A fix and test cases for

Bug#4968 "Stored procedure crash if cursor opened on altered table"
Bug#19733 "Repeated alter, or repeated create/drop, fails"
Bug#19182 "CREATE TABLE bar (m INT) SELECT n FROM foo; doesn't work from 
stored procedure."
Bug#6895 "Prepared Statements: ALTER TABLE DROP COLUMN does nothing"
Bug#22060 "ALTER TABLE x AUTO_INCREMENT=y in SP crashes server"

Test cases for bugs 4968, 19733, 6895 will be added in 5.0.

Re-execution of CREATE DATABASE, CREATE TABLE and ALTER TABLE 
statements in stored routines or as prepared statements caused
incorrect results (and crashes in versions prior to 5.0.25).
In 5.1 the problem occured only for CREATE DATABASE, CREATE TABLE
SELECT and CREATE TABLE with INDEX/DATA DIRECTOY options).

The problem of bugs 4968, 19733, 19282 and 6895 was that functions
mysql_prepare_table, mysql_create_table and mysql_alter_table were not
re-execution friendly: during their operation they used to modify contents
of LEX (members create_info, alter_info, key_list, create_list),
thus making the LEX unusable for the next execution.
In particular, these functions removed processed columns and keys from
create_list, key_list and drop_list. Search the code in sql_table.cc 
for drop_it.remove() and similar patterns to find evidence.

The fix is to supply to these functions a usable copy of each of the
above structures at every re-execution of an SQL statement. 

To simplify memory management, LEX::key_list and LEX::create_list
were added to LEX::alter_info, a fresh copy of which is created for
every execution.

The problem of crashing bug 22060 stemmed from the fact that the above 
metnioned functions were not only modifying HA_CREATE_INFO structure in 
LEX, but also were changing it to point to areas in volatile memory of 
the execution memory root.
 
The patch solves this problem by creating and using an on-stack
copy of HA_CREATE_INFO (note that code in 5.1 already creates and
uses a copy of this structure in mysql_create_table()/alter_table(),
but this approach didn't work well for CREATE TABLE SELECT statement).


mysql-test/r/ps.result:
  Update test results (Bug#19182, Bug#22060)
mysql-test/t/ps.test:
  Add a test case for Bug#19182, Bug#22060 (4.1-only parts)
sql/mysql_priv.h:
  LEX::key_list and LEX::create_list were moved to LEX::alter_info.
  Update declarations to use LEX::alter_info instead of these two
  members.
sql/sql_class.h:
  Replace pair<columns, keys> with an instance of Alter_info in
  select_create constructor. We create a new copy of Alter_info
  each time we re-execute SELECT .. CREATE prepared statement.
sql/sql_insert.cc:
  Adjust to a new signature of create_table_from_items.
sql/sql_lex.cc:
  Implement Alter_info::Alter_info that would make a "deep" copy
  of all definition lists (keys, columns).
sql/sql_lex.h:
  Move key_list and create_list to class Alter_info. Implement
  Alter_info::Alter_info that can be used with PS and SP.
sql/sql_list.h:
  Implement a copy constructor of class List that makes a deep copy
  of all list nodes.
sql/sql_parse.cc:
  Adjust to new signatures of mysql_create_table, mysql_alter_table,
  select_create. Functions mysql_create_index and mysql_drop_index has
  become identical after initialization of alter_info was moved to the 
  parser, and were merged. Flag enable_slow_log was not updated for 
  SQLCOM_DROP_INDEX, which is a bug. Just like CREATE INDEX, DROP INDEX
  is currently done via complete table rebuild and is rightfully a slow
  administrative statement.
sql/sql_show.cc:
  Adjust mysqld_show_create_db to a new signature.
sql/sql_table.cc:
  Adjust mysql_alter_table, mysql_recreate_table, mysql_create_table,
  mysql_prepare_table to new signatures.
sql/sql_yacc.yy:
  LEX::key_list and LEX::create_list moved to class Alter_info

1 files changed, 62 insertions, 12 deletions

diff --git a/sql/sql_list.h b/sql/sql_list.h
index e799ecf3d6e..47379ab1ddf 100644
--- a/sql/sql_list.h
+++ b/sql/sql_list.h
@@ -66,21 +66,24 @@ public:
   pointer.
 */
 
-class list_node :public Sql_alloc
+
+/**
+  list_node - a node of a single-linked list.
+  @note We never call a destructor for instances of this class.
+*/
+
+struct list_node :public Sql_alloc
 {
-public:
   list_node *next;
   void *info;
   list_node(void *info_par,list_node *next_par)
     :next(next_par),info(info_par)
-    {}
+  {}
   list_node()					/* For end_of_list */
-    {
-      info=0;
-      next= this;
-    }
-  friend class base_list;
-  friend class base_list_iterator;
+  {
+    info= 0;
+    next= this;
+  }
 };
 
 
@@ -96,11 +99,56 @@ public:
 
   inline void empty() { elements=0; first= &end_of_list; last=&first;}
   inline base_list() { empty(); }
+  /**
+    This is a shallow copy constructor that implicitly passes the ownership
+    from the source list to the new instance. The old instance is not
+    updated, so both objects end up sharing the same nodes. If one of
+    the instances then adds or removes a node, the other becomes out of
+    sync ('last' pointer), while still operational. Some old code uses and
+    relies on this behaviour. This logic is quite tricky: please do not use
+    it in any new code.
+  */
   inline base_list(const base_list &tmp) :Sql_alloc()
   {
-    elements=tmp.elements;
-    first=tmp.first;
-    last=tmp.last;
+    elements= tmp.elements;
+    first= tmp.first;
+    last= elements ? tmp.last : &first;
+  }
+  /**
+    Construct a deep copy of the argument in memory root mem_root.
+    The elements themselves are copied by pointer.
+  */
+  inline base_list(const base_list &rhs, MEM_ROOT *mem_root)
+  {
+    if (rhs.elements)
+    {
+      /*
+        It's okay to allocate an array of nodes at once: we never
+        call a destructor for list_node objects anyway.
+      */
+      first= (list_node*) alloc_root(mem_root,
+                                     sizeof(list_node) * rhs.elements);
+      if (first)
+      {
+        elements= rhs.elements;
+        list_node *dst= first;
+        list_node *src= rhs.first;
+        for (; dst < first + elements - 1; dst++, src= src->next)
+        {
+          dst->info= src->info;
+          dst->next= dst + 1;
+        }
+        /* Copy the last node */
+        dst->info= src->info;
+        dst->next= &end_of_list;
+        /* Setup 'last' member */
+        last= &dst->next;
+        return;
+      }
+    }
+    elements= 0;
+    first= &end_of_list;
+    last= &first;
   }
   inline base_list(bool error) { }
   inline bool push_back(void *info)
@@ -327,6 +375,8 @@ template <class T> class List :public base_list
 public:
   inline List() :base_list() {}
   inline List(const List<T> &tmp) :base_list(tmp) {}
+  inline List(const List<T> &tmp, MEM_ROOT *mem_root) :
+    base_list(tmp, mem_root) {}
   inline bool push_back(T *a) { return base_list::push_back(a); }
   inline bool push_front(T *a) { return base_list::push_front(a); }
   inline T* head() {return (T*) base_list::head(); }