similar: compare between actual file contents for exact identity
Before this patch, similarity detection logic (for addremove and
automv) depends entirely on SHA-1 digesting. But this causes incorrect
rename detection, if:
- removing file A and adding file B occur at same committing, and
- SHA-1 hash values of file A and B are same
This may prevent security experts from managing sample files for
SHAttered issue in Mercurial repository, for example.
https://security.googleblog.com/2017/02/announcing-first-sha1-collision.html
https://shattered.it/
Hash collision itself isn't so serious for core repository
functionality of Mercurial, described by mpm as below, though.
https://www.mercurial-scm.org/wiki/mpm/SHA1
This patch compares between actual file contents after hash comparison
for exact identity.
Even after this patch, SHA-1 is still used, because it is reasonable
enough to quickly detect existence of "(almost) same" file.
- replacing SHA-1 causes decreasing performance, and
- replacement of it has ambiguity, yet
Getting content of removed file (= rfctx.data()) at each exact
comparison should be cheap enough, even though getting content of
added one costs much.
======= ============== =====================
file fctx data() reads from
======= ============== =====================
removed filectx in-memory revlog data
added workingfilectx storage
======= ============== =====================
Verify that pending changesets are seen by pretxn* hooks but not by other
processes that access the destination repo while the hooks are running.
The hooks (python and external) both reject changesets after some think time,
during which another process runs pull. Each hook creates a file ('notify') to
indicate to the controlling process that it is running; the process removes the
file to indicate the hook can terminate.
init env vars
$ d=`pwd`
$ maxwait=20
utility to run the test - start a push in the background and run pull
$ dotest() {
> rm -f notify
> printf 'push '; hg -R child-push tip --template '{node}\n'
> hg -R child-push -q push > push.out 2>&1 &
>
> # wait for hook to create the notify file
> i=$maxwait
> while [ ! -f notify -a $i != 0 ]; do
> sleep 1
> i=`expr $i - 1`
> done
>
> # run pull
> hg -R child-pull -q pull
> rc=$?
>
> # tell hook to finish; notify should exist.
> rm notify
> wait
>
> cat push.out
> printf 'pull '; hg -R child-pull tip --template '{node}\n'
> return $rc
> }
python hook
$ cat <<EOF > reject.py
> import os, time
> from mercurial import ui, localrepo
> def rejecthook(ui, repo, hooktype, node, **opts):
> ui.write('hook %s\\n' % repo['tip'].hex())
> # create the notify file so caller knows we're running
> fpath = os.path.join('$d', 'notify')
> f = open(fpath, 'w')
> f.close()
> # wait for ack - caller should delete the notify file
> i = $maxwait
> while os.path.exists(fpath) and i > 0:
> time.sleep(1)
> i -= 1
> return True # reject the changesets
> EOF
external hook
$ cat <<EOF > reject.sh
> printf 'hook '; hg tip --template '{node}\\n'
> # create the notify file so caller knows we're running
> fpath=$d/notify
> touch \$fpath
> # wait for ack - caller should delete the notify file
> i=$maxwait
> while [ -f \$fpath -a \$i != 0 ]; do
> sleep 1
> i=\`expr \$i - 1\`
> done
> exit 1 # reject the changesets
> EOF
create repos
$ hg init parent
$ hg clone -q parent child-push
$ hg clone -q parent child-pull
$ echo a > child-push/a
$ hg -R child-push add child-push/a
$ hg -R child-push commit -m a -d '1000000 0'
test python hook
$ cat <<EOF > parent/.hg/hgrc
> [extensions]
> reject = $d/reject.py
> [hooks]
> pretxnchangegroup = python:reject.rejecthook
> EOF
$ dotest
push 29b62aeb769fdf78d8d9c5f28b017f76d7ef824b
hook 29b62aeb769fdf78d8d9c5f28b017f76d7ef824b
transaction abort!
rollback completed
abort: pretxnchangegroup hook failed
pull 0000000000000000000000000000000000000000
test external hook
$ cat <<EOF > parent/.hg/hgrc
> [hooks]
> pretxnchangegroup = sh $d/reject.sh
> EOF
$ dotest
push 29b62aeb769fdf78d8d9c5f28b017f76d7ef824b
hook 29b62aeb769fdf78d8d9c5f28b017f76d7ef824b
transaction abort!
rollback completed
abort: pretxnchangegroup hook exited with status 1
pull 0000000000000000000000000000000000000000
Test that pending on transaction without changegroup see the normal changegroup(
(issue4609)
$ cat <<EOF > parent/.hg/hgrc
> [hooks]
> pretxnchangegroup=
> pretxnclose = hg tip -T "tip: {node|short}\n"
> [phases]
> publishing=False
> EOF
setup
$ cd parent
$ echo a > a
$ hg add a
$ hg commit -m a
tip: cb9a9f314b8b
actual test
$ hg phase --public .
tip: cb9a9f314b8b