cborutil: implement sans I/O decoder
The vendored CBOR package decodes by calling read(n) on an object.
There are a number of disadvantages to this:
* Uses blocking I/O. If sufficient data is not available, the decoder
will hang until it is.
* No support for partial reads. If the read(n) returns less data than
requested, the decoder raises an error.
* Requires the use of a file like object. If the original data is in
say a buffer, we need to "cast" it to e.g. a BytesIO to appease the
decoder.
In addition, the vendored CBOR decoder doesn't provide flexibility
that we desire. Specifically:
* It buffers indefinite length bytestrings instead of streaming them.
* It doesn't allow limiting the set of types that can be decoded. This
property is useful when implementing a "hardened" decoder that is
less susceptible to abusive input.
* It doesn't provide sufficient "hook points" and introspection to
institute checks around behavior. These are useful for implementing
a "hardened" decoder.
This all adds up to a reasonable set of justifications for writing our
own decoder.
So, this commit implements our own CBOR decoder.
At the heart of the decoder is a function that decodes a single "item"
from a buffer. This item can be a complete simple value or a special
value, such as "start of array." Using this function, we can build a
decoder that effectively iterates over the stream of decoded items and
builds up higher-level values, such as arrays, maps, sets, and indefinite
length bytestrings. And we can do this without performing I/O in the
decoder itself.
The core of the sans I/O decoder will probably not be used directly.
Instead, it is expected that we'll build utility functions for invoking
the decoder given specific input types. This will allow extreme
flexibility in how data is delivered to the decoder.
I'm pretty happy with the state of the decoder modulo the TODO items
to track wanted features to help with a "hardened" decoder. The one
thing I could be convinced to change is the handling of semantic tags.
Since we only support a single semantic tag (sets), I thought it would
be easier to handle them inline in decodeitem(). This is simpler now.
But if we add support for other semantic tags, it will likely be easier
to move semantic tag handling outside of decodeitem(). But, properly
supporting semantic tags opens up a whole can of worms, as many
semantic tags imply new types. I'm optimistic we won't need these in
Mercurial. But who knows.
I'm also pretty happy with the test coverage. Writing comprehensive
tests for partial decoding did flush out a handful of bugs. One
general improvement to testing would be fuzz testing for partial
decoding. I may implement that later. I also anticipate switching the
wire protocol code to this new decoder will flush out any lingering
bugs.
Differential Revision: https://phab.mercurial-scm.org/D4414
#require cvs
$ cvscall()
> {
> cvs -f "$@"
> }
$ hgcat()
> {
> hg --cwd src-hg cat -r tip "$1"
> }
$ echo "[extensions]" >> $HGRCPATH
$ echo "convert = " >> $HGRCPATH
$ cat > cvshooks.py <<EOF
> def cvslog(ui,repo,hooktype,log):
> ui.write(b'%s hook: %d entries\n' % (hooktype,len(log)))
>
> def cvschangesets(ui,repo,hooktype,changesets):
> ui.write(b'%s hook: %d changesets\n' % (hooktype,len(changesets)))
> EOF
$ hookpath=`pwd`
$ cat <<EOF >> $HGRCPATH
> [hooks]
> cvslog = python:$hookpath/cvshooks.py:cvslog
> cvschangesets = python:$hookpath/cvshooks.py:cvschangesets
> EOF
create cvs repository
$ mkdir cvsrepo
$ cd cvsrepo
$ CVSROOT=`pwd`
$ export CVSROOT
$ CVS_OPTIONS=-f
$ export CVS_OPTIONS
$ cd ..
$ rmdir cvsrepo
$ cvscall -q -d "$CVSROOT" init
create source directory
$ mkdir src-temp
$ cd src-temp
$ echo a > a
$ mkdir b
$ cd b
$ echo c > c
$ cd ..
import source directory
$ cvscall -q import -m import src INITIAL start
N src/a
N src/b/c
No conflicts created by this import
$ cd ..
checkout source directory
$ cvscall -q checkout src
U src/a
U src/b/c
commit a new revision changing b/c
$ cd src
$ sleep 1
$ echo c >> b/c
$ cvscall -q commit -mci0 . | grep '<--'
$TESTTMP/cvsrepo/src/b/c,v <-- *c (glob)
$ cd ..
convert fresh repo and also check localtimezone option
NOTE: This doesn't check all time zones -- it merely determines that
the configuration option is taking effect.
An arbitrary (U.S.) time zone is used here. TZ=US/Hawaii is selected
since it does not use DST (unlike other U.S. time zones) and is always
a fixed difference from UTC.
This choice is limited to work on Linux environments. At least on
FreeBSD 11 this timezone is not known. A better choice is
TZ=Pacific/Johnston. On Linux "US/Hawaii" is just a symlink to this
name and also it is known on FreeBSD and on Solaris.
$ TZ=Pacific/Johnston hg convert --config convert.localtimezone=True src src-hg
initializing destination src-hg repository
connecting to $TESTTMP/cvsrepo
scanning source...
collecting CVS rlog
5 log entries
cvslog hook: 5 entries
creating changesets
3 changeset entries
cvschangesets hook: 3 changesets
sorting...
converting...
2 Initial revision
1 ci0
0 import
updating tags
$ hgcat a
a
$ hgcat b/c
c
c
convert fresh repo with --filemap
$ echo include b/c > filemap
$ hg convert --filemap filemap src src-filemap
initializing destination src-filemap repository
connecting to $TESTTMP/cvsrepo
scanning source...
collecting CVS rlog
5 log entries
cvslog hook: 5 entries
creating changesets
3 changeset entries
cvschangesets hook: 3 changesets
sorting...
converting...
2 Initial revision
1 ci0
0 import
filtering out empty revision
repository tip rolled back to revision 1 (undo convert)
updating tags
$ hgcat b/c
c
c
$ hg -R src-filemap log --template '{rev} {desc} files: {files}\n'
2 update tags files: .hgtags
1 ci0 files: b/c
0 Initial revision files: b/c
convert full repository (issue1649)
$ cvscall -q -d "$CVSROOT" checkout -d srcfull "." | grep -v CVSROOT
U srcfull/src/a
U srcfull/src/b/c
$ ls srcfull
CVS
CVSROOT
src
$ hg convert srcfull srcfull-hg \
> | grep -v 'log entries' | grep -v 'hook:' \
> | grep -v '^[0-3] .*' # filter instable changeset order
initializing destination srcfull-hg repository
connecting to $TESTTMP/cvsrepo
scanning source...
collecting CVS rlog
creating changesets
4 changeset entries
sorting...
converting...
updating tags
$ hg cat -r tip --cwd srcfull-hg src/a
a
$ hg cat -r tip --cwd srcfull-hg src/b/c
c
c
commit new file revisions
$ cd src
$ echo a >> a
$ echo c >> b/c
$ cvscall -q commit -mci1 . | grep '<--'
$TESTTMP/cvsrepo/src/a,v <-- a
$TESTTMP/cvsrepo/src/b/c,v <-- *c (glob)
$ cd ..
convert again
$ TZ=Pacific/Johnston hg convert --config convert.localtimezone=True src src-hg
connecting to $TESTTMP/cvsrepo
scanning source...
collecting CVS rlog
7 log entries
cvslog hook: 7 entries
creating changesets
4 changeset entries
cvschangesets hook: 4 changesets
sorting...
converting...
0 ci1
$ hgcat a
a
a
$ hgcat b/c
c
c
c
convert again with --filemap
$ hg convert --filemap filemap src src-filemap
connecting to $TESTTMP/cvsrepo
scanning source...
collecting CVS rlog
7 log entries
cvslog hook: 7 entries
creating changesets
4 changeset entries
cvschangesets hook: 4 changesets
sorting...
converting...
0 ci1
$ hgcat b/c
c
c
c
$ hg -R src-filemap log --template '{rev} {desc} files: {files}\n'
3 ci1 files: b/c
2 update tags files: .hgtags
1 ci0 files: b/c
0 Initial revision files: b/c
commit branch
$ cd src
$ cvs -q update -r1.1 b/c
U b/c
$ cvs -q tag -b branch
T a
T b/c
$ cvs -q update -r branch > /dev/null
$ sleep 1
$ echo d >> b/c
$ cvs -q commit -mci2 . | grep '<--'
$TESTTMP/cvsrepo/src/b/c,v <-- *c (glob)
$ cd ..
convert again
$ TZ=Pacific/Johnston hg convert --config convert.localtimezone=True src src-hg
connecting to $TESTTMP/cvsrepo
scanning source...
collecting CVS rlog
8 log entries
cvslog hook: 8 entries
creating changesets
5 changeset entries
cvschangesets hook: 5 changesets
sorting...
converting...
0 ci2
$ hgcat b/c
c
d
convert again with --filemap
$ TZ=Pacific/Johnston hg convert --config convert.localtimezone=True --filemap filemap src src-filemap
connecting to $TESTTMP/cvsrepo
scanning source...
collecting CVS rlog
8 log entries
cvslog hook: 8 entries
creating changesets
5 changeset entries
cvschangesets hook: 5 changesets
sorting...
converting...
0 ci2
$ hgcat b/c
c
d
$ hg -R src-filemap log --template '{rev} {desc} files: {files}\n'
4 ci2 files: b/c
3 ci1 files: b/c
2 update tags files: .hgtags
1 ci0 files: b/c
0 Initial revision files: b/c
commit a new revision with funny log message
$ cd src
$ sleep 1
$ echo e >> a
$ cvscall -q commit -m'funny
> ----------------------------
> log message' . | grep '<--' |\
> sed -e 's:.*src/\(.*\),v.*:checking in src/\1,v:g'
checking in src/a,v
commit new file revisions with some fuzz
$ sleep 1
$ echo f >> a
$ cvscall -q commit -mfuzzy . | grep '<--'
$TESTTMP/cvsrepo/src/a,v <-- a
$ sleep 4 # the two changes will be split if fuzz < 4
$ echo g >> b/c
$ cvscall -q commit -mfuzzy . | grep '<--'
$TESTTMP/cvsrepo/src/b/c,v <-- *c (glob)
$ cd ..
convert again
$ TZ=Pacific/Johnston hg convert --config convert.cvsps.fuzz=2 --config convert.localtimezone=True src src-hg
connecting to $TESTTMP/cvsrepo
scanning source...
collecting CVS rlog
11 log entries
cvslog hook: 11 entries
creating changesets
8 changeset entries
cvschangesets hook: 8 changesets
sorting...
converting...
2 funny
1 fuzzy
0 fuzzy
$ hg -R src-hg log -G --template '{rev} ({branches}) {desc} date: {date|date} files: {files}\n'
o 8 (branch) fuzzy date: * -1000 files: b/c (glob)
|
o 7 (branch) fuzzy date: * -1000 files: a (glob)
|
o 6 (branch) funny
| ----------------------------
| log message date: * -1000 files: a (glob)
o 5 (branch) ci2 date: * -1000 files: b/c (glob)
o 4 () ci1 date: * -1000 files: a b/c (glob)
|
o 3 () update tags date: * +0000 files: .hgtags (glob)
|
| o 2 (INITIAL) import date: * -1000 files: (glob)
| |
o | 1 () ci0 date: * -1000 files: b/c (glob)
|/
o 0 () Initial revision date: * -1000 files: a b/c (glob)
testing debugcvsps
$ cd src
$ hg debugcvsps --fuzz=2 -x >/dev/null
commit a new revision changing a and removing b/c
$ cvscall -q update -A
U a
U b/c
$ sleep 1
$ echo h >> a
$ cvscall -Q remove -f b/c
$ cvscall -q commit -mci | grep '<--'
$TESTTMP/cvsrepo/src/a,v <-- a
$TESTTMP/cvsrepo/src/b/c,v <-- *c (glob)
update and verify the cvsps cache
$ hg debugcvsps --fuzz=2 -u
collecting CVS rlog
13 log entries
cvslog hook: 13 entries
creating changesets
11 changeset entries
cvschangesets hook: 11 changesets
---------------------
PatchSet 1
Date: * (glob)
Author: * (glob)
Branch: HEAD
Tag: (none)
Branchpoints: INITIAL
Log:
Initial revision
Members:
a:INITIAL->1.1
---------------------
PatchSet 2
Date: * (glob)
Author: * (glob)
Branch: HEAD
Tag: (none)
Branchpoints: INITIAL, branch
Log:
Initial revision
Members:
b/c:INITIAL->1.1
---------------------
PatchSet 3
Date: * (glob)
Author: * (glob)
Branch: INITIAL
Tag: start
Log:
import
Members:
a:1.1->1.1.1.1
b/c:1.1->1.1.1.1
---------------------
PatchSet 4
Date: * (glob)
Author: * (glob)
Branch: HEAD
Tag: (none)
Log:
ci0
Members:
b/c:1.1->1.2
---------------------
PatchSet 5
Date: * (glob)
Author: * (glob)
Branch: HEAD
Tag: (none)
Branchpoints: branch
Log:
ci1
Members:
a:1.1->1.2
---------------------
PatchSet 6
Date: * (glob)
Author: * (glob)
Branch: HEAD
Tag: (none)
Log:
ci1
Members:
b/c:1.2->1.3
---------------------
PatchSet 7
Date: * (glob)
Author: * (glob)
Branch: branch
Tag: (none)
Log:
ci2
Members:
b/c:1.1->1.1.2.1
---------------------
PatchSet 8
Date: * (glob)
Author: * (glob)
Branch: branch
Tag: (none)
Log:
funny
----------------------------
log message
Members:
a:1.2->1.2.2.1
---------------------
PatchSet 9
Date: * (glob)
Author: * (glob)
Branch: branch
Tag: (none)
Log:
fuzzy
Members:
a:1.2.2.1->1.2.2.2
---------------------
PatchSet 10
Date: * (glob)
Author: * (glob)
Branch: branch
Tag: (none)
Log:
fuzzy
Members:
b/c:1.1.2.1->1.1.2.2
---------------------
PatchSet 11
Date: * (glob)
Author: * (glob)
Branch: HEAD
Tag: (none)
Log:
ci
Members:
a:1.2->1.3
b/c:1.3->1.4(DEAD)
$ cd ..
Test transcoding CVS log messages (issue5597)
=============================================
To emulate commit messages in (non-ascii) multiple encodings portably,
this test scenario writes CVS history file (*,v file) directly via
python code.
Commit messages of version 1.2 - 1.4 use u3042 in 3 encodings below.
|encoding |byte sequence | decodable as: |
| | | utf-8 euc-jp cp932 |
+----------+--------------+--------------------+
|utf-8 |\xe3\x81\x82 | o x x |
|euc-jp |\xa4\xa2 | x o o |
|cp932 |\x82\xa0 | x x o |
$ mkdir -p cvsrepo/transcoding
$ python <<EOF
> fp = open('cvsrepo/transcoding/file,v', 'wb')
> fp.write((b'''
> head 1.4;
> access;
> symbols
> start:1.1.1.1 INITIAL:1.1.1;
> locks; strict;
> comment @# @;
>
>
> 1.4
> date 2017.07.10.00.00.04; author nobody; state Exp;
> branches;
> next 1.3;
> commitid 10059635D016A510FFA;
>
> 1.3
> date 2017.07.10.00.00.03; author nobody; state Exp;
> branches;
> next 1.2;
> commitid 10059635CFF6A4FF34E;
>
> 1.2
> date 2017.07.10.00.00.02; author nobody; state Exp;
> branches;
> next 1.1;
> commitid 10059635CFD6A4D5095;
>
> 1.1
> date 2017.07.10.00.00.01; author nobody; state Exp;
> branches
> 1.1.1.1;
> next ;
> commitid 10059635CFB6A4A3C33;
>
> 1.1.1.1
> date 2017.07.10.00.00.01; author nobody; state Exp;
> branches;
> next ;
> commitid 10059635CFB6A4A3C33;
>
>
> desc
> @@
>
>
> 1.4
> log
> @''' + u'\u3042'.encode('cp932') + b''' (cp932)
> @
> text
> @1
> 2
> 3
> 4
> @
>
>
> 1.3
> log
> @''' + u'\u3042'.encode('euc-jp') + b''' (euc-jp)
> @
> text
> @d4 1
> @
>
>
> 1.2
> log
> @''' + u'\u3042'.encode('utf-8') + b''' (utf-8)
> @
> text
> @d3 1
> @
>
>
> 1.1
> log
> @Initial revision
> @
> text
> @d2 1
> @
>
>
> 1.1.1.1
> log
> @import
> @
> text
> @@
> ''').lstrip())
> EOF
$ cvscall -q checkout transcoding
U transcoding/file
Test converting in normal case
------------------------------
(filtering by grep in order to check only form of debug messages)
$ hg convert --config convert.cvsps.logencoding=utf-8,euc-jp,cp932 -q --debug transcoding transcoding-hg | grep 'transcoding by'
transcoding by utf-8: 1.1 of file
transcoding by utf-8: 1.1.1.1 of file
transcoding by utf-8: 1.2 of file
transcoding by euc-jp: 1.3 of file
transcoding by cp932: 1.4 of file
$ hg -R transcoding-hg --encoding utf-8 log -T "{rev}: {desc}\n"
5: update tags
4: import
3: \xe3\x81\x82 (cp932) (esc)
2: \xe3\x81\x82 (euc-jp) (esc)
1: \xe3\x81\x82 (utf-8) (esc)
0: Initial revision
$ rm -rf transcoding-hg
Test converting in error cases
------------------------------
unknown encoding in convert.cvsps.logencoding
$ hg convert --config convert.cvsps.logencoding=foobar -q transcoding transcoding-hg
abort: unknown encoding: foobar
(check convert.cvsps.logencoding configuration)
[255]
$ rm -rf transcoding-hg
no acceptable encoding in convert.cvsps.logencoding
$ hg convert --config convert.cvsps.logencoding=utf-8,euc-jp -q transcoding transcoding-hg
abort: no encoding can transcode CVS log message for 1.4 of file
(check convert.cvsps.logencoding configuration)
[255]
$ rm -rf transcoding-hg