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Fix numeric_power() when the exponent is INT_MIN.

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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
This commit is contained in:
Dean Rasheed
2021-01-05 11:15:28 +00:00
parent 5a3574d7b3
commit bc43b7c2c0
3 changed files with 8 additions and 1 deletions
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2
src/backend/utils/adt/numeric.c
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@ -10290,7 +10290,7 @@ power_var_int(const NumericVar *base, int exp, NumericVar *result, int rscale)
* to around log10(abs(exp)) digits, so work with this many extra digits
* of precision (plus a few more for good measure).
*/
sig_digits += (int) log(Abs(exp)) + 8;
sig_digits += (int) log(fabs(exp)) + 8;
/*
* Now we can proceed with the multiplications.