view hgext/fsmonitor/pywatchman/pybser.py @ 42961:460f8bf58020

osutil: allow disabling setprocname via a define passed to the compiler

In some situations, we run a custom python launcher that appears to not set up
Py_GetArgcArgv correctly. We then proceed to promptly crash when we attempt to
dereference NULL. Being able to completely disable setprocname is beneficial in
these situations, since we won't even attempt to use it, even if the case that
causes the crash is fixed.

Right now, if I compile osutil.so with -DSETPROCNAME_USE_NONE, the compilation
fails on python3 due to SETPROCNAME_USE_NONE redefinition. I could possibly
work around that, but it's likely helpful to have a way of disabling this
completely without it being brittle (i.e. if python3 ever gains the ability to
perform this operation).

Differential Revision: https://phab.mercurial-scm.org/D6865

# 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.

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
# no unicode literals

import binascii
import collections
import ctypes
import struct
import sys

from . import (
    compat,
)

BSER_ARRAY = b'\x00'
BSER_OBJECT = b'\x01'
BSER_BYTESTRING = b'\x02'
BSER_INT8 = b'\x03'
BSER_INT16 = b'\x04'
BSER_INT32 = b'\x05'
BSER_INT64 = b'\x06'
BSER_REAL = b'\x07'
BSER_TRUE = b'\x08'
BSER_FALSE = b'\x09'
BSER_NULL = b'\x0a'
BSER_TEMPLATE = b'\x0b'
BSER_SKIP = b'\x0c'
BSER_UTF8STRING = b'\x0d'

if compat.PYTHON3:
    STRING_TYPES = (str, bytes)
    unicode = str
    def tobytes(i):
        return str(i).encode('ascii')
    long = int
else:
    STRING_TYPES = (unicode, str)
    tobytes = bytes

# 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 = b"\x00\x01\x05\x00\x00\x00\x00"
EMPTY_HEADER_V2 = b"\x00\x02\x00\x00\x00\x00\x05\x00\x00\x00\x00"

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))

def _buf_pos(buf, pos):
    ret = buf[pos]
    # In Python 2, buf is a str array so buf[pos] is a string. In Python 3, buf
    # is a bytes array and buf[pos] is an integer.
    if compat.PYTHON3:
        ret = bytes((ret,))
    return ret

class _bser_buffer(object):

    def __init__(self, version):
        self.bser_version = version
        self.buf = ctypes.create_string_buffer(8192)
        if self.bser_version == 1:
            struct.pack_into(tobytes(len(EMPTY_HEADER)) + b's', self.buf, 0,
                             EMPTY_HEADER)
            self.wpos = len(EMPTY_HEADER)
        else:
            assert self.bser_version == 2
            struct.pack_into(tobytes(len(EMPTY_HEADER_V2)) + b's', self.buf, 0,
                             EMPTY_HEADER_V2)
            self.wpos = len(EMPTY_HEADER_V2)

    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(b'=cb', self.buf, self.wpos, BSER_INT8, val)
        elif size == 2:
            struct.pack_into(b'=ch', self.buf, self.wpos, BSER_INT16, val)
        elif size == 4:
            struct.pack_into(b'=ci', self.buf, self.wpos, BSER_INT32, val)
        elif size == 8:
            struct.pack_into(b'=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(b'=ccb' + tobytes(s_len) + b's', self.buf,
                self.wpos, BSER_BYTESTRING, BSER_INT8, s_len, s)
        elif size == 2:
            struct.pack_into(b'=cch' + tobytes(s_len) + b's', self.buf,
                self.wpos, BSER_BYTESTRING, BSER_INT16, s_len, s)
        elif size == 4:
            struct.pack_into(b'=cci' + tobytes(s_len) + b's', self.buf,
                self.wpos, BSER_BYTESTRING, BSER_INT32, s_len, s)
        elif size == 8:
            struct.pack_into(b'=ccq' + tobytes(s_len) + b's', self.buf,
                self.wpos, BSER_BYTESTRING, 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(b'=c', self.buf, self.wpos, to_encode)
            self.wpos += needed
        elif val is None:
            needed = 1
            self.ensure_size(needed)
            struct.pack_into(b'=c', self.buf, self.wpos, BSER_NULL)
            self.wpos += needed
        elif isinstance(val, (int, long)):
            self.append_long(val)
        elif isinstance(val, STRING_TYPES):
            self.append_string(val)
        elif isinstance(val, float):
            needed = 9
            self.ensure_size(needed)
            struct.pack_into(b'=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(b'=ccb', self.buf, self.wpos, BSER_OBJECT,
                    BSER_INT8, val_len)
            elif size == 2:
                struct.pack_into(b'=cch', self.buf, self.wpos, BSER_OBJECT,
                    BSER_INT16, val_len)
            elif size == 4:
                struct.pack_into(b'=cci', self.buf, self.wpos, BSER_OBJECT,
                    BSER_INT32, val_len)
            elif size == 8:
                struct.pack_into(b'=ccq', self.buf, self.wpos, BSER_OBJECT,
                    BSER_INT64, val_len)
            else:
                raise RuntimeError('Cannot represent this mapping value')
            self.wpos += needed
            if compat.PYTHON3:
                iteritems = val.items()
            else:
                iteritems = val.iteritems()
            for k, v in 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(b'=ccb', self.buf, self.wpos, BSER_ARRAY,
                    BSER_INT8, val_len)
            elif size == 2:
                struct.pack_into(b'=cch', self.buf, self.wpos, BSER_ARRAY,
                    BSER_INT16, val_len)
            elif size == 4:
                struct.pack_into(b'=cci', self.buf, self.wpos, BSER_ARRAY,
                    BSER_INT32, val_len)
            elif size == 8:
                struct.pack_into(b'=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, version=1, capabilities=0):
    bser_buf = _bser_buffer(version=version)
    bser_buf.append_recursive(obj)
    # Now fill in the overall length
    if version == 1:
        obj_len = bser_buf.wpos - len(EMPTY_HEADER)
        struct.pack_into(b'=i', bser_buf.buf, 3, obj_len)
    else:
        obj_len = bser_buf.wpos - len(EMPTY_HEADER_V2)
        struct.pack_into(b'=i', bser_buf.buf, 2, capabilities)
        struct.pack_into(b'=i', bser_buf.buf, 7, obj_len)
    return bser_buf.buf.raw[:bser_buf.wpos]

# 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:
            raise KeyError('_BunserDict has no key %s' % key)

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

class Bunser(object):
    def __init__(self, mutable=True, value_encoding=None, value_errors=None):
        self.mutable = mutable
        self.value_encoding = value_encoding

        if value_encoding is None:
            self.value_errors = None
        elif value_errors is None:
            self.value_errors = 'strict'
        else:
            self.value_errors = value_errors

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

    def unser_utf8_string(self, buf, pos):
        str_len, pos = self.unser_int(buf, pos + 1)
        str_val = struct.unpack_from(tobytes(str_len) + b's', buf, pos)[0]
        return (str_val.decode('utf-8'), pos + str_len)

    def unser_bytestring(self, buf, pos):
        str_len, pos = self.unser_int(buf, pos + 1)
        str_val = struct.unpack_from(tobytes(str_len) + b's', buf, pos)[0]
        if self.value_encoding is not None:
            str_val = str_val.decode(self.value_encoding, self.value_errors)
            # str_len stays the same because that's the length in bytes
        return (str_val, pos + str_len)

    def unser_array(self, buf, pos):
        arr_len, pos = self.unser_int(buf, pos + 1)
        arr = []
        for i in range(arr_len):
            arr_item, pos = self.loads_recursive(buf, pos)
            arr.append(arr_item)

        if not self.mutable:
          arr = tuple(arr)

        return arr, pos

    def unser_object(self, buf, pos):
        obj_len, pos = self.unser_int(buf, pos + 1)
        if self.mutable:
            obj = {}
        else:
            keys = []
            vals = []

        for i in range(obj_len):
            key, pos = self.unser_utf8_string(buf, pos)
            val, pos = self.loads_recursive(buf, pos)
            if self.mutable:
                obj[key] = val
            else:
                keys.append(key)
                vals.append(val)

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

        return obj, pos

    def unser_template(self, buf, pos):
        val_type = _buf_pos(buf, pos + 1)
        if val_type != BSER_ARRAY:
            raise RuntimeError('Expect ARRAY to follow TEMPLATE')
        # force UTF-8 on keys
        keys_bunser = Bunser(mutable=self.mutable, value_encoding='utf-8')
        keys, pos = keys_bunser.unser_array(buf, pos + 1)
        nitems, pos = self.unser_int(buf, pos)
        arr = []
        for i in range(nitems):
            if self.mutable:
                obj = {}
            else:
                vals = []

            for keyidx in range(len(keys)):
                if _buf_pos(buf, pos) == BSER_SKIP:
                    pos += 1
                    ele = None
                else:
                    ele, pos = self.loads_recursive(buf, pos)

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

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

            arr.append(obj)
        return arr, pos

    def loads_recursive(self, buf, pos):
        val_type = _buf_pos(buf, pos)
        if (val_type == BSER_INT8 or val_type == BSER_INT16 or
            val_type == BSER_INT32 or val_type == BSER_INT64):
            return self.unser_int(buf, pos)
        elif val_type == BSER_REAL:
            val = struct.unpack_from(b'=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_BYTESTRING:
            return self.unser_bytestring(buf, pos)
        elif val_type == BSER_UTF8STRING:
            return self.unser_utf8_string(buf, pos)
        elif val_type == BSER_ARRAY:
            return self.unser_array(buf, pos)
        elif val_type == BSER_OBJECT:
            return self.unser_object(buf, pos)
        elif val_type == BSER_TEMPLATE:
            return self.unser_template(buf, pos)
        else:
            raise ValueError('unhandled bser opcode 0x%s' %
                             binascii.hexlify(val_type).decode('ascii'))


def _pdu_info_helper(buf):
    if buf[0:2] == EMPTY_HEADER[0:2]:
        bser_version = 1
        bser_capabilities = 0
        expected_len, pos2 = Bunser.unser_int(buf, 2)
    elif buf[0:2] == EMPTY_HEADER_V2[0:2]:
        if len(buf) < 8:
            raise ValueError('Invalid BSER header')
        bser_version = 2
        bser_capabilities = struct.unpack_from("I", buf, 2)[0]
        expected_len, pos2 = Bunser.unser_int(buf, 6)
    else:
        raise ValueError('Invalid BSER header')

    return bser_version, bser_capabilities, expected_len, pos2


def pdu_info(buf):
    info = _pdu_info_helper(buf)
    return info[0], info[1], info[2] + info[3]


def pdu_len(buf):
    info = _pdu_info_helper(buf)
    return info[2] + info[3]


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

    @param buf: The buffer to deserialize.
    @type buf: bytes

    @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
    """

    info = _pdu_info_helper(buf)
    expected_len = info[2]
    pos = info[3]

    if len(buf) != expected_len + pos:
        raise ValueError('bser data len != header len')

    bunser = Bunser(mutable=mutable, value_encoding=value_encoding,
                    value_errors=value_errors)

    return bunser.loads_recursive(buf, pos)[0]


def load(fp, mutable=True, value_encoding=None, value_errors=None):
    from . import load
    return load.load(fp, mutable, value_encoding, value_errors)