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 character encoding
$ hg init t
$ cd t
we need a repo with some legacy latin-1 changesets
$ hg unbundle "$TESTDIR/bundles/legacy-encoding.hg"
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
new changesets 1e78a93102a3:0e5b7e3f9c4a
(run 'hg update' to get a working copy)
$ hg co
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ $PYTHON << EOF
> f = open('latin-1', 'wb'); f.write(b"latin-1 e' encoded: \xe9"); f.close()
> f = open('utf-8', 'wb'); f.write(b"utf-8 e' encoded: \xc3\xa9"); f.close()
> f = open('latin-1-tag', 'wb'); f.write(b"\xe9"); f.close()
> EOF
should fail with encoding error
$ echo "plain old ascii" > a
$ hg st
M a
? latin-1
? latin-1-tag
? utf-8
$ HGENCODING=ascii hg ci -l latin-1
transaction abort!
rollback completed
abort: decoding near ' encoded: \xe9': 'ascii' codec can't decode byte 0xe9 in position 20: ordinal not in range(128)! (esc)
[255]
these should work
$ echo "latin-1" > a
$ HGENCODING=latin-1 hg ci -l latin-1
$ echo "utf-8" > a
$ HGENCODING=utf-8 hg ci -l utf-8
$ HGENCODING=latin-1 hg tag `cat latin-1-tag`
$ HGENCODING=latin-1 hg branch `cat latin-1-tag`
marked working directory as branch \xe9 (esc)
(branches are permanent and global, did you want a bookmark?)
$ HGENCODING=latin-1 hg ci -m 'latin1 branch'
$ hg -q rollback
$ HGENCODING=latin-1 hg branch
\xe9 (esc)
$ HGENCODING=latin-1 hg ci -m 'latin1 branch'
$ rm .hg/branch
hg log (ascii)
$ hg --encoding ascii log
changeset: 5:a52c0692f24a
branch: ?
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: latin1 branch
changeset: 4:94db611b4196
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: Added tag ? for changeset ca661e7520de
changeset: 3:ca661e7520de
tag: ?
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: utf-8 e' encoded: ?
changeset: 2:650c6f3d55dd
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: latin-1 e' encoded: ?
changeset: 1:0e5b7e3f9c4a
user: test
date: Mon Jan 12 13:46:40 1970 +0000
summary: koi8-r: ????? = u'\u0440\u0442\u0443\u0442\u044c'
changeset: 0:1e78a93102a3
user: test
date: Mon Jan 12 13:46:40 1970 +0000
summary: latin-1 e': ? = u'\xe9'
hg log (latin-1)
$ hg --encoding latin-1 log
changeset: 5:a52c0692f24a
branch: \xe9 (esc)
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: latin1 branch
changeset: 4:94db611b4196
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: Added tag \xe9 for changeset ca661e7520de (esc)
changeset: 3:ca661e7520de
tag: \xe9 (esc)
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: utf-8 e' encoded: \xe9 (esc)
changeset: 2:650c6f3d55dd
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: latin-1 e' encoded: \xe9 (esc)
changeset: 1:0e5b7e3f9c4a
user: test
date: Mon Jan 12 13:46:40 1970 +0000
summary: koi8-r: \xd2\xd4\xd5\xd4\xd8 = u'\\u0440\\u0442\\u0443\\u0442\\u044c' (esc)
changeset: 0:1e78a93102a3
user: test
date: Mon Jan 12 13:46:40 1970 +0000
summary: latin-1 e': \xe9 = u'\\xe9' (esc)
hg log (utf-8)
$ hg --encoding utf-8 log
changeset: 5:a52c0692f24a
branch: \xc3\xa9 (esc)
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: latin1 branch
changeset: 4:94db611b4196
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: Added tag \xc3\xa9 for changeset ca661e7520de (esc)
changeset: 3:ca661e7520de
tag: \xc3\xa9 (esc)
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: utf-8 e' encoded: \xc3\xa9 (esc)
changeset: 2:650c6f3d55dd
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: latin-1 e' encoded: \xc3\xa9 (esc)
changeset: 1:0e5b7e3f9c4a
user: test
date: Mon Jan 12 13:46:40 1970 +0000
summary: koi8-r: \xc3\x92\xc3\x94\xc3\x95\xc3\x94\xc3\x98 = u'\\u0440\\u0442\\u0443\\u0442\\u044c' (esc)
changeset: 0:1e78a93102a3
user: test
date: Mon Jan 12 13:46:40 1970 +0000
summary: latin-1 e': \xc3\xa9 = u'\\xe9' (esc)
hg tags (ascii)
$ HGENCODING=ascii hg tags
tip 5:a52c0692f24a
? 3:ca661e7520de
hg tags (latin-1)
$ HGENCODING=latin-1 hg tags
tip 5:a52c0692f24a
\xe9 3:ca661e7520de (esc)
hg tags (utf-8)
$ HGENCODING=utf-8 hg tags
tip 5:a52c0692f24a
\xc3\xa9 3:ca661e7520de (esc)
hg tags (JSON)
$ hg tags -Tjson
[
{
"node": "a52c0692f24ad921c0a31e1736e7635a8b23b670",
"rev": 5,
"tag": "tip",
"type": ""
},
{
"node": "ca661e7520dec3f5438a63590c350bebadb04989",
"rev": 3,
"tag": "\xc3\xa9", (esc)
"type": ""
}
]
hg branches (ascii)
$ HGENCODING=ascii hg branches
? 5:a52c0692f24a
default 4:94db611b4196 (inactive)
hg branches (latin-1)
$ HGENCODING=latin-1 hg branches
\xe9 5:a52c0692f24a (esc)
default 4:94db611b4196 (inactive)
hg branches (utf-8)
$ HGENCODING=utf-8 hg branches
\xc3\xa9 5:a52c0692f24a (esc)
default 4:94db611b4196 (inactive)
$ echo '[ui]' >> .hg/hgrc
$ echo 'fallbackencoding = koi8-r' >> .hg/hgrc
hg log (utf-8)
$ HGENCODING=utf-8 hg log
changeset: 5:a52c0692f24a
branch: \xc3\xa9 (esc)
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: latin1 branch
changeset: 4:94db611b4196
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: Added tag \xc3\xa9 for changeset ca661e7520de (esc)
changeset: 3:ca661e7520de
tag: \xc3\xa9 (esc)
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: utf-8 e' encoded: \xc3\xa9 (esc)
changeset: 2:650c6f3d55dd
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: latin-1 e' encoded: \xc3\xa9 (esc)
changeset: 1:0e5b7e3f9c4a
user: test
date: Mon Jan 12 13:46:40 1970 +0000
summary: koi8-r: \xd1\x80\xd1\x82\xd1\x83\xd1\x82\xd1\x8c = u'\\u0440\\u0442\\u0443\\u0442\\u044c' (esc)
changeset: 0:1e78a93102a3
user: test
date: Mon Jan 12 13:46:40 1970 +0000
summary: latin-1 e': \xd0\x98 = u'\\xe9' (esc)
hg log (dolphin)
$ HGENCODING=dolphin hg log
abort: unknown encoding: dolphin
(please check your locale settings)
[255]
$ HGENCODING=ascii hg branch `cat latin-1-tag`
abort: decoding near '\xe9': 'ascii' codec can't decode byte 0xe9 in position 0: ordinal not in range(128)! (esc)
[255]
$ cp latin-1-tag .hg/branch
$ HGENCODING=latin-1 hg ci -m 'auto-promote legacy name'
Test roundtrip encoding of lookup tables when not using UTF-8 (issue2763)
$ HGENCODING=latin-1 hg up `cat latin-1-tag`
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ cd ..
Test roundtrip encoding/decoding of utf8b for generated data
#if hypothesis
>>> from hypothesishelpers import *
>>> from mercurial import encoding
>>> roundtrips(st.binary(), encoding.fromutf8b, encoding.toutf8b)
Round trip OK
#endif