Mercurial > hg
view tests/test-merge-types.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 | 4764e8436b2a |
children | b7fde9237c92 |
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#require symlink execbit $ tellmeabout() { > if [ -h $1 ]; then > echo $1 is a symlink: > $TESTDIR/readlink.py $1 > elif [ -x $1 ]; then > echo $1 is an executable file with content: > cat $1 > else > echo $1 is a plain file with content: > cat $1 > fi > } $ hg init test1 $ cd test1 $ echo a > a $ hg ci -Aqmadd $ chmod +x a $ hg ci -mexecutable $ hg up -q 0 $ rm a $ ln -s symlink a $ hg ci -msymlink created new head Symlink is local parent, executable is other: $ hg merge --debug resolving manifests branchmerge: True, force: False, partial: False ancestor: c334dc3be0da, local: 521a1e40188f+, remote: 3574f3e69b1c preserving a for resolve of a a: versions differ -> m (premerge) tool internal:merge (for pattern a) can't handle symlinks couldn't find merge tool hgmerge no tool found to merge a picked tool ':prompt' for a (binary False symlink True changedelete False) file 'a' needs to be resolved. You can keep (l)ocal [working copy], take (o)ther [merge rev], or leave (u)nresolved. What do you want to do? u 0 files updated, 0 files merged, 0 files removed, 1 files unresolved use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon [1] $ tellmeabout a a is a symlink: a -> symlink $ hg resolve a --tool internal:other (no more unresolved files) $ tellmeabout a a is an executable file with content: a $ hg st M a ? a.orig Symlink is other parent, executable is local: $ hg update -C 1 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg merge --debug --tool :union resolving manifests branchmerge: True, force: False, partial: False ancestor: c334dc3be0da, local: 3574f3e69b1c+, remote: 521a1e40188f preserving a for resolve of a a: versions differ -> m (premerge) picked tool ':union' for a (binary False symlink True changedelete False) merging a my a@3574f3e69b1c+ other a@521a1e40188f ancestor a@c334dc3be0da warning: internal :union cannot merge symlinks for a warning: conflicts while merging a! (edit, then use 'hg resolve --mark') 0 files updated, 0 files merged, 0 files removed, 1 files unresolved use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon [1] $ tellmeabout a a is an executable file with content: a $ hg update -C 1 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg merge --debug --tool :merge3 resolving manifests branchmerge: True, force: False, partial: False ancestor: c334dc3be0da, local: 3574f3e69b1c+, remote: 521a1e40188f preserving a for resolve of a a: versions differ -> m (premerge) picked tool ':merge3' for a (binary False symlink True changedelete False) merging a my a@3574f3e69b1c+ other a@521a1e40188f ancestor a@c334dc3be0da warning: internal :merge3 cannot merge symlinks for a warning: conflicts while merging a! (edit, then use 'hg resolve --mark') 0 files updated, 0 files merged, 0 files removed, 1 files unresolved use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon [1] $ tellmeabout a a is an executable file with content: a $ hg update -C 1 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg merge --debug --tool :merge-local resolving manifests branchmerge: True, force: False, partial: False ancestor: c334dc3be0da, local: 3574f3e69b1c+, remote: 521a1e40188f preserving a for resolve of a a: versions differ -> m (premerge) picked tool ':merge-local' for a (binary False symlink True changedelete False) merging a my a@3574f3e69b1c+ other a@521a1e40188f ancestor a@c334dc3be0da warning: internal :merge-local cannot merge symlinks for a 0 files updated, 0 files merged, 0 files removed, 1 files unresolved use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon [1] $ tellmeabout a a is an executable file with content: a $ hg update -C 1 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg merge --debug --tool :merge-other resolving manifests branchmerge: True, force: False, partial: False ancestor: c334dc3be0da, local: 3574f3e69b1c+, remote: 521a1e40188f preserving a for resolve of a a: versions differ -> m (premerge) picked tool ':merge-other' for a (binary False symlink True changedelete False) merging a my a@3574f3e69b1c+ other a@521a1e40188f ancestor a@c334dc3be0da warning: internal :merge-other cannot merge symlinks for a 0 files updated, 0 files merged, 0 files removed, 1 files unresolved use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon [1] $ tellmeabout a a is an executable file with content: a Update to link without local change should get us a symlink (issue3316): $ hg up -C 0 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg up 1 files updated, 0 files merged, 0 files removed, 0 files unresolved updated to "521a1e40188f: symlink" 1 other heads for branch "default" $ hg st ? a.orig Update to link with local change should cause a merge prompt (issue3200): $ hg up -Cq 0 $ echo data > a $ HGMERGE= hg up -y --debug --config ui.merge= resolving manifests branchmerge: False, force: False, partial: False ancestor: c334dc3be0da, local: c334dc3be0da+, remote: 521a1e40188f preserving a for resolve of a a: versions differ -> m (premerge) (couldn't find merge tool hgmerge|tool hgmerge can't handle symlinks) (re) no tool found to merge a picked tool ':prompt' for a (binary False symlink True changedelete False) file 'a' needs to be resolved. You can keep (l)ocal [working copy], take (o)ther [destination], or leave (u)nresolved. What do you want to do? u 0 files updated, 0 files merged, 0 files removed, 1 files unresolved use 'hg resolve' to retry unresolved file merges updated to "521a1e40188f: symlink" 1 other heads for branch "default" [1] $ hg diff --git diff --git a/a b/a old mode 120000 new mode 100644 --- a/a +++ b/a @@ -1,1 +1,1 @@ -symlink \ No newline at end of file +data Test only 'l' change - happens rarely, except when recovering from situations where that was what happened. $ hg init test2 $ cd test2 $ printf base > f $ hg ci -Aqm0 $ echo file > f $ echo content >> f $ hg ci -qm1 $ hg up -qr0 $ rm f $ ln -s base f $ hg ci -qm2 $ hg merge tool internal:merge (for pattern f) can't handle symlinks no tool found to merge f file 'f' needs to be resolved. You can keep (l)ocal [working copy], take (o)ther [merge rev], or leave (u)nresolved. What do you want to do? u 0 files updated, 0 files merged, 0 files removed, 1 files unresolved use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon [1] $ tellmeabout f f is a symlink: f -> base $ hg up -Cqr1 $ hg merge tool internal:merge (for pattern f) can't handle symlinks no tool found to merge f file 'f' needs to be resolved. You can keep (l)ocal [working copy], take (o)ther [merge rev], or leave (u)nresolved. What do you want to do? u 0 files updated, 0 files merged, 0 files removed, 1 files unresolved use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon [1] $ tellmeabout f f is a plain file with content: file content $ cd .. Test removed 'x' flag merged with change to symlink $ hg init test3 $ cd test3 $ echo f > f $ chmod +x f $ hg ci -Aqm0 $ chmod -x f $ hg ci -qm1 $ hg up -qr0 $ rm f $ ln -s dangling f $ hg ci -qm2 $ hg merge tool internal:merge (for pattern f) can't handle symlinks no tool found to merge f file 'f' needs to be resolved. You can keep (l)ocal [working copy], take (o)ther [merge rev], or leave (u)nresolved. What do you want to do? u 0 files updated, 0 files merged, 0 files removed, 1 files unresolved use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon [1] $ tellmeabout f f is a symlink: f -> dangling $ hg up -Cqr1 $ hg merge tool internal:merge (for pattern f) can't handle symlinks no tool found to merge f file 'f' needs to be resolved. You can keep (l)ocal [working copy], take (o)ther [merge rev], or leave (u)nresolved. What do you want to do? u 0 files updated, 0 files merged, 0 files removed, 1 files unresolved use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon [1] $ tellmeabout f f is a plain file with content: f Test removed 'x' flag merged with content change - both ways $ hg up -Cqr0 $ echo change > f $ hg ci -qm3 $ hg merge -r1 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ tellmeabout f f is a plain file with content: change $ hg up -qCr1 $ hg merge -r3 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ tellmeabout f f is a plain file with content: change $ cd .. Test merge with no common ancestor: a: just different b: x vs -, different (cannot calculate x, cannot ask merge tool) c: x vs -, same (cannot calculate x, merge tool is no good) d: x vs l, different e: x vs l, same f: - vs l, different g: - vs l, same h: l vs l, different (where same means the filelog entry is shared and there thus is an ancestor!) $ hg init test4 $ cd test4 $ echo 0 > 0 $ hg ci -Aqm0 $ echo 1 > a $ echo 1 > b $ chmod +x b $ echo 1 > bx $ chmod +x bx $ echo x > c $ chmod +x c $ echo 1 > d $ chmod +x d $ printf x > e $ chmod +x e $ echo 1 > f $ printf x > g $ ln -s 1 h $ hg ci -qAm1 $ hg up -qr0 $ echo 2 > a $ echo 2 > b $ echo 2 > bx $ chmod +x bx $ echo x > c $ ln -s 2 d $ ln -s x e $ ln -s 2 f $ ln -s x g $ ln -s 2 h $ hg ci -Aqm2 $ hg merge merging a warning: cannot merge flags for b without common ancestor - keeping local flags merging b merging bx warning: cannot merge flags for c without common ancestor - keeping local flags tool internal:merge (for pattern d) can't handle symlinks no tool found to merge d file 'd' needs to be resolved. You can keep (l)ocal [working copy], take (o)ther [merge rev], or leave (u)nresolved. What do you want to do? u tool internal:merge (for pattern f) can't handle symlinks no tool found to merge f file 'f' needs to be resolved. You can keep (l)ocal [working copy], take (o)ther [merge rev], or leave (u)nresolved. What do you want to do? u tool internal:merge (for pattern h) can't handle symlinks no tool found to merge h file 'h' needs to be resolved. You can keep (l)ocal [working copy], take (o)ther [merge rev], or leave (u)nresolved. What do you want to do? u warning: conflicts while merging a! (edit, then use 'hg resolve --mark') warning: conflicts while merging b! (edit, then use 'hg resolve --mark') warning: conflicts while merging bx! (edit, then use 'hg resolve --mark') 3 files updated, 0 files merged, 0 files removed, 6 files unresolved use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon [1] $ hg resolve -l U a U b U bx U d U f U h $ tellmeabout a a is a plain file with content: <<<<<<< working copy: 0c617753b41b - test: 2 2 ======= 1 >>>>>>> merge rev: 2e60aa20b912 - test: 1 $ tellmeabout b b is a plain file with content: <<<<<<< working copy: 0c617753b41b - test: 2 2 ======= 1 >>>>>>> merge rev: 2e60aa20b912 - test: 1 $ tellmeabout c c is a plain file with content: x $ tellmeabout d d is a symlink: d -> 2 $ tellmeabout e e is a symlink: e -> x $ tellmeabout f f is a symlink: f -> 2 $ tellmeabout g g is a symlink: g -> x $ tellmeabout h h is a symlink: h -> 2 $ hg up -Cqr1 $ hg merge merging a warning: cannot merge flags for b without common ancestor - keeping local flags merging b merging bx warning: cannot merge flags for c without common ancestor - keeping local flags tool internal:merge (for pattern d) can't handle symlinks no tool found to merge d file 'd' needs to be resolved. You can keep (l)ocal [working copy], take (o)ther [merge rev], or leave (u)nresolved. What do you want to do? u tool internal:merge (for pattern f) can't handle symlinks no tool found to merge f file 'f' needs to be resolved. You can keep (l)ocal [working copy], take (o)ther [merge rev], or leave (u)nresolved. What do you want to do? u tool internal:merge (for pattern h) can't handle symlinks no tool found to merge h file 'h' needs to be resolved. You can keep (l)ocal [working copy], take (o)ther [merge rev], or leave (u)nresolved. What do you want to do? u warning: conflicts while merging a! (edit, then use 'hg resolve --mark') warning: conflicts while merging b! (edit, then use 'hg resolve --mark') warning: conflicts while merging bx! (edit, then use 'hg resolve --mark') 3 files updated, 0 files merged, 0 files removed, 6 files unresolved use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon [1] $ tellmeabout a a is a plain file with content: <<<<<<< working copy: 2e60aa20b912 - test: 1 1 ======= 2 >>>>>>> merge rev: 0c617753b41b - test: 2 $ tellmeabout b b is an executable file with content: <<<<<<< working copy: 2e60aa20b912 - test: 1 1 ======= 2 >>>>>>> merge rev: 0c617753b41b - test: 2 $ tellmeabout c c is an executable file with content: x $ tellmeabout d d is an executable file with content: 1 $ tellmeabout e e is an executable file with content: x (no-eol) $ tellmeabout f f is a plain file with content: 1 $ tellmeabout g g is a plain file with content: x (no-eol) $ tellmeabout h h is a symlink: h -> 1 $ cd ..