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[3.12] gh-118164: str(10**10000) hangs if the C _decimal module is missing (GH-118503) (GH-118584)

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Serhiy and I independently concluded that exact powers of 10
aren't possible in these contexts, so just checking the
string length is sufficient.

(cherry picked from commit 999f0c5122)

Co-authored-by: Tim Peters <tim.peters@gmail.com>
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
This commit is contained in:
Miss Islington (bot) 2024-05-05 08:34:43 +02:00 • committed by GitHub
parent 53e8bdd1e6
commit 0c605244a8
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3 changed files with 40 additions and 5 deletions
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19
Lib/_pydecimal.py
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@ -2131,10 +2131,16 @@ class Decimal(object):
else:
return None
if xc >= 10**p:
# An exact power of 10 is representable, but can convert to a
# string of any length. But an exact power of 10 shouldn't be
# possible at this point.
assert xc > 1, self
assert xc % 10 != 0, self
strxc = str(xc)
if len(strxc) > p:
return None
xe = -e-xe
return _dec_from_triple(0, str(xc), xe)
return _dec_from_triple(0, strxc, xe)
# now y is positive; find m and n such that y = m/n
if ye >= 0:
@ -2184,13 +2190,18 @@ class Decimal(object):
return None
xc = xc**m
xe *= m
if xc > 10**p:
# An exact power of 10 is representable, but can convert to a string
# of any length. But an exact power of 10 shouldn't be possible at
# this point.
assert xc > 1, self
assert xc % 10 != 0, self
str_xc = str(xc)
if len(str_xc) > p:
return None
# by this point the result *is* exactly representable
# adjust the exponent to get as close as possible to the ideal
# exponent, if necessary
str_xc = str(xc)
if other._isinteger() and other._sign == 0:
ideal_exponent = self._exp*int(other)
zeros = min(xe-ideal_exponent, p-len(str_xc))