PostgreSQL Source Code git master
testlibpq3.c
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1/*
2 * src/test/examples/testlibpq3.c
3 *
4 *
5 * testlibpq3.c
6 * Test out-of-line parameters and binary I/O.
7 *
8 * Before running this, populate a database with the following commands
9 * (provided in src/test/examples/testlibpq3.sql):
10 *
11 * CREATE SCHEMA testlibpq3;
12 * SET search_path = testlibpq3;
13 * SET standard_conforming_strings = ON;
14 * CREATE TABLE test1 (i int4, t text, b bytea);
15 * INSERT INTO test1 values (1, 'joe''s place', '\000\001\002\003\004');
16 * INSERT INTO test1 values (2, 'ho there', '\004\003\002\001\000');
17 *
18 * The expected output is:
19 *
20 * tuple 0: got
21 * i = (4 bytes) 1
22 * t = (11 bytes) 'joe's place'
23 * b = (5 bytes) \000\001\002\003\004
24 *
25 * tuple 0: got
26 * i = (4 bytes) 2
27 * t = (8 bytes) 'ho there'
28 * b = (5 bytes) \004\003\002\001\000
29 */
30
31#ifdef WIN32
32#include <windows.h>
33#endif
34
35#include <stdio.h>
36#include <stdlib.h>
37#include <stdint.h>
38#include <string.h>
39#include <sys/types.h>
40#include "libpq-fe.h"
41
42/* for ntohl/htonl */
43#include <netinet/in.h>
44#include <arpa/inet.h>
45
46
47static void
49{
51 exit(1);
52}
53
54/*
55 * This function prints a query result that is a binary-format fetch from
56 * a table defined as in the comment above. We split it out because the
57 * main() function uses it twice.
58 */
59static void
61{
62 int i,
63 j;
64 int i_fnum,
65 t_fnum,
66 b_fnum;
67
68 /* Use PQfnumber to avoid assumptions about field order in result */
69 i_fnum = PQfnumber(res, "i");
70 t_fnum = PQfnumber(res, "t");
71 b_fnum = PQfnumber(res, "b");
72
73 for (i = 0; i < PQntuples(res); i++)
74 {
75 char *iptr;
76 char *tptr;
77 char *bptr;
78 int blen;
79 int ival;
80
81 /* Get the field values (we ignore possibility they are null!) */
82 iptr = PQgetvalue(res, i, i_fnum);
83 tptr = PQgetvalue(res, i, t_fnum);
84 bptr = PQgetvalue(res, i, b_fnum);
85
86 /*
87 * The binary representation of INT4 is in network byte order, which
88 * we'd better coerce to the local byte order.
89 */
90 ival = ntohl(*((uint32_t *) iptr));
91
92 /*
93 * The binary representation of TEXT is, well, text, and since libpq
94 * was nice enough to append a zero byte to it, it'll work just fine
95 * as a C string.
96 *
97 * The binary representation of BYTEA is a bunch of bytes, which could
98 * include embedded nulls so we have to pay attention to field length.
99 */
100 blen = PQgetlength(res, i, b_fnum);
101
102 printf("tuple %d: got\n", i);
103 printf(" i = (%d bytes) %d\n",
104 PQgetlength(res, i, i_fnum), ival);
105 printf(" t = (%d bytes) '%s'\n",
106 PQgetlength(res, i, t_fnum), tptr);
107 printf(" b = (%d bytes) ", blen);
108 for (j = 0; j < blen; j++)
109 printf("\\%03o", bptr[j]);
110 printf("\n\n");
111 }
112}
113
114int
115main(int argc, char **argv)
116{
117 const char *conninfo;
118 PGconn *conn;
119 PGresult *res;
120 const char *paramValues[1];
121 int paramLengths[1];
122 int paramFormats[1];
123 uint32_t binaryIntVal;
124
125 /*
126 * If the user supplies a parameter on the command line, use it as the
127 * conninfo string; otherwise default to setting dbname=postgres and using
128 * environment variables or defaults for all other connection parameters.
129 */
130 if (argc > 1)
131 conninfo = argv[1];
132 else
133 conninfo = "dbname = postgres";
134
135 /* Make a connection to the database */
136 conn = PQconnectdb(conninfo);
137
138 /* Check to see that the backend connection was successfully made */
140 {
141 fprintf(stderr, "%s", PQerrorMessage(conn));
143 }
144
145 /* Set always-secure search path, so malicious users can't take control. */
146 res = PQexec(conn, "SET search_path = testlibpq3");
148 {
149 fprintf(stderr, "SET failed: %s", PQerrorMessage(conn));
150 PQclear(res);
152 }
153 PQclear(res);
154
155 /*
156 * The point of this program is to illustrate use of PQexecParams() with
157 * out-of-line parameters, as well as binary transmission of data.
158 *
159 * This first example transmits the parameters as text, but receives the
160 * results in binary format. By using out-of-line parameters we can avoid
161 * a lot of tedious mucking about with quoting and escaping, even though
162 * the data is text. Notice how we don't have to do anything special with
163 * the quote mark in the parameter value.
164 */
165
166 /* Here is our out-of-line parameter value */
167 paramValues[0] = "joe's place";
168
170 "SELECT * FROM test1 WHERE t = $1",
171 1, /* one param */
172 NULL, /* let the backend deduce param type */
173 paramValues,
174 NULL, /* don't need param lengths since text */
175 NULL, /* default to all text params */
176 1); /* ask for binary results */
177
179 {
180 fprintf(stderr, "SELECT failed: %s", PQerrorMessage(conn));
181 PQclear(res);
183 }
184
186
187 PQclear(res);
188
189 /*
190 * In this second example we transmit an integer parameter in binary form,
191 * and again retrieve the results in binary form.
192 *
193 * Although we tell PQexecParams we are letting the backend deduce
194 * parameter type, we really force the decision by casting the parameter
195 * symbol in the query text. This is a good safety measure when sending
196 * binary parameters.
197 */
198
199 /* Convert integer value "2" to network byte order */
200 binaryIntVal = htonl((uint32_t) 2);
201
202 /* Set up parameter arrays for PQexecParams */
203 paramValues[0] = (char *) &binaryIntVal;
204 paramLengths[0] = sizeof(binaryIntVal);
205 paramFormats[0] = 1; /* binary */
206
208 "SELECT * FROM test1 WHERE i = $1::int4",
209 1, /* one param */
210 NULL, /* let the backend deduce param type */
211 paramValues,
212 paramLengths,
213 paramFormats,
214 1); /* ask for binary results */
215
217 {
218 fprintf(stderr, "SELECT failed: %s", PQerrorMessage(conn));
219 PQclear(res);
221 }
222
224
225 PQclear(res);
226
227 /* close the connection to the database and cleanup */
228 PQfinish(conn);
229
230 return 0;
231}
#define fprintf(file, fmt, msg)
Definition: cubescan.l:21
PGconn * PQconnectdb(const char *conninfo)
Definition: fe-connect.c:772
ConnStatusType PQstatus(const PGconn *conn)
Definition: fe-connect.c:7444
void PQfinish(PGconn *conn)
Definition: fe-connect.c:5178
char * PQerrorMessage(const PGconn *conn)
Definition: fe-connect.c:7507
int PQgetlength(const PGresult *res, int tup_num, int field_num)
Definition: fe-exec.c:3887
PGresult * PQexecParams(PGconn *conn, const char *command, int nParams, const Oid *paramTypes, const char *const *paramValues, const int *paramLengths, const int *paramFormats, int resultFormat)
Definition: fe-exec.c:2276
char * PQgetvalue(const PGresult *res, int tup_num, int field_num)
Definition: fe-exec.c:3876
ExecStatusType PQresultStatus(const PGresult *res)
Definition: fe-exec.c:3411
int PQntuples(const PGresult *res)
Definition: fe-exec.c:3481
int PQfnumber(const PGresult *res, const char *field_name)
Definition: fe-exec.c:3589
PGresult * PQexec(PGconn *conn, const char *query)
Definition: fe-exec.c:2262
int j
Definition: isn.c:73
int i
Definition: isn.c:72
@ CONNECTION_OK
Definition: libpq-fe.h:81
@ PGRES_COMMAND_OK
Definition: libpq-fe.h:122
@ PGRES_TUPLES_OK
Definition: libpq-fe.h:125
exit(1)
#define printf(...)
Definition: port.h:245
PGconn * conn
Definition: streamutil.c:53
static void exit_nicely(PGconn *conn)
Definition: testlibpq3.c:48
int main(int argc, char **argv)
Definition: testlibpq3.c:115
static void show_binary_results(PGresult *res)
Definition: testlibpq3.c:60