From: Alistair Bayley <alistair@abayley.org>
To: pgsql-interfaces@postgresql.org
Subject: Example libpq program fails when built with mingw ld-2.15.91 on WinXP (but not ld-2.13.90)
Date: Wed, 29 Mar 2006 21:43:10 +0100
Message-ID: <79d7c4980603291243x68c2e4c7tcfe86250f3cb5bad@mail.gmail.com> (raw)
I have a slightly modified version of one of the example C programs
from the help docs. When built with gcc-3.4.2/ld-2.13.90 under MingW
on WinXP it works as expected. When linked with ld-2.15.91 (or later;
same gcc) it segfaults on the first call to PGprepare. Does anyone
else have this problem, or can you reproduce?
Alistair
File: test.c
#include <stdio.h>
#include <stdlib.h>
#include "libpq-fe.h"
static void exit_nicely(PGconn *conn)
{
PQfinish(conn);
exit(1);
}
void check_error(PGconn *conn, PGresult *res, ExecStatusType rc, char *msg)
{
if (PQresultStatus(res) != rc)
{
/* fprintf(stderr, msg, PQerrorMessage(conn)); */
fprintf(stderr, "%s: %s\n", msg, PQerrorMessage(conn));
PQclear(res);
exit_nicely(conn);
}
}
int main(int argc, char **argv)
{
const char *conninfo;
PGconn *conn;
PGresult *res;
int nFields;
int i,
j;
Oid paramTypes[10];
/*
* If the user supplies a parameter on the command line, use it as the
* conninfo string; otherwise default to setting dbname=postgres and using
* environment variables or defaults for all other connection parameters.
*/
if (argc > 1)
conninfo = argv[1];
else
conninfo = "dbname = postgres";
/* Make a connection to the database */
conn = PQconnectdb(conninfo);
/* Check to see that the backend connection was successfully made */
if (PQstatus(conn) != CONNECTION_OK)
{
fprintf(stderr, "Connection to database failed: %s",
PQerrorMessage(conn));
exit_nicely(conn);
}
/* my test case... */
res = PQprepare(conn, "x", "DECLARE myportal CURSOR FOR select *
from pg_database", 0, paramTypes);
check_error(conn, res, PGRES_COMMAND_OK, "Prepare failed");
/*
* Our test case here involves using a cursor, for which we must be inside
* a transaction block. We could do the whole thing with a single
* PQexec() of "select * from pg_database", but that's too trivial to make
* a good example.
*/
/* Start a transaction block */
res = PQexec(conn, "BEGIN");
check_error(conn, res, PGRES_COMMAND_OK, "BEGIN command failed");
/*
* Should PQclear PGresult whenever it is no longer needed to avoid memory
* leaks
*/
PQclear(res);
/*
* Fetch rows from pg_database, the system catalog of databases
*/
res = PQexec(conn, "DECLARE myportal CURSOR FOR select * from pg_database");
check_error(conn, res, PGRES_COMMAND_OK, "DECLARE CURSOR failed");
PQclear(res);
res = PQexec(conn, "FETCH ALL in myportal");
check_error(conn, res, PGRES_TUPLES_OK, "FETCH ALL failed");
/* first, print out the attribute names */
nFields = PQnfields(res);
for (i = 0; i < nFields; i++)
printf("%-15s", PQfname(res, i));
printf("\n\n");
/* next, print out the rows */
for (i = 0; i < PQntuples(res); i++)
{
for (j = 0; j < nFields; j++)
printf("%-15s", PQgetvalue(res, i, j));
printf("\n");
}
PQclear(res);
/* close the portal ... we don't bother to check for errors ... */
res = PQexec(conn, "CLOSE myportal");
PQclear(res);
/* end the transaction */
res = PQexec(conn, "END");
PQclear(res);
/* close the connection to the database and cleanup */
PQfinish(conn);
return 0;
}
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To: pgsql-interfaces@postgresql.org
Cc: alistair@abayley.org
Subject: Re: Example libpq program fails when built with mingw ld-2.15.91 on WinXP (but not ld-2.13.90)
In-Reply-To: <79d7c4980603291243x68c2e4c7tcfe86250f3cb5bad@mail.gmail.com>
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