target_docket.data_unused += data_changed_count
-    else:
+        (
+            src_docket,
+            data_changed_count,
+            data,
+        ) = revlog.index.nodemap_data_incremental()
+        if src_docket != target_docket:
+            data = None
+        else:
+            datafile = _rawdata_filepath(revlog, target_docket)
+            # EXP-TODO: if this is a cache, this should use a cache vfs, not a
+            # store vfs
+            with revlog.opener(datafile, 'a') as fd:
+                fd.write(data)
+            target_docket.data_length += len(data)
+            target_docket.data_unused += data_changed_count
+
+    if data is None:
         # otherwise fallback to a full new export
         target_docket = NodeMapDocket()
         datafile = _rawdata_filepath(revlog, target_docket)
@@ -182,6 +191,17 @@
         new.data_unused = self.data_unused
         return new
 
+    def __cmp__(self, other):
+        if self.uid < other.uid:
+            return -1
+        if self.uid > other.uid:
+            return 1
+        elif self.data_length < other.data_length:
+            return -1
+        elif self.data_length > other.data_length:
+            return 1
+        return 0
+
     def serialize(self):
         """return serialized bytes for a docket using the passed uid"""
         data = []
diff --git a/mercurial/pure/parsers.py b/mercurial/pure/parsers.py
--- a/mercurial/pure/parsers.py
+++ b/mercurial/pure/parsers.py
@@ -164,11 +164,13 @@
         """
         if self._nm_root is None:
             return None
+        docket = self._nm_docket
         changed, data = nodemaputil.update_persistent_data(
-            self, self._nm_root, self._nm_max_idx, self._nm_rev
+            self, self._nm_root, self._nm_max_idx, self._nm_docket.tip_rev
         )
-        self._nm_root = self._nm_max_idx = self._nm_rev = None
-        return changed, data
+
+        self._nm_root = self._nm_max_idx = self._nm_docket = None
+        return docket, changed, data
 
     def update_nodemap_data(self, docket, nm_data):
         """provide full serialiazed data from a nodemap
@@ -178,9 +180,9 @@
         if nm_data is not None:
             self._nm_root, self._nm_max_idx = nodemaputil.parse_data(nm_data)
             if self._nm_root:
-                self._nm_rev = docket.tip_rev
+                self._nm_docket = docket
             else:
-                self._nm_root = self._nm_max_idx = self._nm_rev = None
+                self._nm_root = self._nm_max_idx = self._nm_docket = None
 
 
 class InlinedIndexObject(BaseIndexObject):



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