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A fix for bug #669739 that became a mdb_crack_row4 rewrite. Thanks to Luciano Miguel Wolf and Alexandre Horst for the bug analysis and the initial patch.
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whydoubt
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@ -1,3 +1,11 @@
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Wed Aug 4 21:22:46 CDT 2004 Jeff Smith <whydoubt@yahoo.com>
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* HACKING:
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* include/mdbtools.h:
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* src/libmdb/write.c:
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* src/libmdb/table.c: A fix for bug #669739 that became a mdb_crack_row4
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rewrite. Thanks to Luciano Miguel Wolf and Alexandre Horst for
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the bug analysis and the initial patch.
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Sat Jul 17 23:09:40 CDT 2004 Jeff Smith <whydoubt@yahoo.com>
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* src/libmdb/catalog.c: Clean out some stale code
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* src/libmdb/data.c: Use mdb_unicode2ascii in mdb_col_to_string
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10
HACKING
10
HACKING
@ -147,7 +147,7 @@ The Jet3 row format is:
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| ???? | 1 byte | eod | length of data from begining of record |
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| ???? | n bytes | var_table[]| offset from start of row for each var_col |
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| ???? | 1 byte | var_len | number of variable length columns |
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| ???? | n bytes | jump_table | number of variable length columns |
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| ???? | n bytes | jump_table | Jump table (see description below) |
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| ???? | n bytes | null_mask | Null indicator. size is 1 byte per 8 cols |
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| | | | 0 indicates a null value. Also used to |
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| | | | represent value of boolean type columns |
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@ -163,9 +163,9 @@ Notes:
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. The size of the null table is computed by (num_cols - 1)/8 + 1
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. Fixed columns can be null (unlike some other databases).
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. The var_len field indicates the size of the var_table[].
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. The eod field points at the last byte of the var_cols field. It is used to
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determine where the last var_col ends.
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. For boolean fixed columns, the values are in null_table[]: 0 indicates a false
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. The eod field points at the first byte after the var_cols field. It is used
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to determine where the last var_col ends.
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. For boolean fixed columns, the values are in null_table[]: 0 indicates a false
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value, 1 indicates a true value
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. An 0xFF stored in the var_table indicates that this column has been deleted.
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@ -199,6 +199,8 @@ Notes:
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. All offsets are stored as 2 byte fields including the var_table entries.
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. the jump table was (thankfully) ditched in Jet4.
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. If the number of variable columns, as given in the TDEF, is 0, then the
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only items in the row are num_cols, fixed_cols, and null_mask.
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Each memo column (or other long binary data) in a row
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@ -345,6 +345,7 @@ typedef struct {
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MdbHandle *mdbidx;
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MdbIndexChain *chain;
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MdbProperties *props;
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unsigned int num_var_cols; /* to know if row has variable columns */
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} MdbTableDef;
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struct mdbindex {
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@ -79,6 +79,7 @@ MdbTableDef *mdb_read_table(MdbCatalogEntry *entry)
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len = mdb_pg_get_int16(mdb,8);
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table->num_rows = mdb_pg_get_int32(mdb, fmt->tab_num_rows_offset);
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table->num_var_cols = mdb_pg_get_int16(mdb, fmt->tab_num_cols_offset-2);
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table->num_cols = mdb_pg_get_int16(mdb, fmt->tab_num_cols_offset);
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table->num_idxs = mdb_pg_get_int32(mdb, fmt->tab_num_idxs_offset);
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table->num_real_idxs = mdb_pg_get_int32(mdb, fmt->tab_num_ridxs_offset);
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@ -93,119 +93,69 @@ mdb_crack_row4(MdbTableDef *table, int row_start, int row_end, MdbField *fields)
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MdbCatalogEntry *entry = table->entry;
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MdbHandle *mdb = entry->mdb;
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MdbColumn *col;
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unsigned char *pg_buf = mdb->pg_buf;
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unsigned int i;
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int var_cols = 0, row_var_cols, fixed_cols = 0, row_fixed_cols, num_cols;
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int var_cols_found, fixed_cols_found, var_entry_pos;
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int col_start, next_col;
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unsigned int row_var_cols=0, row_fixed_cols, row_cols;
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unsigned int fixed_cols_found;
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unsigned int col_start;
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unsigned char *nullmask;
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int bitmask_sz;
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int byte_num, bit_num;
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int eod, len; /* end of data */
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int real_offset = 0;
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int row_pos;
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unsigned int bitmask_sz;
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unsigned int byte_num, bit_num;
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unsigned int *var_col_offsets = NULL;
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if (mdb_get_option(MDB_DEBUG_ROW)) {
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buffer_dump(mdb->pg_buf, row_start, row_end+1);
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buffer_dump(pg_buf, row_start, row_end+1);
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}
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num_cols = mdb_pg_get_int16(mdb, row_start);
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row_cols = mdb_pg_get_int16(mdb, row_start);
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/* compute nulls first to help with fixed colnum's */
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bitmask_sz = (num_cols - 1) / 8 + 1;
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nullmask = &mdb->pg_buf[row_end - bitmask_sz + 1];
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bitmask_sz = (row_cols + 7) / 8;
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nullmask = &pg_buf[row_end - bitmask_sz + 1];
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for (i=0;i<table->num_cols;i++) {
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col = g_ptr_array_index (table->columns, i);
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row_pos = col->col_num;
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byte_num = row_pos / 8;
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bit_num = row_pos % 8;
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/* logic on nulls is reverse, 1 is not null, 0 is null */
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fields[i].is_null = nullmask[byte_num] & 1 << bit_num ? 0 : 1;
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//printf("row_pos %d col %d is %s\n", row_pos, i, fields[i].is_null ? "null" : "not null");
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}
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/* fields are ordered fixed then variable */
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for (i = 0; i < table->num_cols; i++) {
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col = g_ptr_array_index (table->columns, i);
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if (mdb_is_fixed_col(col)) {
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fixed_cols++;
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fields[i].colnum = i;
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fields[i].siz = col->col_size;
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fields[i].is_fixed = 1;
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if (table->num_var_cols > 0) {
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row_var_cols = mdb_pg_get_int16(mdb, row_end - bitmask_sz - 1);
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var_col_offsets = (int *)g_malloc((row_var_cols+1)*sizeof(int));
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for (i=0; i<row_var_cols+1; i++) {
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var_col_offsets[i] = mdb_pg_get_int16(mdb,
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row_end - bitmask_sz - 3 - (i*2));
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}
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}
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for (i = 0; i < table->num_cols; i++) {
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col = g_ptr_array_index (table->columns, i);
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if (!mdb_is_fixed_col(col)) {
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var_cols++;
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fields[i].colnum = i;
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fields[i].is_fixed = 0;
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}
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}
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row_var_cols = mdb_pg_get_int16(mdb, row_end - bitmask_sz - 1);
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/* find the end of data pointer */
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eod = mdb_pg_get_int16(mdb, row_end - 3 - var_cols*2 - bitmask_sz);
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/* actual cols on this row */
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fixed_cols_found = 0;
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var_cols_found = 0;
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row_fixed_cols = num_cols - row_var_cols;
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row_fixed_cols = row_cols - row_var_cols;
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for (i=0;i<table->num_cols;i++) {
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col = g_ptr_array_index(table->columns,i);
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if (mdb_is_fixed_col(col)) {
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if (fixed_cols_found <= row_fixed_cols) {
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real_offset += col->col_size;
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fields[i].start = row_start + col->fixed_offset + 2;
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fields[i].value = &mdb->pg_buf[row_start + col->fixed_offset + 2];
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} else {
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fields[i].start = 0;
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fields[i].value = NULL;
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fields[i].siz = 0;
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fields[i].is_null = 1;
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}
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fields[i].colnum = i;
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fields[i].is_fixed = (mdb_is_fixed_col(col)) ? 1 : 0;
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byte_num = col->col_num / 8;
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bit_num = col->col_num % 8;
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/* logic on nulls is reverse, 1 is not null, 0 is null */
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fields[i].is_null = nullmask[byte_num] & (1 << bit_num) ? 0 : 1;
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if ((fields[i].is_fixed)
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&& (fixed_cols_found <= row_fixed_cols)) {
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col_start = col->fixed_offset + 2;
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fields[i].start = row_start + col_start;
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fields[i].value = &pg_buf[row_start + col_start];
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fields[i].siz = col->col_size;
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fixed_cols_found++;
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} else if ((!fields[i].is_fixed)
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&& (col->var_col_num < row_var_cols)) {
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col_start = var_col_offsets[col->var_col_num];
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fields[i].start = row_start + col_start;
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fields[i].value = &pg_buf[row_start + col_start];
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fields[i].siz = var_col_offsets[(col->var_col_num)+1] -
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col_start;
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} else {
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fields[i].start = 0;
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fields[i].value = NULL;
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fields[i].siz = 0;
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fields[i].is_null = 1;
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}
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}
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g_free(var_col_offsets);
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col_start = mdb_pg_get_int16(mdb, row_end - 3 - bitmask_sz);
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for (i=0;i<table->num_cols;i++) {
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col = g_ptr_array_index(table->columns,i);
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if (!mdb_is_fixed_col(col)) {
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var_cols_found++;
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if (var_cols_found <= row_var_cols) {
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if (var_cols_found==row_var_cols) {
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len=eod - col_start;
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//printf("len = %d eod %d col_start %d\n",len, eod, col_start);
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} else {
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/* position of the var table
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* entry for this column */
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var_entry_pos =
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row_end -
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bitmask_sz -
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var_cols_found * 2 - 2 - 1;
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next_col = mdb_pg_get_int16(mdb, var_entry_pos);
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len = next_col - col_start;
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} /* if found==var_cols */
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//printf("len = %d eod %d col_start %d\n",len, eod, col_start);
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//printf("is_null %d\n",fields[i].is_null);
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fields[i].start = row_start + col_start;
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fields[i].value = &mdb->pg_buf[row_start +col_start];
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fields[i].siz = len;
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col_start += len;
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} else {
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fields[i].start = 0;
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fields[i].value = NULL;
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fields[i].siz = 0;
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fields[i].is_null = 1;
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}
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} /* if !fixed */
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} /* for */
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return num_cols;
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return row_cols;
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}
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static int
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mdb_crack_row3(MdbTableDef *table, int row_start, int row_end, MdbField *fields)
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