support routine for index writes

port fix from data.c to mdb_crack_row?()
more tdef4 dissector work in gmdb2

ChangeLog

@@ -1,7 +1,10 @@
 Sat Feb 14 14:41:00 EST 2004	Brian Bruns <brian@bruns.com>
 	* include/.cvsignore: add mdbver.h
 	* include/mdbtools: remove variables for old index algorithm.
-	* src/libmdb/index.c: missing return in mdb_index_find_next, remove old index algorithm
+	* src/libmdb/index.c: missing return in mdb_index_find_next, remove old index algorithm.  Add mdb_index_pack_bitmap() function and rename unpack routine to match.
+	* src/libmdb/write.c: port fix from data.c to mdb_crack_row() routines
+	* src/gmdb2/debug.c: more tdef4 dissector work
+	* HACKING: column deletion revelation/thoughts.
 
 Fri Feb 13 12:51:50 EST 2004	Brian Bruns <brian@bruns.com>
 

HACKING

@@ -467,7 +467,17 @@ Column Type may be one of the following (not complete):
     UNKNOWN_0D      = 0x0D
     REPID           = 0x0F /* GUID */
 
+Notes on deleted columns:
 
+If a fixed length column is deleted the offset_F field will contain the values 
+of the original row definition.  Thus is the number of columns on the row does 
+not match the number in the tdef, the offset_F field could be used to return 
+the proper data.  No idea how multiple column deletions are handled, my instinct
+is that Access can only handle a single column deletion event (which may involve
+more than one column if new rows have not been added) without touching all the 
+rows.
+
+Don't know if variable columns work by the same mechanism yet.  Stay tuned.
 
 Page Usage Maps
 ---------------

src/gmdb2/debug.c

@@ -688,6 +688,22 @@ GtkTreeIter *node, *container;
 
 	gmdb_debug_add_page_ptr(store, NULL, fbuf, "Used Pages Pointer", offset+55);
 	gmdb_debug_add_page_ptr(store, NULL, fbuf, "Pages Freespace Pointer", offset+59);
+
+	container = gmdb_debug_add_item(store, NULL, "Index Entries", -1, -1);
+	for (i=0;i<num_idx;i++) {
+		snprintf(str, 100, "Index %d", i+1);
+		node = gmdb_debug_add_item(store, container, str, offset+63+(12*i), offset+63+(12*i)+11);
+		//gmdb_debug_dissect_index1(store, node, fbuf, offset+63+(12*i));
+	}
+	newbase = offset + 63 + (12*i);
+
+	container = gmdb_debug_add_item(store, NULL, "Column Data", -1, -1);
+	for (i=0;i<num_cols;i++) {
+		snprintf(str, 100, "Column %d", i+1);
+		node = gmdb_debug_add_item(store, container, str, newbase + (25*i), newbase + (25*i) + 24);
+		//gmdb_debug_dissect_column(store, node, fbuf, newbase + (25*i));
+	}
+	newbase += 25*num_cols;
 }
 void 
 gmdb_debug_dissect_tabledef_pg3(GtkTreeStore *store, char *fbuf, int offset, int len)

src/libmdb/index.c

@@ -313,11 +313,49 @@ mdb_index_test_sargs(MdbHandle *mdb, MdbIndex *idx, unsigned char *buf, int len)
 	}
 	return 1;
 }
+/*
+ * pack the pages bitmap
+ */
+int
+mdb_index_pack_bitmap(MdbHandle *mdb, MdbIndexPage *ipg)
+{
+	int mask_bit = 0;
+	int mask_pos = 0x16;
+	int mask_byte;
+	int elem = 0;
+	int len, start, i;
+
+	start = ipg->idx_starts[elem++];
+
+	while (start) {
+		len = ipg->idx_starts[elem] - start;
+		fprintf(stdout, "len is %d\n", len);
+		for (i=0; i < len; i++) {
+			mask_bit++;
+			if (mask_bit==8) {
+				mask_bit=0;
+				mdb->pg_buf[mask_pos++] = mask_byte;
+				mask_byte = 0;
+			}
+			/* upon reaching the len, set the bit */
+		}
+		mask_byte = (1 << mask_bit) | mask_byte;
+		fprintf(stdout, "mask byte is %02x at %d\n", mask_byte, mask_pos);
+		start = ipg->idx_starts[elem++];
+	}
+	/* flush the last byte if any */
+	mdb->pg_buf[mask_pos++] = mask_byte;
+	/* remember to zero the rest of the bitmap */
+	for (i = mask_pos; i < 0xf8; i++) {
+		mdb->pg_buf[mask_pos++] = 0;
+	}
+	return 0;
+}
 /*
  * unpack the pages bitmap
  */
 int
-mdb_index_unpack_page(MdbHandle *mdb, MdbIndexPage *ipg)
+mdb_index_unpack_bitmap(MdbHandle *mdb, MdbIndexPage *ipg)
 {
 	int mask_bit = 0;
 	int mask_pos = 0x16;
@@ -364,7 +402,7 @@ mdb_index_find_next_on_page(MdbHandle *mdb, MdbIndexPage *ipg)
 	/* if this page has not been unpacked to it */
 	if (!ipg->idx_starts[0]){
 		//fprintf(stdout, "Unpacking page %d\n", ipg->pg);
-		mdb_index_unpack_page(mdb, ipg);
+		mdb_index_unpack_bitmap(mdb, ipg);
 	}
 
 	
@@ -377,8 +415,6 @@ mdb_index_find_next_on_page(MdbHandle *mdb, MdbIndexPage *ipg)
 }
 void mdb_index_page_reset(MdbIndexPage *ipg)
 {
-	int i;
-
 	ipg->offset = 0xf8; /* start byte of the index entries */
 	ipg->start_pos=0;
 	ipg->len = 0; 

src/libmdb/write.c

@@ -167,7 +167,7 @@ int eod, len; /* end of data */
 				next_col = mdb_pg_get_int16(mdb, var_entry_pos);
 				len = next_col - col_start;
 			} /* if found==var_cols */
-			if (len<0) len+=256;
+			while (len<0) len+=256;
 			fields[totcols].start = row_start + col_start;
 			fields[totcols].value = &mdb->pg_buf[row_start +col_start];
 			fields[totcols++].siz = len;
@@ -302,7 +302,7 @@ int eod, len; /* end of data */
 					var_cols_found - 1;
 				len=mdb->pg_buf[var_entry_pos] - mdb->pg_buf[var_entry_pos+1];
 			} /* if found==var_cols */
-			if (len<0) len+=256;
+			while (len<0) len+=256;
 			fields[totcols].start = row_start + col_start;
 			fields[totcols].value = &mdb->pg_buf[row_start +col_start];
 			fields[totcols++].siz = len;