internals: document CBOR utilization
I spoke with some people at Mozilla about CBOR and they advised me
that we should be careful about the subset of CBOR we use in order
to mitigate security, performance, and compatibility concerns.
This commit establishes a document that attempts to formalize our
use of CBOR.
Its main limitations are on what types are allowed. It explicitly
enumerates which types are supported. Notable missing features
include:
* Indefinite-length arrays and maps
* Text strings (bytes all the way)
* Floats
* Date/time types
* Big integers
* Use of indefinite-length byte strings for map keys, values in
containers.
If we have a need for any of these, we can have a discussion about
them when the time comes.
Differential Revision: https://phab.mercurial-scm.org/D4412
Check that renames are correctly saved by a commit after a merge
Test with the merge on 3 having the rename on the local parent
$ hg init a
$ cd a
$ echo line1 > foo
$ hg add foo
$ hg ci -m '0: add foo'
$ echo line2 >> foo
$ hg ci -m '1: change foo'
$ hg up -C 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg mv foo bar
$ rm bar
$ echo line0 > bar
$ echo line1 >> bar
$ hg ci -m '2: mv foo bar; change bar'
created new head
$ hg merge 1
merging bar and foo to bar
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat bar
line0
line1
line2
$ hg ci -m '3: merge with local rename'
$ hg debugindex bar
rev linkrev nodeid p1 p2
0 2 d35118874825 000000000000 000000000000
1 3 5345f5ab8abd 000000000000 d35118874825
$ hg debugrename bar
bar renamed from foo:9e25c27b87571a1edee5ae4dddee5687746cc8e2
$ hg debugindex foo
rev linkrev nodeid p1 p2
0 0 690b295714ae 000000000000 000000000000
1 1 9e25c27b8757 690b295714ae 000000000000
Revert the content change from rev 2:
$ hg up -C 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm bar
$ echo line1 > bar
$ hg ci -m '4: revert content change from rev 2'
created new head
$ hg log --template '{rev}:{node|short} {parents}\n'
4:2263c1be0967 2:0f2ff26688b9
3:0555950ead28 2:0f2ff26688b9 1:5cd961e4045d
2:0f2ff26688b9 0:2665aaee66e9
1:5cd961e4045d
0:2665aaee66e9
This should use bar@rev2 as the ancestor:
$ hg --debug merge 3
searching for copies back to rev 1
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: 0f2ff26688b9, local: 2263c1be0967+, remote: 0555950ead28
preserving bar for resolve of bar
starting 4 threads for background file closing (?)
bar: versions differ -> m (premerge)
picked tool ':merge' for bar (binary False symlink False changedelete False)
merging bar
my bar@2263c1be0967+ other bar@0555950ead28 ancestor bar@0f2ff26688b9
premerge successful
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat bar
line1
line2
$ hg ci -m '5: merge'
$ hg debugindex bar
rev linkrev nodeid p1 p2
0 2 d35118874825 000000000000 000000000000
1 3 5345f5ab8abd 000000000000 d35118874825
2 4 ff4b45017382 d35118874825 000000000000
3 5 3701b4893544 ff4b45017382 5345f5ab8abd
Same thing, but with the merge on 3 having the rename
on the remote parent:
$ cd ..
$ hg clone -U -r 1 -r 2 a b
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 2 files (+1 heads)
new changesets 2665aaee66e9:0f2ff26688b9
$ cd b
$ hg up -C 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg merge 2
merging foo and bar to bar
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat bar
line0
line1
line2
$ hg ci -m '3: merge with remote rename'
$ hg debugindex bar
rev linkrev nodeid p1 p2
0 2 d35118874825 000000000000 000000000000
1 3 5345f5ab8abd 000000000000 d35118874825
$ hg debugrename bar
bar renamed from foo:9e25c27b87571a1edee5ae4dddee5687746cc8e2
$ hg debugindex foo
rev linkrev nodeid p1 p2
0 0 690b295714ae 000000000000 000000000000
1 1 9e25c27b8757 690b295714ae 000000000000
Revert the content change from rev 2:
$ hg up -C 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm bar
$ echo line1 > bar
$ hg ci -m '4: revert content change from rev 2'
created new head
$ hg log --template '{rev}:{node|short} {parents}\n'
4:2263c1be0967 2:0f2ff26688b9
3:3ffa6b9e35f0 1:5cd961e4045d 2:0f2ff26688b9
2:0f2ff26688b9 0:2665aaee66e9
1:5cd961e4045d
0:2665aaee66e9
This should use bar@rev2 as the ancestor:
$ hg --debug merge 3
searching for copies back to rev 1
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: 0f2ff26688b9, local: 2263c1be0967+, remote: 3ffa6b9e35f0
preserving bar for resolve of bar
starting 4 threads for background file closing (?)
bar: versions differ -> m (premerge)
picked tool ':merge' for bar (binary False symlink False changedelete False)
merging bar
my bar@2263c1be0967+ other bar@3ffa6b9e35f0 ancestor bar@0f2ff26688b9
premerge successful
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat bar
line1
line2
$ hg ci -m '5: merge'
$ hg debugindex bar
rev linkrev nodeid p1 p2
0 2 d35118874825 000000000000 000000000000
1 3 5345f5ab8abd 000000000000 d35118874825
2 4 ff4b45017382 d35118874825 000000000000
3 5 3701b4893544 ff4b45017382 5345f5ab8abd
$ cd ..