1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
|
/*
This file is part of TALER
Copyright (C) 2014, 2015 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 us to detect the end of the list.
*/
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;
/**
* Where to store 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.
*
* @param result result to process
* @param[in|out] rs result specification to extract for
* @param row row from the result to extract
* @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);
/**
* Extract a currency amount from a query result according to the
* given specification.
*
* @param result the result to extract the amount from
* @param row which row of the result to extract the amount from (needed as results can have multiple rows)
* @param val_name name of the column with the amount's "value", must include the substring "_val".
* @param frac_name name of the column with the amount's "fractional" value, must include the substring "_frac".
* @param curr_name name of the column with the amount's currency name, must include the substring "_curr".
* @param[out] r_amount_nbo where to store the amount, in network byte order
* @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_amount_nbo (PGresult *result,
int row,
const char *val_name,
const char *frac_name,
const char *curr_name,
struct TALER_AmountNBO *r_amount_nbo);
/**
* Extract a currency amount from a query result according to the
* given specification.
*
* @param result the result to extract the amount from
* @param row which row of the result to extract the amount from (needed as results can have multiple rows)
* @param val_name name of the column with the amount's "value", must include the substring "_val".
* @param frac_name name of the column with the amount's "fractional" value, must include the substring "_frac".
* @param curr_name name of the column with the amount's currency name, must include the substring "_curr".
* @param[out] r_amount where to store the amount, in host byte order
* @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_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 */
|
