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fixes for LVAL memo fields

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This commit is contained in:
brianb
2002-04-22 04:54:59 +00:00
parent 695cc9c00a
commit b8bb42ae2b
2 changed files with 67 additions and 21 deletions
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66
src/libmdb/data.c
View File

@@ -392,37 +392,61 @@ int mdb_is_fixed_col(MdbColumn *col)
}
static char *mdb_memo_to_string(MdbHandle *mdb, int start, int size)
{
short memo_len;
guint16 memo_len;
static char text[MDB_BIND_SIZE];
guint16 memo_flags;
guint16 row_start, row_stop;
guint8 memo_row;
guint32 lval_pg;
guint16 len;
if (size<MDB_MEMO_OVERHEAD) {
return "";
} else if (size == MDB_MEMO_OVERHEAD) {
/* If the only thing here is the field information, the
* data is linked. Go read it from another page.
* Question: Do we need to read and evaluate the whole page?
* Question: It seems to be the only record on the page. If
* it weren't, how do we know which record it is?
*
* WARNING: Assuming the storage area is at least 2048 bytes!
*/
}
/* The 16 bit integer at offset 0 is the length of the memo field.
* The 16 bit integer at offset 5 is the page it is stored on.
*/
memo_len = mdb_get_int16(mdb, start);
memo_len = mdb_get_int16(mdb, start);
memo_flags = mdb_get_int16(mdb, start+2);
if(mdb_read_alt_pg(mdb, mdb_get_int16(mdb, start+5)) != mdb->pg_size) {
/* Failed to read */
return "";
}
strncpy(text, &mdb->alt_pg_buf[mdb->pg_size - memo_len], memo_len);
return text;
} else {
if (memo_flags == 0x8000) {
/* inline memo field */
strncpy(text, &mdb->pg_buf[start + MDB_MEMO_OVERHEAD],
size - MDB_MEMO_OVERHEAD);
text[size - MDB_MEMO_OVERHEAD]='\0';
return text;
} else if (memo_flags == 0x4000) {
/* The 16 bit integer at offset 0 is the length of the memo field.
* The 24 bit integer at offset 5 is the page it is stored on.
*/
memo_row = mdb->pg_buf[start+4];
lval_pg = mdb_get_int24(mdb, start+5);
#if MDB_DEBUG
printf("Reading LVAL page %06x\n", lval_pg);
#endif
if(mdb_read_alt_pg(mdb, lval_pg) != mdb->pg_size) {
/* Failed to read */
return "";
}
/* swap the alt and regular page buffers, so we can call get_int16 */
mdb_swap_pgbuf(mdb);
if (memo_row) {
row_stop = mdb_get_int16(mdb, 10 + (memo_row - 1) * 2) & 0x0FFF;
} else {
row_stop = mdb->pg_size - 1;
}
row_start = mdb_get_int16(mdb, 10 + memo_row * 2);
#if MDB_DEBUG
printf("row num %d row start %d row stop %d\n", memo_row, row_start, row_stop);
#endif
len = row_stop - row_start;
strncpy(text, &mdb->pg_buf[row_start], len);
text[len]='\0';
/* make sure to swap page back */
mdb_swap_pgbuf(mdb);
return text;
} else {
fprintf(stderr,"Unhandled memo field flags = %04x\n", memo_flags);
return "";
}
#if 0
strncpy(text, &mdb->pg_buf[start + MDB_MEMO_OVERHEAD],

22
src/libmdb/file.c
View File

@@ -142,6 +142,14 @@ off_t offset = pg * mdb->pg_size;
}
return len;
}
mdb_swap_pgbuf(MdbHandle *mdb)
{
char tmpbuf[MDB_PGSIZE];
memcpy(tmpbuf,mdb->pg_buf, MDB_PGSIZE);
memcpy(mdb->pg_buf,mdb->alt_pg_buf, MDB_PGSIZE);
memcpy(mdb->alt_pg_buf,tmpbuf,MDB_PGSIZE);
}
unsigned char mdb_get_byte(MdbHandle *mdb, int offset)
{
unsigned char c;
@@ -163,6 +171,20 @@ int i;
return i;
}
gint32 mdb_get_int24(MdbHandle *mdb, int offset)
{
gint32 l;
unsigned char *c;
if (offset <0 || offset+3 > mdb->pg_size) return -1;
c = &mdb->pg_buf[offset];
l =c[2]; l<<=8;
l+=c[1]; l<<=8;
l+=c[0];
mdb->cur_pos+=3;
return l;
}
long mdb_get_int32(MdbHandle *mdb, int offset)
{
long l;