~drizzle-trunk/drizzle/development

/* Copyright (C) 2000 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; version 2 of the License.

   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 */

/* This implements 'user defined functions' */

/*

   Known bugs:

   Memory for functions is never freed!

   Shared libraries are not closed before mysqld exits;

     - This is because we can't be sure if some threads are using

       a function.

   The bugs only affect applications that create and free a lot of

   dynamic functions, so this shouldn't be a real problem.

*/

#ifdef USE_PRAGMA_IMPLEMENTATION

#pragma implementation				// gcc: Class implementation

#endif

#include "mysql_priv.h"

#include <my_pthread.h>

#ifdef HAVE_DLOPEN

extern "C"

{

#include <stdarg.h>

#include <hash.h>

}

static bool initialized = 0;

static MEM_ROOT mem;

static HASH udf_hash;

static rw_lock_t THR_LOCK_udf;

static udf_func *add_udf(LEX_STRING *name, Item_result ret,

                         char *dl, Item_udftype typ);

static void del_udf(udf_func *udf);

static void *find_udf_dl(const char *dl);

static char *init_syms(udf_func *tmp, char *nm)

{

  char *end;

  if (!((tmp->func= (Udf_func_any) dlsym(tmp->dlhandle, tmp->name.str))))

    return tmp->name.str;

  end=strmov(nm,tmp->name.str);

  if (tmp->type == UDFTYPE_AGGREGATE)

  {

    (void)strmov(end, "_clear");

    if (!((tmp->func_clear= (Udf_func_clear) dlsym(tmp->dlhandle, nm))))

      return nm;

    (void)strmov(end, "_add");

    if (!((tmp->func_add= (Udf_func_add) dlsym(tmp->dlhandle, nm))))

      return nm;

  }

  (void) strmov(end,"_deinit");

  tmp->func_deinit= (Udf_func_deinit) dlsym(tmp->dlhandle, nm);

  (void) strmov(end,"_init");

  tmp->func_init= (Udf_func_init) dlsym(tmp->dlhandle, nm);

  /*

    to prefent loading "udf" from, e.g. libc.so

    let's ensure that at least one auxiliary symbol is defined

  */

  if (!tmp->func_init && !tmp->func_deinit && tmp->type != UDFTYPE_AGGREGATE)

    return nm;

  return 0;

}

extern "C" uchar* get_hash_key(const uchar *buff, size_t *length,

			      my_bool not_used __attribute__((unused)))

{

  udf_func *udf=(udf_func*) buff;

  *length=(uint) udf->name.length;

  return (uchar*) udf->name.str;

}

/*

  Read all predeclared functions from mysql.func and accept all that

  can be used.

*/

void udf_init()

{

  TABLE_LIST tables;

  if (initialized)

    return;

  my_rwlock_init(&THR_LOCK_udf,NULL);

  init_sql_alloc(&mem, UDF_ALLOC_BLOCK_SIZE, 0);

  THD *new_thd = new THD;

  if (!new_thd ||

      hash_init(&udf_hash,system_charset_info,32,0,0,get_hash_key, NULL, 0))

  {

    sql_print_error("Can't allocate memory for udf structures");

    hash_free(&udf_hash);

    free_root(&mem,MYF(0));

    delete new_thd;

    return;

  }

  initialized = 1;

  close_thread_tables(new_thd);

  delete new_thd;

  /* Remember that we don't have a THD */

  my_pthread_setspecific_ptr(THR_THD,  0);

  return;

}

void udf_free()

{

  /* close all shared libraries */

  for (uint idx=0 ; idx < udf_hash.records ; idx++)

  {

    udf_func *udf=(udf_func*) hash_element(&udf_hash,idx);

    if (udf->dlhandle)				// Not closed before

    {

      /* Mark all versions using the same handler as closed */

      for (uint j=idx+1 ;  j < udf_hash.records ; j++)

      {

	udf_func *tmp=(udf_func*) hash_element(&udf_hash,j);

	if (udf->dlhandle == tmp->dlhandle)

	  tmp->dlhandle=0;			// Already closed

      }

      dlclose(udf->dlhandle);

    }

  }

  hash_free(&udf_hash);

  free_root(&mem,MYF(0));

  if (initialized)

  {

    initialized= 0;

    rwlock_destroy(&THR_LOCK_udf);

  }

  return;

}

static void del_udf(udf_func *udf)

{

  if (!--udf->usage_count)

  {

    hash_delete(&udf_hash,(uchar*) udf);

    using_udf_functions=udf_hash.records != 0;

  }

  else

  {

    /*

      The functions is in use ; Rename the functions instead of removing it.

      The functions will be automaticly removed when the least threads

      doesn't use it anymore

    */

    char *name= udf->name.str;

    uint name_length=udf->name.length;

    udf->name.str=(char*) "*";

    udf->name.length=1;

    hash_update(&udf_hash,(uchar*) udf,(uchar*) name,name_length);

  }

  return;

}

void free_udf(udf_func *udf)

{

  if (!initialized)

    return;

  rw_wrlock(&THR_LOCK_udf);

  if (!--udf->usage_count)

  {

    /*

      We come here when someone has deleted the udf function

      while another thread still was using the udf

    */

    hash_delete(&udf_hash,(uchar*) udf);

    using_udf_functions=udf_hash.records != 0;

    if (!find_udf_dl(udf->dl))

      dlclose(udf->dlhandle);

  }

  rw_unlock(&THR_LOCK_udf);

  return;

}

/* This is only called if using_udf_functions != 0 */

udf_func *find_udf(const char *name,uint length,bool mark_used)

{

  udf_func *udf=0;

  if (!initialized)

    return(NULL);

  /* TODO: This should be changed to reader locks someday! */

  if (mark_used)

    rw_wrlock(&THR_LOCK_udf);  /* Called during fix_fields */

  else

    rw_rdlock(&THR_LOCK_udf);  /* Called during parsing */

  if ((udf=(udf_func*) hash_search(&udf_hash,(uchar*) name,

				   length ? length : (uint) strlen(name))))

  {

    if (!udf->dlhandle)

      udf=0;					// Could not be opened

    else if (mark_used)

      udf->usage_count++;

  }

  rw_unlock(&THR_LOCK_udf);

  return(udf);

}

static void *find_udf_dl(const char *dl)

{

  /*

    Because only the function name is hashed, we have to search trough

    all rows to find the dl.

  */

  for (uint idx=0 ; idx < udf_hash.records ; idx++)

  {

    udf_func *udf=(udf_func*) hash_element(&udf_hash,idx);

    if (!strcmp(dl, udf->dl) && udf->dlhandle != NULL)

      return(udf->dlhandle);

  }

  return(0);

}

/* Assume that name && dl is already allocated */

static udf_func *add_udf(LEX_STRING *name, Item_result ret, char *dl,

			 Item_udftype type)

{

  if (!name || !dl || !(uint) type || (uint) type > (uint) UDFTYPE_AGGREGATE)

    return 0;

  udf_func *tmp= (udf_func*) alloc_root(&mem, sizeof(udf_func));

  if (!tmp)

    return 0;

  bzero((char*) tmp,sizeof(*tmp));

  tmp->name = *name; //dup !!

  tmp->dl = dl;

  tmp->returns = ret;

  tmp->type = type;

  tmp->usage_count=1;

  if (my_hash_insert(&udf_hash,(uchar*)  tmp))

    return 0;

  using_udf_functions=1;

  return tmp;

}

/**

  Create a user defined function. 

  @note Like implementations of other DDL/DML in MySQL, this function

  relies on the caller to close the thread tables. This is done in the

  end of dispatch_command().

*/

int mysql_create_function(THD *thd,udf_func *udf)

{

  int error;

  void *dl=0;

  bool new_dl=0;

  TABLE *table;

  TABLE_LIST tables;

  udf_func *u_d;

  if (!initialized)

  {

    if (opt_noacl)

      my_error(ER_CANT_INITIALIZE_UDF, MYF(0),

               udf->name.str,

               "UDFs are unavailable with the --skip-grant-tables option");

    else

      my_message(ER_OUT_OF_RESOURCES, ER(ER_OUT_OF_RESOURCES), MYF(0));

    return(1);

  }

  /*

    Ensure that the .dll doesn't have a path

    This is done to ensure that only approved dll from the system

    directories are used (to make this even remotely secure).

    On windows we must check both FN_LIBCHAR and '/'.

  */

  if (my_strchr(files_charset_info, udf->dl,

                udf->dl + strlen(udf->dl), FN_LIBCHAR) ||

      IF_WIN(my_strchr(files_charset_info, udf->dl,

                       udf->dl + strlen(udf->dl), '/'), 0))

  {

    my_message(ER_UDF_NO_PATHS, ER(ER_UDF_NO_PATHS), MYF(0));

    return(1);

  }

  if (check_identifier_name(&udf->name, ER_TOO_LONG_IDENT))

    return(1);

  /* 

    Turn off row binlogging of this statement and use statement-based 

    so that all supporting tables are updated for CREATE FUNCTION command.

  */

  if (thd->current_stmt_binlog_row_based)

    thd->clear_current_stmt_binlog_row_based();

  rw_wrlock(&THR_LOCK_udf);

  if ((hash_search(&udf_hash,(uchar*) udf->name.str, udf->name.length)))

  {

    my_error(ER_UDF_EXISTS, MYF(0), udf->name.str);

    goto err;

  }

  if (!(dl = find_udf_dl(udf->dl)))

  {

    char dlpath[FN_REFLEN];

    strxnmov(dlpath, sizeof(dlpath) - 1, opt_plugin_dir, "/", udf->dl, NullS);

    if (!(dl = dlopen(dlpath, RTLD_NOW)))

    {

      my_error(ER_CANT_OPEN_LIBRARY, MYF(0),

               udf->dl, errno, dlerror());

      goto err;

    }

    new_dl=1;

  }

  udf->dlhandle=dl;

  {

    char buf[NAME_LEN+16], *missing;

    if ((missing= init_syms(udf, buf)))

    {

      my_error(ER_CANT_FIND_DL_ENTRY, MYF(0), missing);

      goto err;

    }

  }

  udf->name.str=strdup_root(&mem,udf->name.str);

  udf->dl=strdup_root(&mem,udf->dl);

  if (!(u_d=add_udf(&udf->name,udf->returns,udf->dl,udf->type)))

    goto err;

  u_d->dlhandle = dl;

  u_d->func=udf->func;

  u_d->func_init=udf->func_init;

  u_d->func_deinit=udf->func_deinit;

  u_d->func_clear=udf->func_clear;

  u_d->func_add=udf->func_add;

  /* create entry in mysql.func table */

  bzero((char*) &tables,sizeof(tables));

  tables.db= (char*) "mysql";

  tables.table_name= tables.alias= (char*) "func";

  /* Allow creation of functions even if we can't open func table */

  if (!(table = open_ltable(thd, &tables, TL_WRITE, 0)))

    goto err;

  table->use_all_columns();

  restore_record(table, s->default_values);	// Default values for fields

  table->field[0]->store(u_d->name.str, u_d->name.length, system_charset_info);

  table->field[1]->store((longlong) u_d->returns, TRUE);

  table->field[2]->store(u_d->dl,(uint) strlen(u_d->dl), system_charset_info);

  if (table->s->fields >= 4)			// If not old func format

    table->field[3]->store((longlong) u_d->type, TRUE);

  error = table->file->ha_write_row(table->record[0]);

  if (error)

  {

    my_error(ER_ERROR_ON_WRITE, MYF(0), "mysql.func", error);

    del_udf(u_d);

    goto err;

  }

  rw_unlock(&THR_LOCK_udf);

  /* Binlog the create function. */

  write_bin_log(thd, TRUE, thd->query, thd->query_length);

  return(0);

 err:

  if (new_dl)

    dlclose(dl);

  rw_unlock(&THR_LOCK_udf);

  return(1);

}

int mysql_drop_function(THD *thd,const LEX_STRING *udf_name)

{

  TABLE *table;

  TABLE_LIST tables;

  udf_func *udf;

  char *exact_name_str;

  uint exact_name_len;

  if (!initialized)

  {

    if (opt_noacl)

      my_error(ER_FUNCTION_NOT_DEFINED, MYF(0), udf_name->str);

    else

      my_message(ER_OUT_OF_RESOURCES, ER(ER_OUT_OF_RESOURCES), MYF(0));

    return(1);

  }

  /* 

    Turn off row binlogging of this statement and use statement-based

    so that all supporting tables are updated for DROP FUNCTION command.

  */

  if (thd->current_stmt_binlog_row_based)

    thd->clear_current_stmt_binlog_row_based();

  rw_wrlock(&THR_LOCK_udf);  

  if (!(udf=(udf_func*) hash_search(&udf_hash,(uchar*) udf_name->str,

				    (uint) udf_name->length)))

  {

    my_error(ER_FUNCTION_NOT_DEFINED, MYF(0), udf_name->str);

    goto err;

  }

  exact_name_str= udf->name.str;

  exact_name_len= udf->name.length;

  del_udf(udf);

  /*

    Close the handle if this was function that was found during boot or

    CREATE FUNCTION and it's not in use by any other udf function

  */

  if (udf->dlhandle && !find_udf_dl(udf->dl))

    dlclose(udf->dlhandle);

  bzero((char*) &tables,sizeof(tables));

  tables.db=(char*) "mysql";

  tables.table_name= tables.alias= (char*) "func";

  if (!(table = open_ltable(thd, &tables, TL_WRITE, 0)))

    goto err;

  table->use_all_columns();

  table->field[0]->store(exact_name_str, exact_name_len, &my_charset_bin);

  if (!table->file->index_read_idx_map(table->record[0], 0,

                                       (uchar*) table->field[0]->ptr,

                                       HA_WHOLE_KEY,

                                       HA_READ_KEY_EXACT))

  {

    int error;

    if ((error = table->file->ha_delete_row(table->record[0])))

      table->file->print_error(error, MYF(0));

  }

  close_thread_tables(thd);

  rw_unlock(&THR_LOCK_udf);

  /* Binlog the drop function. */

  write_bin_log(thd, TRUE, thd->query, thd->query_length);

  return(0);

 err:

  rw_unlock(&THR_LOCK_udf);

  return(1);

}

#endif /* HAVE_DLOPEN */