view tests/test-inherit-mode.t @ 46607:e9901d01d135

revlog: add a mechanism to verify expected file position before appending

If someone uses `hg debuglocks`, or some non-hg process writes to the .hg
directory without respecting the locks, or if the repo's on a networked
filesystem, it's possible for the revlog code to write out corrupted data.

The form of this corruption can vary depending on what data was written and how
that happened. We are in the "networked filesystem" case (though I've had users
also do this to themselves with the "`hg debuglocks`" scenario), and most often
see this with the changelog. What ends up happening is we produce two items
(let's call them rev1 and rev2) in the .i file that have the same linkrev,
baserev, and offset into the .d file, while the data in the .d file is appended
properly. rev2's compressed_size is accurate for rev2, but when we go to
decompress the data in the .d file, we use the offset that's recorded in the
index file, which is the same as rev1, and attempt to decompress
rev2.compressed_size bytes of rev1's data. This usually does not succeed. :)

When using inline data, this also fails, though I haven't investigated why too
closely. This shows up as a "patch decode" error. I believe what's happening
there is that we're basically ignoring the offset field, getting the data
properly, but since baserev != rev, it thinks this is a delta based on rev
(instead of a full text) and can't actually apply it as such.

For now, I'm going to make this an optional component and default it to entirely
off. I may increase the default severity of this in the future, once I've
enabled it for my users and we gain more experience with it. Luckily, most of my
users have a versioned filesystem and can roll back to before the corruption has
been written, it's just a hassle to do so and not everyone knows how (so it's a
support burden). Users on other filesystems will not have that luxury, and this
can cause them to have a corrupted repository that they are unlikely to know how
to resolve, and they'll see this as a data-loss event. Refusing to create the
corruption is a much better user experience.

This mechanism is not perfect. There may be false-negatives (racy writes that
are not detected). There should not be any false-positives (non-racy writes that
are detected as such). This is not a mechanism that makes putting a repo on a
networked filesystem "safe" or "supported", just *less* likely to cause
corruption.

Differential Revision: https://phab.mercurial-scm.org/D9952

#require unix-permissions

test that new files created in .hg inherit the permissions from .hg/store

  $ mkdir dir

just in case somebody has a strange $TMPDIR

  $ chmod g-s dir
  $ cd dir

  $ cat >printmodes.py <<EOF
  > from __future__ import absolute_import, print_function
  > import os
  > import sys
  > 
  > allnames = []
  > isdir = {}
  > for root, dirs, files in os.walk(sys.argv[1]):
  >     for d in dirs:
  >         name = os.path.join(root, d)
  >         isdir[name] = 1
  >         allnames.append(name)
  >     for f in files:
  >         name = os.path.join(root, f)
  >         allnames.append(name)
  > allnames.sort()
  > for name in allnames:
  >     suffix = name in isdir and '/' or ''
  >     print('%05o %s%s' % (os.lstat(name).st_mode & 0o7777, name, suffix))
  > EOF

  $ cat >mode.py <<EOF
  > from __future__ import absolute_import, print_function
  > import os
  > import sys
  > print('%05o' % os.lstat(sys.argv[1]).st_mode)
  > EOF

  $ umask 077

  $ hg init repo
  $ cd repo

  $ chmod 0770 .hg/store .hg/cache .hg/wcache

before commit
store can be written by the group, other files cannot
store is setgid

  $ "$PYTHON" ../printmodes.py .
  00700 ./.hg/
  00600 ./.hg/00changelog.i
  00770 ./.hg/cache/
  00600 ./.hg/requires
  00770 ./.hg/store/
  00770 ./.hg/wcache/

  $ mkdir dir
  $ touch foo dir/bar
  $ hg ci -qAm 'add files'

after commit
working dir files can only be written by the owner
files created in .hg can be written by the group
(in particular, store/**, dirstate, branch cache file, undo files)
new directories are setgid

  $ "$PYTHON" ../printmodes.py .
  00700 ./.hg/
  00600 ./.hg/00changelog.i
  00770 ./.hg/cache/
  00660 ./.hg/cache/branch2-served
  00660 ./.hg/cache/rbc-names-v1
  00660 ./.hg/cache/rbc-revs-v1
  00660 ./.hg/dirstate
  00660 ./.hg/fsmonitor.state (fsmonitor !)
  00660 ./.hg/last-message.txt
  00600 ./.hg/requires
  00770 ./.hg/store/
  00660 ./.hg/store/00changelog.i
  00660 ./.hg/store/00manifest.i
  00770 ./.hg/store/data/
  00770 ./.hg/store/data/dir/
  00660 ./.hg/store/data/dir/bar.i (reporevlogstore !)
  00660 ./.hg/store/data/foo.i (reporevlogstore !)
  00770 ./.hg/store/data/dir/bar/ (reposimplestore !)
  00660 ./.hg/store/data/dir/bar/b80de5d138758541c5f05265ad144ab9fa86d1db (reposimplestore !)
  00660 ./.hg/store/data/dir/bar/index (reposimplestore !)
  00770 ./.hg/store/data/foo/ (reposimplestore !)
  00660 ./.hg/store/data/foo/b80de5d138758541c5f05265ad144ab9fa86d1db (reposimplestore !)
  00660 ./.hg/store/data/foo/index (reposimplestore !)
  00660 ./.hg/store/fncache (repofncache !)
  00660 ./.hg/store/phaseroots
  00660 ./.hg/store/undo
  00660 ./.hg/store/undo.backupfiles
  00660 ./.hg/store/undo.phaseroots
  00660 ./.hg/undo.backup.dirstate
  00660 ./.hg/undo.bookmarks
  00660 ./.hg/undo.branch
  00660 ./.hg/undo.desc
  00660 ./.hg/undo.dirstate
  00770 ./.hg/wcache/
  00711 ./.hg/wcache/checkisexec
  007.. ./.hg/wcache/checklink (re)
  00600 ./.hg/wcache/checklink-target
  00660 ./.hg/wcache/manifestfulltextcache (reporevlogstore !)
  00700 ./dir/
  00600 ./dir/bar
  00600 ./foo

  $ umask 007
  $ hg init ../push

before push
group can write everything

  $ "$PYTHON" ../printmodes.py ../push
  00770 ../push/.hg/
  00660 ../push/.hg/00changelog.i
  00770 ../push/.hg/cache/
  00660 ../push/.hg/requires
  00770 ../push/.hg/store/
  00770 ../push/.hg/wcache/

  $ umask 077
  $ hg -q push ../push

after push
group can still write everything

  $ "$PYTHON" ../printmodes.py ../push
  00770 ../push/.hg/
  00660 ../push/.hg/00changelog.i
  00770 ../push/.hg/cache/
  00660 ../push/.hg/cache/branch2-base
  00660 ../push/.hg/cache/rbc-names-v1
  00660 ../push/.hg/cache/rbc-revs-v1
  00660 ../push/.hg/dirstate
  00660 ../push/.hg/requires
  00770 ../push/.hg/store/
  00660 ../push/.hg/store/00changelog.i
  00660 ../push/.hg/store/00manifest.i
  00770 ../push/.hg/store/data/
  00770 ../push/.hg/store/data/dir/
  00660 ../push/.hg/store/data/dir/bar.i (reporevlogstore !)
  00660 ../push/.hg/store/data/foo.i (reporevlogstore !)
  00770 ../push/.hg/store/data/dir/bar/ (reposimplestore !)
  00660 ../push/.hg/store/data/dir/bar/b80de5d138758541c5f05265ad144ab9fa86d1db (reposimplestore !)
  00660 ../push/.hg/store/data/dir/bar/index (reposimplestore !)
  00770 ../push/.hg/store/data/foo/ (reposimplestore !)
  00660 ../push/.hg/store/data/foo/b80de5d138758541c5f05265ad144ab9fa86d1db (reposimplestore !)
  00660 ../push/.hg/store/data/foo/index (reposimplestore !)
  00660 ../push/.hg/store/fncache (repofncache !)
  00660 ../push/.hg/store/undo
  00660 ../push/.hg/store/undo.backupfiles
  00660 ../push/.hg/store/undo.phaseroots
  00660 ../push/.hg/undo.bookmarks
  00660 ../push/.hg/undo.branch
  00660 ../push/.hg/undo.desc
  00660 ../push/.hg/undo.dirstate
  00770 ../push/.hg/wcache/


Test that we don't lose the setgid bit when we call chmod.
Not all systems support setgid directories (e.g. HFS+), so
just check that directories have the same mode.

  $ cd ..
  $ hg init setgid
  $ cd setgid
  $ chmod g+rwx .hg/store
  $ chmod g+s .hg/store 2> /dev/null || true
  $ mkdir dir
  $ touch dir/file
  $ hg ci -qAm 'add dir/file'
  $ storemode=`"$PYTHON" ../mode.py .hg/store`
  $ dirmode=`"$PYTHON" ../mode.py .hg/store/data/dir`
  $ if [ "$storemode" != "$dirmode" ]; then
  >  echo "$storemode != $dirmode"
  > fi
  $ cd ..

  $ cd .. # g-s dir