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| author | Sjoerd Job Postmus <sjoerdjob@sjec.nl> | 2019-04-13 12:11:34 +0200 |
|---|---|---|
| committer | Florian Apolloner <apollo13@users.noreply.github.com> | 2019-04-13 14:30:33 +0200 |
| commit | e6d57c4d652f16ac8f8d4600c0b7c30fcfcde6c2 (patch) | |
| tree | ac61918c13c66528ff42bf868bf43cf5e8b109c5 | |
| parent | ba726067604ce5a8ca3919edf653496722b433ab (diff) | |
Fixed #30363 -- Do not use exponential notation for small decimal numbers.
In 9cc6a60040b0f64f8ea066dd215176d4bd16621d a security patch was
introduced to prevent allocating large segments of memory when a
very large or very small decimal number was to be formatted.
As a side-effect, there was a change in formatting of small decimal
numbers even when the `decimal_pos` argument was provided, which meant
that reasonable small decimal numbers (above 1e-199) would be formatted
as `0.00`, while smaller decimal numbers (under 1e-200) would be
formatted as `1e-200`.
| -rw-r--r-- | django/utils/numberformat.py | 8 | ||||
| -rw-r--r-- | tests/utils_tests/test_numberformat.py | 2 |
2 files changed, 9 insertions, 1 deletions
diff --git a/django/utils/numberformat.py b/django/utils/numberformat.py index 88b35fc435..961a60e37d 100644 --- a/django/utils/numberformat.py +++ b/django/utils/numberformat.py @@ -27,6 +27,14 @@ def format(number, decimal_sep, decimal_pos=None, grouping=0, thousand_sep='', # sign sign = '' if isinstance(number, Decimal): + + if decimal_pos is not None: + # If the provided number is too small to affect any of the visible + # decimal places, consider it equal to '0'. + cutoff = Decimal('0.' + '1'.rjust(decimal_pos, '0')) + if abs(number) < cutoff: + number = Decimal('0') + # Format values with more than 200 digits (an arbitrary cutoff) using # scientific notation to avoid high memory usage in {:f}'.format(). _, digits, exponent = number.as_tuple() diff --git a/tests/utils_tests/test_numberformat.py b/tests/utils_tests/test_numberformat.py index 3d656025ab..1dac45e890 100644 --- a/tests/utils_tests/test_numberformat.py +++ b/tests/utils_tests/test_numberformat.py @@ -94,7 +94,7 @@ class TestNumberFormat(SimpleTestCase): ('1e-10', 8, '0.00000000'), ('1e-11', 8, '0.00000000'), ('1' + ('0' * 300), 3, '1.000e+300'), - ('0.{}1234'.format('0' * 299), 3, '1.234e-300'), + ('0.{}1234'.format('0' * 299), 3, '0.000'), ] for value, decimal_pos, expected_value in tests: with self.subTest(value=value): |