Mercurial > hg
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
author | Kyle Lippincott <spectral@google.com> |
---|---|
date | Wed, 03 Feb 2021 16:33:10 -0800 |
parents | 3e91d9978bec |
children | 7ee07e1a25c0 |
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#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