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
https://bz.mercurial-scm.org/1175
$ hg init
$ touch a
$ hg ci -Am0
adding a
$ hg mv a a1
$ hg ci -m1
$ hg co 0
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg mv a a2
$ hg up
note: possible conflict - a was renamed multiple times to:
a2
a1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg ci -m2
$ touch a
$ hg ci -Am3
adding a
$ hg mv a b
$ hg ci -Am4 a
$ hg ci --debug --traceback -Am5 b
committing files:
b
warning: can't find ancestor for 'b' copied from 'a'!
committing manifest
committing changelog
updating the branch cache
committed changeset 5:83a687e8a97c80992ba385bbfd766be181bfb1d1
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
4 files, 6 changesets, 4 total revisions
$ hg export --git tip
# HG changeset patch
# User test
# Date 0 0
# Thu Jan 01 00:00:00 1970 +0000
# Node ID 83a687e8a97c80992ba385bbfd766be181bfb1d1
# Parent 1d1625283f71954f21d14c3d44d0ad3c019c597f
5
diff --git a/b b/b
new file mode 100644
https://bz.mercurial-scm.org/show_bug.cgi?id=4476
$ hg init foo
$ cd foo
$ touch a && hg ci -Aqm a
$ hg mv a b
$ echo b1 >> b
$ hg ci -Aqm b1
$ hg up 0
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg mv a b
$ echo b2 >> b
$ hg ci -Aqm b2
$ hg graft 1
grafting 1:5974126fad84 "b1"
merging b
warning: conflicts while merging b! (edit, then use 'hg resolve --mark')
abort: unresolved conflicts, can't continue
(use 'hg resolve' and 'hg graft --continue')
[255]
$ echo a > b
$ echo b3 >> b
$ hg resolve --mark b
(no more unresolved files)
continue: hg graft --continue
$ hg graft --continue
grafting 1:5974126fad84 "b1"
warning: can't find ancestor for 'b' copied from 'a'!
$ hg log -f b -T 'changeset: {rev}:{node|short}\nsummary: {desc}\n\n'
changeset: 3:376d30ccffc0
summary: b1
changeset: 2:416baaa2e5e4
summary: b2
changeset: 0:3903775176ed
summary: a