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"""
This module implements siphash-2-4, the hashing algorithm for strings
and unicodes. You can use it explicitly by calling siphash24() with
a byte string, or you can use enable_siphash24() to enable the use
of siphash-2-4 on all RPython strings and unicodes in your program
after translation.
"""
import sys, os, errno
from contextlib import contextmanager
from rpython.rlib import rarithmetic, rurandom
from rpython.rlib.objectmodel import not_rpython, always_inline
from rpython.rlib.objectmodel import we_are_translated, dont_inline
from rpython.rlib.objectmodel import keepalive_until_here
from rpython.rlib.objectmodel import specialize
from rpython.rlib import rgc, jit, rposix
from rpython.rlib.rarithmetic import r_uint64, r_uint32, r_uint
from rpython.rlib.rawstorage import misaligned_is_fine
from rpython.rlib.nonconst import NonConstant
from rpython.rtyper.lltypesystem import lltype, llmemory, rffi, rstr
from rpython.rtyper.lltypesystem.lloperation import llop
from rpython.rtyper.extregistry import ExtRegistryEntry
from rpython.rtyper.annlowlevel import llhelper
if sys.byteorder == 'little':
def _le64toh(x):
return x
def _le32toh(x):
return x
BIG_ENDIAN = False
else:
_le64toh = rarithmetic.byteswap
_le32toh = rarithmetic.byteswap
BIG_ENDIAN = True
def _decode64(s):
return (r_uint64(ord(s[0])) |
r_uint64(ord(s[1])) << 8 |
r_uint64(ord(s[2])) << 16 |
r_uint64(ord(s[3])) << 24 |
r_uint64(ord(s[4])) << 32 |
r_uint64(ord(s[5])) << 40 |
r_uint64(ord(s[6])) << 48 |
r_uint64(ord(s[7])) << 56)
class Seed:
k0l = k1l = r_uint64(0)
seed = Seed()
def select_random_seed(s):
"""'s' is a string of length 16"""
seed.k0l = _decode64(s)
seed.k1l = _decode64(s[8:16])
_update_prebuilt_hashes()
strtoul = rffi.llexternal("strtoul", [rffi.CCHARP, rffi.CCHARPP, rffi.INT],
rffi.ULONG, save_err=rffi.RFFI_SAVE_ERRNO)
env_var_name = "PYTHONHASHSEED"
def initialize_from_env():
# This uses the same algorithms as CPython 3.5. The environment
# variable we read also defaults to "PYTHONHASHSEED". If needed,
# a different RPython interpreter can patch the value of the
# global variable 'env_var_name', or just patch the whole
# initialize_from_env() function.
value = os.environ.get(env_var_name)
if value and value != "random":
with rffi.scoped_view_charp(value) as ptr:
with lltype.scoped_alloc(rffi.CCHARPP.TO, 1) as endptr:
endptr[0] = ptr
seed = strtoul(ptr, endptr, 10)
full = endptr[0][0] == '\x00'
seed = lltype.cast_primitive(lltype.Unsigned, seed)
if not full or seed > r_uint(4294967295) or (
rposix.get_saved_errno() == errno.ERANGE and
seed == lltype.cast_primitive(lltype.Unsigned,
rffi.cast(rffi.ULONG, -1))):
os.write(2,
"%s must be \"random\" or an integer "
"in range [0; 4294967295]\n" % (env_var_name,))
os._exit(1)
if not seed:
# disable the randomized hash
s = '\x00' * 16
else:
s = lcg_urandom(seed)
else:
try:
s = rurandom.urandom(16)
except Exception as e:
os.write(2,
"%s: failed to get random numbers to initialize Python\n" %
(str(e),))
os._exit(1)
raise # makes the annotator happy
select_random_seed(s)
def lcg_urandom(x):
s = ''
for index in range(16):
x *= 214013
x += 2531011
s += chr((x >> 16) & 0xff)
return s
_FUNC = lltype.Ptr(lltype.FuncType([], lltype.Void))
def enable_siphash24():
"""
Enable the use of siphash-2-4 for all RPython strings and unicodes
in the translated program. You must call this function anywhere
from your interpreter (from a place that is annotated). Don't call
more than once.
"""
class Entry(ExtRegistryEntry):
_about_ = enable_siphash24
def compute_result_annotation(self):
translator = self.bookkeeper.annotator.translator
# you should not call enable_siphash24() when translating with the
# reverse-debugger, or with sandbox.
assert not translator.config.translation.reverse_debugger
assert not translator.config.translation.sandbox
#
if hasattr(translator, 'll_hash_string'):
assert translator.ll_hash_string == ll_hash_string_siphash24
else:
translator.ll_hash_string = ll_hash_string_siphash24
bk = self.bookkeeper
s_callable = bk.immutablevalue(initialize_from_env)
key = (enable_siphash24,)
bk.emulate_pbc_call(key, s_callable, [])
def specialize_call(self, hop):
hop.exception_cannot_occur()
translator = hop.rtyper.annotator.translator
if translator.config.translation.reverse_debugger:
return # ignore and use the regular hash, with reverse-debugger
bk = hop.rtyper.annotator.bookkeeper
s_callable = bk.immutablevalue(initialize_from_env)
r_callable = hop.rtyper.getrepr(s_callable)
ll_init = r_callable.get_unique_llfn().value
bk.annotator.translator._call_at_startup.append(ll_init)
@rgc.no_collect
def ll_hash_string_siphash24(ll_s):
"""Called indirectly from lltypesystem/rstr.py, by redirection from
objectmodel.ll_string_hash().
"""
from rpython.rlib.rarithmetic import intmask
# This function is entirely @rgc.no_collect.
length = len(ll_s.chars)
if lltype.typeOf(ll_s).TO.chars.OF == lltype.Char: # regular STR
addr = rstr._get_raw_buf_string(rstr.STR, ll_s, 0)
else:
# NOTE: a latin-1 unicode string must have the same hash as the
# corresponding byte string. If the unicode is all within
# 0-255, then we call _siphash24() with a special argument that
# will make it load only one byte for every unicode char.
# Note also that we give a
# different hash result than CPython on ucs4 platforms, for
# unicode strings where CPython uses 2 bytes per character.
addr = rstr._get_raw_buf_unicode(rstr.UNICODE, ll_s, 0)
SZ = rffi.sizeof(rstr.UNICODE.chars.OF)
i = 0
while i < length:
if ord(ll_s.chars[i]) > 0xFF:
length *= SZ
break
i += 1
else:
x = _siphash24(addr, length, SZ)
keepalive_until_here(ll_s)
return intmask(x)
x = _siphash24(addr, length)
keepalive_until_here(ll_s)
return intmask(x)
@contextmanager
def choosen_seed(new_k0, new_k1, test_misaligned_path=False,
test_prebuilt=False):
"""For tests."""
global misaligned_is_fine, seed
old = seed, misaligned_is_fine
seed = Seed()
seed.k0l = r_uint64(new_k0)
seed.k1l = r_uint64(new_k1)
if test_prebuilt:
_update_prebuilt_hashes()
else:
seed.bound_prebuilt_size = 0
if test_misaligned_path:
misaligned_is_fine = False
yield
seed, misaligned_is_fine = old
magic0 = r_uint64(0x736f6d6570736575)
magic1 = r_uint64(0x646f72616e646f6d)
magic2 = r_uint64(0x6c7967656e657261)
magic3 = r_uint64(0x7465646279746573)
@always_inline
def _rotate(x, b):
return (x << b) | (x >> (64 - b))
@always_inline
def _half_round(a, b, c, d, s, t):
a += b
c += d
b = _rotate(b, s) ^ a
d = _rotate(d, t) ^ c
a = _rotate(a, 32)
return a, b, c, d
@always_inline
def _double_round(v0, v1, v2, v3):
v0,v1,v2,v3 = _half_round(v0,v1,v2,v3,13,16)
v2,v1,v0,v3 = _half_round(v2,v1,v0,v3,17,21)
v0,v1,v2,v3 = _half_round(v0,v1,v2,v3,13,16)
v2,v1,v0,v3 = _half_round(v2,v1,v0,v3,17,21)
return v0, v1, v2, v3
@rgc.no_collect
@specialize.arg(2)
def _siphash24(addr_in, size, SZ=1):
"""Takes an address pointer and a size. Returns the hash as a r_uint64,
which can then be casted to the expected type."""
if size < seed.bound_prebuilt_size:
if size <= 0:
return seed.hash_empty
else:
if BIG_ENDIAN:
index = SZ - 1
else:
index = 0
t = rarithmetic.intmask(llop.raw_load(rffi.UCHAR, addr_in, index))
return seed.hash_single[t]
k0 = seed.k0l
k1 = seed.k1l
return _siphash24_with_key(addr_in, size, k0, k1, SZ)
@rgc.no_collect
@specialize.arg(4)
def _siphash24_with_key(addr_in, size, k0, k1, SZ=1):
if BIG_ENDIAN:
index = SZ - 1
else:
index = 0
b = r_uint64(size) << 56
v0 = k0 ^ magic0
v1 = k1 ^ magic1
v2 = k0 ^ magic2
v3 = k1 ^ magic3
direct = (SZ == 1) and (misaligned_is_fine or
(rffi.cast(lltype.Signed, addr_in) & 7) == 0)
if direct:
assert SZ == 1
while size >= 8:
mi = llop.raw_load(rffi.ULONGLONG, addr_in, index)
mi = _le64toh(mi)
size -= 8
index += 8
v3 ^= mi
v0, v1, v2, v3 = _double_round(v0, v1, v2, v3)
v0 ^= mi
else:
while size >= 8:
mi = (
r_uint64(llop.raw_load(rffi.UCHAR, addr_in, index)) |
r_uint64(llop.raw_load(rffi.UCHAR, addr_in, index + 1*SZ)) << 8 |
r_uint64(llop.raw_load(rffi.UCHAR, addr_in, index + 2*SZ)) << 16 |
r_uint64(llop.raw_load(rffi.UCHAR, addr_in, index + 3*SZ)) << 24 |
r_uint64(llop.raw_load(rffi.UCHAR, addr_in, index + 4*SZ)) << 32 |
r_uint64(llop.raw_load(rffi.UCHAR, addr_in, index + 5*SZ)) << 40 |
r_uint64(llop.raw_load(rffi.UCHAR, addr_in, index + 6*SZ)) << 48 |
r_uint64(llop.raw_load(rffi.UCHAR, addr_in, index + 7*SZ)) << 56
)
size -= 8
index += 8*SZ
v3 ^= mi
v0, v1, v2, v3 = _double_round(v0, v1, v2, v3)
v0 ^= mi
t = r_uint64(0)
if size == 7:
t = r_uint64(llop.raw_load(rffi.UCHAR, addr_in, index + 6*SZ)) << 48
size = 6
if size == 6:
t |= r_uint64(llop.raw_load(rffi.UCHAR, addr_in, index + 5*SZ)) << 40
size = 5
if size == 5:
t |= r_uint64(llop.raw_load(rffi.UCHAR, addr_in, index + 4*SZ)) << 32
size = 4
if size == 4:
if direct:
v = _le32toh(r_uint32(llop.raw_load(rffi.UINT, addr_in, index)))
t |= r_uint64(v)
size = 0
else:
t |= r_uint64(llop.raw_load(rffi.UCHAR, addr_in, index + 3*SZ))<< 24
size = 3
if size == 3:
t |= r_uint64(llop.raw_load(rffi.UCHAR, addr_in, index + 2*SZ)) << 16
size = 2
if size == 2:
t |= r_uint64(llop.raw_load(rffi.UCHAR, addr_in, index + 1*SZ)) << 8
size = 1
if size == 1:
t |= r_uint64(llop.raw_load(rffi.UCHAR, addr_in, index))
size = 0
assert size == 0
b |= t
v3 ^= b
v0, v1, v2, v3 = _double_round(v0, v1, v2, v3)
v0 ^= b
v2 ^= 0xff
v0, v1, v2, v3 = _double_round(v0, v1, v2, v3)
v0, v1, v2, v3 = _double_round(v0, v1, v2, v3)
return (v0 ^ v1) ^ (v2 ^ v3)
@jit.dont_look_inside
def siphash24(s):
"""'s' is a normal string. Returns its siphash-2-4 as a r_uint64.
Don't forget to cast the result to a regular integer if needed,
e.g. with rarithmetic.intmask().
"""
with rffi.scoped_nonmovingbuffer(s) as p:
return _siphash24(llmemory.cast_ptr_to_adr(p), len(s))
@jit.dont_look_inside
def siphash24_with_key(s, k0, k1=0):
"""'s' is a normal string. k0 and k1 are the seed keys
"""
with rffi.scoped_nonmovingbuffer(s) as p:
return _siphash24_with_key(llmemory.cast_ptr_to_adr(p), len(s), k0, k1)
# Prebuilt hashes are precomputed here
def _update_prebuilt_hashes():
seed.bound_prebuilt_size = 0
with lltype.scoped_alloc(rffi.CCHARP.TO, 1) as p:
addr = llmemory.cast_ptr_to_adr(p)
seed.hash_single = [r_uint64(0)] * 256
for i in range(256):
p[0] = chr(i)
seed.hash_single[i] = _siphash24(addr, 1)
seed.hash_empty = _siphash24(addr, 0)
seed.bound_prebuilt_size = 2
_update_prebuilt_hashes()
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