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MDEV-23105 Cast number string with many leading zeros to decimal gives unexpected result

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Skip leading zeros when converting a string to decimal_t.
This commit is contained in:
Alexander Barkov
2020-08-05 08:14:49 +04:00
parent a09a06d597
commit 0e80f5a693
3 changed files with 84 additions and 0 deletions
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18
strings/decimal.c
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@ -812,6 +812,24 @@ internal_str2dec(const char *from, decimal_t *to, char **end, my_bool fixed)
while (s < end_of_string && my_isdigit(&my_charset_latin1, *s))
s++;
intg= (int) (s-s1);
/*
If the integer part is long enough and it has multiple leading zeros,
let's trim them, so this expression can return 1 without overflowing:
CAST(CONCAT(REPEAT('0',90),'1') AS DECIMAL(10))
*/
if (intg > DIG_PER_DEC1 && s1[0] == '0' && s1[1] == '0')
{
/*
Keep at least one digit, to avoid an empty string.
So we trim '0000' to '0' rather than to ''.
Otherwise the below code (converting digits to to->buf)
would fail on a fatal error.
*/
const char *iend= s - 1;
for ( ; s1 < iend && *s1 == '0'; s1++)
{ }
intg= (int) (s-s1);
}
if (s < end_of_string && *s=='.')
{
endp= s+1;