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
Test for the full copytracing algorithm
=======================================
$ hg init t
$ cd t
$ echo 1 > a
$ hg ci -qAm "first"
$ hg cp a b
$ hg mv a c
$ echo 2 >> b
$ echo 2 >> c
$ hg ci -qAm "second"
$ hg co -C 0
1 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ echo 0 > a
$ echo 1 >> a
$ hg ci -qAm "other"
$ hg merge --debug
searching for copies back to rev 1
unmatched files in other:
b
c
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
src: 'a' -> dst: 'b' *
src: 'a' -> dst: 'c' *
checking for directory renames
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: b8bf91eeebbc, local: add3f11052fa+, remote: 17c05bb7fcb6
preserving a for resolve of b
preserving a for resolve of c
removing a
starting 4 threads for background file closing (?)
b: remote moved from a -> m (premerge)
picked tool ':merge' for b (binary False symlink False changedelete False)
merging a and b to b
my b@add3f11052fa+ other b@17c05bb7fcb6 ancestor a@b8bf91eeebbc
premerge successful
c: remote moved from a -> m (premerge)
picked tool ':merge' for c (binary False symlink False changedelete False)
merging a and c to c
my c@add3f11052fa+ other c@17c05bb7fcb6 ancestor a@b8bf91eeebbc
premerge successful
0 files updated, 2 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
file b
$ cat b
0
1
2
file c
$ cat c
0
1
2
Test disabling copy tracing
- first verify copy metadata was kept
$ hg up -qC 2
$ hg rebase --keep -d 1 -b 2 --config extensions.rebase=
rebasing 2:add3f11052fa "other" (tip)
merging b and a to b
merging c and a to c
$ cat b
0
1
2
- next verify copy metadata is lost when disabled
$ hg strip -r . --config extensions.strip=
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
saved backup bundle to $TESTTMP/t/.hg/strip-backup/550bd84c0cd3-fc575957-backup.hg
$ hg up -qC 2
$ hg rebase --keep -d 1 -b 2 --config extensions.rebase= --config experimental.copytrace=off --config ui.interactive=True << EOF
> c
> EOF
rebasing 2:add3f11052fa "other" (tip)
file 'a' was deleted in local [dest] but was modified in other [source].
What do you want to do?
use (c)hanged version, leave (d)eleted, or leave (u)nresolved? c
$ cat b
1
2
$ cd ..
Verify disabling copy tracing still keeps copies from rebase source
$ hg init copydisable
$ cd copydisable
$ touch a
$ hg ci -Aqm 'add a'
$ touch b
$ hg ci -Aqm 'add b, c'
$ hg cp b x
$ echo x >> x
$ hg ci -qm 'copy b->x'
$ hg up -q 1
$ touch z
$ hg ci -Aqm 'add z'
$ hg log -G -T '{rev} {desc}\n'
@ 3 add z
|
| o 2 copy b->x
|/
o 1 add b, c
|
o 0 add a
$ hg rebase -d . -b 2 --config extensions.rebase= --config experimental.copytrace=off
rebasing 2:6adcf8c12e7d "copy b->x"
saved backup bundle to $TESTTMP/copydisable/.hg/strip-backup/6adcf8c12e7d-ce4b3e75-rebase.hg
$ hg up -q 3
$ hg log -f x -T '{rev} {desc}\n'
3 copy b->x
1 add b, c
$ cd ../
Verify we duplicate existing copies, instead of detecting them
$ hg init copydisable3
$ cd copydisable3
$ touch a
$ hg ci -Aqm 'add a'
$ hg cp a b
$ hg ci -Aqm 'copy a->b'
$ hg mv b c
$ hg ci -Aqm 'move b->c'
$ hg up -q 0
$ hg cp a b
$ echo b >> b
$ hg ci -Aqm 'copy a->b (2)'
$ hg log -G -T '{rev} {desc}\n'
@ 3 copy a->b (2)
|
| o 2 move b->c
| |
| o 1 copy a->b
|/
o 0 add a
$ hg rebase -d 2 -s 3 --config extensions.rebase= --config experimental.copytrace=off
rebasing 3:47e1a9e6273b "copy a->b (2)" (tip)
saved backup bundle to $TESTTMP/copydisable3/.hg/strip-backup/47e1a9e6273b-2d099c59-rebase.hg
$ hg log -G -f b
@ changeset: 3:76024fb4b05b
: tag: tip
: user: test
: date: Thu Jan 01 00:00:00 1970 +0000
: summary: copy a->b (2)
:
o changeset: 0:ac82d8b1f7c4
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: add a