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from pypy.interpreter.error import OperationError
from pypy.interpreter.gateway import unwrap_spec
from rpython.rlib.rstring import StringBuilder
from pypy.module.binascii.interp_binascii import raise_Error
from pypy.module.binascii.interp_binascii import AsciiBufferUnwrapper
from rpython.rlib.rarithmetic import ovfcheck
# ____________________________________________________________
PAD = '='
table_a2b_base64 = [
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,
52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1,-1,-1,-1, # Note PAD->-1 here
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11,12,13,14,
15,16,17,18, 19,20,21,22, 23,24,25,-1, -1,-1,-1,-1,
-1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
]
def _transform(n):
if n == -1:
return '\xff'
else:
return chr(n)
table_a2b_base64 = ''.join(map(_transform, table_a2b_base64))
assert len(table_a2b_base64) == 256
@unwrap_spec(ascii=AsciiBufferUnwrapper, strict_mode=int)
def a2b_base64(space, ascii, strict_mode=0):
"Decode a line of base64 data."
res = StringBuilder((len(ascii) // 4) * 3) # maximum estimate
quad_pos = 0
leftchar = 0
leftbits = 0
last_char_was_a_pad = False
bin_used = 0
if strict_mode and len(ascii) > 0 and ascii[0] == '=':
raise_Error(space, "Leading padding not allowed")
i = 0
for c in ascii:
if c == PAD:
if quad_pos > 2 or (quad_pos == 2 and last_char_was_a_pad):
if strict_mode and i + 1 < len(ascii):
raise_Error(space, "Excess data after padding")
break # stop on 'xxx=' or on 'xx=='
last_char_was_a_pad = True
else:
n = ord(table_a2b_base64[ord(c)])
if n == 0xff:
if strict_mode:
raise_Error(space, "Only base64 data is allowed")
continue # ignore strange characters
if strict_mode and last_char_was_a_pad:
raise_Error(space, "Discontinuous padding not allowed")
#
# Shift it in on the low end, and see if there's
# a byte ready for output.
quad_pos = (quad_pos + 1) & 3
leftchar = (leftchar << 6) | n
leftbits += 6
#
if leftbits >= 8:
leftbits -= 8
res.append(chr(leftchar >> leftbits))
leftchar &= ((1 << leftbits) - 1)
bin_used += 1
#
last_char_was_a_pad = False
i += 1
else:
if leftbits != 0:
if leftbits == 6:
# There is exactly one extra valid, non-padding, base64 character.
# This is an invalid length, as there is no possible input that
# could encoded into such a base64 string.
msg = ("Invalid base64-encoded string: number of data "
"characters (%d) cannot be 1 more than a multiple of 4" %
((bin_used // 3) * 4 + 1))
raise_Error(space, msg)
raise_Error(space, "Incorrect padding")
return space.newbytes(res.build())
# ____________________________________________________________
table_b2a_base64 = (
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/")
@unwrap_spec(bin='bufferstr', newline=bool)
def b2a_base64(space, bin, __kwonly__, newline=True):
"Base64-code line of data."
newlength = (len(bin) + 2) // 3
try:
newlength = ovfcheck(newlength * 4)
except OverflowError:
raise OperationError(space.w_MemoryError, space.w_None)
newlength += 1
res = StringBuilder(newlength)
leftchar = 0
leftbits = 0
for c in bin:
# Shift into our buffer, and output any 6bits ready
leftchar = (leftchar << 8) | ord(c)
leftbits += 8
res.append(table_b2a_base64[(leftchar >> (leftbits-6)) & 0x3f])
leftbits -= 6
if leftbits >= 6:
res.append(table_b2a_base64[(leftchar >> (leftbits-6)) & 0x3f])
leftbits -= 6
#
if leftbits == 2:
res.append(table_b2a_base64[(leftchar & 3) << 4])
res.append(PAD)
res.append(PAD)
elif leftbits == 4:
res.append(table_b2a_base64[(leftchar & 0xf) << 2])
res.append(PAD)
if newline:
res.append('\n')
return space.newbytes(res.build())
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