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/* Copyright (c) 2000, 2025, 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, version 2.0,
as published by the Free Software Foundation.
This program is designed to work with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation. The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have either included with
the program or referenced in the documentation.
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, version 2.0, 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 02110-1301 USA */
/*
Read a record with random-access. The position to the record must
get by myrg_info(). The next record can be read with pos= -1 */
#include <sys/types.h>
#include "my_dbug.h"
#include "my_inttypes.h"
#include "my_thread_local.h"
#include "storage/myisam/myisamdef.h"
#include "storage/myisammrg/myrg_def.h"
static MYRG_TABLE *find_table(MYRG_TABLE *start, MYRG_TABLE *end,
ulonglong pos);
/*
If filepos == HA_OFFSET_ERROR, read next
Returns same as mi_rrnd:
0 = Ok.
HA_ERR_RECORD_DELETED = Record is deleted.
HA_ERR_END_OF_FILE = EOF.
*/
int myrg_rrnd(MYRG_INFO *info, uchar *buf, ulonglong filepos) {
int error;
MI_INFO *isam_info;
DBUG_TRACE;
DBUG_PRINT("info", ("offset: %lu", (ulong)filepos));
if (filepos == HA_OFFSET_ERROR) {
if (!info->current_table) {
if (info->open_tables == info->end_table) { /* No tables */
set_my_errno(HA_ERR_END_OF_FILE);
return HA_ERR_END_OF_FILE;
}
isam_info = (info->current_table = info->open_tables)->table;
filepos = isam_info->s->pack.header_length;
isam_info->lastinx = (uint)-1; /* Can't forward or backward */
} else {
isam_info = info->current_table->table;
filepos = isam_info->nextpos;
}
for (;;) {
isam_info->update &= HA_STATE_CHANGED;
if ((error = (*isam_info->s->read_rnd)(isam_info, (uchar *)buf,
(my_off_t)filepos, true)) !=
HA_ERR_END_OF_FILE)
return error;
if (info->current_table + 1 == info->end_table) return HA_ERR_END_OF_FILE;
info->current_table++;
info->last_used_table = info->current_table;
info->current_table->file_offset =
info->current_table[-1].file_offset +
info->current_table[-1].table->state->data_file_length;
isam_info = info->current_table->table;
filepos = isam_info->s->pack.header_length;
isam_info->lastinx = (uint)-1;
}
}
info->current_table =
find_table(info->open_tables, info->end_table - 1, filepos);
isam_info = info->current_table->table;
isam_info->update &= HA_STATE_CHANGED;
return (*isam_info->s->read_rnd)(
isam_info, (uchar *)buf,
(my_off_t)(filepos - info->current_table->file_offset), false);
}
/* Find which table to use according to file-pos */
static MYRG_TABLE *find_table(MYRG_TABLE *start, MYRG_TABLE *end,
ulonglong pos) {
MYRG_TABLE *mid;
DBUG_TRACE;
while (start != end) {
mid = start + ((uint)(end - start) + 1) / 2;
if (mid->file_offset > pos)
end = mid - 1;
else
start = mid;
}
DBUG_PRINT("info",
("offset: %lu, table: %s", (ulong)pos, start->table->filename));
return start;
}
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