From: clubley@remove_me.eisner.decus.org-Earth.UFP
On 2025-08-12, Arne Vajhøj wrote:
> Code:
>
> #include
>
> #include
>
> my_bool demo_init(UDF_INIT *initid, UDF_ARGS *args, char *message)
> {
> if(args->arg_count == 2 && args->arg_type[0] == STRING_RESULT &&
> args->arg_type[1] == INT_RESULT)
Is it guaranteed that arg_type[] will always have at least elements ?
If not, that's dangerous unless the compiler you are using does
expression short-circuiting.
> {
> return 0;
> }
> else
> {
> strcpy(message, "demo function requires two arguments: one
> string and one integer");
> return 1;
YUCK!!! :-) Does MySQL provide a maximum error message size field or
constant that you can use with strncpy() instead ?
> }
> }
>
> long long demo(UDF_INIT *initid, UDF_ARGS *args, char *result, unsigned
> long *length, unsigned char *is_null, unsigned char *error)
> {
> const char *sv = args->args[0];
> long long iv = *((long long *)args->args[1]);
> return strlen(sv) + iv;
> }
>
> void demo_deinit(UDF_INIT *initid)
> {
> }
>
> Build:
>
> $ cc /include=mysql055_root:[include.mysql] /names=as_is demo.c
> $ link/share=demo_shr.exe demo + sys$input/opt
> mysql055_root:[lib.alpha]libclientlib/lib
> mysql055_root:[lib.alpha]libsql/lib
> mysql055_root:[lib.alpha]libmysys/lib
> mysql055_root:[lib.alpha]libdbug/lib
> mysql055_root:[lib.alpha]libstrings/lib
> mysql055_root:[lib.alpha]libvio/lib
> mysql055_root:[lib.alpha]libz/lib
> mysql055_root:[lib.alpha]ssl_libssl32/lib
> mysql055_root:[lib.alpha]ssl_libcrypto32/lib
> CASE_SENSITIVE=YES
> SYMBOL_VECTOR=(demo_init=PROCEDURE, -
> demo=PROCEDURE, -
> demo_deinit=PROCEDURE)
> $
>
> Install (DCL):
>
> $ copy/log demo_shr.exe mysql055_root:[plugin.alpha]*.*
> $ def/sys demo_shr
> "''f$parse("mysql055_root:[plugin.alpha]demo_shr.exe",,,,"NO_CONCEAL")'"
>
> Install (SQL):
>
> CREATE FUNCTION demo
> RETURNS INTEGER
> SONAME 'demo_shr';
>
> Demo:
>
> MariaDB [test]> select demo('ABC', 1);
> +----------------+
>| demo('ABC', 1) |
> +----------------+
>| 4 |
> +----------------+
> 1 row in set (0.01 sec)
>
> MariaDB [test]> select demo('ABCD', 1);
> +-----------------+
>| demo('ABCD', 1) |
> +-----------------+
>| 5 |
> +-----------------+
> 1 row in set (0.00 sec)
>
> MariaDB [test]> select demo('ABC', 2);
> +----------------+
>| demo('ABC', 2) |
> +----------------+
>| 5 |
> +----------------+
> 1 row in set (0.00 sec)
>
> MariaDB [test]> SELECT demo();
> ERROR 1123 (HY000): Can't initialize function 'demo'; demo function
> requires two arguments: one string and one integer
> MariaDB [test]> SELECT demo('ABC');
> ERROR 1123 (HY000): Can't initialize function 'demo'; demo function
> requires two arguments: one string and one integer
> MariaDB [test]> SELECT demo('ABC', 'DEF');
> ERROR 1123 (HY000): Can't initialize function 'demo'; demo function
> requires two arguments: one string and one integer
> MariaDB [test]> SELECT demo('ABC', 1, 1);
> ERROR 1123 (HY000): Can't initialize function 'demo'; demo function
> requires two arguments: one string and one integer
>
> Arne
>
--
Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP
Walking destinations on a map are further away than they appear.
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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