postgres.git / summary / log / commit / refs

commit    160a9e425f18b248c87130fec9f04b77dceb60a3
Author:   Dean Rasheed <dean.a.rasheed@gmail.com>
Date:     Tue Jan 05 11:05:58 2021 +0000
First released in: 14.0, 9.6.21, 10.16, 11.11, 12.6, 13.2

    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


 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(-)

diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index 6391407795d..67fbf20a9d2 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -8433,7 +8433,7 @@ 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.
diff --git a/src/test/regress/expected/numeric.out b/src/test/regress/expected/numeric.out
index 1cb3c3bfab7..7ea2c81afac 100644
--- a/src/test/regress/expected/numeric.out
+++ b/src/test/regress/expected/numeric.out
@@ -1623,6 +1623,12 @@ select 0.12 ^ (-20);
  2608405330458882702.5529619561355838
 (1 row)
 
+select 1.000000000123 ^ (-2147483648);
+      ?column?      
+--------------------
+ 0.7678656556403084
+(1 row)
+
 -- cases that used to error out
 select 0.12 ^ (-25);
                  ?column?                  
diff --git a/src/test/regress/sql/numeric.sql b/src/test/regress/sql/numeric.sql
index a9394123596..4b8a7ca53eb 100644
--- a/src/test/regress/sql/numeric.sql
+++ b/src/test/regress/sql/numeric.sql
@@ -896,6 +896,7 @@ select 3.789 ^ 21;
 select 3.789 ^ 35;
 select 1.2 ^ 345;
 select 0.12 ^ (-20);
+select 1.000000000123 ^ (-2147483648);
 
 -- cases that used to error out
 select 0.12 ^ (-25);


[parent: 50a420bee0c2]