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When a table status is requested by statement like SHOW TABLE STATUS and there is another statement (e.g. DELETE) sets number of records to 0 concurrently, we may get division by zero error, which crashes a server. This is fixed by using thread local variable x->records instead of shared info->state->records when we check if it is zero and divide by it. myisam/mi_info.c: Information schema does not lock a table when it requests table state info. If another thread sets info->state->records to 0 after we check if it is 0 and before we divide by it we may get division by zero error. Check and divide by local x->records variable instead of shared info->state->records.
139 lines
4.4 KiB
C
139 lines
4.4 KiB
C
/* Copyright (C) 2000-2001, 2003-2004 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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/* Return useful base information for an open table */
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#include "myisamdef.h"
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#ifdef __WIN__
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#include <sys/stat.h>
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#endif
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/* Get position to last record */
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my_off_t mi_position(MI_INFO *info)
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{
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return info->lastpos;
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}
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/* Get information about the table */
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/* if flag == 2 one get current info (no sync from database */
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int mi_status(MI_INFO *info, register MI_ISAMINFO *x, uint flag)
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{
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MY_STAT state;
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MYISAM_SHARE *share=info->s;
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DBUG_ENTER("mi_status");
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x->recpos = info->lastpos;
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if (flag == HA_STATUS_POS)
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DBUG_RETURN(0); /* Compatible with ISAM */
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if (!(flag & HA_STATUS_NO_LOCK))
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{
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pthread_mutex_lock(&share->intern_lock);
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VOID(_mi_readinfo(info,F_RDLCK,0));
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fast_mi_writeinfo(info);
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pthread_mutex_unlock(&share->intern_lock);
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}
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if (flag & HA_STATUS_VARIABLE)
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{
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x->records = info->state->records;
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x->deleted = info->state->del;
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x->delete_length = info->state->empty;
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x->data_file_length =info->state->data_file_length;
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x->index_file_length=info->state->key_file_length;
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x->keys = share->state.header.keys;
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x->check_time = share->state.check_time;
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x->mean_reclength= x->records ?
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(ulong) ((x->data_file_length - x->delete_length) / x->records) :
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(ulong) share->min_pack_length;
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}
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if (flag & HA_STATUS_ERRKEY)
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{
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x->errkey = info->errkey;
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x->dupp_key_pos= info->dupp_key_pos;
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}
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if (flag & HA_STATUS_CONST)
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{
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x->reclength = share->base.reclength;
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x->max_data_file_length=share->base.max_data_file_length;
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x->max_index_file_length=info->s->base.max_key_file_length;
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x->filenr = info->dfile;
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x->options = share->options;
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x->create_time=share->state.create_time;
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x->reflength= mi_get_pointer_length(share->base.max_data_file_length,
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myisam_data_pointer_size);
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x->record_offset= ((share->options &
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(HA_OPTION_PACK_RECORD | HA_OPTION_COMPRESS_RECORD)) ?
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0L : share->base.pack_reclength);
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x->sortkey= -1; /* No clustering */
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x->rec_per_key = share->state.rec_per_key_part;
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x->key_map = share->state.key_map;
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x->data_file_name = share->data_file_name;
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x->index_file_name = share->index_file_name;
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/*
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The following should be included even if we are not compiling with
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USE_RAID as the client must be able to request it!
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*/
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x->raid_type= share->base.raid_type;
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x->raid_chunks= share->base.raid_chunks;
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x->raid_chunksize= share->base.raid_chunksize;
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}
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if ((flag & HA_STATUS_TIME) && !my_fstat(info->dfile,&state,MYF(0)))
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x->update_time=state.st_mtime;
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else
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x->update_time=0;
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if (flag & HA_STATUS_AUTO)
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{
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x->auto_increment= share->state.auto_increment+1;
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if (!x->auto_increment) /* This shouldn't happen */
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x->auto_increment= ~(ulonglong) 0;
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}
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DBUG_RETURN(0);
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}
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/*
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Write a message to the error log.
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SYNOPSIS
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mi_report_error()
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file_name Name of table file (e.g. index_file_name).
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errcode Error number.
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DESCRIPTION
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This function supplies my_error() with a table name. Most error
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messages need one. Since string arguments in error messages are limited
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to 64 characters by convention, we ensure that in case of truncation,
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that the end of the index file path is in the message. This contains
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the most valuable information (the table name and the database name).
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RETURN
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void
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*/
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void mi_report_error(int errcode, const char *file_name)
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{
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size_t lgt;
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DBUG_ENTER("mi_report_error");
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DBUG_PRINT("enter",("errcode %d, table '%s'", errcode, file_name));
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if ((lgt= strlen(file_name)) > 64)
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file_name+= lgt - 64;
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my_error(errcode, MYF(ME_NOREFRESH), file_name);
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DBUG_VOID_RETURN;
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}
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