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sql_help.cc
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/* Copyright (c) 2002, 2012, Oracle and/or its affiliates.
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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */
#include "mariadb.h"
#include "sql_priv.h"
#include "unireg.h"
#include "sql_help.h"
#include "sql_table.h" // primary_key_name
#include "sql_base.h" // REPORT_ALL_ERRORS, setup_tables
#include "opt_range.h" // SQL_SELECT
#include "records.h" // init_read_record, end_read_record
struct st_find_field
{
const char *table_name, *field_name;
Field *field;
};
/* Used fields */
static struct st_find_field init_used_fields[]=
{
{ "help_topic", "help_topic_id", 0},
{ "help_topic", "name", 0},
{ "help_topic", "help_category_id", 0},
{ "help_topic", "description", 0},
{ "help_topic", "example", 0},
{ "help_category", "help_category_id", 0},
{ "help_category", "parent_category_id", 0},
{ "help_category", "name", 0},
{ "help_keyword", "help_keyword_id", 0},
{ "help_keyword", "name", 0},
{ "help_relation", "help_topic_id", 0},
{ "help_relation", "help_keyword_id", 0}
};
enum enum_used_fields
{
help_topic_help_topic_id= 0,
help_topic_name,
help_topic_help_category_id,
help_topic_description,
help_topic_example,
help_category_help_category_id,
help_category_parent_category_id,
help_category_name,
help_keyword_help_keyword_id,
help_keyword_name,
help_relation_help_topic_id,
help_relation_help_keyword_id
};
/*
Allocate string field in MEM_ROOT and return it as String
SYNOPSIS
get_field()
mem MEM_ROOT for allocating
field Field for retrieving of string
res result String
*/
static void get_field(MEM_ROOT *mem, Field *field, String *res)
{
THD *thd= field->get_thd();
Sql_mode_instant_remove sms(thd, MODE_PAD_CHAR_TO_FULL_LENGTH);
LEX_STRING ls= field->val_lex_string_strmake(mem);
DBUG_ASSERT((!ls.str && !ls.length) || ls.str[ls.length] == '\0');
if (!ls.str)
res->length(0); // EOM
else
res->set((const char *) ls.str, ls.length, field->charset());
}
/*
Fill st_find_field structure with pointers to fields
SYNOPSIS
init_fields()
thd Thread handler
tables list of all tables for fields
find_fields array of structures
count size of previous array
RETURN VALUES
0 all ok
1 one of the fileds was not found
*/
static bool init_fields(THD *thd, TABLE_LIST *tables,
struct st_find_field *find_fields, uint count)
{
Name_resolution_context *context= &thd->lex->first_select_lex()->context;
DBUG_ENTER("init_fields");
context->resolve_in_table_list_only(tables);
for (; count-- ; find_fields++)
{
/* We have to use 'new' here as field will be re_linked on free */
Item_field *field= (new (thd->mem_root)
Item_field(thd, context,
{STRING_WITH_LEN("mysql")},
Lex_cstring_strlen(find_fields->table_name),
Lex_cstring_strlen(find_fields->field_name)));
if (!(find_fields->field= find_field_in_tables(thd, field, tables, NULL,
ignored_tables_list_t(NULL),
0, REPORT_ALL_ERRORS, 1,
TRUE)))
DBUG_RETURN(1);
bitmap_set_bit(find_fields->field->table->read_set,
find_fields->field->field_index);
/* To make life easier when setting values in keys */
bitmap_set_bit(find_fields->field->table->write_set,
find_fields->field->field_index);
}
DBUG_RETURN(0);
}
/*
Returns variants of found topic for help (if it is just single topic,
returns description and example, or else returns only names..)
SYNOPSIS
memorize_variant_topic()
thd Thread handler
topics Table of topics
count number of alredy found topics
find_fields Filled array of information for work with fields
RETURN VALUES
names array of names of found topics (out)
name name of found topic (out)
description description of found topic (out)
example example for found topic (out)
NOTE
Field 'names' is set only if more than one topic is found.
Fields 'name', 'description', 'example' are set only if
found exactly one topic.
*/
void memorize_variant_topic(THD *thd, TABLE *topics, int count,
struct st_find_field *find_fields,
List<String> *names,
String *name, String *description, String *example)
{
DBUG_ENTER("memorize_variant_topic");
MEM_ROOT *mem_root= thd->mem_root;
if (count==0)
{
get_field(mem_root,find_fields[help_topic_name].field, name);
get_field(mem_root,find_fields[help_topic_description].field, description);
get_field(mem_root,find_fields[help_topic_example].field, example);
}
else
{
if (count == 1)
names->push_back(name, thd->mem_root);
String *new_name= new (thd->mem_root) String;
get_field(mem_root,find_fields[help_topic_name].field,new_name);
names->push_back(new_name, thd->mem_root);
}
DBUG_VOID_RETURN;
}
/*
Look for topics by mask
SYNOPSIS
search_topics()
thd Thread handler
topics Table of topics
find_fields Filled array of info for fields
select Function to test for matching help topic.
Normally 'help_topic.name like 'bit%'
RETURN VALUES
# number of topics found
names array of names of found topics (out)
name name of found topic (out)
description description of found topic (out)
example example for found topic (out)
NOTE
Field 'names' is set only if more than one topic was found.
Fields 'name', 'description', 'example' are set only if
exactly one topic was found.
*/
int search_topics(THD *thd, TABLE *topics, struct st_find_field *find_fields,
SQL_SELECT *select, List<String> *names,
String *name, String *description, String *example)
{
int count= 0;
READ_RECORD read_record_info;
DBUG_ENTER("search_topics");
/* Should never happen. As this is part of help, we can ignore this */
if (init_read_record(&read_record_info, thd, topics, select, NULL, 1, 0,
FALSE))
DBUG_RETURN(0);
while (!read_record_info.read_record())
{
if (!select->cond->val_bool()) // Doesn't match like
continue;
memorize_variant_topic(thd,topics,count,find_fields,
names,name,description,example);
count++;
}
end_read_record(&read_record_info);
DBUG_RETURN(count);
}
/*
Look for keyword by mask
SYNOPSIS
search_keyword()
thd Thread handler
keywords Table of keywords
find_fields Filled array of info for fields
select Function to test for matching keyword.
Normally 'help_keyword.name like 'bit%'
key_id help_keyword_if of found topics (out)
RETURN VALUES
0 didn't find any topics matching the mask
1 found exactly one topic matching the mask
2 found more then one topic matching the mask
*/
int search_keyword(THD *thd, TABLE *keywords,
struct st_find_field *find_fields,
SQL_SELECT *select, int *key_id)
{
int count= 0;
READ_RECORD read_record_info;
DBUG_ENTER("search_keyword");
/* Should never happen. As this is part of help, we can ignore this */
if (init_read_record(&read_record_info, thd, keywords, select, NULL, 1, 0,
FALSE))
DBUG_RETURN(0);
while (!read_record_info.read_record() && count<2)
{
if (!select->cond->val_bool()) // Doesn't match like
continue;
*key_id= (int)find_fields[help_keyword_help_keyword_id].field->val_int();
count++;
}
end_read_record(&read_record_info);
DBUG_RETURN(count);
}
/*
Look for all topics with keyword
SYNOPSIS
get_topics_for_keyword()
thd Thread handler
topics Table of topics
relations Table of m:m relation "topic/keyword"
find_fields Filled array of info for fields
key_id Primary index to use to find for keyword
RETURN VALUES
# number of topics found
names array of name of found topics (out)
name name of found topic (out)
description description of found topic (out)
example example for found topic (out)
NOTE
Field 'names' is set only if more than one topic was found.
Fields 'name', 'description', 'example' are set only if
exactly one topic was found.
*/
int get_topics_for_keyword(THD *thd, TABLE *topics, TABLE *relations,
struct st_find_field *find_fields, int16 key_id,
List<String> *names,
String *name, String *description, String *example)
{
uchar buff[8]; // Max int length
int count= 0;
int iindex_topic, iindex_relations;
Field *rtopic_id, *rkey_id;
DBUG_ENTER("get_topics_for_keyword");
if ((iindex_topic=
find_type(primary_key_name.str, &topics->s->keynames,
FIND_TYPE_NO_PREFIX) - 1) < 0 ||
(iindex_relations=
find_type(primary_key_name.str, &relations->s->keynames,
FIND_TYPE_NO_PREFIX) - 1) < 0)
{
my_message(ER_CORRUPT_HELP_DB, ER_THD(thd, ER_CORRUPT_HELP_DB), MYF(0));
DBUG_RETURN(-1);
}
rtopic_id= find_fields[help_relation_help_topic_id].field;
rkey_id= find_fields[help_relation_help_keyword_id].field;
if (topics->file->ha_index_init(iindex_topic,1) ||
relations->file->ha_index_init(iindex_relations,1))
{
if (topics->file->inited)
topics->file->ha_index_end();
my_message(ER_CORRUPT_HELP_DB, ER_THD(thd, ER_CORRUPT_HELP_DB), MYF(0));
DBUG_RETURN(-1);
}
rkey_id->store((longlong) key_id, TRUE);
rkey_id->get_key_image(buff, rkey_id->pack_length(), Field::itRAW);
int key_res= relations->file->ha_index_read_map(relations->record[0],
buff, (key_part_map) 1,
HA_READ_KEY_EXACT);
for ( ;
!key_res && key_id == (int16) rkey_id->val_int() ;
key_res= relations->file->ha_index_next(relations->record[0]))
{
uchar topic_id_buff[8];
longlong topic_id= rtopic_id->val_int();
Field *field= find_fields[help_topic_help_topic_id].field;
field->store((longlong) topic_id, TRUE);
field->get_key_image(topic_id_buff, field->pack_length(), Field::itRAW);
if (!topics->file->ha_index_read_map(topics->record[0], topic_id_buff,
(key_part_map)1, HA_READ_KEY_EXACT))
{
memorize_variant_topic(thd,topics,count,find_fields,
names,name,description,example);
count++;
}
}
topics->file->ha_index_end();
relations->file->ha_index_end();
DBUG_RETURN(count);
}
/*
Look for categories by mask
SYNOPSIS
search_categories()
thd THD for init_read_record
categories Table of categories
find_fields Filled array of info for fields
select Function to test for if matching help topic.
Normally 'help_vategory.name like 'bit%'
names List of found categories names (out)
res_id Primary index of found category (only if
found exactly one category)
RETURN VALUES
# Number of categories found
*/
int search_categories(THD *thd, TABLE *categories,
struct st_find_field *find_fields,
SQL_SELECT *select, List<String> *names, int16 *res_id)
{
Field *pfname= find_fields[help_category_name].field;
Field *pcat_id= find_fields[help_category_help_category_id].field;
int count= 0;
READ_RECORD read_record_info;
DBUG_ENTER("search_categories");
/* Should never happen. As this is part of help, we can ignore this */
if (init_read_record(&read_record_info, thd, categories, select, NULL,
1, 0, FALSE))
DBUG_RETURN(0);
while (!read_record_info.read_record())
{
if (select && !select->cond->val_bool())
continue;
String *lname= new (thd->mem_root) String;
get_field(thd->mem_root,pfname,lname);
if (++count == 1 && res_id)
*res_id= (int16) pcat_id->val_int();
names->push_back(lname, thd->mem_root);
}
end_read_record(&read_record_info);
DBUG_RETURN(count);
}
/*
Look for all topics or subcategories of category
SYNOPSIS
get_all_items_for_category()
thd Thread handler
items Table of items
pfname Field "name" in items
select "where" part of query..
res list of finded names
*/
void get_all_items_for_category(THD *thd, TABLE *items, Field *pfname,
SQL_SELECT *select, List<String> *res)
{
READ_RECORD read_record_info;
DBUG_ENTER("get_all_items_for_category");
/* Should never happen. As this is part of help, we can ignore this */
if (init_read_record(&read_record_info, thd, items, select, NULL, 1, 0,
FALSE))
DBUG_VOID_RETURN;
while (!read_record_info.read_record())
{
if (!select->cond->val_bool())
continue;
String *name= new (thd->mem_root) String();
get_field(thd->mem_root,pfname,name);
res->push_back(name, thd->mem_root);
}
end_read_record(&read_record_info);
DBUG_VOID_RETURN;
}
/**
Collect field names of HELP header that will be sent to a client
@param thd Thread data object
@param[out] field_list List of fields whose metadata should be collected for
sending to client
*/
static void fill_answer_1_fields(THD *thd, List<Item> *field_list)
{
MEM_ROOT *mem_root= thd->mem_root;
field_list->push_back(new (mem_root) Item_empty_string(thd, "name", 64),
mem_root);
field_list->push_back(new (mem_root) Item_empty_string(thd, "description",
1000),
mem_root);
field_list->push_back(new (mem_root) Item_empty_string(thd, "example", 1000),
mem_root);
}
/**
Send metadata of an answer on help request to a client
@param protocol protocol for sending
*/
static bool send_answer_1_metadata(Protocol *protocol)
{
List<Item> field_list;
fill_answer_1_fields(protocol->thd, &field_list);
return protocol->send_result_set_metadata(&field_list,
Protocol::SEND_NUM_ROWS |
Protocol::SEND_EOF);
}
/*
Send to client answer for help request
SYNOPSIS
send_answer_1()
protocol - protocol for sending
s1 - value of column "Name"
s2 - value of column "Description"
s3 - value of column "Example"
IMPLEMENTATION
Format used:
+----------+------------+------------+
|name |description |example |
+----------+------------+------------+
|String(64)|String(1000)|String(1000)|
+----------+------------+------------+
with exactly one row!
RETURN VALUES
1 Writing of head failed
-1 Writing of row failed
0 Successful send
*/
static int send_answer_1(Protocol *protocol, String *s1, String *s2, String *s3)
{
DBUG_ENTER("send_answer_1");
if (send_answer_1_metadata(protocol))
DBUG_RETURN(1);
protocol->prepare_for_resend();
protocol->store(s1);
protocol->store(s2);
protocol->store(s3);
if (protocol->write())
DBUG_RETURN(-1);
DBUG_RETURN(0);
}
/**
Collect field names of HELP header that will be sent to a client
@param thd Thread data object
@param[out] field_list List of fields whose metadata should be collected for
sending to client
@param for_category need column 'source_category_name'
*/
static void fill_header_2_fields(THD *thd, List<Item> *field_list,
bool for_category)
{
MEM_ROOT *mem_root= thd->mem_root;
if (for_category)
field_list->push_back(new (mem_root)
Item_empty_string(thd, "source_category_name", 64),
mem_root);
field_list->push_back(new (mem_root)
Item_empty_string(thd, "name", 64),
mem_root);
field_list->push_back(new (mem_root)
Item_empty_string(thd, "is_it_category", 1),
mem_root);
}
/*
Send to client help header
SYNOPSIS
send_header_2()
protocol - protocol for sending
for_category - need column 'source_category_name'
IMPLEMENTATION
+- -+
|+-------------------- | +----------+--------------+
||source_category_name | |name |is_it_category|
|+-------------------- | +----------+--------------+
||String(64) | |String(64)|String(1) |
|+-------------------- | +----------+--------------+
+- -+
RETURN VALUES
result of protocol->send_result_set_metadata
*/
static int send_header_2(Protocol *protocol, bool for_category)
{
DBUG_ENTER("send_header_2");
List<Item> field_list;
fill_header_2_fields(protocol->thd, &field_list, for_category);
DBUG_RETURN(protocol->send_result_set_metadata(&field_list,
Protocol::SEND_NUM_ROWS |
Protocol::SEND_EOF));
}
/*
strcmp for using in qsort
SYNOPSIS
strptrcmp()
ptr1 (const void*)&str1
ptr2 (const void*)&str2
RETURN VALUES
same as strcmp
*/
extern "C" int string_ptr_cmp(const void* ptr1, const void* ptr2)
{
String *str1= *(String**)ptr1;
String *str2= *(String**)ptr2;
uint length1= str1->length();
uint length2= str2->length();
int tmp= memcmp(str1->ptr(),str2->ptr(), MY_MIN(length1, length2));
if (tmp)
return tmp;
return (int) length2 - (int) length1;
}
/*
Send to client rows in format:
column1 : <name>
column2 : <is_it_category>
SYNOPSIS
send_variant_2_list()
protocol Protocol for sending
names List of names
cat Value of the column <is_it_category>
source_name name of category for all items..
RETURN VALUES
-1 Writing fail
0 Data was successfully send
*/
int send_variant_2_list(MEM_ROOT *mem_root, Protocol *protocol,
List<String> *names,
const char *cat, String *source_name)
{
DBUG_ENTER("send_variant_2_list");
String **pointers= (String**)alloc_root(mem_root,
sizeof(String*)*names->elements);
String **pos;
String **end= pointers + names->elements;
List_iterator<String> it(*names);
for (pos= pointers; pos!=end; (*pos++= it++))
;
my_qsort(pointers,names->elements,sizeof(String*),string_ptr_cmp);
for (pos= pointers; pos!=end; pos++)
{
protocol->prepare_for_resend();
if (source_name)
protocol->store(source_name);
protocol->store(*pos);
protocol->store(cat,1,&my_charset_latin1);
if (protocol->write())
DBUG_RETURN(-1);
}
DBUG_RETURN(0);
}
/*
Prepare simple SQL_SELECT table.* WHERE <Item>
SYNOPSIS
prepare_simple_select()
thd Thread handler
cond WHERE part of select
table goal table
error code of error (out)
RETURN VALUES
# created SQL_SELECT
*/
SQL_SELECT *prepare_simple_select(THD *thd, Item *cond,
TABLE *table, int *error)
{
cond->fix_fields_if_needed(thd, &cond); // can never fail
/* Assume that no indexes cover all required fields */
table->covering_keys.clear_all();
table->file->info(HA_STATUS_VARIABLE);
table->used_stat_records= table->file->stats.records;
SQL_SELECT *res= make_select(table, 0, 0, cond, 0, 0, error);
if (unlikely(!res) || unlikely(*error))
goto error;
(void) res->check_quick(thd, 0, HA_POS_ERROR, Item_func::BITMAP_ALL);
if (!res->quick || res->quick->reset() == 0)
return res;
error:
delete res;
return 0;
}
/*
Prepare simple SQL_SELECT table.* WHERE table.name LIKE mask
SYNOPSIS
prepare_select_for_name()
thd Thread handler
mask mask for compare with name
mlen length of mask
table goal table
pfname field "name" in table
error code of error (out)
RETURN VALUES
# created SQL_SELECT
*/
SQL_SELECT *prepare_select_for_name(THD *thd, const char *mask, size_t mlen,
TABLE *table, Field *pfname, int *error)
{
MEM_ROOT *mem_root= thd->mem_root;
Item *cond= new (mem_root)
Item_func_like(thd,
new (mem_root)
Item_field(thd, pfname),
new (mem_root) Item_string(thd, mask, (uint)mlen,
pfname->charset()),
new (mem_root) Item_string_ascii(thd, "\\"),
FALSE);
if (unlikely(thd->is_fatal_error))
return 0; // OOM
return prepare_simple_select(thd, cond, table, error);
}
/**
Initialize the TABLE_LIST with tables used in HELP statement handling.
@param thd Thread handler
@param tables Array of four TABLE_LIST objects to initialize with data
about the tables help_topic, help_category, help_relation,
help_keyword
*/
static void initialize_tables_for_help_command(THD *thd, TABLE_LIST *tables)
{
LEX_CSTRING MYSQL_HELP_TOPIC_NAME= {STRING_WITH_LEN("help_topic") };
LEX_CSTRING MYSQL_HELP_CATEGORY_NAME= {STRING_WITH_LEN("help_category") };
LEX_CSTRING MYSQL_HELP_RELATION_NAME= {STRING_WITH_LEN("help_relation") };
LEX_CSTRING MYSQL_HELP_KEYWORD_NAME= {STRING_WITH_LEN("help_keyword") };
tables[0].init_one_table(&MYSQL_SCHEMA_NAME, &MYSQL_HELP_TOPIC_NAME, 0,
TL_READ);
tables[1].init_one_table(&MYSQL_SCHEMA_NAME, &MYSQL_HELP_CATEGORY_NAME, 0,
TL_READ);
tables[2].init_one_table(&MYSQL_SCHEMA_NAME, &MYSQL_HELP_RELATION_NAME, 0,
TL_READ);
tables[3].init_one_table(&MYSQL_SCHEMA_NAME, &MYSQL_HELP_KEYWORD_NAME, 0,
TL_READ);
tables[0].next_global= tables[0].next_local=
tables[0].next_name_resolution_table= &tables[1];
tables[1].next_global= tables[1].next_local=
tables[1].next_name_resolution_table= &tables[2];
tables[2].next_global= tables[2].next_local=
tables[2].next_name_resolution_table= &tables[3];
}
/**
Setup tables and fields for query.
@param thd Thread handler
@param first_select_lex SELECT_LEX of the parsed statement
@param tables Array of tables used in handling of the HELP
statement
@param used_fields Array of fields used in handling of the HELP
statement
@return false on success, else true.
*/
template <size_t M, size_t N>
static bool init_items_for_help_command(THD *thd,
SELECT_LEX *first_select_lex,
TABLE_LIST (&tables)[M],
st_find_field (& used_fields)[N])
{
List<TABLE_LIST> leaves;
/*
Initialize tables and fields to be usable from items.
tables do not contain VIEWs => we can pass 0 as conds
*/
first_select_lex->context.table_list=
first_select_lex->context.first_name_resolution_table=
&tables[0];
if (setup_tables(thd, &first_select_lex->context,
&first_select_lex->top_join_list,
&tables[0], leaves, false, false))
return true;
memcpy((char*) used_fields, (char*) init_used_fields,
sizeof(used_fields[0]) * N);
if (init_fields(thd, &tables[0], used_fields, N))
return true;
for (size_t i= 0; i < M; i++)
tables[i].table->file->init_table_handle_for_HANDLER();
return false;
}
/**
Prepare (in the sense of prepared statement) the HELP statement.
@param thd Thread handler
@param mask string value passed to the HELP statement
@oaram[out] fields fields for result set metadata
@return false on success, else true.
*/
bool mysqld_help_prepare(THD *thd, const char *mask, List<Item> *fields)
{
TABLE_LIST tables[4];
st_find_field used_fields[array_elements(init_used_fields)];
SQL_SELECT *select;
List<String> topics_list;
Sql_mode_instant_remove sms(thd, MODE_PAD_CHAR_TO_FULL_LENGTH);
initialize_tables_for_help_command(thd, tables);
/*
HELP must be available under LOCK TABLES.
Reset and backup the current open tables state to
make it possible.
*/
start_new_trans new_trans(thd);
if (open_system_tables_for_read(thd, tables))
return true;
auto cleanup_and_return= [&](bool ret)
{
thd->commit_whole_transaction_and_close_tables();
new_trans.restore_old_transaction();
return ret;
};
if (init_items_for_help_command(thd, thd->lex->first_select_lex(),
tables, used_fields))
return cleanup_and_return(false);
size_t mlen= strlen(mask);
int error;
/*
Prepare the query 'SELECT * FROM help_topic WHERE name LIKE mask'
for execution
*/
if (!(select=
prepare_select_for_name(thd,mask, mlen, tables[0].table,
used_fields[help_topic_name].field, &error)))
return cleanup_and_return(true);
String name, description, example;
/*
Run the query 'SELECT * FROM help_topic WHERE name LIKE mask'
*/
int count_topics= search_topics(thd, tables[0].table, used_fields,
select, &topics_list,
&name, &description, &example);
delete select;
if (thd->is_error())
return cleanup_and_return(true);
if (count_topics == 0)
{
int UNINIT_VAR(key_id);
/*
Prepare the query 'SELECT * FROM help_keyword WHERE name LIKE mask'
for execution
*/
if (!(select=
prepare_select_for_name(thd, mask, mlen, tables[3].table,
used_fields[help_keyword_name].field,
&error)))
return cleanup_and_return(true);
/*
Run the query 'SELECT * FROM help_keyword WHERE name LIKE mask'
*/
count_topics= search_keyword(thd,tables[3].table, used_fields, select,
&key_id);
delete select;
count_topics= (count_topics != 1) ? 0 :
get_topics_for_keyword(thd, tables[0].table, tables[2].table,
used_fields, key_id, &topics_list, &name,
&description, &example);
}
if (count_topics == 0)
{
if (!(select=
prepare_select_for_name(thd, mask, mlen, tables[1].table,
used_fields[help_category_name].field,
&error)))
return cleanup_and_return(true);
List<String> categories_list;
int16 category_id;
int count_categories= search_categories(thd, tables[1].table, used_fields,
select,
&categories_list,&category_id);
delete select;
if (count_categories == 1)
fill_header_2_fields(thd, fields, true);
else
fill_header_2_fields(thd, fields, false);
}
else if (count_topics == 1)
fill_answer_1_fields(thd, fields);
else
fill_header_2_fields(thd, fields, false);
return cleanup_and_return(false);
}
/*
Server-side function 'help'
SYNOPSIS
mysqld_help()
thd Thread handler
RETURN VALUES
FALSE Success
TRUE Error and send_error already committed
*/
static bool mysqld_help_internal(THD *thd, const char *mask)
{
Protocol *protocol= thd->protocol;
SQL_SELECT *select;
st_find_field used_fields[array_elements(init_used_fields)];
TABLE_LIST tables[4];
List<String> topics_list, categories_list, subcategories_list;
String name, description, example;
int count_topics, count_categories, error;
size_t mlen= strlen(mask);
MEM_ROOT *mem_root= thd->mem_root;
DBUG_ENTER("mysqld_help");
initialize_tables_for_help_command(thd, tables);
/*
HELP must be available under LOCK TABLES.
Reset and backup the current open tables state to
make it possible.
*/
start_new_trans new_trans(thd);
if (open_system_tables_for_read(thd, tables))
goto error2;
if (init_items_for_help_command(thd, thd->lex->first_select_lex(),
tables, used_fields))
goto error;
if (!(select=
prepare_select_for_name(thd,mask,mlen,tables[0].table,
used_fields[help_topic_name].field,&error)))
goto error;
count_topics= search_topics(thd,tables[0].table,used_fields,
select,&topics_list,
&name, &description, &example);
delete select;
if (thd->is_error())
goto error;
if (count_topics == 0)
{
int UNINIT_VAR(key_id);
if (!(select=
prepare_select_for_name(thd,mask,mlen,tables[3].table,
used_fields[help_keyword_name].field,
&error)))
goto error;