Example of binary IO using libpq

pgtest.c

//  This is a demonstration of binary input into postgres using libpq.  It
//  is based on   postgresql-9.0.2/src/test/examples/testlibpq3.c
//
//  Create a table appropriate to this test in a database as follows:
//
//      CREATE TABLE test (name BYTEA);
//
//  See also http://article.gmane.org/gmane.comp.lang.haskell.cafe/85116


#ifdef WIN32
#include <windows.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <sys/types.h>
#include <libpq-fe.h>

/* for ntohl/htonl */
#include <netinet/in.h>
#include <arpa/inet.h>


static void
exit_nicely(PGconn *conn)
{
	PQfinish(conn);
	exit(1);
}

int
main(int argc, char **argv)
{
	const char *conninfo;
	PGconn	   *conn;
	PGresult   *res;
	const char *paramValues[1];
	int         paramLengths[1];
	int         paramFormats[1];
	uint32_t    binaryIntVal;

	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);
	}

        /* Here is our out-of-line parameter value */
        paramValues[0] = "\x41\x00\x41";
        paramLengths[0] = 3;
        paramFormats[0] = 1;   /* parameters are passed in a binary format */

        res = PQexecParams(conn,
                           "INSERT INTO test (name) VALUES ($1::bytea)",
                           1,            /* one param */
                           NULL,         /* let the backend deduce param type */
                           paramValues,
                           paramLengths,
                           paramFormats,
                           1);           /* ask for binary results */

        if (PQresultStatus(res) != PGRES_COMMAND_OK)
        {
                fprintf(stderr, "INSERT failed: %s\n", PQerrorMessage(conn));
                PQclear(res);
                exit_nicely(conn);
        }

        PQclear(res);

	PQfinish(conn);

	return 0;
}