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
Use hgrc within $TESTTMP
$ HGRCPATH=`pwd`/hgrc
$ export HGRCPATH
hide outer repo
$ hg init
Use an alternate var for scribbling on hgrc to keep check-code from
complaining about the important settings we may be overwriting:
$ HGRC=`pwd`/hgrc
$ export HGRC
Basic syntax error
$ echo "invalid" > $HGRC
$ hg version
hg: parse error at $TESTTMP/hgrc:1: invalid
[255]
$ echo "" > $HGRC
Issue1199: Can't use '%' in hgrc (eg url encoded username)
$ hg init "foo%bar"
$ hg clone "foo%bar" foobar
updating to branch default
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd foobar
$ cat .hg/hgrc
# example repository config (see 'hg help config' for more info)
[paths]
default = $TESTTMP/foo%bar
# path aliases to other clones of this repo in URLs or filesystem paths
# (see 'hg help config.paths' for more info)
#
# default:pushurl = ssh://jdoe@example.net/hg/jdoes-fork
# my-fork = ssh://jdoe@example.net/hg/jdoes-fork
# my-clone = /home/jdoe/jdoes-clone
[ui]
# name and email (local to this repository, optional), e.g.
# username = Jane Doe <jdoe@example.com>
$ hg paths
default = $TESTTMP/foo%bar
$ hg showconfig
bundle.mainreporoot=$TESTTMP/foobar
paths.default=$TESTTMP/foo%bar
$ cd ..
issue1829: wrong indentation
$ echo '[foo]' > $HGRC
$ echo ' x = y' >> $HGRC
$ hg version
hg: parse error at $TESTTMP/hgrc:2: x = y
unexpected leading whitespace
[255]
$ $PYTHON -c "from __future__ import print_function; print('[foo]\nbar = a\n b\n c \n de\n fg \nbaz = bif cb \n')" \
> > $HGRC
$ hg showconfig foo
foo.bar=a\nb\nc\nde\nfg
foo.baz=bif cb
$ FAKEPATH=/path/to/nowhere
$ export FAKEPATH
$ echo '%include $FAKEPATH/no-such-file' > $HGRC
$ hg version
Mercurial Distributed SCM (version *) (glob)
(see https://mercurial-scm.org for more information)
Copyright (C) 2005-* Matt Mackall and others (glob)
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$ unset FAKEPATH
make sure global options given on the cmdline take precedence
$ hg showconfig --config ui.verbose=True --quiet
bundle.mainreporoot=$TESTTMP
ui.verbose=False
ui.debug=False
ui.quiet=True
$ touch foobar/untracked
$ cat >> foobar/.hg/hgrc <<EOF
> [ui]
> verbose=True
> EOF
$ hg -R foobar st -q
username expansion
$ olduser=$HGUSER
$ unset HGUSER
$ FAKEUSER='John Doe'
$ export FAKEUSER
$ echo '[ui]' > $HGRC
$ echo 'username = $FAKEUSER' >> $HGRC
$ hg init usertest
$ cd usertest
$ touch bar
$ hg commit --addremove --quiet -m "added bar"
$ hg log --template "{author}\n"
John Doe
$ cd ..
$ hg showconfig
bundle.mainreporoot=$TESTTMP
ui.username=$FAKEUSER
$ unset FAKEUSER
$ HGUSER=$olduser
$ export HGUSER
showconfig with multiple arguments
$ echo "[alias]" > $HGRC
$ echo "log = log -g" >> $HGRC
$ echo "[defaults]" >> $HGRC
$ echo "identify = -n" >> $HGRC
$ hg showconfig alias defaults
alias.log=log -g
defaults.identify=-n
$ hg showconfig alias alias
alias.log=log -g
$ hg showconfig alias.log alias.log
alias.log=log -g
$ hg showconfig alias defaults.identify
alias.log=log -g
defaults.identify=-n
$ hg showconfig alias.log defaults.identify
alias.log=log -g
defaults.identify=-n
HGPLAIN
$ echo "[ui]" > $HGRC
$ echo "debug=true" >> $HGRC
$ echo "fallbackencoding=ASCII" >> $HGRC
$ echo "quiet=true" >> $HGRC
$ echo "slash=true" >> $HGRC
$ echo "traceback=true" >> $HGRC
$ echo "verbose=true" >> $HGRC
$ echo "style=~/.hgstyle" >> $HGRC
$ echo "logtemplate={node}" >> $HGRC
$ echo "[defaults]" >> $HGRC
$ echo "identify=-n" >> $HGRC
$ echo "[alias]" >> $HGRC
$ echo "log=log -g" >> $HGRC
customized hgrc
$ hg showconfig
read config from: $TESTTMP/hgrc
$TESTTMP/hgrc:13: alias.log=log -g
repo: bundle.mainreporoot=$TESTTMP
$TESTTMP/hgrc:11: defaults.identify=-n
$TESTTMP/hgrc:2: ui.debug=true
$TESTTMP/hgrc:3: ui.fallbackencoding=ASCII
$TESTTMP/hgrc:4: ui.quiet=true
$TESTTMP/hgrc:5: ui.slash=true
$TESTTMP/hgrc:6: ui.traceback=true
$TESTTMP/hgrc:7: ui.verbose=true
$TESTTMP/hgrc:8: ui.style=~/.hgstyle
$TESTTMP/hgrc:9: ui.logtemplate={node}
plain hgrc
$ HGPLAIN=; export HGPLAIN
$ hg showconfig --config ui.traceback=True --debug
read config from: $TESTTMP/hgrc
repo: bundle.mainreporoot=$TESTTMP
--config: ui.traceback=True
--verbose: ui.verbose=False
--debug: ui.debug=True
--quiet: ui.quiet=False
with environment variables
$ PAGER=p1 EDITOR=e1 VISUAL=e2 hg showconfig --debug
set config by: $EDITOR
set config by: $VISUAL
set config by: $PAGER
read config from: $TESTTMP/hgrc
repo: bundle.mainreporoot=$TESTTMP
$PAGER: pager.pager=p1
$VISUAL: ui.editor=e2
--verbose: ui.verbose=False
--debug: ui.debug=True
--quiet: ui.quiet=False
plain mode with exceptions
$ cat > plain.py <<EOF
> from mercurial import commands, extensions
> def _config(orig, ui, repo, *values, **opts):
> ui.write(b'plain: %r\n' % ui.plain())
> return orig(ui, repo, *values, **opts)
> def uisetup(ui):
> extensions.wrapcommand(commands.table, b'config', _config)
> EOF
$ echo "[extensions]" >> $HGRC
$ echo "plain=./plain.py" >> $HGRC
$ HGPLAINEXCEPT=; export HGPLAINEXCEPT
$ hg showconfig --config ui.traceback=True --debug
plain: True
read config from: $TESTTMP/hgrc
repo: bundle.mainreporoot=$TESTTMP
$TESTTMP/hgrc:15: extensions.plain=./plain.py
--config: ui.traceback=True
--verbose: ui.verbose=False
--debug: ui.debug=True
--quiet: ui.quiet=False
$ unset HGPLAIN
$ hg showconfig --config ui.traceback=True --debug
plain: True
read config from: $TESTTMP/hgrc
repo: bundle.mainreporoot=$TESTTMP
$TESTTMP/hgrc:15: extensions.plain=./plain.py
--config: ui.traceback=True
--verbose: ui.verbose=False
--debug: ui.debug=True
--quiet: ui.quiet=False
$ HGPLAINEXCEPT=i18n; export HGPLAINEXCEPT
$ hg showconfig --config ui.traceback=True --debug
plain: True
read config from: $TESTTMP/hgrc
repo: bundle.mainreporoot=$TESTTMP
$TESTTMP/hgrc:15: extensions.plain=./plain.py
--config: ui.traceback=True
--verbose: ui.verbose=False
--debug: ui.debug=True
--quiet: ui.quiet=False
source of paths is not mangled
$ cat >> $HGRCPATH <<EOF
> [paths]
> foo = bar
> EOF
$ hg showconfig --debug paths
plain: True
read config from: $TESTTMP/hgrc
$TESTTMP/hgrc:17: paths.foo=$TESTTMP/bar