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# Copyright 2016 Facebook, Inc.
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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#
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# * Redistributions of source code must retain the above copyright notice,
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# this list of conditions and the following disclaimer.
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#
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# * Redistributions in binary form must reproduce the above copyright notice,
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# this list of conditions and the following disclaimer in the documentation
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# and/or other materials provided with the distribution.
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#
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# * Neither the name Facebook nor the names of its contributors may be used to
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# endorse or promote products derived from this software without specific
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# prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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import ctypes
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try:
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from . import bser
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except ImportError:
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from . import pybser as bser
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EMPTY_HEADER = b"\x00\x01\x05\x00\x00\x00\x00"
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def _read_bytes(fp, buf):
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"""Read bytes from a file-like object
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@param fp: File-like object that implements read(int)
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@type fp: file
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@param buf: Buffer to read into
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@type buf: bytes
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@return: buf
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"""
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# Do the first read without resizing the input buffer
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offset = 0
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remaining = len(buf)
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while remaining > 0:
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l = fp.readinto((ctypes.c_char * remaining).from_buffer(buf, offset))
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if l is None or l == 0:
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return offset
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offset += l
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remaining -= l
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return offset
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def load(fp, mutable=True, value_encoding=None, value_errors=None):
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"""Deserialize a BSER-encoded blob.
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@param fp: The file-object to deserialize.
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@type file:
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@param mutable: Whether to return mutable results.
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@type mutable: bool
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@param value_encoding: Optional codec to use to decode values. If
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unspecified or None, return values as bytestrings.
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@type value_encoding: str
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@param value_errors: Optional error handler for codec. 'strict' by default.
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The other most common argument is 'surrogateescape' on
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Python 3. If value_encoding is None, this is ignored.
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@type value_errors: str
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"""
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buf = ctypes.create_string_buffer(8192)
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SNIFF_BUFFER_SIZE = len(EMPTY_HEADER)
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header = (ctypes.c_char * SNIFF_BUFFER_SIZE).from_buffer(buf)
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read_len = _read_bytes(fp, header)
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if read_len < len(header):
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return None
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total_len = bser.pdu_len(buf)
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if total_len > len(buf):
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ctypes.resize(buf, total_len)
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body = (ctypes.c_char * (total_len - len(header))).from_buffer(
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buf, len(header)
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)
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read_len = _read_bytes(fp, body)
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if read_len < len(body):
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raise RuntimeError("bser data ended early")
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return bser.loads(
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(ctypes.c_char * total_len).from_buffer(buf, 0),
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mutable,
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value_encoding,
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value_errors,
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)
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