comparison mercurial/wireprotoframing.py @ 37290:cc5a040fe150

wireproto: syntax for encoding CBOR into frames

We just vendored a library for encoding and decoding the CBOR
data format. While the intent of that vendor was to support state
files, CBOR is really a nice data format. It is extensible and
compact.

I've been feeling dirty inventing my own data formats for
frame payloads. While custom formats can always beat out a generic
format, there is a cost to be paid in terms of implementation,
comprehension, etc. CBOR is compact enough that I'm not too
worried about efficiency loss. I think the benefits of using
a standardized format outweigh rolling our own formats. So
I plan to make heavy use of CBOR in the wire protocol going
forward.

This commit introduces support for encoding CBOR data in frame
payloads to our function to make a frame from a human string.
We do need to employ some low-level Python code in order to
evaluate a string as a Python expression. But other than that,
this should hopefully be pretty straightforward.

Unit tests for this function have been added.

Differential Revision: https://phab.mercurial-scm.org/D2948

37289:5fadc63ac99f

import struct

from .i18n import _
from .thirdparty import (
    attr,
)
from . import (
    error,
    util,
)

    return frame

def makeframefromhumanstring(s):
    """Create a frame from a human readable string

    Strings have the form:

        <request-id> <stream-id> <stream-flags> <type> <flags> <payload>

    This can be used by user-facing applications and tests for creating

    Stream flags, frame type, and flags can be specified by integer or
    named constant.

    Flags can be delimited by `|` to bitwise OR them together.
    """
    fields = s.split(b' ', 5)
    requestid, streamid, streamflags, frametype, frameflags, payload = fields

    requestid = int(requestid)

        if flag in validflags:
            finalflags |= validflags[flag]
        else:
            finalflags |= int(flag)

    payload = stringutil.unescapestr(payload)

    return makeframe(requestid=requestid, streamid=streamid,
                     streamflags=finalstreamflags, typeid=frametype,
                     flags=finalflags, payload=payload)

37290:cc5a040fe150

import struct

from .i18n import _
from .thirdparty import (
    attr,
    cbor,
)
from . import (
    error,
    util,
)

    return frame

def makeframefromhumanstring(s):
    """Create a frame from a human readable string

    DANGER: NOT SAFE TO USE WITH UNTRUSTED INPUT BECAUSE OF POTENTIAL
    eval() USAGE. DO NOT USE IN CORE.

    Strings have the form:

        <request-id> <stream-id> <stream-flags> <type> <flags> <payload>

    This can be used by user-facing applications and tests for creating

    Stream flags, frame type, and flags can be specified by integer or
    named constant.

    Flags can be delimited by `|` to bitwise OR them together.

    If the payload begins with ``cbor:``, the following string will be
    evaluated as Python code and the resulting object will be fed into
    a CBOR encoder. Otherwise, the payload is interpreted as a Python
    byte string literal.
    """
    fields = s.split(b' ', 5)
    requestid, streamid, streamflags, frametype, frameflags, payload = fields

    requestid = int(requestid)

        if flag in validflags:
            finalflags |= validflags[flag]
        else:
            finalflags |= int(flag)

    if payload.startswith(b'cbor:'):
        payload = cbor.dumps(stringutil.evalpython(payload[5:]), canonical=True)

    else:
        payload = stringutil.unescapestr(payload)

    return makeframe(requestid=requestid, streamid=streamid,
                     streamflags=finalstreamflags, typeid=frametype,
                     flags=finalflags, payload=payload)