Bug#22684 (BENCHMARK, ENCODE, DECODE and FORMAT are not real functions)

Before this change, the functions BENCHMARK, ENCODE, DECODE and FORMAT could
only accept a constant for some parameters.

After this change, this restriction has been removed. An implication is that
these functions can also be used in prepared statements.

The change consist of changing the following classes:
- Item_func_benchmark
- Item_func_encode
- Item_func_decode
- Item_func_format
to:
- only accept Item* in the constructor,
- and evaluate arguments during calls to val_xxx()
which fits the general design of all the other functions.

The 'TODO' items identified in item_create.cc during the work done for
Bug 21114 are addressed by this fix, as a natural consequence of aligning
the design.

In the 'func_str' test, a single very long test line involving an explain
extended select with many functions has been rewritten into multiple
separate tests, to improve maintainability.
The result of explain extended select decode(encode(...)) has changed,
since the encode and decode functions now print all their parameters.

1 files changed, 108 insertions, 1 deletions

diff --git a/mysql-test/t/func_str.test b/mysql-test/t/func_str.test
index 45415882ac7..d4620e6059b 100644
--- a/mysql-test/t/func_str.test
+++ b/mysql-test/t/func_str.test
@@ -460,7 +460,51 @@ drop table t7;
 
 select substring_index("1abcd;2abcd;3abcd;4abcd", ';', 2),substring_index("1abcd;2abcd;3abcd;4abcd", ';', -2);
 
-explain extended select md5('hello'), sha('abc'), sha1('abc'), soundex(''), 'mood' sounds like 'mud', aes_decrypt(aes_encrypt('abc','1'),'1'),concat('*',space(5),'*'), reverse('abc'), rpad('a',4,'1'), lpad('a',4,'1'),  concat_ws(',','',NULL,'a'),make_set(255,_latin2'a',_latin2'b',_latin2'c'),elt(2,1),locate("a","b",2),format(130,10),char(0),conv(130,16,10),hex(130),binary 'HE', export_set(255,_latin2'y',_latin2'n',_latin2' '),FIELD('b' COLLATE latin1_bin,'A','B'),FIND_IN_SET(_latin1'B',_latin1'a,b,c,d'),collation(conv(130,16,10)), coercibility(conv(130,16,10)),length('\n\t\r\b\0\_\%\\'),bit_length('\n\t\r\b\0\_\%\\'),bit_length('\n\t\r\b\0\_\%\\'),concat('monty',' was here ','again'),length('hello'),char(ascii('h')),ord('h'),quote(1/0),crc32("123"),replace('aaaa','a','b'),insert('txs',2,1,'hi'),left(_latin2'a',1),right(_latin2'a',1),lcase(_latin2'a'),ucase(_latin2'a'),SUBSTR('abcdefg',3,2),substring_index("1abcd;2abcd;3abcd;4abcd", ';', 2),trim(_latin2' a '),ltrim(_latin2' a '),rtrim(_latin2' a '), decode(encode(repeat("a",100000),"monty"),"monty");
+explain extended select md5('hello');
+explain extended select sha('abc');
+explain extended select sha1('abc');
+explain extended select soundex('');
+explain extended select 'mood' sounds like 'mud';
+explain extended select aes_decrypt(aes_encrypt('abc','1'),'1');
+explain extended select concat('*',space(5),'*');
+explain extended select reverse('abc');
+explain extended select rpad('a',4,'1');
+explain extended select lpad('a',4,'1');
+explain extended select concat_ws(',','',NULL,'a');
+explain extended select make_set(255,_latin2'a', _latin2'b', _latin2'c');
+explain extended select elt(2,1);
+explain extended select locate("a","b",2);
+explain extended select format(130,10);
+explain extended select char(0);
+explain extended select conv(130,16,10);
+explain extended select hex(130);
+explain extended select binary 'HE';
+explain extended select export_set(255,_latin2'y', _latin2'n', _latin2' ');
+explain extended select FIELD('b' COLLATE latin1_bin,'A','B');
+explain extended select FIND_IN_SET(_latin1'B', _latin1'a,b,c,d');
+explain extended select collation(conv(130,16,10));
+explain extended select coercibility(conv(130,16,10));
+explain extended select length('\n\t\r\b\0\_\%\\');
+explain extended select bit_length('\n\t\r\b\0\_\%\\');
+explain extended select bit_length('\n\t\r\b\0\_\%\\');
+explain extended select concat('monty',' was here ','again');
+explain extended select length('hello');
+explain extended select char(ascii('h'));
+explain extended select ord('h');
+explain extended select quote(1/0);
+explain extended select crc32("123");
+explain extended select replace('aaaa','a','b');
+explain extended select insert('txs',2,1,'hi');
+explain extended select left(_latin2'a',1);
+explain extended select right(_latin2'a',1);
+explain extended select lcase(_latin2'a');
+explain extended select ucase(_latin2'a');
+explain extended select SUBSTR('abcdefg',3,2);
+explain extended select substring_index("1abcd;2abcd;3abcd;4abcd", ';', 2);
+explain extended select trim(_latin2' a ');
+explain extended select ltrim(_latin2' a ');
+explain extended select rtrim(_latin2' a ');
+explain extended select decode(encode(repeat("a",100000),"monty"),"monty");
 
 #
 # lpad returns incorrect result (Bug #2182)
@@ -780,4 +824,67 @@ SELECT * FROM t1 INNER JOIN t2 ON code=id
 
 DROP TABLE t1,t2;
 
+#
+# Bug#22684: The Functions ENCODE, DECODE and FORMAT are not real functions
+#
+
+select encode(NULL, NULL);
+select encode("data", NULL);
+select encode(NULL, "password");
+
+select decode(NULL, NULL);
+select decode("data", NULL);
+select decode(NULL, "password");
+
+select format(NULL, NULL);
+select format(pi(), NULL);
+select format(NULL, 2);
+
+select benchmark(NULL, NULL);
+select benchmark(0, NULL);
+select benchmark(100, NULL);
+select benchmark(NULL, 1+1);
+
+#
+# Please note:
+# 1) The collation of the password is irrelevant, the encryption uses
+# the binary representation of the string without charset/collation.
+# 2) These tests can not print the encoded text directly, because it's binary,
+# and doing this would cause problems with source control.
+# Instead, an md5() checksum is used, to verify the result indirectly.
+# 3) Each md5() result must be identical.
+# 4) The md5() result must never change, and must be stable across releases.
+#
+set @password="password";
+set @my_data="clear text to encode";
+select md5(encode(@my_data, "password"));
+select md5(encode(@my_data, _utf8 "password"));
+select md5(encode(@my_data, binary "password"));
+select md5(encode(@my_data, _latin1 "password"));
+select md5(encode(@my_data, _koi8r "password"));
+select md5(encode(@my_data, (select "password" from dual)));
+select md5(encode(@my_data, concat("pass", "word")));
+select md5(encode(@my_data, @password));
+
+set @my_data="binary encoded data";
+select md5(decode(@my_data, "password"));
+select md5(decode(@my_data, _utf8 "password"));
+select md5(decode(@my_data, binary "password"));
+select md5(decode(@my_data, _latin1 "password"));
+select md5(decode(@my_data, _koi8r "password"));
+select md5(decode(@my_data, (select "password" from dual)));
+select md5(decode(@my_data, concat("pass", "word")));
+select md5(decode(@my_data, @password));
+
+set @dec=5;
+select format(pi(), (1+1));
+select format(pi(), (select 3 from dual));
+select format(pi(), @dec);
+
+set @bench_count=10;
+select benchmark(10, pi());
+select benchmark(5+5, pi());
+select benchmark((select 10 from dual), pi());
+select benchmark(@bench_count, pi());
+
 --echo End of 5.0 tests