view hgext/fsmonitor/pywatchman/load.py @ 51481:4456c15bde9e

stream-clone-test: simplify bookmark clone

The important things to test here is the number of file included (to catch that
the bookmark file was sent). So we keep that part non glob'ed but glob the
rest.

The glob'ed numbers are very fragile and consume a lot of time for little value
when adjusting formats, caches, and protocol.

# Copyright 2016 Facebook, Inc.
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# modification, are permitted provided that the following conditions are met:
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import ctypes


try:
    from . import bser
except ImportError:
    from . import pybser as bser


EMPTY_HEADER = b"\x00\x01\x05\x00\x00\x00\x00"


def _read_bytes(fp, buf):
    """Read bytes from a file-like object

    @param fp: File-like object that implements read(int)
    @type fp: file

    @param buf: Buffer to read into
    @type buf: bytes

    @return: buf
    """

    # Do the first read without resizing the input buffer
    offset = 0
    remaining = len(buf)
    while remaining > 0:
        l = fp.readinto((ctypes.c_char * remaining).from_buffer(buf, offset))
        if l is None or l == 0:
            return offset
        offset += l
        remaining -= l
    return offset


def load(fp, mutable=True, value_encoding=None, value_errors=None):
    """Deserialize a BSER-encoded blob.

    @param fp: The file-object to deserialize.
    @type file:

    @param mutable: Whether to return mutable results.
    @type mutable: bool

    @param value_encoding: Optional codec to use to decode values. If
                           unspecified or None, return values as bytestrings.
    @type value_encoding: str

    @param value_errors: Optional error handler for codec. 'strict' by default.
                         The other most common argument is 'surrogateescape' on
                         Python 3. If value_encoding is None, this is ignored.
    @type value_errors: str
    """
    buf = ctypes.create_string_buffer(8192)
    SNIFF_BUFFER_SIZE = len(EMPTY_HEADER)
    header = (ctypes.c_char * SNIFF_BUFFER_SIZE).from_buffer(buf)
    read_len = _read_bytes(fp, header)
    if read_len < len(header):
        return None

    total_len = bser.pdu_len(buf)
    if total_len > len(buf):
        ctypes.resize(buf, total_len)

    body = (ctypes.c_char * (total_len - len(header))).from_buffer(
        buf, len(header)
    )
    read_len = _read_bytes(fp, body)
    if read_len < len(body):
        raise RuntimeError("bser data ended early")

    return bser.loads(
        (ctypes.c_char * total_len).from_buffer(buf, 0),
        mutable,
        value_encoding,
        value_errors,
    )