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5.0 version of fix for:

Browse Source 
Bug #23667 "CREATE TABLE LIKE is not isolated from alteration
             by other connections"
 Bug #18950 "CREATE TABLE LIKE does not obtain LOCK_open"
As well as:
 Bug #25578 "CREATE TABLE LIKE does not require any privileges
             on source table".

The first and the second bugs resulted in various errors and wrong
binary log order when one tried to execute concurrently CREATE TABLE LIKE
statement and DDL statements on source table or DML/DDL statements on its
target table.

The problem was caused by incomplete protection/table-locking against
concurrent statements implemented in mysql_create_like_table() routine.
We solve it by simply implementing such protection in proper way (see
comment for sql_table.cc for details).

The third bug allowed user who didn't have any privileges on table create
its copy and therefore circumvent privilege check for SHOW CREATE TABLE.

This patch solves this problem by adding privilege check, which was missing.

Finally it also removes some duplicated code from mysql_create_like_table().

Note that, altough tests covering concurrency-related aspects of CREATE TABLE
LIKE behaviour will only be introduced in 5.1, they were run manually for
this patch as well.
This commit is contained in:
dlenev@mockturtle.local
2007-05-23 15:22:13 +04:00
parent 1016aa36ec
commit c07b3670d7
7 changed files with 146 additions and 77 deletions
Download Patch File Download Diff File Expand all files Collapse all files

91
sql/sql_table.cc
View File

@ -2718,7 +2718,8 @@ bool mysql_preload_keys(THD* thd, TABLE_LIST* tables)
SYNOPSIS
mysql_create_like_table()
thd Thread object
table Table list (one table only)
table Table list element for target table
src_table Table list element for source table
create_info Create info
table_ident Src table_ident
@ -2727,61 +2728,52 @@ bool mysql_preload_keys(THD* thd, TABLE_LIST* tables)
TRUE error
*/
bool mysql_create_like_table(THD* thd, TABLE_LIST* table,
HA_CREATE_INFO *create_info,
Table_ident *table_ident)
bool mysql_create_like_table(THD* thd, TABLE_LIST* table, TABLE_LIST *src_table,
HA_CREATE_INFO *create_info)
{
TABLE **tmp_table;
char src_path[FN_REFLEN], dst_path[FN_REFLEN];
char *db= table->db;
char *table_name= table->table_name;
char *src_db;
char *src_table= table_ident->table.str;
int err;
bool res= TRUE;
db_type not_used;
TABLE_LIST src_tables_list;
DBUG_ENTER("mysql_create_like_table");
DBUG_ASSERT(table_ident->db.str); /* Must be set in the parser */
src_db= table_ident->db.str;
/*
Validate the source table
By taking name-lock on the source table and holding LOCK_open mutex we
ensure that no concurrent DDL operation will mess with this table. Note
that holding only name-lock is not enough for this, because it won't block
other DDL statements that only take name-locks on the table and don't
open it (simple name-locks are not exclusive between each other).
Unfortunately, simply opening this table is not enough for our purproses,
since in 5.0 ALTER TABLE may change .FRM files on disk even if there are
connections that still have old version of table open. This 'optimization'
was removed in 5.1 so there we open the source table instead of taking
name-lock on it.
We also have to acquire LOCK_open to make copying of .frm file, call to
ha_create_table() and binlogging atomic against concurrent DML and DDL
operations on the target table.
*/
if (table_ident->table.length > NAME_LEN ||
(table_ident->table.length &&
check_table_name(src_table,table_ident->table.length)))
{
my_error(ER_WRONG_TABLE_NAME, MYF(0), src_table);
DBUG_RETURN(TRUE);
}
if (!src_db || check_db_name(src_db))
{
my_error(ER_WRONG_DB_NAME, MYF(0), src_db ? src_db : "NULL");
DBUG_RETURN(-1);
}
bzero((gptr)&src_tables_list, sizeof(src_tables_list));
src_tables_list.db= src_db;
src_tables_list.table_name= src_table;
if (lock_and_wait_for_table_name(thd, &src_tables_list))
if (lock_and_wait_for_table_name(thd, src_table))
goto err;
if ((tmp_table= find_temporary_table(thd, src_db, src_table)))
pthread_mutex_lock(&LOCK_open);
if ((tmp_table= find_temporary_table(thd, src_table->db,
src_table->table_name)))
strxmov(src_path, (*tmp_table)->s->path, reg_ext, NullS);
else
{
strxmov(src_path, mysql_data_home, "/", src_db, "/", src_table,
reg_ext, NullS);
strxmov(src_path, mysql_data_home, "/", src_table->db, "/",
src_table->table_name, reg_ext, NullS);
/* Resolve symlinks (for windows) */
fn_format(src_path, src_path, "", "", MYF(MY_UNPACK_FILENAME));
if (lower_case_table_names)
my_casedn_str(files_charset_info, src_path);
if (access(src_path, F_OK))
{
my_error(ER_BAD_TABLE_ERROR, MYF(0), src_table);
my_error(ER_BAD_TABLE_ERROR, MYF(0), src_table->table_name);
goto err;
}
}
@ -2791,10 +2783,13 @@ bool mysql_create_like_table(THD* thd, TABLE_LIST* table,
*/
if (mysql_frm_type(thd, src_path, &not_used) != FRMTYPE_TABLE)
{
my_error(ER_WRONG_OBJECT, MYF(0), src_db, src_table, "BASE TABLE");
my_error(ER_WRONG_OBJECT, MYF(0), src_table->db, src_table->table_name,
"BASE TABLE");
goto err;
}
DBUG_EXECUTE_IF("sleep_create_like_before_check_if_exists", my_sleep(6000000););
/*
Validate the destination table
@ -2810,27 +2805,22 @@ bool mysql_create_like_table(THD* thd, TABLE_LIST* table,
}
else
{
bool exists;
strxmov(dst_path, mysql_data_home, "/", db, "/", table_name,
reg_ext, NullS);
fn_format(dst_path, dst_path, "", "", MYF(MY_UNPACK_FILENAME));
/*
Note that this critical section should actually cover most
of mysql_create_like_table() function. See bugs #18950 and
#23667 for more information.
Also note that starting from 5.1 we obtain name-lock on
target table instead of inspecting table cache for presence
Note that starting from 5.1 we obtain name-lock on target
table instead of inspecting table cache for presence
of open placeholders (see comment in mysql_create_table()).
*/
pthread_mutex_lock(&LOCK_open);
exists= (table_cache_has_open_placeholder(thd, db, table_name) ||
!access(dst_path, F_OK));
pthread_mutex_unlock(&LOCK_open);
if (exists)
if (table_cache_has_open_placeholder(thd, db, table_name) ||
!access(dst_path, F_OK))
goto table_exists;
}
DBUG_EXECUTE_IF("sleep_create_like_before_copy", my_sleep(6000000););
/*
Create a new table by copying from source table
*/
@ -2843,6 +2833,8 @@ bool mysql_create_like_table(THD* thd, TABLE_LIST* table,
goto err;
}
DBUG_EXECUTE_IF("sleep_create_like_before_ha_create", my_sleep(6000000););
/*
As mysql_truncate don't work on a new table at this stage of
creation, instead create the table directly (for both normal
@ -2867,6 +2859,8 @@ bool mysql_create_like_table(THD* thd, TABLE_LIST* table,
goto err; /* purecov: inspected */
}
DBUG_EXECUTE_IF("sleep_create_like_before_binlogging", my_sleep(6000000););
// Must be written before unlock
if (mysql_bin_log.is_open())
{
@ -2891,8 +2885,7 @@ table_exists:
my_error(ER_TABLE_EXISTS_ERROR, MYF(0), table_name);
err:
pthread_mutex_lock(&LOCK_open);
unlock_table_name(thd, &src_tables_list);
unlock_table_name(thd, src_table);
pthread_mutex_unlock(&LOCK_open);
DBUG_RETURN(res);
}