filelog: don't crash on invalid copy metadata (issue5748)

"copy" and "copyrev" are both supposed to appear next to each other.
However, a user report demonstrated a crash that indicates that
something in the wild is producing "copy" without "copyrev"
(probably `hg convert`).

While we should definitely fix the source of the bad metadata,
the bad code causing the crash is already in the wild and who knows
how many repositories are impacted. So let's be more defensive
when accessing the file revision metadata.

mercurial/filelog.py

@@ -1,267 +1,269 b''
 # filelog.py - file history class for mercurial
 #
 # Copyright 2005-2007 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import
 
 from . import (
     error,
     repository,
     revlog,
 )
 from .utils import (
     interfaceutil,
 )
 
 @interfaceutil.implementer(repository.ifilestorage)
 class filelog(object):
     def __init__(self, opener, path):
         self._revlog = revlog.revlog(opener,
                                      '/'.join(('data', path + '.i')),
                                      censorable=True)
         # full name of the user visible file, relative to the repository root
         self.filename = path
         self.index = self._revlog.index
         self.version = self._revlog.version
         self.storedeltachains = self._revlog.storedeltachains
         self._generaldelta = self._revlog._generaldelta
 
     def __len__(self):
         return len(self._revlog)
 
     def __iter__(self):
         return self._revlog.__iter__()
 
     def revs(self, start=0, stop=None):
         return self._revlog.revs(start=start, stop=stop)
 
     def parents(self, node):
         return self._revlog.parents(node)
 
     def parentrevs(self, rev):
         return self._revlog.parentrevs(rev)
 
     def rev(self, node):
         return self._revlog.rev(node)
 
     def node(self, rev):
         return self._revlog.node(rev)
 
     def lookup(self, node):
         return self._revlog.lookup(node)
 
     def linkrev(self, rev):
         return self._revlog.linkrev(rev)
 
     def flags(self, rev):
         return self._revlog.flags(rev)
 
     def commonancestorsheads(self, node1, node2):
         return self._revlog.commonancestorsheads(node1, node2)
 
     def descendants(self, revs):
         return self._revlog.descendants(revs)
 
     def headrevs(self):
         return self._revlog.headrevs()
 
     def heads(self, start=None, stop=None):
         return self._revlog.heads(start, stop)
 
     def children(self, node):
         return self._revlog.children(node)
 
     def deltaparent(self, rev):
         return self._revlog.deltaparent(rev)
 
     def candelta(self, baserev, rev):
         return self._revlog.candelta(baserev, rev)
 
     def iscensored(self, rev):
         return self._revlog.iscensored(rev)
 
     def rawsize(self, rev):
         return self._revlog.rawsize(rev)
 
     def checkhash(self, text, node, p1=None, p2=None, rev=None):
         return self._revlog.checkhash(text, node, p1=p1, p2=p2, rev=rev)
 
     def revision(self, node, _df=None, raw=False):
         return self._revlog.revision(node, _df=_df, raw=raw)
 
     def revdiff(self, rev1, rev2):
         return self._revlog.revdiff(rev1, rev2)
 
     def addrevision(self, revisiondata, transaction, linkrev, p1, p2,
                     node=None, flags=revlog.REVIDX_DEFAULT_FLAGS,
                     cachedelta=None):
         return self._revlog.addrevision(revisiondata, transaction, linkrev,
                                     p1, p2, node=node, flags=flags,
                                     cachedelta=cachedelta)
 
     def addgroup(self, deltas, linkmapper, transaction, addrevisioncb=None):
         return self._revlog.addgroup(deltas, linkmapper, transaction,
                                  addrevisioncb=addrevisioncb)
 
     def getstrippoint(self, minlink):
         return self._revlog.getstrippoint(minlink)
 
     def strip(self, minlink, transaction):
         return self._revlog.strip(minlink, transaction)
 
     def files(self):
         return self._revlog.files()
 
     def checksize(self):
         return self._revlog.checksize()
 
     def read(self, node):
         t = self.revision(node)
         if not t.startswith('\1\n'):
             return t
         s = t.index('\1\n', 2)
         return t[s + 2:]
 
     def add(self, text, meta, transaction, link, p1=None, p2=None):
         if meta or text.startswith('\1\n'):
             text = revlog.packmeta(meta, text)
         return self.addrevision(text, transaction, link, p1, p2)
 
     def renamed(self, node):
         if self.parents(node)[0] != revlog.nullid:
             return False
         t = self.revision(node)
         m = revlog.parsemeta(t)[0]
-        if m and "copy" in m:
+        # copy and copyrev occur in pairs. In rare cases due to bugs,
+        # one can occur without the other.
+        if m and "copy" in m and "copyrev" in m:
             return (m["copy"], revlog.bin(m["copyrev"]))
         return False
 
     def size(self, rev):
         """return the size of a given revision"""
 
         # for revisions with renames, we have to go the slow way
         node = self.node(rev)
         if self.renamed(node):
             return len(self.read(node))
         if self.iscensored(rev):
             return 0
 
         # XXX if self.read(node).startswith("\1\n"), this returns (size+4)
         return self._revlog.size(rev)
 
     def cmp(self, node, text):
         """compare text with a given file revision
 
         returns True if text is different than what is stored.
         """
 
         t = text
         if text.startswith('\1\n'):
             t = '\1\n\1\n' + text
 
         samehashes = not self._revlog.cmp(node, t)
         if samehashes:
             return False
 
         # censored files compare against the empty file
         if self.iscensored(self.rev(node)):
             return text != ''
 
         # renaming a file produces a different hash, even if the data
         # remains unchanged. Check if it's the case (slow):
         if self.renamed(node):
             t2 = self.read(node)
             return t2 != text
 
         return True
 
     @property
     def filename(self):
         return self._revlog.filename
 
     @filename.setter
     def filename(self, value):
         self._revlog.filename = value
 
     # TODO these aren't part of the interface and aren't internal methods.
     # Callers should be fixed to not use them.
     @property
     def indexfile(self):
         return self._revlog.indexfile
 
     @indexfile.setter
     def indexfile(self, value):
         self._revlog.indexfile = value
 
     @property
     def datafile(self):
         return self._revlog.datafile
 
     @property
     def opener(self):
         return self._revlog.opener
 
     @property
     def _lazydeltabase(self):
         return self._revlog._lazydeltabase
 
     @_lazydeltabase.setter
     def _lazydeltabase(self, value):
         self._revlog._lazydeltabase = value
 
     @property
     def _aggressivemergedeltas(self):
         return self._revlog._aggressivemergedeltas
 
     @_aggressivemergedeltas.setter
     def _aggressivemergedeltas(self, value):
         self._revlog._aggressivemergedeltas = value
 
     @property
     def _inline(self):
         return self._revlog._inline
 
     @property
     def _withsparseread(self):
         return getattr(self._revlog, '_withsparseread', False)
 
     @property
     def _srmingapsize(self):
         return self._revlog._srmingapsize
 
     @property
     def _srdensitythreshold(self):
         return self._revlog._srdensitythreshold
 
     def _deltachain(self, rev, stoprev=None):
         return self._revlog._deltachain(rev, stoprev)
 
     def chainbase(self, rev):
         return self._revlog.chainbase(rev)
 
     def chainlen(self, rev):
         return self._revlog.chainlen(rev)
 
     def clone(self, tr, destrevlog, **kwargs):
         if not isinstance(destrevlog, filelog):
             raise error.ProgrammingError('expected filelog to clone()')
 
         return self._revlog.clone(tr, destrevlog._revlog, **kwargs)
 
     def start(self, rev):
         return self._revlog.start(rev)
 
     def end(self, rev):
         return self._revlog.end(rev)
 
     def length(self, rev):
         return self._revlog.length(rev)
 
     def compress(self, data):
         return self._revlog.compress(data)
 
     def _addrevision(self, *args, **kwargs):
         return self._revlog._addrevision(*args, **kwargs)