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support variable-size results

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This commit is contained in:
Christian Grothoff 2015-01-26 11:04:46 +01:00
parent c2b32e75dc
commit d4506f8a04
2 changed files with 111 additions and 36 deletions
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90
src/include/taler_db_lib.h
View File

@ -13,13 +13,12 @@
You should have received a copy of the GNU General Public License along with
TALER; see the file COPYING. If not, If not, see <http://www.gnu.org/licenses/>
*/
/**
* @file include/taler_db_lib.h
* @brief helper functions for DB interactions
* @author Sree Harsha Totakura <sreeharsha@totakura.in>
* @author Florian Dold
* @author Christian Grothoff
*/
#ifndef TALER_DB_LIB_H_
@ -28,16 +27,6 @@
#include <libpq-fe.h>
#include "taler_util.h"
#define TALER_DB_QUERY_PARAM_END { NULL, 0, 0 }
#define TALER_DB_QUERY_PARAM_PTR(x) { (x), sizeof (*(x)), 1 }
#define TALER_DB_QUERY_PARAM_PTR_SIZED(x, s) { (x), (s), 1 }
#define TALER_DB_RESULT_SPEC_END { NULL, 0, NULL }
#define TALER_DB_RESULT_SPEC(name, dst) { (void *) (dst), sizeof (*(dst)), (name) }
#define TALER_DB_RESULT_SPEC_SIZED(name, dst, s) { (void *) (dst), (s), (name) }
/**
* Description of a DB query parameter.
*/
@ -47,10 +36,12 @@ struct TALER_DB_QueryParam
* Data or NULL
*/
const void *data;
/**
* Size of 'data'
* Size of @e data
*/
size_t size;
/**
* Non-null if this is not the last parameter.
* This allows for null as sentinal value.
@ -58,6 +49,27 @@ struct TALER_DB_QueryParam
int more;
};
/**
* End of query parameter specification.
*/
#define TALER_DB_QUERY_PARAM_END { NULL, 0, 0 }
/**
* Generate fixed-size query parameter with size given explicitly.
*
* @param x pointer to the query parameter to pass
* @param s number of bytes of @a x to use for the query
*/
#define TALER_DB_QUERY_PARAM_PTR_SIZED(x, s) { (x), (s), 1 }
/**
* Generate fixed-size query parameter with size determined
* by variable type.
*
* @param x pointer to the query parameter to pass.
*/
#define TALER_DB_QUERY_PARAM_PTR(x) TALER_DB_QUERY_PARAM_PTR_SIZED(x, sizeof (*(x)))
/**
* Description of a DB result cell.
@ -70,7 +82,9 @@ struct TALER_DB_ResultSpec
void *dst;
/**
* Allowed size for the data.
* Allowed size for the data, 0 for variable-size
* (in this case, the type of @e dst is a `void **`
* and we need to allocate a buffer of the right size).
*/
size_t dst_size;
@ -78,9 +92,47 @@ struct TALER_DB_ResultSpec
* Field name of the desired result.
*/
char *fname;
/**
* Actual size of the result.
*/
size_t *result_size;
};
/**
* End of result parameter specification.
*/
#define TALER_DB_RESULT_SPEC_END { NULL, 0, NULL, NULL }
/**
* We expect a fixed-size result, with size given explicitly
*
* @param name name of the field in the table
* @param dst point to where to store the result
* @param s number of bytes we should use in @a dst
*/
#define TALER_DB_RESULT_SPEC_SIZED(name, dst, s) { (void *) (dst), (s), (name), NULL }
/**
* We expect a fixed-size result, with size determined by the type of `* dst`
*
* @param name name of the field in the table
* @param dst point to where to store the result, type fits expected result size
*/
#define TALER_DB_RESULT_SPEC(name, dst) TALER_DB_RESULT_SPEC_SIZED(name, dst, sizeof (*(dst)))
/**
* Variable-size result expected.
*
* @param name name of the field in the table
* @param dst where to store the result (of type void **), to be allocated
* @param sptr pointer to a `size_t` for where to store the size of @a dst
*/
#define TALER_DB_RESULT_SPEC_VAR(name, dst, sptr) { (void *) (dst), 0, (name), sptr }
/**
* Execute a prepared statement.
*/
@ -96,12 +148,14 @@ TALER_DB_exec_prepared (PGconn *db_conn,
* is returned.
*
* @return
* GNUNET_YES if all results could be extracted
* GNUNET_NO if at least one result was NULL
* GNUNET_SYSERR if a result was invalid (non-existing field)
* #GNUNET_YES if all results could be extracted
* #GNUNET_NO if at least one result was NULL
* #GNUNET_SYSERR if a result was invalid (non-existing field)
*/
int
TALER_DB_extract_result (PGresult *result, struct TALER_DB_ResultSpec *rs, int row);
TALER_DB_extract_result (PGresult *result,
struct TALER_DB_ResultSpec *rs,
int row);
int

57
src/util/db.c
View File

@ -13,15 +13,13 @@
You should have received a copy of the GNU General Public License along with
TALER; see the file COPYING. If not, If not, see <http://www.gnu.org/licenses/>
*/
/**
* @file util/db.c
* @brief helper functions for DB interactions
* @author Sree Harsha Totakura <sreeharsha@totakura.in>
* @author Florian Dold
* @author Christian Grothoff
*/
#include "platform.h"
#include <gnunet/gnunet_util_lib.h>
#include "taler_db_lib.h"
@ -39,12 +37,11 @@ TALER_DB_exec_prepared (PGconn *db_conn,
unsigned i;
/* count the number of parameters */
{
const struct TALER_DB_QueryParam *x;
for (len = 0, x = params;
x->more;
len +=1, x += 1);
len++, x++);
}
/* new scope to allow stack allocation without alloca */
@ -61,20 +58,22 @@ TALER_DB_exec_prepared (PGconn *db_conn,
param_formats[i] = 1;
}
return PQexecPrepared (db_conn, name, len,
(const char **) param_values, param_lengths, param_formats, 1);
(const char **) param_values,
param_lengths,
param_formats, 1);
}
}
/**
* Extract results from a query result according to the given specification.
* If colums are NULL, the destination is not modified, and GNUNET_NO
* If colums are NULL, the destination is not modified, and #GNUNET_NO
* is returned.
*
* @return
* GNUNET_YES if all results could be extracted
* GNUNET_NO if at least one result was NULL
* GNUNET_SYSERR if a result was invalid (non-existing field)
* #GNUNET_YES if all results could be extracted
* #GNUNET_NO if at least one result was NULL
* #GNUNET_SYSERR if a result was invalid (non-existing field)
*/
int
TALER_DB_extract_result (PGresult *result,
@ -82,35 +81,56 @@ TALER_DB_extract_result (PGresult *result,
int row)
{
int had_null = GNUNET_NO;
size_t len;
unsigned int i;
unsigned int j;
for (; NULL != rs->fname; rs += 1)
for (i=0; NULL != rs[i].fname; i++)
{
int fnum;
fnum = PQfnumber (result, rs->fname);
fnum = PQfnumber (result, rs[i].fname);
if (fnum < 0)
{
GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "field '%s' does not exist in result\n", rs->fname);
GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
"field '%s' does not exist in result\n",
rs->fname);
return GNUNET_SYSERR;
}
/* if a field is null, continue but
* remember that we now return a different result */
if (PQgetisnull (result, row, fnum))
{
had_null = GNUNET_YES;
continue;
}
const char *res;
if (rs->dst_size != PQgetlength (result, row, fnum))
len = PQgetlength (result, row, fnum);
if ( (0 != rs[i].dst_size) &&
(rs[i].dst_size != len) )
{
GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "field '%s' has wrong size (got %u, expected %u)\n",
rs->fname, (int) PQgetlength (result, row, fnum), (int) rs->dst_size);
GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
"field '%s' has wrong size (got %d, expected %d)\n",
rs[i].fname,
(int) len,
(int) rs->dst_size);
for (j=0;j<i;j++)
if (0 == rs[i].dst_size)
{
GNUNET_free (rs[i].dst);
rs[i].dst = NULL;
*rs[i].result_size = 0;
}
return GNUNET_SYSERR;
}
res = PQgetvalue (result, row, fnum);
GNUNET_assert (NULL != res);
memcpy (rs->dst, res, rs->dst_size);
if (0 == rs->dst_size)
*(void**) rs->dst = GNUNET_malloc (*rs->result_size = len);
memcpy (rs->dst,
res,
len);
}
if (GNUNET_YES == had_null)
return GNUNET_NO;
@ -124,6 +144,7 @@ TALER_DB_field_isnull (PGresult *result,
const char *fname)
{
int fnum;
fnum = PQfnumber (result, fname);
GNUNET_assert (fnum >= 0);
if (PQgetisnull (result, row, fnum))