~drizzle-trunk/drizzle/development

/* 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; 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 */

/**

  @file

  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 <stdarg.h>

static const unsigned int PACKET_BUFFER_EXTRA_ALLOC= 1024;

/* Declared non-static only because of the embedded library. */

void net_send_error_packet(THD *thd, uint sql_errno, const char *err);

void net_send_ok(THD *, uint, uint, ha_rows, ulonglong, const char *);

void net_send_eof(THD *thd, uint server_status, uint total_warn_count);

static void write_eof_packet(THD *thd, NET *net,

                             uint server_status, uint total_warn_count);

bool Protocol::net_store_data(const uchar *from, size_t length)

{

  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;

  uchar *to= net_store_length((uchar*) packet->ptr()+packet_length, length);

  memcpy(to,from,length);

  packet->length((uint) (to+length-(uchar*) packet->ptr()));

  return 0;

}

/*

  net_store_data() - extended version with character set conversion.

  It is optimized for short strings whose length after

  conversion is garanteed to be less than 251, which accupies

  exactly one byte to store length. It allows not to use

  the "convert" member as a temporary buffer, conversion

  is done directly to the "packet" member.

  The limit 251 is good enough to optimize send_fields()

  because column, table, database names fit into this limit.

*/

bool Protocol::net_store_data(const uchar *from, size_t length,

                              CHARSET_INFO *from_cs, CHARSET_INFO *to_cs)

{

  uint dummy_errors;

  /* Calculate maxumum possible result length */

  uint conv_length= to_cs->mbmaxlen * length / from_cs->mbminlen;

  if (conv_length > 250)

  {

    /*

      For strings with conv_length greater than 250 bytes

      we don't know how many bytes we will need to store length: one or two,

      because we don't know result length until conversion is done.

      For example, when converting from utf8 (mbmaxlen=3) to latin1,

      conv_length=300 means that the result length can vary between 100 to 300.

      length=100 needs one byte, length=300 needs to bytes.

      Thus conversion directly to "packet" is not worthy.

      Let's use "convert" as a temporary buffer.

    */

    return (convert->copy((const char*) from, length, from_cs,

                          to_cs, &dummy_errors) ||

            net_store_data((const uchar*) convert->ptr(), convert->length()));

  }

  ulong packet_length= packet->length();

  ulong new_length= packet_length + conv_length + 1;

  if (new_length > packet->alloced_length() && packet->realloc(new_length))

    return 1;

  char *length_pos= (char*) packet->ptr() + packet_length;

  char *to= length_pos + 1;

  to+= copy_and_convert(to, conv_length, to_cs,

                        (const char*) from, length, from_cs, &dummy_errors);

  net_store_length((uchar*) length_pos, to - length_pos - 1);

  packet->length((uint) (to - packet->ptr()));

  return 0;

}

/**

  Send a error string to client.

  Design note:

  net_printf_error and net_send_error are low-level functions

  that shall be used only when a new connection is being

  established or at server startup.

  For SIGNAL/RESIGNAL and GET DIAGNOSTICS functionality it's

  critical that every error that can be intercepted is issued in one

  place only, my_message_sql.

*/

void net_send_error(THD *thd, uint sql_errno, const char *err)

{

  DBUG_ENTER("net_send_error");

  DBUG_ASSERT(sql_errno);

  DBUG_ASSERT(err && err[0]);

  DBUG_PRINT("enter",("sql_errno: %d  err: %s", sql_errno, err));

  /*

    It's one case when we can push an error even though there

    is an OK or EOF already.

  */

  thd->main_da.can_overwrite_status= TRUE;

  /* Abort multi-result sets */

  thd->server_status&= ~SERVER_MORE_RESULTS_EXISTS;

  net_send_error_packet(thd, sql_errno, err);

  thd->main_da.can_overwrite_status= FALSE;

  DBUG_VOID_RETURN;

}

/**

  Return ok to the client.

  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.

  @param thd		   Thread handler

  @param affected_rows	   Number of rows changed by statement

  @param id		   Auto_increment id for first row (if used)

  @param message	   Message to send to the client (Used by mysql_status)

*/

void

net_send_ok(THD *thd,

            uint server_status, uint total_warn_count,

            ha_rows affected_rows, ulonglong id, const char *message)

{

  NET *net= &thd->net;

  uchar buff[MYSQL_ERRMSG_SIZE+10],*pos;

  DBUG_ENTER("my_ok");

  if (! net->vio)	// hack for re-parsing queries

  {

    DBUG_PRINT("info", ("vio present: NO"));

    DBUG_VOID_RETURN;

  }

  buff[0]=0;					// No fields

  pos=net_store_length(buff+1,affected_rows);

  pos=net_store_length(pos, 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) (server_status & 0xffff),

		(uint) total_warn_count));

    int2store(pos, server_status);

    pos+=2;

    /* We can only return up to 65535 warnings in two bytes */

    uint tmp= min(total_warn_count, 65535);

    int2store(pos, tmp);

    pos+= 2;

  }

  else if (net->return_status)			// For 4.0 protocol

  {

    int2store(pos, server_status);

    pos+=2;

  }

  thd->main_da.can_overwrite_status= TRUE;

  if (message && message[0])

    pos= net_store_data(pos, (uchar*) message, strlen(message));

  VOID(my_net_write(net, buff, (size_t) (pos-buff)));

  VOID(net_flush(net));

  thd->main_da.can_overwrite_status= FALSE;

  DBUG_PRINT("info", ("OK sent, so no more error sending allowed"));

  DBUG_VOID_RETURN;

}

static uchar eof_buff[1]= { (uchar) 254 };      /* Marker for end of fields */

/**

  Send eof (= end of result set) to the client.

  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_MORE_RESULTS_EXISTS.

  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.

  @param thd		Thread handler

  @param no_flush	Set to 1 if there will be more data to the client,

                    like in send_fields().

*/    

void

net_send_eof(THD *thd, uint server_status, uint total_warn_count)

{

  NET *net= &thd->net;

  DBUG_ENTER("net_send_eof");

  /* Set to TRUE if no active vio, to work well in case of --init-file */

  if (net->vio != 0)

  {

    thd->main_da.can_overwrite_status= TRUE;

    write_eof_packet(thd, net, server_status, total_warn_count);

    VOID(net_flush(net));

    thd->main_da.can_overwrite_status= FALSE;

    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,

                             uint server_status,

                             uint total_warn_count)

{

  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= min(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)

      server_status&= ~SERVER_MORE_RESULTS_EXISTS;

    int2store(buff + 3, server_status);

    VOID(my_net_write(net, buff, 5));

  }

  else

    VOID(my_net_write(net, eof_buff, 1));

}

/**

  Please client to send scrambled_password in old format.

  @param thd thread handle

  @retval

    0  ok

  @retval

   !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;

  /*

    buff[]: sql_errno:2 + ('#':1 + SQLSTATE_LENGTH:5) + MYSQL_ERRMSG_SIZE:512

  */

  uchar buff[2+1+SQLSTATE_LENGTH+MYSQL_ERRMSG_SIZE], *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;

  }

  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= (uchar*) strmov((char*) buff+3, mysql_errno_to_sqlstate(sql_errno));

  }

  length= (uint) (strmake((char*) pos, err, MYSQL_ERRMSG_SIZE-1) -

                  (char*) buff);

  err= (char*) buff;

  VOID(net_write_command(net,(uchar) 255, (uchar*) "", 0, (uchar*) err,

                         length));

  DBUG_VOID_RETURN;

}

/**

  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.

*/

static uchar *net_store_length_fast(uchar *packet, uint length)

{

  if (length < 251)

  {

    *packet=(uchar) length;

    return packet+1;

  }

  *packet++=252;

  int2store(packet,(uint) length);

  return packet+2;

}

/**

  Send the status of the current statement execution over network.

  @param  thd   in fact, carries two parameters, NET for the transport and

                Diagnostics_area as the source of status information.

  In MySQL, there are two types of SQL statements: those that return

  a result set and those that return status information only.

  If a statement returns a result set, it consists of 3 parts:

  - result set meta-data

  - variable number of result set rows (can be 0)

  - followed and terminated by EOF or ERROR packet

  Once the  client has seen the meta-data information, it always

  expects an EOF or ERROR to terminate the result set. If ERROR is

  received, the result set rows are normally discarded (this is up

  to the client implementation, libmysql at least does discard them).

  EOF, on the contrary, means "successfully evaluated the entire

  result set". Since we don't know how many rows belong to a result

  set until it's evaluated, EOF/ERROR is the indicator of the end

  of the row stream. Note, that we can not buffer result set rows

  on the server -- there may be an arbitrary number of rows. But

  we do buffer the last packet (EOF/ERROR) in the Diagnostics_area and

  delay sending it till the very end of execution (here), to be able to

  change EOF to an ERROR if commit failed or some other error occurred

  during the last cleanup steps taken after execution.

  A statement that does not return a result set doesn't send result

  set meta-data either. Instead it returns one of:

  - OK packet

  - ERROR packet.

  Similarly to the EOF/ERROR of the previous statement type, OK/ERROR

  packet is "buffered" in the diagnostics area and sent to the client

  in the end of statement.

  @pre  The diagnostics area is assigned or disabled. It can not be empty

        -- we assume that every SQL statement or COM_* command

        generates OK, ERROR, or EOF status.

  @post The status information is encoded to protocol format and sent to the

        client.

  @return We conventionally return void, since the only type of error

          that can happen here is a NET (transport) error, and that one

          will become visible when we attempt to read from the NET the

          next command.

          Diagnostics_area::is_sent is set for debugging purposes only.

*/

void net_end_statement(THD *thd)

{

  DBUG_ASSERT(! thd->main_da.is_sent);

  /* Can not be true, but do not take chances in production. */

  if (thd->main_da.is_sent)

    return;

  switch (thd->main_da.status()) {

  case Diagnostics_area::DA_ERROR:

    /* The query failed, send error to log and abort bootstrap. */

    net_send_error(thd,

                   thd->main_da.sql_errno(),

                   thd->main_da.message());

    break;

  case Diagnostics_area::DA_EOF:

    net_send_eof(thd,

                 thd->main_da.server_status(),

                 thd->main_da.total_warn_count());

    break;

  case Diagnostics_area::DA_OK:

    net_send_ok(thd,

                thd->main_da.server_status(),

                thd->main_da.total_warn_count(),

                thd->main_da.affected_rows(),

                thd->main_da.last_insert_id(),

                thd->main_da.message());

    break;

  case Diagnostics_area::DA_DISABLED:

    break;

  case Diagnostics_area::DA_EMPTY:

  default:

    DBUG_ASSERT(0);

    net_send_ok(thd, thd->server_status, thd->total_warn_count,

                0, 0, NULL);

    break;

  }

  thd->main_da.is_sent= TRUE;

}

/****************************************************************************

  Functions used by the protocol functions (like net_send_ok) to store

  strings and numbers in the header result packet.

****************************************************************************/

/* The following will only be used for short strings < 65K */

uchar *net_store_data(uchar *to, const uchar *from, size_t length)

{

  to=net_store_length_fast(to,length);

  memcpy(to,from,length);

  return to+length;

}

uchar *net_store_data(uchar *to,int32 from)

{

  char buff[20];

  uint length=(uint) (int10_to_str(from,buff,10)-buff);

  to=net_store_length_fast(to,length);

  memcpy(to,buff,length);

  return to+length;

}

uchar *net_store_data(uchar *to,longlong from)

{

  char buff[22];

  uint length=(uint) (longlong10_to_str(from,buff,10)-buff);

  to=net_store_length_fast(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

}

/**

  Finish the result set with EOF packet, as is expected by the client,

  if there is an error evaluating the next row and a continue handler

  for the error.

*/

void Protocol::end_partial_result_set(THD *thd)

{

  net_send_eof(thd, thd->server_status, 0 /* no warnings, we're inside SP */);

}

bool Protocol::flush()

{

  return net_flush(&thd->net);

}

/**

  Send name and type of result to client.

  Sum fields has table name empty and field_name.

  @param THD		Thread data object

  @param list	        List of items to send to client

  @param flag	        Bit mask with the following functions:

                        - 1 send number of rows

                        - 2 send default values

                        - 4 don't write eof packet

  @retval

    0	ok

  @retval

    1	Error  (Note that in this case the error is not sent to the

    client)

*/

bool Protocol::send_fields(List<Item> *list, uint flags)

{

  List_iterator_fast<Item> it(*list);

  Item *item;

  uchar buff[80];

  String tmp((char*) buff,sizeof(buff),&my_charset_bin);

  Protocol_text 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

    uchar *pos= net_store_length(buff, list->elements);

    (void) my_net_write(&thd->net, buff, (size_t) (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)

  {

    /*

      Mark the end of meta-data result set, and store thd->server_status,

      to show that there is no cursor.

      Send no warning information, as it will be sent at statement end.

    */

    write_eof_packet(thd, &thd->net, thd->server_status, thd->total_warn_count);

  }

  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, (uchar*) packet->ptr(),

                           packet->length()));

}

/**

  Send \\0 end terminated string.

  @param from	NullS or \\0 terminated string

  @note

    In most cases one should use store(from, length) instead of this function

  @retval

    0		ok

  @retval

    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'

****************************************************************************/

void Protocol_text::prepare_for_resend()

{

  packet->length(0);

#ifndef DBUG_OFF

  field_pos= 0;

#endif

}

bool Protocol_text::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);

}

/**

  Auxilary function to convert string to the given character set

  and store in network buffer.

*/

bool Protocol::store_string_aux(const char *from, size_t 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)

  {

    /* Store with conversion */

    return net_store_data((uchar*) from, length, fromcs, tocs);

  }

  /* Store without conversion */

  return net_store_data((uchar*) from, length);

}

bool Protocol_text::store(const char *from, size_t 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_text::store(const char *from, size_t length,

                          CHARSET_INFO *fromcs)