Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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5.5(EOL), 10.0(EOL), 10.1(EOL), 10.2(EOL), 10.3(EOL), 10.4(EOL)
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None
Description
The code in str_to_time() in sql-common/my_time.c is not portable.
It can return different results on different architectures.
Platforms with sizeof(ulong)==4 (e.g. Linux 32bit, Windows)
SELECT TIME('42949672955959-01'), TIME('42949672965959-01'); |
+---------------------------+---------------------------+
|
| TIME('42949672955959-01') | TIME('42949672965959-01') |
|
+---------------------------+---------------------------+
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| 838:59:59 | 00:59:59 |
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+---------------------------+---------------------------+
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1 row in set, 2 warnings (0.001 sec)
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The result for the second column is wrong.
Platforms with sizeof(ulong)==8 (e.g. Linux 64bit)
SELECT TIME('42949672955959-01'), TIME('42949672965959-01'); |
+---------------------------+---------------------------+
|
| TIME('42949672955959-01') | TIME('42949672965959-01') |
|
+---------------------------+---------------------------+
|
| 838:59:59 | NULL |
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+---------------------------+---------------------------+
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1 row in set, 2 warnings (0.00 sec)
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The result for the second column is correct.
The underlying code description
else |
{
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/* String given as one number; assume HHMMSS format */ |
date[0]= 0;
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date[1]= (ulong) (value/10000); //This line is not portable |
date[2]= (ulong) (value/100 % 100);
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date[3]= (ulong) (value % 100);
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state=4;
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goto fractional; |
}
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The difference happens in the line assigning date[1]. For TIME('42949672965959-01'), "value" is 4294967296595.
Assigning (4294967296595/10000) to data[1]:
- makes 4294967296 on platforms with sizeof(ulong)=8
- overflows to 0 on platforms with sizeof(ulong)=4
On 64bit platforms a similar problem is repeatable with TIME('18446744073709551616-01')
SELECT TIME('18446744073709551615-01'), TIME('18446744073709551616-01'); |
+---------------------------------+---------------------------------+
|
| TIME('18446744073709551615-01') | TIME('18446744073709551616-01') |
|
+---------------------------------+---------------------------------+
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| NULL | 00:00:00 |
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+---------------------------------+---------------------------------+
|
Notice, the value for the second column is wrong. The expected value is NULL.
Attachments
Issue Links
- blocks
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MDEV-16991 Rounding vs truncation for TIME, DATETIME, TIMESTAMP
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- Closed
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