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
This test makes sure that we don't mark a file as merged with its ancestor
when we do a merge.
$ cat <<EOF > merge
> from __future__ import print_function
> import sys, os
> print("merging for", os.path.basename(sys.argv[1]))
> EOF
$ HGMERGE="$PYTHON ../merge"; export HGMERGE
Creating base:
$ hg init a
$ cd a
$ echo 1 > foo
$ echo 1 > bar
$ echo 1 > baz
$ echo 1 > quux
$ hg add foo bar baz quux
$ hg commit -m "base"
$ cd ..
$ hg clone a b
updating to branch default
4 files updated, 0 files merged, 0 files removed, 0 files unresolved
Creating branch a:
$ cd a
$ echo 2a > foo
$ echo 2a > bar
$ hg commit -m "branch a"
Creating branch b:
$ cd ..
$ cd b
$ echo 2b > foo
$ echo 2b > baz
$ hg commit -m "branch b"
We shouldn't have anything but n state here:
$ hg debugstate --nodates | grep -v "^n"
[1]
Merging:
$ hg pull ../a
pulling from ../a
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 2 changes to 2 files (+1 heads)
new changesets bdd988058d16
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg merge -v
resolving manifests
getting bar
merging foo
merging for foo
1 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ echo 2m > foo
$ echo 2b > baz
$ echo new > quux
$ hg ci -m "merge"
main: we should have a merge here:
$ hg debugindex --changelog
rev linkrev nodeid p1 p2
0 0 cdca01651b96 000000000000 000000000000
1 1 f6718a9cb7f3 cdca01651b96 000000000000
2 2 bdd988058d16 cdca01651b96 000000000000
3 3 d8a521142a3c f6718a9cb7f3 bdd988058d16
log should show foo and quux changed:
$ hg log -v -r tip
changeset: 3:d8a521142a3c
tag: tip
parent: 1:f6718a9cb7f3
parent: 2:bdd988058d16
user: test
date: Thu Jan 01 00:00:00 1970 +0000
files: foo quux
description:
merge
foo: we should have a merge here:
$ hg debugindex foo
rev linkrev nodeid p1 p2
0 0 b8e02f643373 000000000000 000000000000
1 1 2ffeddde1b65 b8e02f643373 000000000000
2 2 33d1fb69067a b8e02f643373 000000000000
3 3 aa27919ee430 2ffeddde1b65 33d1fb69067a
bar: we should not have a merge here:
$ hg debugindex bar
rev linkrev nodeid p1 p2
0 0 b8e02f643373 000000000000 000000000000
1 2 33d1fb69067a b8e02f643373 000000000000
baz: we should not have a merge here:
$ hg debugindex baz
rev linkrev nodeid p1 p2
0 0 b8e02f643373 000000000000 000000000000
1 1 2ffeddde1b65 b8e02f643373 000000000000
quux: we should not have a merge here:
$ hg debugindex quux
rev linkrev nodeid p1 p2
0 0 b8e02f643373 000000000000 000000000000
1 3 6128c0f33108 b8e02f643373 000000000000
Manifest entries should match tips of all files:
$ hg manifest --debug
33d1fb69067a0139622a3fa3b7ba1cdb1367972e 644 bar
2ffeddde1b65b4827f6746174a145474129fa2ce 644 baz
aa27919ee4303cfd575e1fb932dd64d75aa08be4 644 foo
6128c0f33108e8cfbb4e0824d13ae48b466d7280 644 quux
Everything should be clean now:
$ hg status
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
4 files, 4 changesets, 10 total revisions
$ cd ..