• unknown's avatar
    A fix and test cases for · cd8c9ef0
    unknown authored
    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
    cd8c9ef0
sql_list.h 13.6 KB
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/* Copyright (C) 2000-2003 MySQL AB

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */


#ifdef USE_PRAGMA_INTERFACE
#pragma interface			/* gcc class implementation */
#endif

/* mysql standard class memory allocator */

#ifdef SAFEMALLOC
#define TRASH(XX,YY) bfill((XX), (YY), 0x8F)
#else
#define TRASH(XX,YY) /* no-op */
#endif

class Sql_alloc
{
public:
  static void *operator new(size_t size)
  {
    return (void*) sql_alloc((uint) size);
  }
  static void *operator new[](size_t size)
  {
    return (void*) sql_alloc((uint) size);
  }
  static void *operator new(size_t size, MEM_ROOT *mem_root)
  { return (void*) alloc_root(mem_root, (uint) size); }
  static void operator delete(void *ptr, size_t size) { TRASH(ptr, size); }
  static void operator delete(void *ptr, MEM_ROOT *mem_root)
  { /* never called */ }
  static void operator delete[](void *ptr, size_t size) { TRASH(ptr, size); }
#ifdef HAVE_purify
  bool dummy;
  inline Sql_alloc() :dummy(0) {}
  inline ~Sql_alloc() {}
#else
  inline Sql_alloc() {}
  inline ~Sql_alloc() {}
#endif

};


/*
  Basic single linked list
  Used for item and item_buffs.
  All list ends with a pointer to the 'end_of_list' element, which
  data pointer is a null pointer and the next pointer points to itself.
  This makes it very fast to traverse lists as we don't have to
  test for a specialend condition for list that can't contain a null
  pointer.
*/


/**
  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
{
  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;
  }
};


extern list_node end_of_list;

class base_list :public Sql_alloc
{
protected:
  list_node *first,**last;

public:
  uint elements;

  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= 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)
  {
    if (((*last)=new list_node(info, &end_of_list)))
    {
      last= &(*last)->next;
      elements++;
      return 0;
    }
    return 1;
  }
  inline bool push_front(void *info)
  {
    list_node *node=new list_node(info,first);
    if (node)
    {
      if (last == &first)
	last= &node->next;
      first=node;
      elements++;
      return 0;
    }
    return 1;
  }
  void remove(list_node **prev)
  {
    list_node *node=(*prev)->next;
    if (&(*prev)->next == last)
    {
      /*
        We're removing the last element from the list. Adjust "last" to point
        to the previous element.
        The other way to fix this would be to change this function to
        remove_next() and have base_list_iterator save ptr to previous node
        (one extra assignment in iterator++) but as the remove() of the last
        element isn't a common operation it's faster to just walk through the
        list from the beginning here.
      */
      list_node *cur= first;
      if (cur == *prev)
      {
        last= &first;
      }
      else
      {
        while (cur->next != *prev)
          cur= cur->next;
        last= &(cur->next);
      }
    }
    delete *prev;
    *prev=node;
    elements--;
  }
  inline void concat(base_list *list)
  {
    if (!list->is_empty())
    {
      *last= list->first;
      last= list->last;
      elements+= list->elements;
    }
  }
  inline void *pop(void)
  {
    if (first == &end_of_list) return 0;
    list_node *tmp=first;
    first=first->next;
    if (!--elements)
      last= &first;
    return tmp->info;
  }
  inline list_node* last_node() { return *last; }
  inline list_node* first_node() { return first;}
  inline void *head() { return first->info; }
  inline void **head_ref() { return first != &end_of_list ? &first->info : 0; }
  inline bool is_empty() { return first == &end_of_list ; }
  inline list_node *last_ref() { return &end_of_list; }
  friend class base_list_iterator;
  friend class error_list;
  friend class error_list_iterator;

#ifdef LIST_EXTRA_DEBUG
  /*
    Check list invariants and print results into trace. Invariants are:
      - (*last) points to end_of_list
      - There are no NULLs in the list.
      - base_list::elements is the number of elements in the list.

    SYNOPSIS
      check_list()
        name  Name to print to trace file

    RETURN 
      1  The list is Ok.
      0  List invariants are not met.
  */

  bool check_list(const char *name)
  {
    base_list *list= this;
    list_node *node= first;
    uint cnt= 0;

    while (node->next != &end_of_list)
    {
      if (!node->info)
      {
        DBUG_PRINT("list_invariants",("%s: error: NULL element in the list", 
                                      name));
        return FALSE;
      }
      node= node->next;
      cnt++;
    }
    if (last != &(node->next))
    {
      DBUG_PRINT("list_invariants", ("%s: error: wrong last pointer", name));
      return FALSE;
    }
    if (cnt+1 != elements)
    {
      DBUG_PRINT("list_invariants", ("%s: error: wrong element count", name));
      return FALSE;
    }
    DBUG_PRINT("list_invariants", ("%s: list is ok", name));
    return TRUE;
  }
#endif // LIST_EXTRA_DEBUG

protected:
  void after(void *info,list_node *node)
  {
    list_node *new_node=new list_node(info,node->next);
    node->next=new_node;
    elements++;
    if (last == &(node->next))
      last= &new_node->next;
  }
};


class base_list_iterator
{
protected:
  base_list *list;
  list_node **el,**prev,*current;
  void sublist(base_list &ls, uint elm)
  {
    ls.first= *el;
    ls.last= list->last;
    ls.elements= elm;
  }
public:
  base_list_iterator(base_list &list_par) 
    :list(&list_par), el(&list_par.first), prev(0), current(0)
  {}

  inline void *next(void)
  {
    prev=el;
    current= *el;
    el= &current->next;
    return current->info;
  }
  inline void *next_fast(void)
  {
    list_node *tmp;
    tmp= *el;
    el= &tmp->next;
    return tmp->info;
  }
  inline void rewind(void)
  {
    el= &list->first;
  }
  inline void *replace(void *element)
  {						// Return old element
    void *tmp=current->info;
    DBUG_ASSERT(current->info != 0);
    current->info=element;
    return tmp;
  }
  void *replace(base_list &new_list)
  {
    void *ret_value=current->info;
    if (!new_list.is_empty())
    {
      *new_list.last=current->next;
      current->info=new_list.first->info;
      current->next=new_list.first->next;
      if ((list->last == &current->next) && (new_list.elements > 1))
	list->last= new_list.last;
      list->elements+=new_list.elements-1;
    }
    return ret_value;				// return old element
  }
  inline void remove(void)			// Remove current
  {
    list->remove(prev);
    el=prev;
    current=0;					// Safeguard
  }
  void after(void *element)			// Insert element after current
  {
    list->after(element,current);
    current=current->next;
    el= &current->next;
  }
  inline void **ref(void)			// Get reference pointer
  {
    return &current->info;
  }
  inline bool is_last(void)
  {
    return el == &list->last_ref()->next;
  }
  friend class error_list_iterator;
};

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(); }
  inline T** head_ref() {return (T**) base_list::head_ref(); }
  inline T* pop()  {return (T*) base_list::pop(); }
  void delete_elements(void)
  {
    list_node *element,*next;
    for (element=first; element != &end_of_list; element=next)
    {
      next=element->next;
      delete (T*) element->info;
    }
    empty();
  }
};


template <class T> class List_iterator :public base_list_iterator
{
public:
  List_iterator(List<T> &a) : base_list_iterator(a) {}
  inline T* operator++(int) { return (T*) base_list_iterator::next(); }
  inline T *replace(T *a)   { return (T*) base_list_iterator::replace(a); }
  inline T *replace(List<T> &a) { return (T*) base_list_iterator::replace(a); }
  inline void after(T *a)   { base_list_iterator::after(a); }
  inline T** ref(void)	    { return (T**) base_list_iterator::ref(); }
};


template <class T> class List_iterator_fast :public base_list_iterator
{
protected:
  inline T *replace(T *a)   { return (T*) 0; }
  inline T *replace(List<T> &a) { return (T*) 0; }
  inline void remove(void)  { }
  inline void after(T *a)   { }
  inline T** ref(void)	    { return (T**) 0; }

public:
  inline List_iterator_fast(List<T> &a) : base_list_iterator(a) {}
  inline T* operator++(int) { return (T*) base_list_iterator::next_fast(); }
  inline void rewind(void)  { base_list_iterator::rewind(); }
  void sublist(List<T> &list_arg, uint el_arg)
  {
    base_list_iterator::sublist(list_arg, el_arg);
  }
};


/*
  A simple intrusive list which automaticly removes element from list
  on delete (for THD element)
*/

struct ilink
{
  struct ilink **prev,*next;
  static void *operator new(size_t size)
  {
    return (void*)my_malloc((uint)size, MYF(MY_WME | MY_FAE));
  }
  static void operator delete(void* ptr_arg, size_t size)
  {
     my_free((gptr)ptr_arg, MYF(MY_WME|MY_ALLOW_ZERO_PTR));
  }

  inline ilink()
  {
    prev=0; next=0;
  }
  inline void unlink()
  {
    /* Extra tests because element doesn't have to be linked */
    if (prev) *prev= next;
    if (next) next->prev=prev;
    prev=0 ; next=0;
  }
  virtual ~ilink() { unlink(); }		/*lint -e1740 */
};


template <class T> class I_List_iterator;

class base_ilist
{
  public:
  struct ilink *first,last;
  inline void empty() { first= &last; last.prev= &first; }
  base_ilist() { empty(); }
  inline bool is_empty() {  return first == &last; }
  inline void append(ilink *a)
  {
    first->prev= &a->next;
    a->next=first; a->prev= &first; first=a;
  }
  inline void push_back(ilink *a)
  {
    *last.prev= a;
    a->next= &last;
    a->prev= last.prev;
    last.prev= &a->next;
  }
  inline struct ilink *get()
  {
    struct ilink *first_link=first;
    if (first_link == &last)
      return 0;
    first_link->unlink();			// Unlink from list
    return first_link;
  }
  inline struct ilink *head()
  {
    return (first != &last) ? first : 0;
  }
  friend class base_list_iterator;
};


class base_ilist_iterator
{
  base_ilist *list;
  struct ilink **el,*current;
public:
  base_ilist_iterator(base_ilist &list_par) :list(&list_par),
    el(&list_par.first),current(0) {}
  void *next(void)
  {
    /* This is coded to allow push_back() while iterating */
    current= *el;
    if (current == &list->last) return 0;
    el= &current->next;
    return current;
  }
};


template <class T>
class I_List :private base_ilist
{
public:
  I_List() :base_ilist()	{}
  inline void empty()		{ base_ilist::empty(); }
  inline bool is_empty()        { return base_ilist::is_empty(); } 
  inline void append(T* a)	{ base_ilist::append(a); }
  inline void push_back(T* a)	{ base_ilist::push_back(a); }
  inline T* get()		{ return (T*) base_ilist::get(); }
  inline T* head()		{ return (T*) base_ilist::head(); }
#ifndef _lint
  friend class I_List_iterator<T>;
#endif
};


template <class T> class I_List_iterator :public base_ilist_iterator
{
public:
  I_List_iterator(I_List<T> &a) : base_ilist_iterator(a) {}
  inline T* operator++(int) { return (T*) base_ilist_iterator::next(); }
};