pgsql: Fix numeric_power() when the exponent is INT_MIN.

From: Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
To: pgsql-committers(at)lists(dot)postgresql(dot)org
Subject: pgsql: Fix numeric_power() when the exponent is INT_MIN.
Date: 2021-01-05 11:18:33
Message-ID: E1kwkMD-0007K2-IK@gemulon.postgresql.org
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Fix numeric_power() when the exponent is INT_MIN.

In power_var_int(), the computation of the number of significant
digits to use in the computation used log(Abs(exp)), which isn't safe
because Abs(exp) returns INT_MIN when exp is INT_MIN. Use fabs()
instead of Abs(), so that the exponent is cast to a double before the
absolute value is taken.

Back-patch to 9.6, where this was introduced (by 7d9a4737c2).

Discussion: https://postgr.es/m/CAEZATCVd6pMkz=BrZEgBKyqqJrt2xghr=fNc8+Z=5xC6cgWrWA@mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/bc43b7c2c06c32264efe79d0b86abd41236f1d5b

Modified Files
--------------
src/backend/utils/adt/numeric.c | 2 +-
src/test/regress/expected/numeric.out | 6 ++++++
src/test/regress/sql/numeric.sql | 1 +
3 files changed, 8 insertions(+), 1 deletion(-)

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