filelog: raise CensoredNodeError when hash checks fail with censor metadata
With this change, when a revlog revision hash does not match its content, and
the content is empty with a special metadata key, the integrity failure is
assumed to be intentionally caused to remove sensitive content from repository
history.
To allow different Mercurial functionality to handle this scenario differently
a more specific exception is raised than "ordinary" hash failures.
Alternatives to this approach include, but are not limited to:
- Calling a hook when hashes mismatch to allow arbitrary tombstone validation.
Cons: Irresponsibly easy to disable integrity checking altogether.
- Returning empty revision data eagerly instead of raising, masking the error.
Cons: Push/pull won't roundtrip the tombstone, so client repos are unusable.
- Doing nothing differently at this layer. Callers must do their own detection
of tombstoned data if they want to handle some hash checks and not others.
- Impacts dozens of callsites, many of which don't have the revision data
- Would probably be missing one or two callsites at any given time
- Currently we throw a RevlogError, as do 12 other places in revlog.py.
Callers would need to parse the exception message and/or ensure
RevlogError is not thrown from any other part of their call tree.
#require serve fifo
Test hangup signal in the middle of transaction
$ hg init
$ mkfifo p
$ hg serve --stdio < p 1>out 2>&1 &
$ P=$!
Do test while holding fifo open
$ (
> echo lock
> echo addchangegroup
> start=`date +%s`
> # 10 second seems much enough to let the server catch up
> deadline=`expr $start + 10`
> while [ ! -s .hg/store/journal ]; do
> sleep 0;
> if [ `date +%s` -gt $deadline ]; then
> echo "transaction did not start after 10 seconds" >&2;
> exit 1;
> fi
> done
> kill -HUP $P
> ) > p
$ wait
$ cat out
0
0
adding changesets
transaction abort!
rollback completed
killed!
$ echo .hg/* .hg/store/*
.hg/00changelog.i .hg/journal.bookmarks .hg/journal.branch .hg/journal.desc .hg/journal.dirstate .hg/requires .hg/store .hg/store/00changelog.i .hg/store/00changelog.i.a .hg/store/journal.phaseroots