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Message-ID: <79d7c4980603291243x68c2e4c7tcfe86250f3cb5bad@mail.gmail.com>
Date: Wed, 29 Mar 2006 21:43:10 +0100
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)
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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) !=3D 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=3Dpostgres and =
using
     * environment variables or defaults for all other connection parameter=
s.
     */
    if (argc > 1)
        conninfo =3D argv[1];
    else
        conninfo =3D "dbname =3D postgres";

    /* Make a connection to the database */
    conn =3D PQconnectdb(conninfo);

    /* Check to see that the backend connection was successfully made */
    if (PQstatus(conn) !=3D CONNECTION_OK)
    {
        fprintf(stderr, "Connection to database failed: %s",
PQerrorMessage(conn));
        exit_nicely(conn);
    }

    /* my test case... */
    res =3D 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 ins=
ide
     * a transaction block.  We could do the whole thing with a single
     * PQexec() of "select * from pg_database", but that's too trivial to m=
ake
     * a good example.
     */

    /* Start a transaction block */
    res =3D PQexec(conn, "BEGIN");
    check_error(conn, res, PGRES_COMMAND_OK, "BEGIN command failed");

    /*
     * Should PQclear PGresult whenever it is no longer needed to avoid mem=
ory
     * leaks
     */
    PQclear(res);

    /*
     * Fetch rows from pg_database, the system catalog of databases
     */
    res =3D PQexec(conn, "DECLARE myportal CURSOR FOR select * from pg_data=
base");
    check_error(conn, res, PGRES_COMMAND_OK, "DECLARE CURSOR failed");
    PQclear(res);

    res =3D PQexec(conn, "FETCH ALL in myportal");
    check_error(conn, res, PGRES_TUPLES_OK, "FETCH ALL failed");

    /* first, print out the attribute names */
    nFields =3D PQnfields(res);
    for (i =3D 0; i < nFields; i++)
        printf("%-15s", PQfname(res, i));
    printf("\n\n");

    /* next, print out the rows */
    for (i =3D 0; i < PQntuples(res); i++)
    {
        for (j =3D 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 =3D PQexec(conn, "CLOSE myportal");
    PQclear(res);

    /* end the transaction */
    res =3D PQexec(conn, "END");
    PQclear(res);

    /* close the connection to the database and cleanup */
    PQfinish(conn);

    return 0;
}