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Commit4f74741

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Make int64_div_fast_to_numeric() more robust.
The prior coding of int64_div_fast_to_numeric() had a number of bugsthat would cause it to fail under different circumstances, such aswith log10val2 <= 0, or log10val2 a multiple of 4, or in the "slow"numeric path with log10val2 >= 10.None of those could be triggered by any of our current code, whichonly uses log10val2 = 3 or 6. However, they made it a hazard for anyfuture code that might use it. Also, since this is exported bynumeric.c, users writing their own C code might choose to use it.Therefore fix, and back-patch to v14, where it was introduced.Dean Rasheed, reviewed by Tom Lane.Discussion:https://postgr.es/m/CAEZATCW8gXgW0tgPxPgHDPhVX71%2BSWFRkhnXy%2BTfGDsKLepu2g%40mail.gmail.com
1 parente7c2e02 commit4f74741

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‎src/backend/utils/adt/numeric.c

Lines changed: 54 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -4151,58 +4151,86 @@ int64_to_numeric(int64 val)
41514151
}
41524152

41534153
/*
4154-
* Convert val1/(10**val2) to numeric. This is much faster than normal
4154+
* Convert val1/(10**log10val2) to numeric. This is much faster than normal
41554155
* numeric division.
41564156
*/
41574157
Numeric
41584158
int64_div_fast_to_numeric(int64val1,intlog10val2)
41594159
{
41604160
Numericres;
41614161
NumericVarresult;
4162-
int64saved_val1=val1;
4162+
intrscale;
41634163
intw;
41644164
intm;
41654165

4166+
init_var(&result);
4167+
4168+
/* result scale */
4169+
rscale=log10val2<0 ?0 :log10val2;
4170+
41664171
/* how much to decrease the weight by */
41674172
w=log10val2 /DEC_DIGITS;
4168-
/* how much is left */
4173+
/* how much is leftto divide by*/
41694174
m=log10val2 %DEC_DIGITS;
4175+
if (m<0)
4176+
{
4177+
m+=DEC_DIGITS;
4178+
w--;
4179+
}
41704180

41714181
/*
4172-
* If there is anything left, multiply the dividend by what's left, then
4173-
* shift the weight by one more.
4182+
* If there is anything left to divide by (10^m with 0 < m < DEC_DIGITS),
4183+
* multiply the dividend by 10^(DEC_DIGITS - m), and shift the weight by
4184+
* one more.
41744185
*/
41754186
if (m>0)
41764187
{
4177-
staticintpow10[]= {1,10,100,1000};
4188+
#ifDEC_DIGITS==4
4189+
staticconstintpow10[]= {1,10,100,1000};
4190+
#elifDEC_DIGITS==2
4191+
staticconstintpow10[]= {1,10};
4192+
#elifDEC_DIGITS==1
4193+
staticconstintpow10[]= {1};
4194+
#else
4195+
#error unsupported NBASE
4196+
#endif
4197+
int64factor=pow10[DEC_DIGITS-m];
4198+
int64new_val1;
41784199

41794200
StaticAssertStmt(lengthof(pow10)==DEC_DIGITS,"mismatch with DEC_DIGITS");
4180-
if (unlikely(pg_mul_s64_overflow(val1,pow10[DEC_DIGITS-m],&val1)))
4201+
4202+
if (unlikely(pg_mul_s64_overflow(val1,factor,&new_val1)))
41814203
{
4182-
/*
4183-
* If it doesn't fit, do the whole computation in numeric the slow
4184-
* way. Note that va1l may have been overwritten, so use
4185-
* saved_val1 instead.
4186-
*/
4187-
intval2=1;
4188-
4189-
for (inti=0;i<log10val2;i++)
4190-
val2 *=10;
4191-
res=numeric_div_opt_error(int64_to_numeric(saved_val1),int64_to_numeric(val2),NULL);
4192-
res=DatumGetNumeric(DirectFunctionCall2(numeric_round,
4193-
NumericGetDatum(res),
4194-
Int32GetDatum(log10val2)));
4195-
returnres;
4204+
#ifdefHAVE_INT128
4205+
/* do the multiplication using 128-bit integers */
4206+
int128tmp;
4207+
4208+
tmp= (int128)val1* (int128)factor;
4209+
4210+
int128_to_numericvar(tmp,&result);
4211+
#else
4212+
/* do the multiplication using numerics */
4213+
NumericVartmp;
4214+
4215+
init_var(&tmp);
4216+
4217+
int64_to_numericvar(val1,&result);
4218+
int64_to_numericvar(factor,&tmp);
4219+
mul_var(&result,&tmp,&result,0);
4220+
4221+
free_var(&tmp);
4222+
#endif
41964223
}
4224+
else
4225+
int64_to_numericvar(new_val1,&result);
4226+
41974227
w++;
41984228
}
4199-
4200-
init_var(&result);
4201-
4202-
int64_to_numericvar(val1,&result);
4229+
else
4230+
int64_to_numericvar(val1,&result);
42034231

42044232
result.weight-=w;
4205-
result.dscale+=w*DEC_DIGITS- (DEC_DIGITS-m);
4233+
result.dscale=rscale;
42064234

42074235
res=make_result(&result);
42084236

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