/*!
* \brief Gets a partial result set, fetch rows from a result
*
* Gets a partial result set, fetch a number of rows from a databae result.
* This function initialize the given result structure on the first run, and
* fetches the nrows number of rows. On subsequenting runs, it uses the
* existing result and fetches more rows, until it reaches the end of the
* result set. Because of this the result needs to be null in the first
* invocation of the function. If the number of wanted rows is zero, the
* function returns anything with a result of zero.
* \param _h structure representing the database connection
* \param _r pointer to a structure representing the result
* \param nrows number of fetched rows
* \return return zero on success, negative value on failure
*/
int db_unixodbc_fetch_result(const db1_con_t* _h, db1_res_t** _r, const int nrows)
{
int row_n = 0, i = 0, ret = 0, len;
SQLSMALLINT columns;
list* rows = NULL;
list* rowstart = NULL;
strn* temp_row = NULL;
if ((!_h) || (!_r) || nrows < 0)
{
LM_ERR("invalid parameter value\n");
return -1;
}
/* exit if the fetch count is zero */
if (nrows == 0) {
if (*_r)
db_free_result(*_r);
*_r = 0;
return 0;
}
/* On the first fetch for a query, allocate structures and get columns */
if(*_r == NULL) {
/* Allocate a new result structure */
*_r = db_new_result();
LM_DBG("just allocated a new db result structure");
if (*_r == NULL) {
LM_ERR("no memory left\n");
return -2;
}
/* Get columns names and count */
if (db_unixodbc_get_columns(_h, *_r) < 0) {
LM_ERR("getting column names failed\n");
db_free_columns(*_r);
return -2;
}
/* On subsequent fetch attempts, reuse already allocated structures */
} else {
LM_DBG("db result structure already exist, reusing\n");
/* free old rows */
if(RES_ROWS(*_r) != NULL)
db_free_rows(*_r);
RES_ROWS(*_r) = 0;
RES_ROW_N(*_r) = 0;
}
SQLNumResultCols(CON_RESULT(_h), (SQLSMALLINT *)&columns);
/* Now fetch nrows at most */
len = sizeof(db_row_t) * nrows;
RES_ROWS(*_r) = (struct db_row*)pkg_malloc(len);
if (!RES_ROWS(*_r)) {
LM_ERR("no memory left\n");
return -5;
}
LM_DBG("allocated %d bytes for RES_ROWS at %p\n", len, RES_ROWS(*_r));
LM_DBG("Now fetching %i rows at most\n", nrows);
while(SQL_SUCCEEDED(ret = SQLFetch(CON_RESULT(_h)))) {
/* Allocate a temporary row */
temp_row = db_unixodbc_new_cellrow(columns);
if (!temp_row) {
LM_ERR("no private memory left\n");
pkg_free(RES_ROWS(*_r));
pkg_free(*_r);
*_r = 0;
return -1;
}
LM_DBG("fetching %d columns for row %d...\n",columns, row_n);
for(i=0; i < columns; i++) {
LM_DBG("fetching column %d\n",i);
if (!db_unixodbc_load_cell(_h, i+1, temp_row + i, RES_TYPES(*_r)[i])) {
pkg_free(RES_ROWS(*_r));
db_unixodbc_free_cellrow(columns, temp_row);
pkg_free(*_r);
*_r = 0;
return -5;
}
}
LM_DBG("got temp_row at %p\n", temp_row);
if (db_unixodbc_list_insert(&rowstart, &rows, columns, temp_row) < 0) {
LM_ERR("SQL result row insert failed\n");
pkg_free(RES_ROWS(*_r));
db_unixodbc_free_cellrow(columns, temp_row);
pkg_free(*_r);
*_r = 0;
return -5;
}
/* Free temporary row data */
LM_DBG("freeing temp_row at %p\n", temp_row);
db_unixodbc_free_cellrow(columns, temp_row);
temp_row = NULL;
row_n++;
if (row_n == nrows) {
break;
}
}
CON_ROW(_h) = NULL;
RES_ROW_N(*_r) = row_n;
if (!row_n) {
LM_DBG("no more rows to process for db fetch");
pkg_free(RES_ROWS(*_r));
RES_ROWS(*_r) = 0;
return 0;
}
/* Convert rows to internal format */
memset(RES_ROWS(*_r), 0, len);
i = 0;
rows = rowstart;
while(rows)
{
LM_DBG("converting row #%d\n", i);
CON_ROW(_h) = rows->data;
if (!CON_ROW(_h))
{
LM_ERR("string null\n");
RES_ROW_N(*_r) = row_n;
db_free_rows(*_r);
return -3;
}
if (db_unixodbc_convert_row(_h, *_r, &(RES_ROWS(*_r)[i]), rows->lengths) < 0) {
LM_ERR("converting fetched row #%d failed\n", i);
RES_ROW_N(*_r) = i;
db_free_rows(*_r);
return -4;
}
i++;
rows = rows->next;
}
db_unixodbc_list_destroy(rowstart);
/* update the total number of rows processed */
RES_LAST_ROW(*_r) += row_n;
LM_DBG("fetch from db processed %d rows so far\n", RES_LAST_ROW(*_r));
return 0;
}
/*
* Convert rows from UNIXODBC to db API representation
*/
static inline int db_unixodbc_convert_rows(const db1_con_t* _h, db1_res_t* _r)
{
int i = 0, ret = 0;
SQLSMALLINT columns;
list* rows = NULL;
list* rowstart = NULL;
strn* temp_row = NULL;
if((!_h) || (!_r)) {
LM_ERR("invalid parameter\n");
return -1;
}
SQLNumResultCols(CON_RESULT(_h), (SQLSMALLINT *)&columns);
temp_row = (strn*)pkg_malloc( columns*sizeof(strn) );
if(!temp_row) {
LM_ERR("no private memory left\n");
return -1;
}
while(SQL_SUCCEEDED(ret = SQLFetch(CON_RESULT(_h))))
{
for(i=0; i < columns; i++)
{
SQLLEN indicator;
ret = SQLGetData(CON_RESULT(_h), i+1, SQL_C_CHAR,
temp_row[i].s, STRN_LEN, &indicator);
if (SQL_SUCCEEDED(ret)) {
if (indicator == SQL_NULL_DATA)
strcpy(temp_row[i].s, "NULL");
}
else {
LM_ERR("SQLGetData failed\n");
}
}
if (db_unixodbc_list_insert(&rowstart, &rows, columns, temp_row) < 0) {
LM_ERR("insert failed\n");
pkg_free(temp_row);
temp_row= NULL;
return -5;
}
RES_ROW_N(_r)++;
}
/* free temporary row data */
pkg_free(temp_row);
CON_ROW(_h) = NULL;
if (!RES_ROW_N(_r)) {
RES_ROWS(_r) = 0;
return 0;
}
if (db_allocate_rows(_r) != 0) {
LM_ERR("could not allocate rows");
db_unixodbc_list_destroy(rowstart);
return -2;
}
i = 0;
rows = rowstart;
while(rows)
{
CON_ROW(_h) = rows->data;
if (!CON_ROW(_h))
{
LM_ERR("string null\n");
RES_ROW_N(_r) = i;
db_free_rows(_r);
db_unixodbc_list_destroy(rowstart);
return -3;
}
if (db_unixodbc_convert_row(_h, _r, &(RES_ROWS(_r)[i]), rows->lengths) < 0) {
LM_ERR("converting row failed #%d\n", i);
RES_ROW_N(_r) = i;
db_free_rows(_r);
db_unixodbc_list_destroy(rowstart);
return -4;
}
i++;
rows = rows->next;
}
db_unixodbc_list_destroy(rowstart);
return 0;
}