cborutil: remove readindefinitebytestringtoiter() This was implemented as part of implementing streaming encoding. It was never used outside of tests. Now that we have a full CBOR decoder, it can be used for incremental decoding of indefinite-length byte strings. This also removes the last use of the vendored cbor2 package from this module. Differential Revision: https://phab.mercurial-scm.org/D4433

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

tests: remove use of string in CBOR test We don't use the CBOR string major type in the wire protocol. Let's not test for it. Differential Revision: https://phab.mercurial-scm.org/D4413

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

py3: add new passing test to whitelist found by buildbot Differential Revision: https://phab.mercurial-scm.org/D4451

py3: alias xrange to range in tests/test-fastannotate-revmap.py xrange is not available on Python 3. Differential Revision: https://phab.mercurial-scm.org/D4450

py3: add r'' prefix to prevent b'' being prepended The keys of keyword arguments should be str. # skip-blame because we are adding just r'' prefixes. Differential Revision: https://phab.mercurial-scm.org/D4449

revert: fix the inconsistency of status msgs in --interactive mode Before this patch we were priting every action msg before actually performing that action and that was resulting in inconsistencies; like in --interactive session if user decided to not revert any changes in a file foo, still there will be a msg on console saying "reverting foo". To fix this, I have made some changes to print status msg just before the action it is going to perform, no matter if --interactive or not. Changes made in test-revert-interactive.t reflect the changed behavior. There are also some changes in test-revert.t because of change in the order of messages. Differential Revision: https://phab.mercurial-scm.org/D4380

revert: remove unnecessary check as `msg` should never be a callable now Differential Revision: https://phab.mercurial-scm.org/D4448

run-tests: drop support for --with-python3 and $PYTHON3 This backs out cdbc25306696. We can run many tests on python3 without this hack.