Preserve existing hardlinks during merge.

The previous code created hardlinks rather aggressively, which was
helpful as a workaround for lack of hardlinks in tarballs created
by quickpkg due to bug #185305. Since bug #338509, quickpkg tarballs
preserve hardlinks, so there's no need for aggressive hardlink
creation. Therefore, simply preserve existing hardlinks during merge,
by comparison of st_dev and st_ino from the source files.

diff --git a/pym/portage/dbapi/vartree.py b/pym/portage/dbapi/vartree.py
index d3704b598bbbf7851013741ae53b23ae302330f6..d269e93ea8a882d4e0c8853d652599908010cd89 100644 (file)
--- a/pym/portage/dbapi/vartree.py
+++ b/pym/portage/dbapi/vartree.py
@@ -3762,25 +3762,14 @@ class dblink(object):
                                # whether config protection or not, we merge the new file the
                                # same way.  Unless moveme=0 (blocking directory)
                                if moveme:
-                                       # Do not hardlink files unless they are in the same
-                                       # directory, since otherwise tar may not be able to
-                                       # extract a tarball of the resulting hardlinks due to
-                                       # 'Invalid cross-device link' errors (depends on layout of
-                                       # mount points). Also, don't hardlink zero-byte files since
-                                       # it doesn't save any space, and don't hardlink
-                                       # CONFIG_PROTECTed files since config files shouldn't be
-                                       # hardlinked to eachother (for example, shadow installs
-                                       # several identical config files inside /etc/pam.d/).
-                                       parent_dir = os.path.dirname(myrealdest)
-                                       hardlink_key = (parent_dir, mymd5, mystat.st_size,
-                                               mystat.st_mode, mystat.st_uid, mystat.st_gid)
-
-                                       hardlink_candidates = None
-                                       if not protected and mystat.st_size != 0:
-                                               hardlink_candidates = self._md5_merge_map.get(hardlink_key)
-                                               if hardlink_candidates is None:
-                                                       hardlink_candidates = []
-                                                       self._md5_merge_map[hardlink_key] = hardlink_candidates
+                                       # Create hardlinks only for source files that already exist
+                                       # as hardlinks (having identical st_dev and st_ino).
+                                       hardlink_key = (mystat.st_dev, mystat.st_ino)
+
+                                       hardlink_candidates = self._md5_merge_map.get(hardlink_key)
+                                       if hardlink_candidates is None:
+                                               hardlink_candidates = []
+                                               self._md5_merge_map[hardlink_key] = hardlink_candidates
 
                                        mymtime = movefile(mysrc, mydest, newmtime=thismtime,
                                                sstat=mystat, mysettings=self.settings,