mariadb/sql/protocol.cc
monty@mysql.com 74cc73d461 This changeset is largely a handler cleanup changeset (WL#3281), but includes fixes and cleanups that was found necessary while testing the handler changes
Changes that requires code changes in other code of other storage engines.
(Note that all changes are very straightforward and one should find all issues
by compiling a --debug build and fixing all compiler errors and all
asserts in field.cc while running the test suite),

- New optional handler function introduced: reset()
  This is called after every DML statement to make it easy for a handler to
  statement specific cleanups.
  (The only case it's not called is if force the file to be closed)

- handler::extra(HA_EXTRA_RESET) is removed. Code that was there before
  should be moved to handler::reset()

- table->read_set contains a bitmap over all columns that are needed
  in the query.  read_row() and similar functions only needs to read these
  columns
- table->write_set contains a bitmap over all columns that will be updated
  in the query. write_row() and update_row() only needs to update these
  columns.
  The above bitmaps should now be up to date in all context
  (including ALTER TABLE, filesort()).

  The handler is informed of any changes to the bitmap after
  fix_fields() by calling the virtual function
  handler::column_bitmaps_signal(). If the handler does caching of
  these bitmaps (instead of using table->read_set, table->write_set),
  it should redo the caching in this code. as the signal() may be sent
  several times, it's probably best to set a variable in the signal
  and redo the caching on read_row() / write_row() if the variable was
  set.

- Removed the read_set and write_set bitmap objects from the handler class

- Removed all column bit handling functions from the handler class.
  (Now one instead uses the normal bitmap functions in my_bitmap.c instead
  of handler dedicated bitmap functions)

- field->query_id is removed. One should instead instead check
  table->read_set and table->write_set if a field is used in the query.

- handler::extra(HA_EXTRA_RETRIVE_ALL_COLS) and
  handler::extra(HA_EXTRA_RETRIEVE_PRIMARY_KEY) are removed. One should now
  instead use table->read_set to check for which columns to retrieve.

- If a handler needs to call Field->val() or Field->store() on columns
  that are not used in the query, one should install a temporary
  all-columns-used map while doing so. For this, we provide the following
  functions:

  my_bitmap_map *old_map= dbug_tmp_use_all_columns(table, table->read_set);
  field->val();
  dbug_tmp_restore_column_map(table->read_set, old_map);

  and similar for the write map:

  my_bitmap_map *old_map= dbug_tmp_use_all_columns(table, table->write_set);
  field->val();
  dbug_tmp_restore_column_map(table->write_set, old_map);

  If this is not done, you will sooner or later hit a DBUG_ASSERT
  in the field store() / val() functions.
  (For not DBUG binaries, the dbug_tmp_restore_column_map() and
  dbug_tmp_restore_column_map() are inline dummy functions and should
  be optimized away be the compiler).

- If one needs to temporary set the column map for all binaries (and not
  just to avoid the DBUG_ASSERT() in the Field::store() / Field::val()
  methods) one should use the functions tmp_use_all_columns() and
  tmp_restore_column_map() instead of the above dbug_ variants.

- All 'status' fields in the handler base class (like records,
  data_file_length etc) are now stored in a 'stats' struct. This makes
  it easier to know what status variables are provided by the base
  handler.  This requires some trivial variable names in the extra()
  function.

- New virtual function handler::records().  This is called to optimize
  COUNT(*) if (handler::table_flags() & HA_HAS_RECORDS()) is true.
  (stats.records is not supposed to be an exact value. It's only has to
  be 'reasonable enough' for the optimizer to be able to choose a good
  optimization path).

- Non virtual handler::init() function added for caching of virtual
  constants from engine.

- Removed has_transactions() virtual method. Now one should instead return
  HA_NO_TRANSACTIONS in table_flags() if the table handler DOES NOT support
  transactions.

- The 'xxxx_create_handler()' function now has a MEM_ROOT_root argument
  that is to be used with 'new handler_name()' to allocate the handler
  in the right area.  The xxxx_create_handler() function is also
  responsible for any initialization of the object before returning.

  For example, one should change:

  static handler *myisam_create_handler(TABLE_SHARE *table)
  {
    return new ha_myisam(table);
  }

  ->

  static handler *myisam_create_handler(TABLE_SHARE *table, MEM_ROOT *mem_root)
  {
    return new (mem_root) ha_myisam(table);
  }

- New optional virtual function: use_hidden_primary_key().
  This is called in case of an update/delete when
  (table_flags() and HA_PRIMARY_KEY_REQUIRED_FOR_DELETE) is defined
  but we don't have a primary key. This allows the handler to take precisions
  in remembering any hidden primary key to able to update/delete any
  found row. The default handler marks all columns to be read.

- handler::table_flags() now returns a ulonglong (to allow for more flags).

- New/changed table_flags()
  - HA_HAS_RECORDS	    Set if ::records() is supported
  - HA_NO_TRANSACTIONS	    Set if engine doesn't support transactions
  - HA_PRIMARY_KEY_REQUIRED_FOR_DELETE
                            Set if we should mark all primary key columns for
			    read when reading rows as part of a DELETE
			    statement. If there is no primary key,
			    all columns are marked for read.
  - HA_PARTIAL_COLUMN_READ  Set if engine will not read all columns in some
			    cases (based on table->read_set)
 - HA_PRIMARY_KEY_ALLOW_RANDOM_ACCESS
   			    Renamed to HA_PRIMARY_KEY_REQUIRED_FOR_POSITION.
 - HA_DUPP_POS              Renamed to HA_DUPLICATE_POS
 - HA_REQUIRES_KEY_COLUMNS_FOR_DELETE
			    Set this if we should mark ALL key columns for
			    read when when reading rows as part of a DELETE
			    statement. In case of an update we will mark
			    all keys for read for which key part changed
			    value.
  - HA_STATS_RECORDS_IS_EXACT
			     Set this if stats.records is exact.
			     (This saves us some extra records() calls
			     when optimizing COUNT(*))
			    

- Removed table_flags()
  - HA_NOT_EXACT_COUNT     Now one should instead use HA_HAS_RECORDS if
			   handler::records() gives an exact count() and
			   HA_STATS_RECORDS_IS_EXACT if stats.records is exact.
  - HA_READ_RND_SAME	   Removed (no one supported this one)

- Removed not needed functions ha_retrieve_all_cols() and ha_retrieve_all_pk()

- Renamed handler::dupp_pos to handler::dup_pos

- Removed not used variable handler::sortkey


Upper level handler changes:

- ha_reset() now does some overall checks and calls ::reset()
- ha_table_flags() added. This is a cached version of table_flags(). The
  cache is updated on engine creation time and updated on open.


MySQL level changes (not obvious from the above):

- DBUG_ASSERT() added to check that column usage matches what is set
  in the column usage bit maps. (This found a LOT of bugs in current
  column marking code).

- In 5.1 before, all used columns was marked in read_set and only updated
  columns was marked in write_set. Now we only mark columns for which we
  need a value in read_set.

- Column bitmaps are created in open_binary_frm() and open_table_from_share().
  (Before this was in table.cc)

- handler::table_flags() calls are replaced with handler::ha_table_flags()

- For calling field->val() you must have the corresponding bit set in
  table->read_set. For calling field->store() you must have the
  corresponding bit set in table->write_set. (There are asserts in
  all store()/val() functions to catch wrong usage)

- thd->set_query_id is renamed to thd->mark_used_columns and instead
  of setting this to an integer value, this has now the values:
  MARK_COLUMNS_NONE, MARK_COLUMNS_READ, MARK_COLUMNS_WRITE
  Changed also all variables named 'set_query_id' to mark_used_columns.

- In filesort() we now inform the handler of exactly which columns are needed
  doing the sort and choosing the rows.

- The TABLE_SHARE object has a 'all_set' column bitmap one can use
  when one needs a column bitmap with all columns set.
  (This is used for table->use_all_columns() and other places)

- The TABLE object has 3 column bitmaps:
  - def_read_set     Default bitmap for columns to be read
  - def_write_set    Default bitmap for columns to be written
  - tmp_set          Can be used as a temporary bitmap when needed.
  The table object has also two pointer to bitmaps read_set and write_set
  that the handler should use to find out which columns are used in which way.

- count() optimization now calls handler::records() instead of using
  handler->stats.records (if (table_flags() & HA_HAS_RECORDS) is true).

- Added extra argument to Item::walk() to indicate if we should also
  traverse sub queries.

- Added TABLE parameter to cp_buffer_from_ref()

- Don't close tables created with CREATE ... SELECT but keep them in
  the table cache. (Faster usage of newly created tables).


New interfaces:

- table->clear_column_bitmaps() to initialize the bitmaps for tables
  at start of new statements.

- table->column_bitmaps_set() to set up new column bitmaps and signal
  the handler about this.

- table->column_bitmaps_set_no_signal() for some few cases where we need
  to setup new column bitmaps but don't signal the handler (as the handler
  has already been signaled about these before). Used for the momement
  only in opt_range.cc when doing ROR scans.

- table->use_all_columns() to install a bitmap where all columns are marked
  as use in the read and the write set.

- table->default_column_bitmaps() to install the normal read and write
  column bitmaps, but not signaling the handler about this.
  This is mainly used when creating TABLE instances.

- table->mark_columns_needed_for_delete(),
  table->mark_columns_needed_for_delete() and
  table->mark_columns_needed_for_insert() to allow us to put additional
  columns in column usage maps if handler so requires.
  (The handler indicates what it neads in handler->table_flags())

- table->prepare_for_position() to allow us to tell handler that it
  needs to read primary key parts to be able to store them in
  future table->position() calls.
  (This replaces the table->file->ha_retrieve_all_pk function)

- table->mark_auto_increment_column() to tell handler are going to update
  columns part of any auto_increment key.

- table->mark_columns_used_by_index() to mark all columns that is part of
  an index.  It will also send extra(HA_EXTRA_KEYREAD) to handler to allow
  it to quickly know that it only needs to read colums that are part
  of the key.  (The handler can also use the column map for detecting this,
  but simpler/faster handler can just monitor the extra() call).

- table->mark_columns_used_by_index_no_reset() to in addition to other columns,
  also mark all columns that is used by the given key.

- table->restore_column_maps_after_mark_index() to restore to default
  column maps after a call to table->mark_columns_used_by_index().

- New item function register_field_in_read_map(), for marking used columns
  in table->read_map. Used by filesort() to mark all used columns

- Maintain in TABLE->merge_keys set of all keys that are used in query.
  (Simplices some optimization loops)

- Maintain Field->part_of_key_not_clustered which is like Field->part_of_key
  but the field in the clustered key is not assumed to be part of all index.
  (used in opt_range.cc for faster loops)

-  dbug_tmp_use_all_columns(), dbug_tmp_restore_column_map()
   tmp_use_all_columns() and tmp_restore_column_map() functions to temporally
   mark all columns as usable.  The 'dbug_' version is primarily intended
   inside a handler when it wants to just call Field:store() & Field::val()
   functions, but don't need the column maps set for any other usage.
   (ie:: bitmap_is_set() is never called)

- We can't use compare_records() to skip updates for handlers that returns
  a partial column set and the read_set doesn't cover all columns in the
  write set. The reason for this is that if we have a column marked only for
  write we can't in the MySQL level know if the value changed or not.
  The reason this worked before was that MySQL marked all to be written
  columns as also to be read. The new 'optimal' bitmaps exposed this 'hidden
  bug'.

- open_table_from_share() does not anymore setup temporary MEM_ROOT
  object as a thread specific variable for the handler. Instead we
  send the to-be-used MEMROOT to get_new_handler().
  (Simpler, faster code)



Bugs fixed:

- Column marking was not done correctly in a lot of cases.
  (ALTER TABLE, when using triggers, auto_increment fields etc)
  (Could potentially result in wrong values inserted in table handlers
  relying on that the old column maps or field->set_query_id was correct)
  Especially when it comes to triggers, there may be cases where the
  old code would cause lost/wrong values for NDB and/or InnoDB tables.

- Split thd->options flag OPTION_STATUS_NO_TRANS_UPDATE to two flags:
  OPTION_STATUS_NO_TRANS_UPDATE and OPTION_KEEP_LOG.
  This allowed me to remove some wrong warnings about:
  "Some non-transactional changed tables couldn't be rolled back"

- Fixed handling of INSERT .. SELECT and CREATE ... SELECT that wrongly reset
  (thd->options & OPTION_STATUS_NO_TRANS_UPDATE) which caused us to loose
  some warnings about
  "Some non-transactional changed tables couldn't be rolled back")

- Fixed use of uninitialized memory in ha_ndbcluster.cc::delete_table()
  which could cause delete_table to report random failures.

- Fixed core dumps for some tests when running with --debug

- Added missing FN_LIBCHAR in mysql_rm_tmp_tables()
  (This has probably caused us to not properly remove temporary files after
  crash)

- slow_logs was not properly initialized, which could maybe cause
  extra/lost entries in slow log.

- If we get an duplicate row on insert, change column map to read and
  write all columns while retrying the operation. This is required by
  the definition of REPLACE and also ensures that fields that are only
  part of UPDATE are properly handled.  This fixed a bug in NDB and
  REPLACE where REPLACE wrongly copied some column values from the replaced
  row.

- For table handler that doesn't support NULL in keys, we would give an error
  when creating a primary key with NULL fields, even after the fields has been
  automaticly converted to NOT NULL.

- Creating a primary key on a SPATIAL key, would fail if field was not
  declared as NOT NULL.


Cleanups:

- Removed not used condition argument to setup_tables

- Removed not needed item function reset_query_id_processor().

- Field->add_index is removed. Now this is instead maintained in
  (field->flags & FIELD_IN_ADD_INDEX)

- Field->fieldnr is removed (use field->field_index instead)

- New argument to filesort() to indicate that it should return a set of
  row pointers (not used columns). This allowed me to remove some references
  to sql_command in filesort and should also enable us to return column
  results in some cases where we couldn't before.

- Changed column bitmap handling in opt_range.cc to be aligned with TABLE
  bitmap, which allowed me to use bitmap functions instead of looping over
  all fields to create some needed bitmaps. (Faster and smaller code)

- Broke up found too long lines

- Moved some variable declaration at start of function for better code
  readability.

- Removed some not used arguments from functions.
  (setup_fields(), mysql_prepare_insert_check_table())

- setup_fields() now takes an enum instead of an int for marking columns
   usage.

- For internal temporary tables, use handler::write_row(),
  handler::delete_row() and handler::update_row() instead of
  handler::ha_xxxx() for faster execution.

- Changed some constants to enum's and define's.

- Using separate column read and write sets allows for easier checking
  of timestamp field was set by statement.

- Remove calls to free_io_cache() as this is now done automaticly in ha_reset()

- Don't build table->normalized_path as this is now identical to table->path
  (after bar's fixes to convert filenames)

- Fixed some missed DBUG_PRINT(.."%lx") to use "0x%lx" to make it easier to
  do comparision with the 'convert-dbug-for-diff' tool.


Things left to do in 5.1:

- We wrongly log failed CREATE TABLE ... SELECT in some cases when using
  row based logging (as shown by testcase binlog_row_mix_innodb_myisam.result)
  Mats has promised to look into this.

- Test that my fix for CREATE TABLE ... SELECT is indeed correct.
  (I added several test cases for this, but in this case it's better that
  someone else also tests this throughly).
  Lars has promosed to do this.
2006-06-04 18:52:22 +03:00

1226 lines
32 KiB
C++

/* 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 */
/*
Low level functions for storing data to be send to the MySQL client
The actual communction is handled by the net_xxx functions in net_serv.cc
*/
#ifdef USE_PRAGMA_IMPLEMENTATION
#pragma implementation // gcc: Class implementation
#endif
#include "mysql_priv.h"
#include "sp_rcontext.h"
#include <stdarg.h>
static const unsigned int PACKET_BUFFER_EXTRA_ALLOC= 1024;
static void write_eof_packet(THD *thd, NET *net);
void net_send_error_packet(THD *thd, uint sql_errno, const char *err);
#ifndef EMBEDDED_LIBRARY
bool Protocol::net_store_data(const char *from, uint length)
#else
bool Protocol_prep::net_store_data(const char *from, uint length)
#endif
{
ulong packet_length=packet->length();
/*
The +9 comes from that strings of length longer than 16M require
9 bytes to be stored (see net_store_length).
*/
if (packet_length+9+length > packet->alloced_length() &&
packet->realloc(packet_length+9+length))
return 1;
char *to=(char*) net_store_length((char*) packet->ptr()+packet_length,
(ulonglong) length);
memcpy(to,from,length);
packet->length((uint) (to+length-packet->ptr()));
return 0;
}
/* Send a error string to client */
void net_send_error(THD *thd, uint sql_errno, const char *err)
{
NET *net= &thd->net;
bool generate_warning= thd->killed != THD::KILL_CONNECTION;
DBUG_ENTER("net_send_error");
DBUG_PRINT("enter",("sql_errno: %d err: %s", sql_errno,
err ? err : net->last_error[0] ?
net->last_error : "NULL"));
if (net && net->no_send_error)
{
thd->clear_error();
DBUG_PRINT("info", ("sending error messages prohibited"));
DBUG_VOID_RETURN;
}
if (thd->spcont && thd->spcont->find_handler(sql_errno,
MYSQL_ERROR::WARN_LEVEL_ERROR))
{
if (! thd->spcont->found_handler_here())
thd->net.report_error= 1; /* Make "select" abort correctly */
DBUG_VOID_RETURN;
}
thd->query_error= 1; // needed to catch query errors during replication
if (!err)
{
if (sql_errno)
err=ER(sql_errno);
else
{
if ((err=net->last_error)[0])
{
sql_errno=net->last_errno;
generate_warning= 0; // This warning has already been given
}
else
{
sql_errno=ER_UNKNOWN_ERROR;
err=ER(sql_errno); /* purecov: inspected */
}
}
}
if (generate_warning)
{
/* Error that we have not got with my_error() */
push_warning(thd, MYSQL_ERROR::WARN_LEVEL_ERROR, sql_errno, err);
}
net_send_error_packet(thd, sql_errno, err);
thd->is_fatal_error=0; // Error message is given
thd->net.report_error= 0;
/* Abort multi-result sets */
thd->server_status&= ~SERVER_MORE_RESULTS_EXISTS;
DBUG_VOID_RETURN;
}
/*
Write error package and flush to client
It's a little too low level, but I don't want to use another buffer for
this
*/
void
net_printf_error(THD *thd, uint errcode, ...)
{
va_list args;
uint length,offset;
const char *format;
#ifndef EMBEDDED_LIBRARY
const char *text_pos;
int head_length= NET_HEADER_SIZE;
#else
char text_pos[1024];
#endif
NET *net= &thd->net;
DBUG_ENTER("net_printf_error");
DBUG_PRINT("enter",("message: %u",errcode));
if (net && net->no_send_error)
{
thd->clear_error();
DBUG_PRINT("info", ("sending error messages prohibited"));
DBUG_VOID_RETURN;
}
if (thd->spcont && thd->spcont->find_handler(errcode,
MYSQL_ERROR::WARN_LEVEL_ERROR))
{
if (! thd->spcont->found_handler_here())
thd->net.report_error= 1; /* Make "select" abort correctly */
DBUG_VOID_RETURN;
}
thd->query_error= 1; // needed to catch query errors during replication
#ifndef EMBEDDED_LIBRARY
query_cache_abort(net); // Safety
#endif
va_start(args,errcode);
/*
The following is needed to make net_printf_error() work with 0 argument
for errorcode and use the argument after that as the format string. This
is useful for rare errors that are not worth the hassle to put in
errmsg.sys, but at the same time, the message is not fixed text
*/
if (errcode)
format= ER(errcode);
else
{
format=va_arg(args,char*);
errcode= ER_UNKNOWN_ERROR;
}
offset= (net->return_errno ?
((thd->client_capabilities & CLIENT_PROTOCOL_41) ?
2+SQLSTATE_LENGTH+1 : 2) : 0);
#ifndef EMBEDDED_LIBRARY
text_pos=(char*) net->buff + head_length + offset + 1;
length= (uint) ((char*)net->buff_end - text_pos);
#else
length=sizeof(text_pos)-1;
#endif
length=my_vsnprintf(my_const_cast(char*) (text_pos),
min(length, sizeof(net->last_error)),
format,args);
va_end(args);
/* Replication slave relies on net->last_* to see if there was error */
net->last_errno= errcode;
strmake(net->last_error, text_pos, sizeof(net->last_error)-1);
#ifndef EMBEDDED_LIBRARY
if (net->vio == 0)
{
if (thd->bootstrap)
{
/*
In bootstrap it's ok to print on stderr
This may also happen when we get an error from a slave thread
*/
fprintf(stderr,"ERROR: %d %s\n",errcode,text_pos);
thd->fatal_error();
}
DBUG_VOID_RETURN;
}
int3store(net->buff,length+1+offset);
net->buff[3]= (net->compress) ? 0 : (uchar) (net->pkt_nr++);
net->buff[head_length]=(uchar) 255; // Error package
if (offset)
{
uchar *pos= net->buff+head_length+1;
int2store(pos, errcode);
if (thd->client_capabilities & CLIENT_PROTOCOL_41)
{
pos[2]= '#'; /* To make the protocol backward compatible */
memcpy(pos+3, mysql_errno_to_sqlstate(errcode), SQLSTATE_LENGTH);
}
}
VOID(net_real_write(net,(char*) net->buff,length+head_length+1+offset));
#else
net->last_errno= errcode;
strmake(net->last_error, text_pos, length);
strmake(net->sqlstate, mysql_errno_to_sqlstate(errcode), SQLSTATE_LENGTH);
#endif
if (thd->killed != THD::KILL_CONNECTION)
push_warning(thd, MYSQL_ERROR::WARN_LEVEL_ERROR, errcode,
text_pos ? text_pos : ER(errcode));
thd->is_fatal_error=0; // Error message is given
DBUG_VOID_RETURN;
}
/*
Return ok to the client.
SYNOPSIS
send_ok()
thd Thread handler
affected_rows Number of rows changed by statement
id Auto_increment id for first row (if used)
message Message to send to the client (Used by mysql_status)
DESCRIPTION
The ok packet has the following structure
0 Marker (1 byte)
affected_rows Stored in 1-9 bytes
id Stored in 1-9 bytes
server_status Copy of thd->server_status; Can be used by client
to check if we are inside an transaction
New in 4.0 protocol
warning_count Stored in 2 bytes; New in 4.1 protocol
message Stored as packed length (1-9 bytes) + message
Is not stored if no message
If net->no_send_ok return without sending packet
*/
#ifndef EMBEDDED_LIBRARY
void
send_ok(THD *thd, ha_rows affected_rows, ulonglong id, const char *message)
{
NET *net= &thd->net;
char buff[MYSQL_ERRMSG_SIZE+10],*pos;
DBUG_ENTER("send_ok");
if (net->no_send_ok || !net->vio) // hack for re-parsing queries
{
DBUG_PRINT("info", ("no send ok: %s, vio present: %s",
(net->no_send_ok ? "YES" : "NO"),
(net->vio ? "YES" : "NO")));
DBUG_VOID_RETURN;
}
buff[0]=0; // No fields
pos=net_store_length(buff+1,(ulonglong) affected_rows);
pos=net_store_length(pos, (ulonglong) id);
if (thd->client_capabilities & CLIENT_PROTOCOL_41)
{
DBUG_PRINT("info",
("affected_rows: %lu id: %lu status: %u warning_count: %u",
(ulong) affected_rows,
(ulong) id,
(uint) (thd->server_status & 0xffff),
(uint) thd->total_warn_count));
int2store(pos,thd->server_status);
pos+=2;
/* We can only return up to 65535 warnings in two bytes */
uint tmp= min(thd->total_warn_count, 65535);
int2store(pos, tmp);
pos+= 2;
}
else if (net->return_status) // For 4.0 protocol
{
int2store(pos,thd->server_status);
pos+=2;
}
if (message)
pos=net_store_data((char*) pos, message, strlen(message));
VOID(my_net_write(net,buff,(uint) (pos-buff)));
VOID(net_flush(net));
/* We can't anymore send an error to the client */
thd->net.report_error= 0;
thd->net.no_send_error= 1;
DBUG_PRINT("info", ("OK sent, so no more error sending allowed"));
DBUG_VOID_RETURN;
}
static char eof_buff[1]= { (char) 254 }; /* Marker for end of fields */
/*
Send eof (= end of result set) to the client
SYNOPSIS
send_eof()
thd Thread handler
no_flush Set to 1 if there will be more data to the client,
like in send_fields().
DESCRIPTION
The eof packet has the following structure
254 Marker (1 byte)
warning_count Stored in 2 bytes; New in 4.1 protocol
status_flag Stored in 2 bytes;
For flags like SERVER_STATUS_MORE_RESULTS
Note that the warning count will not be sent if 'no_flush' is set as
we don't want to report the warning count until all data is sent to the
client.
*/
void
send_eof(THD *thd)
{
NET *net= &thd->net;
DBUG_ENTER("send_eof");
if (net->vio != 0 && !net->no_send_eof)
{
write_eof_packet(thd, net);
VOID(net_flush(net));
thd->net.no_send_error= 1;
DBUG_PRINT("info", ("EOF sent, so no more error sending allowed"));
}
DBUG_VOID_RETURN;
}
/*
Format EOF packet according to the current protocol and
write it to the network output buffer.
*/
static void write_eof_packet(THD *thd, NET *net)
{
if (thd->client_capabilities & CLIENT_PROTOCOL_41)
{
uchar buff[5];
/*
Don't send warn count during SP execution, as the warn_list
is cleared between substatements, and mysqltest gets confused
*/
uint tmp= (thd->spcont ? 0 : min(thd->total_warn_count, 65535));
buff[0]= 254;
int2store(buff+1, tmp);
/*
The following test should never be true, but it's better to do it
because if 'is_fatal_error' is set the server is not going to execute
other queries (see the if test in dispatch_command / COM_QUERY)
*/
if (thd->is_fatal_error)
thd->server_status&= ~SERVER_MORE_RESULTS_EXISTS;
int2store(buff+3, thd->server_status);
VOID(my_net_write(net, (char*) buff, 5));
}
else
VOID(my_net_write(net, eof_buff, 1));
}
/*
Please client to send scrambled_password in old format.
SYNOPSYS
send_old_password_request()
thd thread handle
RETURN VALUE
0 ok
!0 error
*/
bool send_old_password_request(THD *thd)
{
NET *net= &thd->net;
return my_net_write(net, eof_buff, 1) || net_flush(net);
}
void net_send_error_packet(THD *thd, uint sql_errno, const char *err)
{
NET *net= &thd->net;
uint length;
char buff[MYSQL_ERRMSG_SIZE+2], *pos;
DBUG_ENTER("send_error_packet");
if (net->vio == 0)
{
if (thd->bootstrap)
{
/* In bootstrap it's ok to print on stderr */
fprintf(stderr,"ERROR: %d %s\n",sql_errno,err);
}
DBUG_VOID_RETURN;
}
if (net->return_errno)
{ // new client code; Add errno before message
int2store(buff,sql_errno);
pos= buff+2;
if (thd->client_capabilities & CLIENT_PROTOCOL_41)
{
/* The first # is to make the protocol backward compatible */
buff[2]= '#';
pos= strmov(buff+3, mysql_errno_to_sqlstate(sql_errno));
}
length= (uint) (strmake(pos, err, MYSQL_ERRMSG_SIZE-1) - buff);
err=buff;
}
else
{
length=(uint) strlen(err);
set_if_smaller(length,MYSQL_ERRMSG_SIZE-1);
}
VOID(net_write_command(net,(uchar) 255, "", 0, (char*) err,length));
DBUG_VOID_RETURN;
}
#endif /* EMBEDDED_LIBRARY */
/*
Faster net_store_length when we know that length is less than 65536.
We keep a separate version for that range because it's widely used in
libmysql.
uint is used as agrument type because of MySQL type conventions:
uint for 0..65536
ulong for 0..4294967296
ulonglong for bigger numbers.
*/
char *net_store_length(char *pkg, uint length)
{
uchar *packet=(uchar*) pkg;
if (length < 251)
{
*packet=(uchar) length;
return (char*) packet+1;
}
*packet++=252;
int2store(packet,(uint) length);
return (char*) packet+2;
}
/****************************************************************************
Functions used by the protocol functions (like send_ok) to store strings
and numbers in the header result packet.
****************************************************************************/
/* The following will only be used for short strings < 65K */
char *net_store_data(char *to,const char *from, uint length)
{
to=net_store_length(to,length);
memcpy(to,from,length);
return to+length;
}
char *net_store_data(char *to,int32 from)
{
char buff[20];
uint length=(uint) (int10_to_str(from,buff,10)-buff);
to=net_store_length(to,length);
memcpy(to,buff,length);
return to+length;
}
char *net_store_data(char *to,longlong from)
{
char buff[22];
uint length=(uint) (longlong10_to_str(from,buff,10)-buff);
to=net_store_length(to,length);
memcpy(to,buff,length);
return to+length;
}
/*****************************************************************************
Default Protocol functions
*****************************************************************************/
void Protocol::init(THD *thd_arg)
{
thd=thd_arg;
packet= &thd->packet;
convert= &thd->convert_buffer;
#ifndef DBUG_OFF
field_types= 0;
#endif
}
bool Protocol::flush()
{
#ifndef EMBEDDED_LIBRARY
return net_flush(&thd->net);
#else
return 0;
#endif
}
/*
Send name and type of result to client.
SYNOPSIS
send_fields()
THD Thread data object
list List of items to send to client
flag Bit mask with the following functions:
1 send number of rows
2 send default values
4 don't write eof packet
DESCRIPTION
Sum fields has table name empty and field_name.
RETURN VALUES
0 ok
1 Error (Note that in this case the error is not sent to the client)
*/
#ifndef EMBEDDED_LIBRARY
bool Protocol::send_fields(List<Item> *list, uint flags)
{
List_iterator_fast<Item> it(*list);
Item *item;
char buff[80];
String tmp((char*) buff,sizeof(buff),&my_charset_bin);
Protocol_simple prot(thd);
String *local_packet= prot.storage_packet();
CHARSET_INFO *thd_charset= thd->variables.character_set_results;
DBUG_ENTER("send_fields");
if (flags & SEND_NUM_ROWS)
{ // Packet with number of elements
char *pos=net_store_length(buff, (uint) list->elements);
(void) my_net_write(&thd->net, buff,(uint) (pos-buff));
}
#ifndef DBUG_OFF
field_types= (enum_field_types*) thd->alloc(sizeof(field_types) *
list->elements);
uint count= 0;
#endif
while ((item=it++))
{
char *pos;
CHARSET_INFO *cs= system_charset_info;
Send_field field;
item->make_field(&field);
/* Keep things compatible for old clients */
if (field.type == MYSQL_TYPE_VARCHAR)
field.type= MYSQL_TYPE_VAR_STRING;
prot.prepare_for_resend();
if (thd->client_capabilities & CLIENT_PROTOCOL_41)
{
if (prot.store(STRING_WITH_LEN("def"), cs, thd_charset) ||
prot.store(field.db_name, (uint) strlen(field.db_name),
cs, thd_charset) ||
prot.store(field.table_name, (uint) strlen(field.table_name),
cs, thd_charset) ||
prot.store(field.org_table_name, (uint) strlen(field.org_table_name),
cs, thd_charset) ||
prot.store(field.col_name, (uint) strlen(field.col_name),
cs, thd_charset) ||
prot.store(field.org_col_name, (uint) strlen(field.org_col_name),
cs, thd_charset) ||
local_packet->realloc(local_packet->length()+12))
goto err;
/* Store fixed length fields */
pos= (char*) local_packet->ptr()+local_packet->length();
*pos++= 12; // Length of packed fields
if (item->collation.collation == &my_charset_bin || thd_charset == NULL)
{
/* No conversion */
int2store(pos, field.charsetnr);
int4store(pos+2, field.length);
}
else
{
/* With conversion */
uint max_char_len;
int2store(pos, thd_charset->number);
/*
For TEXT/BLOB columns, field_length describes the maximum data
length in bytes. There is no limit to the number of characters
that a TEXT column can store, as long as the data fits into
the designated space.
For the rest of textual columns, field_length is evaluated as
char_count * mbmaxlen, where character count is taken from the
definition of the column. In other words, the maximum number
of characters here is limited by the column definition.
*/
max_char_len= (field.type >= (int) MYSQL_TYPE_TINY_BLOB &&
field.type <= (int) MYSQL_TYPE_BLOB) ?
field.length / item->collation.collation->mbminlen :
field.length / item->collation.collation->mbmaxlen;
int4store(pos+2, max_char_len * thd_charset->mbmaxlen);
}
pos[6]= field.type;
int2store(pos+7,field.flags);
pos[9]= (char) field.decimals;
pos[10]= 0; // For the future
pos[11]= 0; // For the future
pos+= 12;
}
else
{
if (prot.store(field.table_name, (uint) strlen(field.table_name),
cs, thd_charset) ||
prot.store(field.col_name, (uint) strlen(field.col_name),
cs, thd_charset) ||
local_packet->realloc(local_packet->length()+10))
goto err;
pos= (char*) local_packet->ptr()+local_packet->length();
#ifdef TO_BE_DELETED_IN_6
if (!(thd->client_capabilities & CLIENT_LONG_FLAG))
{
pos[0]=3;
int3store(pos+1,field.length);
pos[4]=1;
pos[5]=field.type;
pos[6]=2;
pos[7]= (char) field.flags;
pos[8]= (char) field.decimals;
pos+= 9;
}
else
#endif
{
pos[0]=3;
int3store(pos+1,field.length);
pos[4]=1;
pos[5]=field.type;
pos[6]=3;
int2store(pos+7,field.flags);
pos[9]= (char) field.decimals;
pos+= 10;
}
}
local_packet->length((uint) (pos - local_packet->ptr()));
if (flags & SEND_DEFAULTS)
item->send(&prot, &tmp); // Send default value
if (prot.write())
break; /* purecov: inspected */
#ifndef DBUG_OFF
field_types[count++]= field.type;
#endif
}
if (flags & SEND_EOF)
write_eof_packet(thd, &thd->net);
DBUG_RETURN(prepare_for_send(list));
err:
my_message(ER_OUT_OF_RESOURCES, ER(ER_OUT_OF_RESOURCES),
MYF(0)); /* purecov: inspected */
DBUG_RETURN(1); /* purecov: inspected */
}
bool Protocol::write()
{
DBUG_ENTER("Protocol::write");
DBUG_RETURN(my_net_write(&thd->net, packet->ptr(), packet->length()));
}
#endif /* EMBEDDED_LIBRARY */
/*
Send \0 end terminated string
SYNOPSIS
store()
from NullS or \0 terminated string
NOTES
In most cases one should use store(from, length) instead of this function
RETURN VALUES
0 ok
1 error
*/
bool Protocol::store(const char *from, CHARSET_INFO *cs)
{
if (!from)
return store_null();
uint length= strlen(from);
return store(from, length, cs);
}
/*
Send a set of strings as one long string with ',' in between
*/
bool Protocol::store(I_List<i_string>* str_list)
{
char buf[256];
String tmp(buf, sizeof(buf), &my_charset_bin);
uint32 len;
I_List_iterator<i_string> it(*str_list);
i_string* s;
tmp.length(0);
while ((s=it++))
{
tmp.append(s->ptr);
tmp.append(',');
}
if ((len= tmp.length()))
len--; // Remove last ','
return store((char*) tmp.ptr(), len, tmp.charset());
}
/****************************************************************************
Functions to handle the simple (default) protocol where everything is
This protocol is the one that is used by default between the MySQL server
and client when you are not using prepared statements.
All data are sent as 'packed-string-length' followed by 'string-data'
****************************************************************************/
#ifndef EMBEDDED_LIBRARY
void Protocol_simple::prepare_for_resend()
{
packet->length(0);
#ifndef DBUG_OFF
field_pos= 0;
#endif
}
bool Protocol_simple::store_null()
{
#ifndef DBUG_OFF
field_pos++;
#endif
char buff[1];
buff[0]= (char)251;
return packet->append(buff, sizeof(buff), PACKET_BUFFER_EXTRA_ALLOC);
}
#endif
/*
Auxilary function to convert string to the given character set
and store in network buffer.
*/
bool Protocol::store_string_aux(const char *from, uint length,
CHARSET_INFO *fromcs, CHARSET_INFO *tocs)
{
/* 'tocs' is set 0 when client issues SET character_set_results=NULL */
if (tocs && !my_charset_same(fromcs, tocs) &&
fromcs != &my_charset_bin &&
tocs != &my_charset_bin)
{
uint dummy_errors;
return convert->copy(from, length, fromcs, tocs, &dummy_errors) ||
net_store_data(convert->ptr(), convert->length());
}
return net_store_data(from, length);
}
bool Protocol_simple::store(const char *from, uint length,
CHARSET_INFO *fromcs, CHARSET_INFO *tocs)
{
#ifndef DBUG_OFF
DBUG_ASSERT(field_types == 0 ||
field_types[field_pos] == MYSQL_TYPE_DECIMAL ||
field_types[field_pos] == MYSQL_TYPE_BIT ||
field_types[field_pos] == MYSQL_TYPE_NEWDECIMAL ||
(field_types[field_pos] >= MYSQL_TYPE_ENUM &&
field_types[field_pos] <= MYSQL_TYPE_GEOMETRY));
field_pos++;
#endif
return store_string_aux(from, length, fromcs, tocs);
}
bool Protocol_simple::store(const char *from, uint length,
CHARSET_INFO *fromcs)
{
CHARSET_INFO *tocs= this->thd->variables.character_set_results;
#ifndef DBUG_OFF
DBUG_ASSERT(field_types == 0 ||
field_types[field_pos] == MYSQL_TYPE_DECIMAL ||
field_types[field_pos] == MYSQL_TYPE_BIT ||
field_types[field_pos] == MYSQL_TYPE_NEWDECIMAL ||
(field_types[field_pos] >= MYSQL_TYPE_ENUM &&
field_types[field_pos] <= MYSQL_TYPE_GEOMETRY));
field_pos++;
#endif
return store_string_aux(from, length, fromcs, tocs);
}
bool Protocol_simple::store_tiny(longlong from)
{
#ifndef DBUG_OFF
DBUG_ASSERT(field_types == 0 || field_types[field_pos] == MYSQL_TYPE_TINY);
field_pos++;
#endif
char buff[20];
return net_store_data((char*) buff,
(uint) (int10_to_str((int) from,buff, -10)-buff));
}
bool Protocol_simple::store_short(longlong from)
{
#ifndef DBUG_OFF
DBUG_ASSERT(field_types == 0 ||
field_types[field_pos] == MYSQL_TYPE_YEAR ||
field_types[field_pos] == MYSQL_TYPE_SHORT);
field_pos++;
#endif
char buff[20];
return net_store_data((char*) buff,
(uint) (int10_to_str((int) from,buff, -10)-buff));
}
bool Protocol_simple::store_long(longlong from)
{
#ifndef DBUG_OFF
DBUG_ASSERT(field_types == 0 ||
field_types[field_pos] == MYSQL_TYPE_INT24 ||
field_types[field_pos] == MYSQL_TYPE_LONG);
field_pos++;
#endif
char buff[20];
return net_store_data((char*) buff,
(uint) (int10_to_str((long int)from,buff, (from <0)?-10:10)-buff));
}
bool Protocol_simple::store_longlong(longlong from, bool unsigned_flag)
{
#ifndef DBUG_OFF
DBUG_ASSERT(field_types == 0 ||
field_types[field_pos] == MYSQL_TYPE_LONGLONG);
field_pos++;
#endif
char buff[22];
return net_store_data((char*) buff,
(uint) (longlong10_to_str(from,buff,
unsigned_flag ? 10 : -10)-
buff));
}
bool Protocol_simple::store_decimal(const my_decimal *d)
{
#ifndef DBUG_OFF
DBUG_ASSERT(field_types == 0 ||
field_types[field_pos] == MYSQL_TYPE_NEWDECIMAL);
field_pos++;
#endif
char buff[DECIMAL_MAX_STR_LENGTH];
String str(buff, sizeof(buff), &my_charset_bin);
(void) my_decimal2string(E_DEC_FATAL_ERROR, d, 0, 0, 0, &str);
return net_store_data(str.ptr(), str.length());
}
bool Protocol_simple::store(float from, uint32 decimals, String *buffer)
{
#ifndef DBUG_OFF
DBUG_ASSERT(field_types == 0 ||
field_types[field_pos] == MYSQL_TYPE_FLOAT);
field_pos++;
#endif
buffer->set((double) from, decimals, thd->charset());
return net_store_data((char*) buffer->ptr(), buffer->length());
}
bool Protocol_simple::store(double from, uint32 decimals, String *buffer)
{
#ifndef DBUG_OFF
DBUG_ASSERT(field_types == 0 ||
field_types[field_pos] == MYSQL_TYPE_DOUBLE);
field_pos++;
#endif
buffer->set(from, decimals, thd->charset());
return net_store_data((char*) buffer->ptr(), buffer->length());
}
bool Protocol_simple::store(Field *field)
{
if (field->is_null())
return store_null();
#ifndef DBUG_OFF
field_pos++;
#endif
char buff[MAX_FIELD_WIDTH];
String str(buff,sizeof(buff), &my_charset_bin);
CHARSET_INFO *tocs= this->thd->variables.character_set_results;
TABLE *table= field->table;
#ifdef DBUG_OFF
my_bitmap_map *old_map= 0;
if (table->file)
old_map= dbug_tmp_use_all_columns(table, table->read_set);
#endif
field->val_str(&str);
#ifdef DBUG_OFF
if (old_map)
dbug_tmp_restore_column_map(table->read_set, old_map);
#endif
return store_string_aux(str.ptr(), str.length(), str.charset(), tocs);
}
/*
TODO:
Second_part format ("%06") needs to change when
we support 0-6 decimals for time.
*/
bool Protocol_simple::store(TIME *tm)
{
#ifndef DBUG_OFF
DBUG_ASSERT(field_types == 0 ||
field_types[field_pos] == MYSQL_TYPE_DATETIME ||
field_types[field_pos] == MYSQL_TYPE_TIMESTAMP);
field_pos++;
#endif
char buff[40];
uint length;
length= my_sprintf(buff,(buff, "%04d-%02d-%02d %02d:%02d:%02d",
(int) tm->year,
(int) tm->month,
(int) tm->day,
(int) tm->hour,
(int) tm->minute,
(int) tm->second));
if (tm->second_part)
length+= my_sprintf(buff+length,(buff+length, ".%06d", (int)tm->second_part));
return net_store_data((char*) buff, length);
}
bool Protocol_simple::store_date(TIME *tm)
{
#ifndef DBUG_OFF
DBUG_ASSERT(field_types == 0 ||
field_types[field_pos] == MYSQL_TYPE_DATE);
field_pos++;
#endif
char buff[MAX_DATE_STRING_REP_LENGTH];
int length= my_date_to_str(tm, buff);
return net_store_data(buff, (uint) length);
}
/*
TODO:
Second_part format ("%06") needs to change when
we support 0-6 decimals for time.
*/
bool Protocol_simple::store_time(TIME *tm)
{
#ifndef DBUG_OFF
DBUG_ASSERT(field_types == 0 ||
field_types[field_pos] == MYSQL_TYPE_TIME);
field_pos++;
#endif
char buff[40];
uint length;
uint day= (tm->year || tm->month) ? 0 : tm->day;
length= my_sprintf(buff,(buff, "%s%02ld:%02d:%02d",
tm->neg ? "-" : "",
(long) day*24L+(long) tm->hour,
(int) tm->minute,
(int) tm->second));
if (tm->second_part)
length+= my_sprintf(buff+length,(buff+length, ".%06d", (int)tm->second_part));
return net_store_data((char*) buff, length);
}
/****************************************************************************
Functions to handle the binary protocol used with prepared statements
Data format:
[ok:1] reserved ok packet
[null_field:(field_count+7+2)/8] reserved to send null data. The size is
calculated using:
bit_fields= (field_count+7+2)/8;
2 bits are reserved for identifying type
of package.
[[length]data] data field (the length applies only for
string/binary/time/timestamp fields and
rest of them are not sent as they have
the default length that client understands
based on the field type
[..]..[[length]data] data
****************************************************************************/
bool Protocol_prep::prepare_for_send(List<Item> *item_list)
{
Protocol::prepare_for_send(item_list);
bit_fields= (field_count+9)/8;
if (packet->alloc(bit_fields+1))
return 1;
/* prepare_for_resend will be called after this one */
return 0;
}
void Protocol_prep::prepare_for_resend()
{
packet->length(bit_fields+1);
bzero((char*) packet->ptr(), 1+bit_fields);
field_pos=0;
}
bool Protocol_prep::store(const char *from, uint length, CHARSET_INFO *fromcs)
{
CHARSET_INFO *tocs= thd->variables.character_set_results;
field_pos++;
return store_string_aux(from, length, fromcs, tocs);
}
bool Protocol_prep::store(const char *from,uint length,
CHARSET_INFO *fromcs, CHARSET_INFO *tocs)
{
field_pos++;
return store_string_aux(from, length, fromcs, tocs);
}
bool Protocol_prep::store_null()
{
uint offset= (field_pos+2)/8+1, bit= (1 << ((field_pos+2) & 7));
/* Room for this as it's allocated in prepare_for_send */
char *to= (char*) packet->ptr()+offset;
*to= (char) ((uchar) *to | (uchar) bit);
field_pos++;
return 0;
}
bool Protocol_prep::store_tiny(longlong from)
{
char buff[1];
field_pos++;
buff[0]= (uchar) from;
return packet->append(buff, sizeof(buff), PACKET_BUFFER_EXTRA_ALLOC);
}
bool Protocol_prep::store_short(longlong from)
{
field_pos++;
char *to= packet->prep_append(2, PACKET_BUFFER_EXTRA_ALLOC);
if (!to)
return 1;
int2store(to, (int) from);
return 0;
}
bool Protocol_prep::store_long(longlong from)
{
field_pos++;
char *to= packet->prep_append(4, PACKET_BUFFER_EXTRA_ALLOC);
if (!to)
return 1;
int4store(to, from);
return 0;
}
bool Protocol_prep::store_longlong(longlong from, bool unsigned_flag)
{
field_pos++;
char *to= packet->prep_append(8, PACKET_BUFFER_EXTRA_ALLOC);
if (!to)
return 1;
int8store(to, from);
return 0;
}
bool Protocol_prep::store_decimal(const my_decimal *d)
{
#ifndef DBUG_OFF
DBUG_ASSERT(field_types == 0 ||
field_types[field_pos] == MYSQL_TYPE_NEWDECIMAL);
field_pos++;
#endif
char buff[DECIMAL_MAX_STR_LENGTH];
String str(buff, sizeof(buff), &my_charset_bin);
(void) my_decimal2string(E_DEC_FATAL_ERROR, d, 0, 0, 0, &str);
return store(str.ptr(), str.length(), str.charset());
}
bool Protocol_prep::store(float from, uint32 decimals, String *buffer)
{
field_pos++;
char *to= packet->prep_append(4, PACKET_BUFFER_EXTRA_ALLOC);
if (!to)
return 1;
float4store(to, from);
return 0;
}
bool Protocol_prep::store(double from, uint32 decimals, String *buffer)
{
field_pos++;
char *to= packet->prep_append(8, PACKET_BUFFER_EXTRA_ALLOC);
if (!to)
return 1;
float8store(to, from);
return 0;
}
bool Protocol_prep::store(Field *field)
{
/*
We should not increment field_pos here as send_binary() will call another
protocol function to do this for us
*/
if (field->is_null())
return store_null();
return field->send_binary(this);
}
bool Protocol_prep::store(TIME *tm)
{
char buff[12],*pos;
uint length;
field_pos++;
pos= buff+1;
int2store(pos, tm->year);
pos[2]= (uchar) tm->month;
pos[3]= (uchar) tm->day;
pos[4]= (uchar) tm->hour;
pos[5]= (uchar) tm->minute;
pos[6]= (uchar) tm->second;
int4store(pos+7, tm->second_part);
if (tm->second_part)
length=11;
else if (tm->hour || tm->minute || tm->second)
length=7;
else if (tm->year || tm->month || tm->day)
length=4;
else
length=0;
buff[0]=(char) length; // Length is stored first
return packet->append(buff, length+1, PACKET_BUFFER_EXTRA_ALLOC);
}
bool Protocol_prep::store_date(TIME *tm)
{
tm->hour= tm->minute= tm->second=0;
tm->second_part= 0;
return Protocol_prep::store(tm);
}
bool Protocol_prep::store_time(TIME *tm)
{
char buff[13], *pos;
uint length;
field_pos++;
pos= buff+1;
pos[0]= tm->neg ? 1 : 0;
if (tm->hour >= 24)
{
/* Fix if we come from Item::send */
uint days= tm->hour/24;
tm->hour-= days*24;
tm->day+= days;
}
int4store(pos+1, tm->day);
pos[5]= (uchar) tm->hour;
pos[6]= (uchar) tm->minute;
pos[7]= (uchar) tm->second;
int4store(pos+8, tm->second_part);
if (tm->second_part)
length=12;
else if (tm->hour || tm->minute || tm->second || tm->day)
length=8;
else
length=0;
buff[0]=(char) length; // Length is stored first
return packet->append(buff, length+1, PACKET_BUFFER_EXTRA_ALLOC);
}