Mercurial > hg
view tests/test-githelp.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 | 94f227baa76f |
children |
line wrap: on
line source
$ cat >> $HGRCPATH << EOF > [extensions] > githelp = > EOF $ hg init repo $ cd repo $ echo foo > test_file $ mkdir dir $ echo foo > dir/file $ echo foo > removed_file $ echo foo > deleted_file $ hg add -q . $ hg commit -m 'bar' $ hg bookmark both $ touch both $ touch untracked_file $ hg remove removed_file $ rm deleted_file githelp on a single command should succeed $ hg githelp -- commit hg commit $ hg githelp -- git commit hg commit githelp should fail nicely if we don't give it arguments $ hg githelp abort: missing git command - usage: hg githelp -- <git command> [255] $ hg githelp -- git abort: missing git command - usage: hg githelp -- <git command> [255] githelp on a command with options should succeed $ hg githelp -- commit -pm "abc" hg commit --interactive -m 'abc' githelp on a command with standalone unrecognized option should succeed with warning $ hg githelp -- commit -p -v ignoring unknown option -v hg commit --interactive githelp on a command with unrecognized option packed with other options should fail with error $ hg githelp -- commit -pv abort: unknown option 'v' packed with other options (please try passing the option as its own flag: -v) [255] githelp for git rebase --skip $ hg githelp -- git rebase --skip hg revert --all -r . hg rebase --continue githelp for git commit --amend (hg commit --amend pulls up an editor) $ hg githelp -- commit --amend hg commit --amend githelp for git commit --amend --no-edit (hg amend does not pull up an editor) $ hg githelp -- commit --amend --no-edit hg amend githelp for git checkout -- . (checking out a directory) $ hg githelp -- checkout -- . note: use --no-backup to avoid creating .orig files hg revert . githelp for git checkout "HEAD^" (should still work to pass a rev) $ hg githelp -- checkout "HEAD^" hg update .^ githelp checkout: args after -- should be treated as paths no matter what $ hg githelp -- checkout -- HEAD note: use --no-backup to avoid creating .orig files hg revert HEAD githelp for git checkout with rev and path $ hg githelp -- checkout "HEAD^" -- file.txt note: use --no-backup to avoid creating .orig files hg revert -r .^ file.txt githelp for git with rev and path, without separator $ hg githelp -- checkout "HEAD^" file.txt note: use --no-backup to avoid creating .orig files hg revert -r .^ file.txt githelp for checkout with a file as first argument $ hg githelp -- checkout test_file note: use --no-backup to avoid creating .orig files hg revert test_file githelp for checkout with a removed file as first argument $ hg githelp -- checkout removed_file note: use --no-backup to avoid creating .orig files hg revert removed_file githelp for checkout with a deleted file as first argument $ hg githelp -- checkout deleted_file note: use --no-backup to avoid creating .orig files hg revert deleted_file githelp for checkout with a untracked file as first argument $ hg githelp -- checkout untracked_file note: use --no-backup to avoid creating .orig files hg revert untracked_file githelp for checkout with a directory as first argument $ hg githelp -- checkout dir note: use --no-backup to avoid creating .orig files hg revert dir githelp for checkout when not in repo root $ cd dir $ hg githelp -- checkout file note: use --no-backup to avoid creating .orig files hg revert file $ cd .. githelp for checkout with an argument that is both a file and a revision $ hg githelp -- checkout both hg update both githelp for checkout with the -p option $ hg githelp -- git checkout -p xyz hg revert -i -r xyz $ hg githelp -- git checkout -p xyz -- abc note: use --no-backup to avoid creating .orig files hg revert -i -r xyz abc githelp for checkout with the -f option and a rev $ hg githelp -- git checkout -f xyz hg update -C xyz $ hg githelp -- git checkout --force xyz hg update -C xyz githelp for checkout with the -f option without an arg $ hg githelp -- git checkout -f hg revert --all $ hg githelp -- git checkout --force hg revert --all githelp for grep with pattern and path $ hg githelp -- grep shrubbery flib/intern/ hg grep shrubbery flib/intern/ githelp for reset, checking ~ in git becomes ~1 in mercurial $ hg githelp -- reset HEAD~ hg update .~1 $ hg githelp -- reset "HEAD^" hg update .^ $ hg githelp -- reset HEAD~3 hg update .~3 $ hg githelp -- reset --mixed HEAD note: --mixed has no meaning since Mercurial has no staging area hg update . $ hg githelp -- reset --soft HEAD note: --soft has no meaning since Mercurial has no staging area hg update . $ hg githelp -- reset --hard HEAD hg update --clean . githelp for git show --name-status $ hg githelp -- git show --name-status hg log --style status -r . githelp for git show --pretty=format: --name-status $ hg githelp -- git show --pretty=format: --name-status hg status --change . githelp for show with no arguments $ hg githelp -- show hg export githelp for show with a path $ hg githelp -- show test_file hg cat test_file githelp for show with not a path: $ hg githelp -- show rev hg export rev githelp for show with many arguments $ hg githelp -- show argone argtwo hg export argone argtwo $ hg githelp -- show test_file argone argtwo hg cat test_file argone argtwo githelp for show with --unified options $ hg githelp -- show --unified=10 hg export --config diff.unified=10 $ hg githelp -- show -U100 hg export --config diff.unified=100 githelp for show with a path and --unified $ hg githelp -- show -U20 test_file hg cat test_file --config diff.unified=20 githelp for stash drop without name $ hg githelp -- git stash drop hg shelve -d <shelve name> githelp for stash drop with name $ hg githelp -- git stash drop xyz hg shelve -d xyz githelp for stash list with patch $ hg githelp -- git stash list -p hg shelve -l -p githelp for stash show $ hg githelp -- git stash show hg shelve --stat githelp for stash show with patch and name $ hg githelp -- git stash show -p mystash hg shelve -p mystash githelp for stash clear $ hg githelp -- git stash clear hg shelve --cleanup githelp for whatchanged should show deprecated message $ hg githelp -- whatchanged -p this command has been deprecated in the git project, thus isn't supported by this tool githelp for git branch -m renaming $ hg githelp -- git branch -m old new hg bookmark -m old new When the old name is omitted, git branch -m new renames the current branch. $ hg githelp -- git branch -m new hg bookmark -m `hg log -T"{activebookmark}" -r .` new Branch deletion in git strips commits $ hg githelp -- git branch -d hg strip -B $ hg githelp -- git branch -d feature hg strip -B feature -B $ hg githelp -- git branch --delete experiment1 experiment2 hg strip -B experiment1 -B experiment2 -B githelp for reuse message using the shorthand $ hg githelp -- git commit -C deadbeef hg commit -M deadbeef githelp for reuse message using the the long version $ hg githelp -- git commit --reuse-message deadbeef hg commit -M deadbeef githelp for reuse message using HEAD $ hg githelp -- git commit --reuse-message HEAD~ hg commit -M .~1 githelp for apply with no options $ hg githelp -- apply hg import --no-commit githelp for apply with directory strip custom $ hg githelp -- apply -p 5 hg import --no-commit -p 5 githelp for apply with prefix directory $ hg githelp -- apply --directory=modules hg import --no-commit --prefix modules git merge-base $ hg githelp -- git merge-base --is-ancestor ignoring unknown option --is-ancestor note: ancestors() is part of the revset language (learn more about revsets with 'hg help revsets') hg log -T '{node}\n' -r 'ancestor(A,B)' githelp for git blame $ hg githelp -- git blame hg annotate -udl githelp for add $ hg githelp -- git add hg add $ hg githelp -- git add -p note: Mercurial will commit when complete, as there is no staging area in Mercurial hg commit --interactive $ hg githelp -- git add --all note: use hg addremove to remove files that have been deleted hg add githelp for reflog $ hg githelp -- git reflog hg journal note: in hg commits can be deleted from repo but we always have backups $ hg githelp -- git reflog --all hg journal --all note: in hg commits can be deleted from repo but we always have backups $ hg githelp -- git log -Gnarf hg grep --diff narf $ hg githelp -- git log -S narf hg grep --diff narf $ hg githelp -- git log --pickaxe-regex narf hg grep --diff narf