Category : C Source Code
Archive   : C_DBFS.ZIP
Filename : DB_IDX.C

 
Output of file : DB_IDX.C contained in archive : C_DBFS.ZIP
/****************************************************************************/
/* */
/* */
/* db_idx.c v1.3 (c) 1987-1990 Ken Harris */
/* */
/* */
/****************************************************************************/
/* */
/* This software is made available on an AS-IS basis. Unrestricted */
/* use is granted provided that the copyright notice remains intact. */
/* The author makes no warranties expressed or implied. */
/* */
/****************************************************************************/

#include "dblib.h"


/*
* db_add_idx - Add record to an index file
*/

void db_add_idx(df, user_data)
DATA_FILE df;
char *user_data;
{
FILE_HDR fh;
INDEX_HDR ihdr;
INDEX_REC irec;
BUFFER buf;
char *rbuf, *src, *dst;
ushort rec;
int cnt;

db_error = 0;

fh = (FILE_HDR) df->df_fhdr->buf_data;
buf = df->df_buf;
ihdr = (INDEX_HDR) buf->buf_data;
rbuf = buf->buf_data + sizeof(struct db_index_hdr);

if (!fh->fh_root_ptr)
{ db_get_next_avail(df, buf);
if (db_error) return;
}
else
{ db_find_insert_idx(df, user_data, fh->fh_key_size);
if (db_match_blk)
if (!(fh->fh_file_stat & DB_DUP_ALLOWED))
{ db_error = DB_DUP_NOT_ALLOWED;
return;
}
}

ihdr->idx_rec_cnt++;
rec = buf->buf_rec_inx;

db_add_blk = buf->buf_cur_blk;
db_add_rec = buf->buf_rec_inx;

if (rec <= ihdr->idx_rec_cnt)
{ src = rbuf + (rec - 1) * fh->fh_rec_size;
dst = src + fh->fh_rec_size;
cnt = (ihdr->idx_rec_cnt - rec + 1) * fh->fh_rec_size;
memcpy(dst, src, cnt);
}

irec = (INDEX_REC) src;
irec->idx_idx_ptr = 0;
dst = (char *) irec + fh->fh_ctl_size;
memcpy(dst, user_data, fh->fh_data_size);

fh->fh_rec_cnt++;

db_split_blk_idx(df);
if (db_error) return;

db_put_blk(df, df->df_fhdr);
}

/*
* db_find_insert_idx - Find Insert Point in an index File
*/

void db_find_insert_idx(df, key, key_size)
DATA_FILE df;
char *key;
int key_size;
{
FILE_HDR fh;
INDEX_HDR ihdr;
INDEX_REC irec;
BUFFER buf;
char *rbuf, *ikey;
ulong blk;
ushort rec;
int x;


db_error = 0;
db_match_blk = 0;
db_match_rec = 0;

fh = (FILE_HDR) df->df_fhdr->buf_data;
buf = df->df_buf;
ihdr = (INDEX_HDR) buf->buf_data;
blk = fh->fh_root_ptr;

if (!key_size) key_size = fh->fh_key_size;

while (blk)
{ db_get_blk(df, blk, buf);
if (db_error) return;

rbuf = buf->buf_data + sizeof(struct db_index_hdr);

for (rec=1; rec <= ihdr->idx_rec_cnt; rec++)
{ irec = (INDEX_REC) rbuf;
ikey = rbuf + fh->fh_ctl_size;

x = memcmp(key, ikey, key_size);

if (x == 0)
{ db_match_blk = blk;
db_match_rec = rec;
blk = irec->idx_idx_ptr;
break;
}

if (x < 0)
{ blk = irec->idx_idx_ptr;
break;
}

rbuf += fh->fh_rec_size;

if (rec == ihdr->idx_rec_cnt)
{ irec = (INDEX_REC) rbuf;
blk = irec->idx_idx_ptr;
}
}
}
buf->buf_rec_inx = rec;
}

/*
* db_split_blk_idx - Check for a block split
*/

void db_split_blk_idx(df)
DATA_FILE df;
{
FILE_HDR fh;
BUFFER buf, tmp, aux;
INDEX_HDR ihdr, thdr, ahdr;
INDEX_REC idx;
char *hold, *rbuf, *src, *dst;
ushort cnt, cnt1, cnt2;
ushort rec, left, right;

db_error = 0;


fh = (FILE_HDR) df->df_fhdr->buf_data;
buf = df->df_buf;
tmp = df->df_tmp;

ihdr = (INDEX_HDR) buf->buf_data;

if (ihdr->idx_rec_cnt <= fh->fh_recs_per_blk)
{ db_put_blk(df, buf);
return;
}

buf = df->df_tmp;
tmp = df->df_buf;
df->df_buf = buf;
df->df_tmp = tmp;
aux = df->df_aux;

db_get_next_avail(df, buf);
if (db_error) return;

ihdr = (INDEX_HDR) buf->buf_data;
thdr = (INDEX_HDR) tmp->buf_data;
ahdr = (INDEX_HDR) aux->buf_data;

left = tmp->buf_cur_blk;
right = buf->buf_cur_blk;

cnt1 = thdr->idx_rec_cnt / 2;
cnt2 = thdr->idx_rec_cnt - (cnt1 + 1);

ihdr->idx_parent = thdr->idx_parent;
ihdr->idx_rec_cnt = cnt2;

src = tmp->buf_data + sizeof(struct db_index_hdr)
+ (cnt1 + 1) * fh->fh_rec_size;
dst = buf->buf_data + sizeof(struct db_index_hdr);
cnt = (cnt2 + 1) * fh->fh_rec_size;
memcpy(dst, src, cnt);

db_put_blk(df, buf);
if (db_error) return;

if (db_add_blk == tmp->buf_cur_blk)
if (db_add_rec > cnt1 + 1)
{ db_add_blk = buf->buf_cur_blk;
db_add_rec -= cnt1 + 1;
}

rbuf = buf->buf_data + sizeof(struct db_index_hdr);
if (!thdr->idx_parent)
{ if (tmp->buf_cur_blk != fh->fh_root_ptr)
{ db_error = DB_INVALID_INDEX;
return;
}
db_get_next_avail(df, buf);
thdr->idx_parent = buf->buf_cur_blk;
fh->fh_root_ptr = buf->buf_cur_blk;
idx = (INDEX_REC) rbuf;
rec = 1;
}
else
{ db_get_blk(df, (long)thdr->idx_parent, buf);
if (db_error) return;

for (rec=1; rec <= ihdr->idx_rec_cnt+1; rec++)
{ idx = (INDEX_REC) rbuf;

if (idx->idx_idx_ptr == left)
break;

rbuf += fh->fh_rec_size;
}

if (idx->idx_idx_ptr != left)
{ db_error = DB_INVALID_INDEX;
return;
}
}

idx->idx_idx_ptr = right;

if (db_add_blk == tmp->buf_cur_blk)
if (db_add_rec == cnt1 + 1)
{ db_add_blk = buf->buf_cur_blk;
db_add_rec = rec;
}

src = rbuf;
dst = rbuf + fh->fh_rec_size;
cnt = ((ihdr->idx_rec_cnt + 1) - rec + 1) * fh->fh_rec_size;
memcpy(dst, src, cnt);

src = tmp->buf_data + sizeof(struct db_index_hdr)
+ cnt1 * fh->fh_rec_size;
dst = rbuf;
cnt = fh->fh_rec_size;
memcpy(dst, src, cnt);

idx->idx_idx_ptr = left;
ihdr->idx_rec_cnt++;

thdr->idx_rec_cnt = cnt1;
db_put_blk(df, tmp);
if (db_error) return;

db_get_blk(df, (long) right, tmp);
if (db_error) return;

if (thdr->idx_parent != buf->buf_cur_blk)
{ thdr->idx_parent = buf->buf_cur_blk;
db_put_blk(df, tmp);
if (db_error) return;
}

rbuf = tmp->buf_data + sizeof(struct db_index_hdr);
for (cnt=1; cnt <= thdr->idx_rec_cnt + 1; cnt++)
{ idx = (INDEX_REC) rbuf;

if (idx->idx_idx_ptr)
{ db_get_blk(df, (long)idx->idx_idx_ptr, aux);
if (db_error) return;

ahdr->idx_parent = tmp->buf_cur_blk;
db_put_blk(df, aux);
if (db_error) return;
}

rbuf += fh->fh_rec_size;
}

db_split_blk_idx(df);
}

/*
* db_read_first_idx - Read First Record in an Index File
*/

void db_read_first_idx(df, blk, user_data)
DATA_FILE df;
int blk;
char *user_data;
{
FILE_HDR fh;
BUFFER buf;
INDEX_HDR ihdr;
INDEX_REC idx;
char *src;


db_error = 0;

if (!blk)
{ db_error = DB_END_OF_FILE;
return;
}

fh = (FILE_HDR) df->df_fhdr->buf_data;
buf = df->df_buf;
ihdr = (INDEX_HDR) buf->buf_data;
idx = (INDEX_REC) (buf->buf_data + sizeof(struct db_index_hdr));

while (blk)
{ db_get_blk(df, (long) blk, buf);
if (db_error) return;


if (!ihdr->idx_rec_cnt)
{ db_error = DB_INVALID_INDEX;
return;
}

blk = idx->idx_idx_ptr;
}

src = buf->buf_data + sizeof(struct db_index_hdr) + fh->fh_ctl_size;
buf->buf_rec_inx = 1;
memcpy(user_data, src, fh->fh_data_size);
}

/*
* db_read_next_idx - Read Next Record in an Index File
*/

void db_read_next_idx(df, user_data)
DATA_FILE df;
char *user_data;
{
FILE_HDR fh;
BUFFER buf;
INDEX_HDR ihdr;
INDEX_REC idx;
char *src;


db_error = 0;

fh = (FILE_HDR) df->df_fhdr->buf_data;
buf = df->df_buf;
ihdr = (INDEX_HDR) buf->buf_data;

db_get_blk(df, df->df_prev_blk, buf);
if (db_error) return;

buf->buf_rec_inx = df->df_prev_rec;

if (buf->buf_rec_inx > ihdr->idx_rec_cnt)
{ while (buf->buf_rec_inx > ihdr->idx_rec_cnt)
{ db_get_parent_idx(df);
if (db_error) return;
}

src = buf->buf_data + sizeof(struct db_index_hdr)
+ (buf->buf_rec_inx - 1) * fh->fh_rec_size
+ fh->fh_ctl_size;

memcpy(user_data, src, fh->fh_data_size);
return;
}

buf->buf_rec_inx++;

idx = (INDEX_REC) (buf->buf_data + sizeof(struct db_index_hdr)
+ (buf->buf_rec_inx - 1) * fh->fh_rec_size);

if (idx->idx_idx_ptr)
{ db_read_first_idx(df, idx->idx_idx_ptr, user_data);
return;
}

if (buf->buf_rec_inx > ihdr->idx_rec_cnt)
{ df->df_prev_rec = buf->buf_rec_inx;
db_read_next_idx(df, user_data);
return;
}

src = ((char *) idx) + fh->fh_ctl_size;
memcpy(user_data, src, fh->fh_data_size);
}

/*
* db_read_last_idx - Read Last Record in an Index File
*/

void db_read_last_idx(df, blk, user_data)
DATA_FILE df;
int blk;
char *user_data;
{
FILE_HDR fh;
BUFFER buf;
INDEX_HDR ihdr;
INDEX_REC idx;
char *src;


db_error = 0;

if (!blk)
{ db_error = DB_END_OF_FILE;
return;
}

fh = (FILE_HDR) df->df_fhdr->buf_data;
buf = df->df_buf;
ihdr = (INDEX_HDR) buf->buf_data;

while (blk)
{ db_get_blk(df, (long) blk, buf);
if (db_error) return;


if (!ihdr->idx_rec_cnt)
{ db_error = DB_INVALID_INDEX;
return;
}

idx = (INDEX_REC) (buf->buf_data + sizeof(struct db_index_hdr)
+ ihdr->idx_rec_cnt * fh->fh_rec_size);

blk = idx->idx_idx_ptr;
}

src = buf->buf_data + sizeof(struct db_index_hdr)
+ (ihdr->idx_rec_cnt - 1) * fh->fh_rec_size + fh->fh_ctl_size;

buf->buf_rec_inx = ihdr->idx_rec_cnt;
memcpy(user_data, src, fh->fh_data_size);
}

/*
* db_read_prev_idx - Read Prev Record in an Index File
*/

void db_read_prev_idx(df, user_data)
DATA_FILE df;
char *user_data;
{
FILE_HDR fh;
BUFFER buf;
INDEX_HDR ihdr;
INDEX_REC idx;
char *src;


db_error = 0;

fh = (FILE_HDR) df->df_fhdr->buf_data;
buf = df->df_buf;
ihdr = (INDEX_HDR) buf->buf_data;

db_get_blk(df, df->df_prev_blk, buf);
if (db_error) return;

buf->buf_rec_inx = df->df_prev_rec;

idx = (INDEX_REC) (buf->buf_data + sizeof(struct db_index_hdr)
+ (buf->buf_rec_inx - 1) * fh->fh_rec_size);

if (buf->buf_rec_inx == 1 && idx->idx_idx_ptr == 0)
{ while (buf->buf_rec_inx == 1)
{ db_get_parent_idx(df);
if (db_error) return;
}

buf->buf_rec_inx--;

src = buf->buf_data + sizeof(struct db_index_hdr)
+ (buf->buf_rec_inx - 1) * fh->fh_rec_size
+ fh->fh_ctl_size;

memcpy(user_data, src, fh->fh_data_size);
return;
}

if (idx->idx_idx_ptr)
{ db_read_last_idx(df, idx->idx_idx_ptr, user_data);
return;
}

buf->buf_rec_inx--;

idx = (INDEX_REC) (buf->buf_data + sizeof(struct db_index_hdr)
+ (buf->buf_rec_inx - 1) * fh->fh_rec_size);

src = ((char *) idx) + fh->fh_ctl_size;
memcpy(user_data, src, fh->fh_data_size);
}


/*
* db_get_parent_idx - Get Parent Block
*/

void db_get_parent_idx(df)
DATA_FILE df;
{
FILE_HDR fh;
BUFFER buf;
INDEX_HDR ihdr;
INDEX_REC idx;
char *rbuf;
ushort hold_blk;
int rec;


db_error = 0;

fh = (FILE_HDR) df->df_fhdr->buf_data;
buf = df->df_buf;
rbuf = buf->buf_data + sizeof(struct db_index_hdr);
ihdr = (INDEX_HDR) buf->buf_data;

hold_blk = buf->buf_cur_blk;
if (!ihdr->idx_parent)
{ db_error = DB_END_OF_FILE;
return;
}

db_get_blk(df, (long)ihdr->idx_parent, buf);
if (db_error) return;

for (rec=1; rec <= ihdr->idx_rec_cnt + 1; rec++)
{ idx = (INDEX_REC) rbuf;

if (idx->idx_idx_ptr == hold_blk)
break;

rbuf += fh->fh_rec_size;
}

if (idx->idx_idx_ptr != hold_blk)
{ db_error = DB_INVALID_INDEX;
return;
}

buf->buf_rec_inx = rec;
}

/*
* db_find_first_idx - Find First Record
*/

void db_find_first_idx(df, user_data, key, key_size)
DATA_FILE df;
char *user_data;
char *key;
int key_size;
{
FILE_HDR fh;
BUFFER buf;
char *rbuf;

db_error = 0;

fh = (FILE_HDR) df->df_fhdr->buf_data;
buf = df->df_buf;

db_find_insert_idx(df, key, key_size);
if (db_error) return;

if (!db_match_blk)
{ db_error = DB_REC_NOT_FOUND;
return;
}

db_get_blk(df, db_match_blk, buf);
if (db_error) return;

buf->buf_rec_inx = db_match_rec;

rbuf = buf->buf_data + sizeof(struct db_index_hdr)
+ (buf->buf_rec_inx - 1) * fh->fh_rec_size + fh->fh_ctl_size;

memcpy(user_data, rbuf, fh->fh_data_size);
}

/*
* db_delete_idx - Delete an Index Record
*/

void db_delete_idx(df)
DATA_FILE df;
{
FILE_HDR fh;
BUFFER buf;
INDEX_HDR ihdr;
char *src, *dst;
int cnt, move_flag;

db_error = 0;

move_flag = db_move_to_leaf_idx(df);
if (db_error) return;

fh = (FILE_HDR) df->df_fhdr->buf_data;
buf = df->df_buf;
ihdr = (INDEX_HDR) buf->buf_data;

dst = buf->buf_data + sizeof(struct db_index_hdr)
+ (buf->buf_rec_inx - 1) * fh->fh_rec_size;
src = dst + fh->fh_rec_size;
cnt = (ihdr->idx_rec_cnt - buf->buf_rec_inx + 1) * fh->fh_rec_size;

if (cnt) memcpy(dst, src, cnt);

df->df_prev_blk = buf->buf_cur_blk;
df->df_prev_rec = buf->buf_rec_inx - 1;

ihdr->idx_rec_cnt--;
if (fh->fh_rec_cnt) fh->fh_rec_cnt--;

if (buf->buf_cur_blk == fh->fh_root_ptr && ihdr->idx_rec_cnt == 0)
{ fh->fh_root_ptr = 0;
db_free_rec(df, buf);
if (db_error) return;
}
else
{ db_balance_idx(df);
if (db_error) return;
}

db_put_blk(df, df->df_fhdr);

if (move_flag)
db_read_next(df, df->df_tmp->buf_data);
}

/*
* db_move_to_leaf_idx - Move index record to a leaf node
* before deleting it
*/

short db_move_to_leaf_idx(df)
DATA_FILE df;
{
FILE_HDR fh;
BUFFER buf, tmp;
INDEX_HDR ihdr, thdr;
INDEX_REC idx, tdx;
ulong blk;

db_error = 0;

fh = (FILE_HDR) df->df_fhdr->buf_data;
buf = df->df_buf;

tdx = (INDEX_REC)(buf->buf_data + sizeof(struct db_index_hdr)
+ (buf->buf_rec_inx - 1) * fh->fh_rec_size);

if (!tdx->idx_idx_ptr) return(0);

tmp = df->df_buf;
buf = df->df_tmp;
df->df_buf = buf;
df->df_tmp = tmp;

ihdr = (INDEX_HDR) buf->buf_data;
thdr = (INDEX_HDR) tmp->buf_data;

blk = tdx->idx_idx_ptr;

while (blk)
{ db_get_blk(df, blk, buf);
if (db_error) return(0);

idx = (INDEX_REC)(buf->buf_data + sizeof(struct db_index_hdr)
+ ihdr->idx_rec_cnt * fh->fh_rec_size);

blk = idx->idx_idx_ptr;
}

idx = (INDEX_REC)((char *) idx - fh->fh_rec_size);

idx->idx_idx_ptr = tdx->idx_idx_ptr;
memcpy(tdx, idx, fh->fh_rec_size);
idx->idx_idx_ptr = 0;

db_put_blk(df, tmp);
if (db_error) return(0);

buf->buf_rec_inx = ihdr->idx_rec_cnt;

return(1);
}

/*
* db_balance_idx - Rebalance tree after a delete
*/

void db_balance_idx(df)
DATA_FILE df;
{
FILE_HDR fh;
BUFFER buf, tmp, aux;
INDEX_HDR ihdr, thdr, ahdr;
INDEX_REC idx, tdx, adx;
int min_cnt, hold, cnt, op;
char *src, *dst;

db_error = 0;

fh = (FILE_HDR) df->df_fhdr->buf_data;
buf = df->df_buf;
ihdr = (INDEX_HDR) buf->buf_data;

if (buf->buf_cur_blk == fh->fh_root_ptr)
{ db_put_blk(df, buf);
return;
}

min_cnt = (fh->fh_recs_per_blk + 1) / 2;
if (ihdr->idx_rec_cnt >= min_cnt)
{ db_put_blk(df, buf);
return;
}

tmp = df->df_buf;
buf = df->df_tmp;
df->df_buf = buf;
df->df_tmp = tmp;
aux = df->df_aux;

thdr = (INDEX_HDR) tmp->buf_data;
ahdr = (INDEX_HDR) aux->buf_data;
ihdr = (INDEX_HDR) buf->buf_data;

buf->buf_cur_blk = tmp->buf_cur_blk;
buf->buf_rec_inx = tmp->buf_rec_inx;
ihdr->idx_parent = thdr->idx_parent;

db_get_parent_idx(df);
if (db_error) return;

idx = (INDEX_REC)(buf->buf_data + sizeof(struct db_index_hdr)
+ (buf->buf_rec_inx - 1) * fh->fh_rec_size);

if (buf->buf_rec_inx == 1)
{ adx = (INDEX_REC) ((char *) idx + fh->fh_rec_size);
op = 1;
}
else
{ idx = adx = (INDEX_REC) ((char *) idx - fh->fh_rec_size);
buf->buf_rec_inx--;
op = 2;
}

db_get_blk(df, (long)adx->idx_idx_ptr, aux);
if (db_error) return;

if (ahdr->idx_rec_cnt <= min_cnt) op += 2;

switch (op)
{ case 1: /* Rotate Left */
if (df->df_prev_blk == aux->buf_cur_blk &&
df->df_prev_rec == 0)
{ df->df_prev_blk = buf->buf_cur_blk;
df->df_prev_rec = buf->buf_rec_inx;
}

if (df->df_prev_blk == buf->buf_cur_blk &&
df->df_prev_rec == buf->buf_rec_inx)
{ df->df_prev_blk = tmp->buf_cur_blk;
df->df_prev_rec = thdr->idx_rec_cnt + 1;
}
else
if (df->df_prev_blk == aux->buf_cur_blk &&
df->df_prev_rec == 1)
{ df->df_prev_blk = buf->buf_cur_blk;
df->df_prev_rec = buf->buf_rec_inx;
}
else
if (df->df_prev_blk == aux->buf_cur_blk)
df->df_prev_rec--;

tdx = (INDEX_REC)(tmp->buf_data + sizeof(struct db_index_hdr)
+ thdr->idx_rec_cnt * fh->fh_rec_size);
adx = (INDEX_REC)(aux->buf_data + sizeof(struct db_index_hdr));

hold = tdx->idx_idx_ptr;
memcpy(tdx, idx, fh->fh_rec_size);
tdx->idx_idx_ptr = hold;
tdx = (INDEX_REC) ((char *) tdx + fh->fh_rec_size);
tdx->idx_idx_ptr = adx->idx_idx_ptr;
thdr->idx_rec_cnt++;
db_put_blk(df,tmp);
if (db_error) return;

if (tdx->idx_idx_ptr)
{ hold = tmp->buf_cur_blk;
db_get_blk(df, (long)tdx->idx_idx_ptr, tmp);
if (db_error) return;

thdr->idx_parent = hold;
db_put_blk(df, tmp);
if (db_error) return;
}

hold = idx->idx_idx_ptr;
memcpy(idx, adx, fh->fh_rec_size);
idx->idx_idx_ptr = hold;
db_put_blk(df, buf);
if (db_error) return;

src = (char*) adx + fh->fh_rec_size;
cnt = ahdr->idx_rec_cnt * fh->fh_rec_size;
memcpy(adx, src, cnt);
ahdr->idx_rec_cnt--;
db_put_blk(df, aux);
if (db_error) return;
return;

case 2: /* Rotate Right */
if (df->df_prev_blk == buf->buf_cur_blk &&
df->df_prev_rec == buf->buf_rec_inx)
{ df->df_prev_blk = tmp->buf_cur_blk;
df->df_prev_rec = 1;
}
else
if (df->df_prev_blk == aux->buf_cur_blk &&
df->df_prev_rec == ahdr->idx_rec_cnt)
{ df->df_prev_blk = buf->buf_cur_blk;
df->df_prev_rec = buf->buf_rec_inx;
}
else
if (df->df_prev_blk == tmp->buf_cur_blk)
df->df_prev_rec++;

tdx = (INDEX_REC)(tmp->buf_data + sizeof(struct db_index_hdr));
adx = (INDEX_REC)(aux->buf_data + sizeof(struct db_index_hdr)
+ ahdr->idx_rec_cnt * fh->fh_rec_size);

dst = (char *) tdx + fh->fh_rec_size;
cnt = (thdr->idx_rec_cnt + 1) * fh->fh_rec_size;
memcpy(dst, tdx, cnt);
memcpy(tdx, idx, fh->fh_rec_size);
tdx->idx_idx_ptr = adx->idx_idx_ptr;
thdr->idx_rec_cnt++;
db_put_blk(df, tmp);
if (db_error) return;

if (tdx->idx_idx_ptr)
{ hold = tmp->buf_cur_blk;
db_get_blk(df, (long)tdx->idx_idx_ptr, tmp);
if (db_error) return;

thdr->idx_parent = hold;
db_put_blk(df, tmp);
if (db_error) return;
}

hold = idx->idx_idx_ptr;
adx = (INDEX_REC) ((char *) adx - fh->fh_rec_size);
memcpy(idx, adx, fh->fh_rec_size);
idx->idx_idx_ptr = hold;
db_put_blk(df, buf);
if (db_error) return;

ahdr->idx_rec_cnt--;
db_put_blk(df, aux);
if (db_error) return;
return;

case 4: /* Merge Right */
tmp = df->df_aux;
aux = df->df_tmp;
df->df_aux = aux;
df->df_tmp = tmp;
thdr = (INDEX_HDR) tmp->buf_data;
ahdr = (INDEX_HDR) aux->buf_data;

case 3: /* Merge Left */
if (df->df_prev_blk == buf->buf_cur_blk &&
df->df_prev_rec == buf->buf_rec_inx)
{ df->df_prev_blk = tmp->buf_cur_blk;
df->df_prev_rec = thdr->idx_rec_cnt + 1;
}
else
if (df->df_prev_blk == aux->buf_cur_blk)
{ df->df_prev_blk = tmp->buf_cur_blk;
df->df_prev_rec += thdr->idx_rec_cnt + 1;
}

tdx = (INDEX_REC)(tmp->buf_data + sizeof(struct db_index_hdr)
+ thdr->idx_rec_cnt * fh->fh_rec_size);
adx = (INDEX_REC)(aux->buf_data + sizeof(struct db_index_hdr));

hold = tdx->idx_idx_ptr;
memcpy(tdx, idx, fh->fh_rec_size);
tdx->idx_idx_ptr = hold;
tdx = (INDEX_REC) ((char *) tdx + fh->fh_rec_size);
thdr->idx_rec_cnt++;

cnt = ahdr->idx_rec_cnt * fh->fh_rec_size + fh->fh_ctl_size;
memcpy(tdx, adx, cnt);
thdr->idx_rec_cnt += ahdr->idx_rec_cnt;

src = (char *) idx + fh->fh_rec_size;
cnt = (ihdr->idx_rec_cnt - buf->buf_rec_inx)
* fh->fh_rec_size + fh->fh_ctl_size;
memcpy(idx, src, cnt);
idx->idx_idx_ptr = tmp->buf_cur_blk;
ihdr->idx_rec_cnt--;

src = buf->buf_data + sizeof(struct db_index_hdr)
+ ihdr->idx_rec_cnt * fh->fh_rec_size + fh->fh_ctl_size;
cnt = fh->fh_rec_size;
memset(src, 0, cnt);

if (buf->buf_cur_blk == fh->fh_root_ptr)
if (!ihdr->idx_rec_cnt)
thdr->idx_parent = 0;

db_put_blk(df, tmp);
if (db_error) return;

hold = ahdr->idx_rec_cnt + 1;
db_free_rec(df, aux);
if (db_error) return;

for (cnt=1; cnt <= hold; cnt++)
{ if (tdx->idx_idx_ptr)
{ db_get_blk(df, (long)tdx->idx_idx_ptr, aux);
if (db_error) return;

ahdr->idx_parent = tmp->buf_cur_blk;
db_put_blk(df, aux);
if (db_error) return;
}
tdx = (INDEX_REC)((char *) tdx + fh->fh_rec_size);
}

if (buf->buf_cur_blk == fh->fh_root_ptr)
{ if (!ihdr->idx_rec_cnt)
{ fh->fh_root_ptr = tmp->buf_cur_blk;
db_free_rec(df, buf);
if (db_error) return;
}
else
{ db_put_blk(df, buf);
if (db_error) return;
}
}
else
{ db_balance_idx(df);
if (db_error) return;
}

return;
}
}

/*
* db_update_idx - Update an Index record
*/

void db_update_idx(df, user_data)
DATA_FILE df;
char *user_data;
{
INDEX_HDR ihdr;
FILE_HDR fh;
BUFFER buf;
char *rbuf;

db_error = 0;

fh = (FILE_HDR) df->df_fhdr->buf_data;
buf = df->df_buf;
ihdr = (INDEX_HDR) buf->buf_data;

if (ihdr->idx_rec_cnt < buf->buf_rec_inx)
{ db_error = DB_DELETED_REC;
return;
}

rbuf = buf->buf_data + sizeof(struct db_index_hdr)
+ (buf->buf_rec_inx - 1) * fh->fh_rec_size;

memcpy(rbuf+fh->fh_ctl_size, user_data, fh->fh_data_size);
db_put_blk(df, buf);
return;
}


  3 Responses to “Category : C Source Code
Archive   : C_DBFS.ZIP
Filename : DB_IDX.C

  1. Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!

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