194 lines
5.0 KiB
C
194 lines
5.0 KiB
C
/*
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This file is part of TALER
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Copyright (C) 2014 Christian Grothoff (and other contributing authors)
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TALER is free software; you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation; either version 3, or (at your option) any later version.
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TALER is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
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A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along with
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TALER; see the file COPYING. If not, If not, see <http://www.gnu.org/licenses/>
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*/
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/**
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* @file include/taler_pq_lib.h
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* @brief helper functions for DB interactions
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* @author Sree Harsha Totakura <sreeharsha@totakura.in>
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* @author Florian Dold
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* @author Christian Grothoff
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*/
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#ifndef TALER_PQ_LIB_H_
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#define TALER_PQ_LIB_H_
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#include <libpq-fe.h>
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#include "taler_util.h"
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/**
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* @brief Description of a DB query parameter.
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*/
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struct TALER_PQ_QueryParam
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{
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/**
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* Data or NULL
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*/
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const void *data;
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/**
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* Size of @e data
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*/
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size_t size;
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/**
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* Non-null if this is not the last parameter.
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* This allows for null as sentinal value.
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*/
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int more;
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};
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/**
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* End of query parameter specification.
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*/
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#define TALER_PQ_QUERY_PARAM_END { NULL, 0, 0 }
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/**
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* Generate fixed-size query parameter with size given explicitly.
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*
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* @param x pointer to the query parameter to pass
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* @param s number of bytes of @a x to use for the query
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*/
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#define TALER_PQ_QUERY_PARAM_PTR_SIZED(x, s) { (x), (s), 1 }
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/**
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* Generate fixed-size query parameter with size determined
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* by variable type.
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*
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* @param x pointer to the query parameter to pass.
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*/
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#define TALER_PQ_QUERY_PARAM_PTR(x) TALER_PQ_QUERY_PARAM_PTR_SIZED(x, sizeof (*(x)))
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/**
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* @brief Description of a DB result cell.
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*/
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struct TALER_PQ_ResultSpec
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{
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/**
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* Destination for the data.
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*/
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void *dst;
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/**
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* Allowed size for the data, 0 for variable-size
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* (in this case, the type of @e dst is a `void **`
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* and we need to allocate a buffer of the right size).
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*/
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size_t dst_size;
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/**
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* Field name of the desired result.
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*/
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char *fname;
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/**
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* Actual size of the result.
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*/
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size_t *result_size;
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};
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/**
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* End of result parameter specification.
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*/
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#define TALER_PQ_RESULT_SPEC_END { NULL, 0, NULL, NULL }
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/**
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* We expect a fixed-size result, with size given explicitly
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*
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* @param name name of the field in the table
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* @param dst point to where to store the result
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* @param s number of bytes we should use in @a dst
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*/
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#define TALER_PQ_RESULT_SPEC_SIZED(name, dst, s) { (void *) (dst), (s), (name), NULL }
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/**
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* We expect a fixed-size result, with size determined by the type of `* dst`
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*
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* @param name name of the field in the table
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* @param dst point to where to store the result, type fits expected result size
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*/
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#define TALER_PQ_RESULT_SPEC(name, dst) TALER_PQ_RESULT_SPEC_SIZED(name, dst, sizeof (*(dst)))
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/**
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* Variable-size result expected.
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*
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* @param name name of the field in the table
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* @param dst where to store the result (of type void **), to be allocated
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* @param sptr pointer to a `size_t` for where to store the size of @a dst
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*/
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#define TALER_PQ_RESULT_SPEC_VAR(name, dst, sptr) { (void *) (dst), 0, (name), sptr }
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/**
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* Execute a prepared statement.
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*
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* @param db_conn database connection
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* @param name name of the prepared statement
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* @param params parameters to the statement
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* @return postgres result
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*/
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PGresult *
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TALER_PQ_exec_prepared (PGconn *db_conn,
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const char *name,
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const struct TALER_PQ_QueryParam *params);
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/**
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* Extract results from a query result according to the given specification.
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* If colums are NULL, the destination is not modified, and GNUNET_NO
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* is returned.
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*
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* @return
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* #GNUNET_YES if all results could be extracted
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* #GNUNET_NO if at least one result was NULL
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* #GNUNET_SYSERR if a result was invalid (non-existing field)
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*/
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int
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TALER_PQ_extract_result (PGresult *result,
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struct TALER_PQ_ResultSpec *rs,
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int row);
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int
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TALER_PQ_field_isnull (PGresult *result,
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int row,
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const char *fname);
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int
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TALER_PQ_extract_amount_nbo (PGresult *result,
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int row,
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const char *val_name,
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const char *frac_name,
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const char *curr_name,
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struct TALER_AmountNBO *r_amount_nbo);
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int
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TALER_PQ_extract_amount (PGresult *result,
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int row,
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const char *val_name,
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const char *frac_name,
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const char *curr_name,
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struct TALER_Amount *r_amount);
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#endif /* TALER_PQ_LIB_H_ */
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/* end of db/taler_pq_lib.h */
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