hgext/fsmonitor/pywatchman/pybser.py

fsmonitor: dependencies for new experimental extension

In preparation for the filesystem monitor extension, include the pywatchman
library. The fbmonitor extension relies on this library to communicate with
the Watchman service. The library is BSD licensed and is taken from
https://github.com/facebook/watchman/tree/master/python.

This package has not been updated to mercurial code standards.

# Copyright 2015 Facebook, Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
#  * Redistributions of source code must retain the above copyright notice,
#    this list of conditions and the following disclaimer.
#
#  * Redistributions in binary form must reproduce the above copyright notice,
#    this list of conditions and the following disclaimer in the documentation
#    and/or other materials provided with the distribution.
#
#  * Neither the name Facebook nor the names of its contributors may be used to
#    endorse or promote products derived from this software without specific
#    prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

import collections
import ctypes
import struct
import sys

BSER_ARRAY = '\x00'
BSER_OBJECT = '\x01'
BSER_STRING = '\x02'
BSER_INT8 = '\x03'
BSER_INT16 = '\x04'
BSER_INT32 = '\x05'
BSER_INT64 = '\x06'
BSER_REAL = '\x07'
BSER_TRUE = '\x08'
BSER_FALSE = '\x09'
BSER_NULL = '\x0a'
BSER_TEMPLATE = '\x0b'
BSER_SKIP = '\x0c'

# Leave room for the serialization header, which includes
# our overall length.  To make things simpler, we'll use an
# int32 for the header
EMPTY_HEADER = "\x00\x01\x05\x00\x00\x00\x00"

# Python 3 conditional for supporting Python 2's int/long types
if sys.version_info > (3,):
    long = int

def _int_size(x):
    """Return the smallest size int that can store the value"""
    if -0x80 <= x <= 0x7F:
        return 1
    elif -0x8000 <= x <= 0x7FFF:
        return 2
    elif -0x80000000 <= x <= 0x7FFFFFFF:
        return 4
    elif long(-0x8000000000000000) <= x <= long(0x7FFFFFFFFFFFFFFF):
        return 8
    else:
        raise RuntimeError('Cannot represent value: ' + str(x))


class _bser_buffer(object):

    def __init__(self):
        self.buf = ctypes.create_string_buffer(8192)
        struct.pack_into(str(len(EMPTY_HEADER)) + 's', self.buf, 0, EMPTY_HEADER)
        self.wpos = len(EMPTY_HEADER)

    def ensure_size(self, size):
        while ctypes.sizeof(self.buf) - self.wpos < size:
            ctypes.resize(self.buf, ctypes.sizeof(self.buf) * 2)

    def append_long(self, val):
        size = _int_size(val)
        to_write = size + 1
        self.ensure_size(to_write)
        if size == 1:
            struct.pack_into('=cb', self.buf, self.wpos, BSER_INT8, val)
        elif size == 2:
            struct.pack_into('=ch', self.buf, self.wpos, BSER_INT16, val)
        elif size == 4:
            struct.pack_into('=ci', self.buf, self.wpos, BSER_INT32, val)
        elif size == 8:
            struct.pack_into('=cq', self.buf, self.wpos, BSER_INT64, val)
        else:
            raise RuntimeError('Cannot represent this long value')
        self.wpos += to_write


    def append_string(self, s):
        if isinstance(s, unicode):
            s = s.encode('utf-8')
        s_len = len(s)
        size = _int_size(s_len)
        to_write = 2 + size + s_len
        self.ensure_size(to_write)
        if size == 1:
            struct.pack_into('=ccb' + str(s_len) + 's', self.buf, self.wpos, BSER_STRING, BSER_INT8, s_len, s)
        elif size == 2:
            struct.pack_into('=cch' + str(s_len) + 's', self.buf, self.wpos, BSER_STRING, BSER_INT16, s_len, s)
        elif size == 4:
            struct.pack_into('=cci' + str(s_len) + 's', self.buf, self.wpos, BSER_STRING, BSER_INT32, s_len, s)
        elif size == 8:
            struct.pack_into('=ccq' + str(s_len) + 's', self.buf, self.wpos, BSER_STRING, BSER_INT64, s_len, s)
        else:
            raise RuntimeError('Cannot represent this string value')
        self.wpos += to_write


    def append_recursive(self, val):
        if isinstance(val, bool):
            needed = 1
            self.ensure_size(needed)
            if val:
                to_encode = BSER_TRUE
            else:
                to_encode = BSER_FALSE
            struct.pack_into('=c', self.buf, self.wpos, to_encode)
            self.wpos += needed
        elif val is None:
            needed = 1
            self.ensure_size(needed)
            struct.pack_into('=c', self.buf, self.wpos, BSER_NULL)
            self.wpos += needed
        elif isinstance(val, (int, long)):
            self.append_long(val)
        elif isinstance(val, (str, unicode)):
            self.append_string(val)
        elif isinstance(val, float):
            needed = 9
            self.ensure_size(needed)
            struct.pack_into('=cd', self.buf, self.wpos, BSER_REAL, val)
            self.wpos += needed
        elif isinstance(val, collections.Mapping) and isinstance(val, collections.Sized):
            val_len = len(val)
            size = _int_size(val_len)
            needed = 2 + size
            self.ensure_size(needed)
            if size == 1:
                struct.pack_into('=ccb', self.buf, self.wpos, BSER_OBJECT, BSER_INT8, val_len)
            elif size == 2:
                struct.pack_into('=cch', self.buf, self.wpos, BSER_OBJECT, BSER_INT16, val_len)
            elif size == 4:
                struct.pack_into('=cci', self.buf, self.wpos, BSER_OBJECT, BSER_INT32, val_len)
            elif size == 8:
                struct.pack_into('=ccq', self.buf, self.wpos, BSER_OBJECT, BSER_INT64, val_len)
            else:
                raise RuntimeError('Cannot represent this mapping value')
            self.wpos += needed
            for k, v in val.iteritems():
                self.append_string(k)
                self.append_recursive(v)
        elif isinstance(val, collections.Iterable) and isinstance(val, collections.Sized):
            val_len = len(val)
            size = _int_size(val_len)
            needed = 2 + size
            self.ensure_size(needed)
            if size == 1:
                struct.pack_into('=ccb', self.buf, self.wpos, BSER_ARRAY, BSER_INT8, val_len)
            elif size == 2:
                struct.pack_into('=cch', self.buf, self.wpos, BSER_ARRAY, BSER_INT16, val_len)
            elif size == 4:
                struct.pack_into('=cci', self.buf, self.wpos, BSER_ARRAY, BSER_INT32, val_len)
            elif size == 8:
                struct.pack_into('=ccq', self.buf, self.wpos, BSER_ARRAY, BSER_INT64, val_len)
            else:
                raise RuntimeError('Cannot represent this sequence value')
            self.wpos += needed
            for v in val:
                self.append_recursive(v)
        else:
            raise RuntimeError('Cannot represent unknown value type')


def dumps(obj):
    bser_buf = _bser_buffer()
    bser_buf.append_recursive(obj)
    # Now fill in the overall length
    obj_len = bser_buf.wpos - len(EMPTY_HEADER)
    struct.pack_into('=i', bser_buf.buf, 3, obj_len)
    return bser_buf.buf.raw[:bser_buf.wpos]


def _bunser_int(buf, pos):
    try:
        int_type = buf[pos]
    except IndexError:
        raise ValueError('Invalid bser int encoding, pos out of range')
    if int_type == BSER_INT8:
        needed = 2
        fmt = '=b'
    elif int_type == BSER_INT16:
        needed = 3
        fmt = '=h'
    elif int_type == BSER_INT32:
        needed = 5
        fmt = '=i'
    elif int_type == BSER_INT64:
        needed = 9
        fmt = '=q'
    else:
        raise ValueError('Invalid bser int encoding 0x%02x' % int(int_type))
    int_val = struct.unpack_from(fmt, buf, pos + 1)[0]
    return (int_val, pos + needed)


def _bunser_string(buf, pos):
    str_len, pos = _bunser_int(buf, pos + 1)
    str_val = struct.unpack_from(str(str_len) + 's', buf, pos)[0]
    return (str_val, pos + str_len)


def _bunser_array(buf, pos, mutable=True):
    arr_len, pos = _bunser_int(buf, pos + 1)
    arr = []
    for i in range(arr_len):
        arr_item, pos = _bser_loads_recursive(buf, pos, mutable)
        arr.append(arr_item)

    if not mutable:
      arr = tuple(arr)

    return arr, pos


# This is a quack-alike with the bserObjectType in bser.c
# It provides by getattr accessors and getitem for both index
# and name.
class _BunserDict(object):
    __slots__ = ('_keys', '_values')

    def __init__(self, keys, values):
        self._keys = keys
        self._values = values

    def __getattr__(self, name):
        return self.__getitem__(name)

    def __getitem__(self, key):
        if isinstance(key, (int, long)):
            return self._values[key]
        elif key.startswith('st_'):
            # hack^Wfeature to allow mercurial to use "st_size" to
            # reference "size"
            key = key[3:]
        try:
            return self._values[self._keys.index(key)]
        except ValueError as ex:
            raise KeyError('_BunserDict has no key %s' % key)

    def __len__(self):
        return len(self._keys)

def _bunser_object(buf, pos, mutable=True):
    obj_len, pos = _bunser_int(buf, pos + 1)
    if mutable:
        obj = {}
    else:
        keys = []
        vals = []

    for i in range(obj_len):
        key, pos = _bunser_string(buf, pos)
        val, pos = _bser_loads_recursive(buf, pos, mutable)
        if mutable:
            obj[key] = val
        else:
            keys.append(key)
            vals.append(val)

    if not mutable:
        obj = _BunserDict(keys, vals)

    return obj, pos


def _bunser_template(buf, pos, mutable=True):
    if buf[pos + 1] != BSER_ARRAY:
        raise RuntimeError('Expect ARRAY to follow TEMPLATE')
    keys, pos = _bunser_array(buf, pos + 1)
    nitems, pos = _bunser_int(buf, pos)
    arr = []
    for i in range(nitems):
        if mutable:
            obj = {}
        else:
            vals = []

        for keyidx in range(len(keys)):
            if buf[pos] == BSER_SKIP:
                pos += 1
                ele = None
            else:
                ele, pos = _bser_loads_recursive(buf, pos, mutable)

            if mutable:
                key = keys[keyidx]
                obj[key] = ele
            else:
                vals.append(ele)

        if not mutable:
            obj = _BunserDict(keys, vals)

        arr.append(obj)
    return arr, pos


def _bser_loads_recursive(buf, pos, mutable=True):
    val_type = buf[pos]
    if (val_type == BSER_INT8 or val_type == BSER_INT16 or
        val_type == BSER_INT32 or val_type == BSER_INT64):
        return _bunser_int(buf, pos)
    elif val_type == BSER_REAL:
        val = struct.unpack_from('=d', buf, pos + 1)[0]
        return (val, pos + 9)
    elif val_type == BSER_TRUE:
        return (True, pos + 1)
    elif val_type == BSER_FALSE:
        return (False, pos + 1)
    elif val_type == BSER_NULL:
        return (None, pos + 1)
    elif val_type == BSER_STRING:
        return _bunser_string(buf, pos)
    elif val_type == BSER_ARRAY:
        return _bunser_array(buf, pos, mutable)
    elif val_type == BSER_OBJECT:
        return _bunser_object(buf, pos, mutable)
    elif val_type == BSER_TEMPLATE:
        return _bunser_template(buf, pos, mutable)
    else:
        raise RuntimeError('unhandled bser opcode 0x%02x' % (val_type,))


def pdu_len(buf):
    if buf[0:2] != EMPTY_HEADER[0:2]:
        raise RuntimeError('Invalid BSER header')
    expected_len, pos = _bunser_int(buf, 2)
    return expected_len + pos


def loads(buf, mutable=True):
    if buf[0:2] != EMPTY_HEADER[0:2]:
        raise RuntimeError('Invalid BSER header')
    expected_len, pos = _bunser_int(buf, 2)
    if len(buf) != expected_len + pos:
        raise RuntimeError('bser data len != header len')
    return _bser_loads_recursive(buf, pos, mutable)[0]

# no-check-code -- this is a 3rd party library