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/*
This file is part of TALER
Copyright (C) 2014 Christian Grothoff (and other contributing authors)
TALER is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation; either version 3, or (at your option) any later version.
TALER is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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_pq_lib.h
* @brief helper functions for DB interactions
* @author Sree Harsha Totakura <sreeharsha@totakura.in>
* @author Florian Dold
* @author Christian Grothoff
*/
#ifndef TALER_PQ_LIB_H_
#define TALER_PQ_LIB_H_
#include <libpq-fe.h>
#include "taler_util.h"
/**
* @brief Description of a DB query parameter.
*/
struct TALER_PQ_QueryParam
{
/**
* Data or NULL
*/
const void *data;
/**
* Size of @e data
*/
size_t size;
/**
* Non-null if this is not the last parameter.
* This allows for null as sentinal value.
*/
int more;
};
/**
* End of query parameter specification.
*/
#define TALER_PQ_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_PQ_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_PQ_QUERY_PARAM_PTR(x) TALER_PQ_QUERY_PARAM_PTR_SIZED(x, sizeof (*(x)))
/**
* @brief Description of a DB result cell.
*/
struct TALER_PQ_ResultSpec
{
/**
* Destination for the data.
*/
void *dst;
/**
* 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;
/**
* Field name of the desired result.
*/
char *fname;
/**
* Actual size of the result.
*/
size_t *result_size;
};
/**
* End of result parameter specification.
*/
#define TALER_PQ_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_PQ_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_PQ_RESULT_SPEC(name, dst) TALER_PQ_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_PQ_RESULT_SPEC_VAR(name, dst, sptr) { (void *) (dst), 0, (name), sptr }
/**
* Execute a prepared statement.
*
* @param db_conn database connection
* @param name name of the prepared statement
* @param params parameters to the statement
* @return postgres result
*/
PGresult *
TALER_PQ_exec_prepared (PGconn *db_conn,
const char *name,
const struct TALER_PQ_QueryParam *params);
/**
* Extract results from a query result according to the given specification.
* 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)
*/
int
TALER_PQ_extract_result (PGresult *result,
struct TALER_PQ_ResultSpec *rs,
int row);
int
TALER_PQ_field_isnull (PGresult *result,
int row,
const char *fname);
int
TALER_PQ_extract_amount_nbo (PGresult *result,
int row,
const char *val_name,
const char *frac_name,
const char *curr_name,
struct TALER_AmountNBO *r_amount_nbo);
int
TALER_PQ_extract_amount (PGresult *result,
int row,
const char *val_name,
const char *frac_name,
const char *curr_name,
struct TALER_Amount *r_amount);
#endif /* TALER_PQ_LIB_H_ */
/* end of db/taler_pq_lib.h */
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