Function lo_initialize

src/interfaces/libpq/fe-lobj.c:852–1036

* lo_initialize * * Initialize for a new large-object operation on an existing connection. * Return 0 if OK, -1 on failure. * * If we haven't previously done so, we collect the function OIDs from * pg_proc for all functions that are required for large object operations. */

 * pg_proc for all functions that are required for large object operations.
 */
static int
lo_initialize(PGconn *conn)
{
	PGresult   *res;
	PGlobjfuncs *lobjfuncs;
	int			n;
	const char *query;
	const char *fname;
	Oid			foid;

	/* Nothing we can do with no connection */
	if (conn == NULL)
		return -1;

	/* Since this is the beginning of a query cycle, reset the error buffer */
	resetPQExpBuffer(&conn->errorMessage);

	/* Nothing else to do if we already collected info */
	if (conn->lobjfuncs != NULL)
		return 0;

	/*
	 * Allocate the structure to hold the function OIDs.  We don't store it
	 * into the PGconn until it's successfully filled.
	 */
	lobjfuncs = (PGlobjfuncs *) malloc(sizeof(PGlobjfuncs));
	if (lobjfuncs == NULL)
	{
		appendPQExpBufferStr(&conn->errorMessage,
							 libpq_gettext("out of memory\n"));
		return -1;
	}
	MemSet((char *) lobjfuncs, 0, sizeof(PGlobjfuncs));

	/*
	 * Execute the query to get all the functions at once.  (Not all of them
	 * may exist in older server versions.)
	 */
	query = "select proname, oid from pg_catalog.pg_proc "
		"where proname in ("
		"'lo_open', "
		"'lo_close', "
		"'lo_creat', "
		"'lo_create', "
		"'lo_unlink', "
		"'lo_lseek', "
		"'lo_lseek64', "
		"'lo_tell', "
		"'lo_tell64', "
		"'lo_truncate', "
		"'lo_truncate64', "
		"'loread', "
		"'lowrite') "
		"and pronamespace = (select oid from pg_catalog.pg_namespace "
		"where nspname = 'pg_catalog')";

	res = PQexec(conn, query);
	if (res == NULL)