view hgext/fsmonitor/pywatchman/load.py @ 50725:7e5be4a7cda7 stable

tests: use grep -E instead of obsolescent egrep

Testing on Fedora 38 failed with:
  egrep: warning: egrep is obsolescent; using grep -E

The warning comes from
https://git.savannah.gnu.org/cgit/grep.git/commit/?id=a9515624709865d480e3142fd959bccd1c9372d1
. For further anecdotal evidence of the change, see
https://www.phoronix.com/news/GNU-Grep-3.8-Stop-egrep-fgrep .

This reverses the code check that goes back to e7d3b509af8b. grep -E is POSIX,
but there is a risk that it doesn't work the same on all platforms - especially
older Unix versions. It should however always be possible to put a GNU grep in
$PATH before running the tests.

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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,
    )