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
#testcases obsstore-off obsstore-on
$ cat << EOF >> $HGRCPATH
> [extensions]
> amend=
> debugdrawdag=$TESTDIR/drawdag.py
> [diff]
> git=1
> EOF
#if obsstore-on
$ cat << EOF >> $HGRCPATH
> [experimental]
> evolution.createmarkers=True
> EOF
#endif
Basic amend
$ hg init repo1
$ cd repo1
$ hg debugdrawdag <<'EOS'
> B
> |
> A
> EOS
$ hg update B -q
$ echo 2 >> B
$ hg amend
saved backup bundle to $TESTTMP/repo1/.hg/strip-backup/112478962961-7e959a55-amend.hg (obsstore-off !)
#if obsstore-off
$ hg log -p -G --hidden -T '{rev} {node|short} {desc}\n'
@ 1 be169c7e8dbe B
| diff --git a/B b/B
| new file mode 100644
| --- /dev/null
| +++ b/B
| @@ -0,0 +1,1 @@
| +B2
|
o 0 426bada5c675 A
diff --git a/A b/A
new file mode 100644
--- /dev/null
+++ b/A
@@ -0,0 +1,1 @@
+A
\ No newline at end of file
#else
$ hg log -p -G --hidden -T '{rev} {node|short} {desc}\n'
@ 2 be169c7e8dbe B
| diff --git a/B b/B
| new file mode 100644
| --- /dev/null
| +++ b/B
| @@ -0,0 +1,1 @@
| +B2
|
| x 1 112478962961 B
|/ diff --git a/B b/B
| new file mode 100644
| --- /dev/null
| +++ b/B
| @@ -0,0 +1,1 @@
| +B
| \ No newline at end of file
|
o 0 426bada5c675 A
diff --git a/A b/A
new file mode 100644
--- /dev/null
+++ b/A
@@ -0,0 +1,1 @@
+A
\ No newline at end of file
#endif
Nothing changed
$ hg amend
nothing changed
[1]
$ hg amend -d "0 0"
nothing changed
[1]
$ hg amend -d "Thu Jan 01 00:00:00 1970 UTC"
nothing changed
[1]
Matcher and metadata options
$ echo 3 > C
$ echo 4 > D
$ hg add C D
$ hg amend -m NEWMESSAGE -I C
saved backup bundle to $TESTTMP/repo1/.hg/strip-backup/be169c7e8dbe-7684ddc5-amend.hg (obsstore-off !)
$ hg log -r . -T '{node|short} {desc} {files}\n'
c7ba14d9075b NEWMESSAGE B C
$ echo 5 > E
$ rm C
$ hg amend -d '2000 1000' -u 'Foo <foo@example.com>' -A C D
saved backup bundle to $TESTTMP/repo1/.hg/strip-backup/c7ba14d9075b-b3e76daa-amend.hg (obsstore-off !)
$ hg log -r . -T '{node|short} {desc} {files} {author} {date}\n'
14f6c4bcc865 NEWMESSAGE B D Foo <foo@example.com> 2000.01000
Amend with editor
$ cat > $TESTTMP/prefix.sh <<'EOF'
> printf 'EDITED: ' > $TESTTMP/msg
> cat "$1" >> $TESTTMP/msg
> mv $TESTTMP/msg "$1"
> EOF
$ chmod +x $TESTTMP/prefix.sh
$ HGEDITOR="sh $TESTTMP/prefix.sh" hg amend --edit
saved backup bundle to $TESTTMP/repo1/.hg/strip-backup/14f6c4bcc865-6591f15d-amend.hg (obsstore-off !)
$ hg log -r . -T '{node|short} {desc}\n'
298f085230c3 EDITED: NEWMESSAGE
$ HGEDITOR="sh $TESTTMP/prefix.sh" hg amend -e -m MSG
saved backup bundle to $TESTTMP/repo1/.hg/strip-backup/298f085230c3-d81a6ad3-amend.hg (obsstore-off !)
$ hg log -r . -T '{node|short} {desc}\n'
974f07f28537 EDITED: MSG
$ echo FOO > $TESTTMP/msg
$ hg amend -l $TESTTMP/msg -m BAR
abort: options --message and --logfile are mutually exclusive
[255]
$ hg amend -l $TESTTMP/msg
saved backup bundle to $TESTTMP/repo1/.hg/strip-backup/974f07f28537-edb6470a-amend.hg (obsstore-off !)
$ hg log -r . -T '{node|short} {desc}\n'
507be9bdac71 FOO
Interactive mode
$ touch F G
$ hg add F G
$ cat <<EOS | hg amend -i --config ui.interactive=1
> y
> n
> EOS
diff --git a/F b/F
new file mode 100644
examine changes to 'F'? [Ynesfdaq?] y
diff --git a/G b/G
new file mode 100644
examine changes to 'G'? [Ynesfdaq?] n
saved backup bundle to $TESTTMP/repo1/.hg/strip-backup/507be9bdac71-c8077452-amend.hg (obsstore-off !)
$ hg log -r . -T '{files}\n'
B D F
Amend in the middle of a stack
$ hg init $TESTTMP/repo2
$ cd $TESTTMP/repo2
$ hg debugdrawdag <<'EOS'
> C
> |
> B
> |
> A
> EOS
$ hg update -q B
$ echo 2 >> B
$ hg amend
abort: cannot amend changeset with children
[255]
#if obsstore-on
With allowunstable, amend could work in the middle of a stack
$ cat >> $HGRCPATH <<EOF
> [experimental]
> evolution.createmarkers=True
> evolution.allowunstable=True
> EOF
$ hg amend
1 new orphan changesets
$ hg log -T '{rev} {node|short} {desc}\n' -G
@ 3 be169c7e8dbe B
|
| * 2 26805aba1e60 C
| |
| x 1 112478962961 B
|/
o 0 426bada5c675 A
Checking the note stored in the obsmarker
$ echo foo > bar
$ hg add bar
$ hg amend --note 'yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy'
abort: cannot store a note of more than 255 bytes
[255]
$ hg amend --note "adding bar"
$ hg debugobsolete -r .
112478962961147124edd43549aedd1a335e44bf be169c7e8dbe21cd10b3d79691cbe7f241e3c21c 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '8', 'operation': 'amend', 'user': 'test'}
be169c7e8dbe21cd10b3d79691cbe7f241e3c21c 16084da537dd8f84cfdb3055c633772269d62e1b 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '8', 'note': 'adding bar', 'operation': 'amend', 'user': 'test'}
#endif
Cannot amend public changeset
$ hg phase -r A --public
$ hg update -C -q A
$ hg amend -m AMEND
abort: cannot amend public changesets
(see 'hg help phases' for details)
[255]
Amend a merge changeset
$ hg init $TESTTMP/repo3
$ cd $TESTTMP/repo3
$ hg debugdrawdag <<'EOS'
> C
> /|
> A B
> EOS
$ hg update -q C
$ hg amend -m FOO
saved backup bundle to $TESTTMP/repo3/.hg/strip-backup/a35c07e8a2a4-15ff4612-amend.hg (obsstore-off !)
$ rm .hg/localtags
$ hg log -G -T '{desc}\n'
@ FOO
|\
| o B
|
o A
More complete test for status changes (issue5732)
-------------------------------------------------
Generates history of files having 3 states, r0_r1_wc:
r0: ground (content/missing)
r1: old state to be amended (content/missing, where missing means removed)
wc: changes to be included in r1 (content/missing-tracked/untracked)
$ hg init $TESTTMP/wcstates
$ cd $TESTTMP/wcstates
$ $PYTHON $TESTDIR/generate-working-copy-states.py state 2 1
$ hg addremove -q --similarity 0
$ hg commit -m0
$ $PYTHON $TESTDIR/generate-working-copy-states.py state 2 2
$ hg addremove -q --similarity 0
$ hg commit -m1
$ $PYTHON $TESTDIR/generate-working-copy-states.py state 2 wc
$ hg addremove -q --similarity 0
$ hg forget *_*_*-untracked
$ rm *_*_missing-*
amend r1 to include wc changes
$ hg amend
saved backup bundle to * (glob) (obsstore-off !)
clean/modified/removed/added states of the amended revision
$ hg status --all --change . 'glob:content1_*_content1-tracked'
C content1_content1_content1-tracked
C content1_content2_content1-tracked
C content1_missing_content1-tracked
$ hg status --all --change . 'glob:content1_*_content[23]-tracked'
M content1_content1_content3-tracked
M content1_content2_content2-tracked
M content1_content2_content3-tracked
M content1_missing_content3-tracked
$ hg status --all --change . 'glob:content1_*_missing-tracked'
M content1_content2_missing-tracked
R content1_missing_missing-tracked
C content1_content1_missing-tracked
$ hg status --all --change . 'glob:content1_*_*-untracked'
R content1_content1_content1-untracked
R content1_content1_content3-untracked
R content1_content1_missing-untracked
R content1_content2_content1-untracked
R content1_content2_content2-untracked
R content1_content2_content3-untracked
R content1_content2_missing-untracked
R content1_missing_content1-untracked
R content1_missing_content3-untracked
R content1_missing_missing-untracked
$ hg status --all --change . 'glob:missing_content2_*'
A missing_content2_content2-tracked
A missing_content2_content3-tracked
A missing_content2_missing-tracked
$ hg status --all --change . 'glob:missing_missing_*'
A missing_missing_content3-tracked
working directory should be all clean (with some missing/untracked files)
$ hg status --all 'glob:*_content?-tracked'
C content1_content1_content1-tracked
C content1_content1_content3-tracked
C content1_content2_content1-tracked
C content1_content2_content2-tracked
C content1_content2_content3-tracked
C content1_missing_content1-tracked
C content1_missing_content3-tracked
C missing_content2_content2-tracked
C missing_content2_content3-tracked
C missing_missing_content3-tracked
$ hg status --all 'glob:*_missing-tracked'
! content1_content1_missing-tracked
! content1_content2_missing-tracked
! content1_missing_missing-tracked
! missing_content2_missing-tracked
! missing_missing_missing-tracked
$ hg status --all 'glob:*-untracked'
? content1_content1_content1-untracked
? content1_content1_content3-untracked
? content1_content2_content1-untracked
? content1_content2_content2-untracked
? content1_content2_content3-untracked
? content1_missing_content1-untracked
? content1_missing_content3-untracked
? missing_content2_content2-untracked
? missing_content2_content3-untracked
? missing_missing_content3-untracked
==========================================
Test history-editing-backup config option|
==========================================
$ hg init $TESTTMP/repo4
$ cd $TESTTMP/repo4
$ echo a>a
$ hg ci -Aqma
$ echo oops>b
$ hg ci -Aqm "b"
$ echo partiallyfixed > b
#if obsstore-off
$ hg amend
saved backup bundle to $TESTTMP/repo4/.hg/strip-backup/95e899acf2ce-f11cb050-amend.hg
When history-editing-backup config option is set:
$ cat << EOF >> $HGRCPATH
> [ui]
> history-editing-backup = False
> EOF
$ echo fixed > b
$ hg amend
#else
$ hg amend
When history-editing-backup config option is set:
$ cat << EOF >> $HGRCPATH
> [ui]
> history-editing-backup = False
> EOF
$ echo fixed > b
$ hg amend
#endif