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mariadb/sql/sql_binlog.cc
Andrei Elkin 44c8d84908 MDEV-22520 Assertion gathered_length == thd->lex->comment.length failed in binlog_defragment 
The assert was caused by early cleanup of a user variable participant
in BINLOG @var,@var where it plays twice. That was unexpected by the base
code to clear its value prematurely.

Fixed with relocating the user var destruction after operations with
its value is over.
2020-05-18 15:14:16 +03:00

351 lines
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/*
Copyright (c) 2005, 2013, 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 St, Fifth Floor, Boston, MA 02110-1335 USA */
#include <my_global.h>
#include "sql_priv.h"
#include "sql_binlog.h"
#include "sql_parse.h" // check_global_access
#include "sql_acl.h" // *_ACL
#include "rpl_rli.h"
#include "slave.h" // apply_event_and_update_pos
#include "log_event.h" // Format_description_log_event,
// EVENT_LEN_OFFSET,
// EVENT_TYPE_OFFSET,
// FORMAT_DESCRIPTION_LOG_EVENT,
// START_EVENT_V3,
// Log_event_type,
// Log_event
/**
Copy fragments into the standard placeholder thd->lex->comment.str.
Compute the size of the (still) encoded total,
allocate and then copy fragments one after another.
The size can exceed max(max_allowed_packet) which is not a
problem as no String instance is created off this char array.
@param thd THD handle
@return
0 at success,
-1 otherwise.
*/
int binlog_defragment(THD *thd)
{
user_var_entry *entry[2];
LEX_STRING name[2]= { thd->lex->comment, thd->lex->ident };
/* compute the total size */
thd->lex->comment.str= NULL;
thd->lex->comment.length= 0;
for (uint k= 0; k < 2; k++)
{
entry[k]=
(user_var_entry*) my_hash_search(&thd->user_vars, (uchar*) name[k].str,
name[k].length);
if (!entry[k] || entry[k]->type != STRING_RESULT)
{
my_error(ER_WRONG_TYPE_FOR_VAR, MYF(0), name[k].str);
return -1;
}
thd->lex->comment.length += entry[k]->length;
}
thd->lex->comment.str= // to be freed by the caller
(char *) my_malloc(thd->lex->comment.length, MYF(MY_WME));
if (!thd->lex->comment.str)
{
my_error(ER_OUTOFMEMORY, MYF(ME_FATALERROR), 1);
return -1;
}
/* fragments are merged into allocated buf while the user var:s get reset */
size_t gathered_length= 0;
for (uint k=0; k < 2; k++)
{
memcpy(thd->lex->comment.str + gathered_length, entry[k]->value,
entry[k]->length);
gathered_length += entry[k]->length;
}
for (uint k=0; k < 2; k++)
update_hash(entry[k], true, NULL, 0, STRING_RESULT, &my_charset_bin, 0);
DBUG_ASSERT(gathered_length == thd->lex->comment.length);
return 0;
}
/**
Execute a BINLOG statement.
To execute the BINLOG command properly the server needs to know
which format the BINLOG command's event is in. Therefore, the first
BINLOG statement seen must be a base64 encoding of the
Format_description_log_event, as outputted by mysqlbinlog. This
Format_description_log_event is cached in
rli->description_event_for_exec.
@param thd Pointer to THD object for the client thread executing the
statement.
*/
void mysql_client_binlog_statement(THD* thd)
{
DBUG_ENTER("mysql_client_binlog_statement");
DBUG_PRINT("info",("binlog base64: '%*s'",
(int) (thd->lex->comment.length < 2048 ?
thd->lex->comment.length : 2048),
thd->lex->comment.str));
if (check_global_access(thd, SUPER_ACL))
DBUG_VOID_RETURN;
/*
option_bits will be changed when applying the event. But we don't expect
it be changed permanently after BINLOG statement, so backup it first.
It will be restored at the end of this function.
*/
ulonglong thd_options= thd->variables.option_bits;
/*
Allocation
*/
/*
If we do not have a Format_description_event, we create a dummy
one here. In this case, the first event we read must be a
Format_description_event.
*/
my_bool have_fd_event= TRUE;
int err;
Relay_log_info *rli;
rpl_group_info *rgi;
char *buf= NULL;
size_t coded_len= 0, decoded_len= 0;
rli= thd->rli_fake;
if (!rli)
{
rli= thd->rli_fake= new Relay_log_info(FALSE);
#ifdef HAVE_valgrind
rli->is_fake= TRUE;
#endif
have_fd_event= FALSE;
}
if (rli && !rli->relay_log.description_event_for_exec)
{
rli->relay_log.description_event_for_exec=
new Format_description_log_event(4);
have_fd_event= FALSE;
}
if (!(rgi= thd->rgi_fake))
rgi= thd->rgi_fake= new rpl_group_info(rli);
rgi->thd= thd;
const char *error= 0;
Log_event *ev = 0;
my_bool is_fragmented= FALSE;
/*
Out of memory check
*/
if (!(rli && rli->relay_log.description_event_for_exec))
{
my_error(ER_OUTOFMEMORY, MYF(ME_FATALERROR), 1); /* needed 1 bytes */
goto end;
}
rli->sql_driver_thd= thd;
rli->no_storage= TRUE;
if (unlikely(is_fragmented= thd->lex->comment.str && thd->lex->ident.str))
if (binlog_defragment(thd))
goto end;
if (!(coded_len= thd->lex->comment.length))
{
my_error(ER_SYNTAX_ERROR, MYF(0));
goto end;
}
decoded_len= base64_needed_decoded_length(coded_len);
if (!(buf= (char *) my_malloc(decoded_len, MYF(MY_WME))))
{
my_error(ER_OUTOFMEMORY, MYF(ME_FATALERROR), 1);
goto end;
}
for (char const *strptr= thd->lex->comment.str ;
strptr < thd->lex->comment.str + thd->lex->comment.length ; )
{
char const *endptr= 0;
int bytes_decoded= base64_decode(strptr, coded_len, buf, &endptr,
MY_BASE64_DECODE_ALLOW_MULTIPLE_CHUNKS);
#ifndef HAVE_valgrind
/*
This debug printout should not be used for valgrind builds
since it will read from unassigned memory.
*/
DBUG_PRINT("info",
("bytes_decoded: %d strptr: 0x%lx endptr: 0x%lx ('%c':%d)",
bytes_decoded, (long) strptr, (long) endptr, *endptr,
*endptr));
#endif
if (bytes_decoded < 0)
{
my_error(ER_BASE64_DECODE_ERROR, MYF(0));
goto end;
}
else if (bytes_decoded == 0)
break; // If no bytes where read, the string contained only whitespace
DBUG_ASSERT(bytes_decoded > 0);
DBUG_ASSERT(endptr > strptr);
coded_len-= endptr - strptr;
strptr= endptr;
/*
Now we have one or more events stored in the buffer. The size of
the buffer is computed based on how much base64-encoded data
there were, so there should be ample space for the data (maybe
even too much, since a statement can consist of a considerable
number of events).
TODO: Switch to use a stream-based base64 encoder/decoder in
order to be able to read exactly what is necessary.
*/
DBUG_PRINT("info",("binlog base64 decoded_len: %lu bytes_decoded: %d",
(ulong) decoded_len, bytes_decoded));
/*
Now we start to read events of the buffer, until there are no
more.
*/
for (char *bufptr= buf ; bytes_decoded > 0 ; )
{
/*
Checking that the first event in the buffer is not truncated.
*/
ulong event_len;
if (bytes_decoded < EVENT_LEN_OFFSET + 4 ||
(event_len= uint4korr(bufptr + EVENT_LEN_OFFSET)) >
(uint) bytes_decoded)
{
my_error(ER_SYNTAX_ERROR, MYF(0));
goto end;
}
DBUG_PRINT("info", ("event_len=%lu, bytes_decoded=%d",
event_len, bytes_decoded));
/*
If we have not seen any Format_description_event, then we must
see one; it is the only statement that can be read in base64
without a prior Format_description_event.
*/
if (!have_fd_event)
{
int type = (uchar)bufptr[EVENT_TYPE_OFFSET];
if (type == FORMAT_DESCRIPTION_EVENT || type == START_EVENT_V3)
have_fd_event= TRUE;
else
{
my_error(ER_NO_FORMAT_DESCRIPTION_EVENT_BEFORE_BINLOG_STATEMENT,
MYF(0), Log_event::get_type_str((Log_event_type)type));
goto end;
}
}
ev= Log_event::read_log_event(bufptr, event_len, &error,
rli->relay_log.description_event_for_exec,
0);
DBUG_PRINT("info",("binlog base64 err=%s", error));
if (!ev)
{
/*
This could actually be an out-of-memory, but it is more likely
causes by a bad statement
*/
my_error(ER_SYNTAX_ERROR, MYF(0));
goto end;
}
bytes_decoded -= event_len;
bufptr += event_len;
DBUG_PRINT("info",("ev->get_type_code()=%d", ev->get_type_code()));
ev->thd= thd;
/*
We go directly to the application phase, since we don't need
to check if the event shall be skipped or not.
Neither do we have to update the log positions, since that is
not used at all: the rli_fake instance is used only for error
reporting.
*/
#if !defined(MYSQL_CLIENT) && defined(HAVE_REPLICATION)
ulonglong save_skip_replication=
thd->variables.option_bits & OPTION_SKIP_REPLICATION;
thd->variables.option_bits=
(thd->variables.option_bits & ~OPTION_SKIP_REPLICATION) |
(ev->flags & LOG_EVENT_SKIP_REPLICATION_F ?
OPTION_SKIP_REPLICATION : 0);
err= ev->apply_event(rgi);
thd->variables.option_bits=
(thd->variables.option_bits & ~OPTION_SKIP_REPLICATION) |
save_skip_replication;
#else
err= 0;
#endif
/*
Format_description_log_event should not be deleted because it
will be used to read info about the relay log's format; it
will be deleted when the SQL thread does not need it,
i.e. when this thread terminates.
*/
if (ev->get_type_code() != FORMAT_DESCRIPTION_EVENT)
delete ev;
ev= 0;
if (err)
{
/*
TODO: Maybe a better error message since the BINLOG statement
now contains several events.
*/
my_error(ER_UNKNOWN_ERROR, MYF(0));
goto end;
}
}
}
DBUG_PRINT("info",("binlog base64 execution finished successfully"));
my_ok(thd);
end:
if (unlikely(is_fragmented))
my_free(thd->lex->comment.str);
thd->variables.option_bits= thd_options;
rgi->slave_close_thread_tables(thd);
my_free(buf);
DBUG_VOID_RETURN;
}
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