A fix for Bug#32007 select udf_function() doesn't return an error if error

during udf initialization. The bug is spotted while working on Bug 12713.

If a user-defined function was used in a SELECT statement, and an
error would occur during UDF initialization, this error would not terminate
execution of the SELECT, but rather would be converted to a warning.

The fix is to use a stack buffer to store the message from udf_init instead
of private my_error() buffer.


mysql-test/r/udf.result:
  Update the result to reflect the fix for Bug#32007 select udf_function() 
  doesn't return an error if error during udf initialization
mysql-test/t/udf.test:
  Update the test to reflect the fix for Bug #32007 select udf_function() 
  doesn't return an error if error during udf initialization
sql/item_func.cc:
  A fix for Bug#32007.
  
  net.last_error buffer was used to store the temporary message from udf_init.
  Then, when my_error() was called, net.last_error was not empty so 
  my_error() would conclude that there is already an error in the error stack, 
  and not "overwrite" it.
  However, thd->net.report_error was not set, so the the 
  SELECT was not aborted.
  
  The fix is to use a stack buffer instead of thd->net.last_error
  to store the message from udf_init. The message will end up in
  thd->net.last_error anyway after a call to my_error.

mysql-test/r/udf.result

@@ -11,7 +11,7 @@ RETURNS STRING SONAME "UDF_EXAMPLE_LIB";
 CREATE AGGREGATE FUNCTION avgcost
 RETURNS REAL SONAME "UDF_EXAMPLE_LIB";
 select myfunc_double();
-ERROR HY000: myfunc_double must have at least one argument
+ERROR HY000: Can't initialize function 'myfunc_double'; myfunc_double must have at least one argument
 select myfunc_double(1);
 myfunc_double(1)
 49.00
@@ -24,26 +24,26 @@ select myfunc_int();
 myfunc_int()
 0
 select lookup();
-ERROR HY000: Wrong arguments to lookup;  Use the source
+ERROR HY000: Can't initialize function 'lookup'; Wrong arguments to lookup;  Use the source
 select lookup("127.0.0.1");
 lookup("127.0.0.1")
 127.0.0.1
 select lookup(127,0,0,1);
-ERROR HY000: Wrong arguments to lookup;  Use the source
+ERROR HY000: Can't initialize function 'lookup'; Wrong arguments to lookup;  Use the source
 select lookup("localhost");
 lookup("localhost")
 127.0.0.1
 select reverse_lookup();
-ERROR HY000: Wrong number of arguments to reverse_lookup;  Use the source
+ERROR HY000: Can't initialize function 'reverse_lookup'; Wrong number of arguments to reverse_lookup;  Use the source
 select reverse_lookup("127.0.0.1");
 select reverse_lookup(127,0,0,1);
 select reverse_lookup("localhost");
 reverse_lookup("localhost")
 NULL
 select avgcost();
-ERROR HY000: wrong number of arguments: AVGCOST() requires two arguments
+ERROR HY000: Can't initialize function 'avgcost'; wrong number of arguments: AVGCOST() requires two arguments
 select avgcost(100,23.76);
-ERROR HY000: wrong argument type: AVGCOST() requires an INT and a REAL
+ERROR HY000: Can't initialize function 'avgcost'; wrong argument type: AVGCOST() requires an INT and a REAL
 create table t1(sum int, price float(24));
 insert into t1 values(100, 50.00), (100, 100.00);
 select avgcost(sum, price) from t1;

mysql-test/t/udf.test

@@ -35,20 +35,20 @@ eval CREATE FUNCTION reverse_lookup
 eval CREATE AGGREGATE FUNCTION avgcost
         RETURNS REAL SONAME "$UDF_EXAMPLE_LIB";
 
---error 0
+--error ER_CANT_INITIALIZE_UDF
 select myfunc_double();
 select myfunc_double(1);
 select myfunc_double(78654);
 --error 1305
 select myfunc_nonexist();
 select myfunc_int();
---error 0
+--error ER_CANT_INITIALIZE_UDF
 select lookup();
 select lookup("127.0.0.1");
---error 0
+--error ER_CANT_INITIALIZE_UDF
 select lookup(127,0,0,1);
 select lookup("localhost");
---error 0
+--error ER_CANT_INITIALIZE_UDF
 select reverse_lookup();
 
 # These two functions should return "localhost", but it's
@@ -59,9 +59,9 @@ select reverse_lookup(127,0,0,1);
 --enable_result_log
 
 select reverse_lookup("localhost");
---error 0
+--error ER_CANT_INITIALIZE_UDF
 select avgcost();
---error 0
+--error ER_CANT_INITIALIZE_UDF
 select avgcost(100,23.76);
 create table t1(sum int, price float(24));
 insert into t1 values(100, 50.00), (100, 100.00);

sql/item_func.cc

@@ -2897,6 +2897,7 @@ udf_handler::fix_fields(THD *thd, Item_result_field *func,
 
   if (u_d->func_init)
   {
+    char init_msg_buff[MYSQL_ERRMSG_SIZE];
     char *to=num_buffer;
     for (uint i=0; i < arg_count; i++)
     {
@@ -2949,10 +2950,10 @@ udf_handler::fix_fields(THD *thd, Item_result_field *func,
     }
     thd->net.last_error[0]=0;
     Udf_func_init init= u_d->func_init;
-    if ((error=(uchar) init(&initid, &f_args, thd->net.last_error)))
+    if ((error=(uchar) init(&initid, &f_args, init_msg_buff)))
     {
       my_error(ER_CANT_INITIALIZE_UDF, MYF(0),
-               u_d->name.str, thd->net.last_error);
+               u_d->name.str, init_msg_buff);
       free_udf(u_d);
       DBUG_RETURN(TRUE);
     }