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/* ``The contents of this file are subject to the Erlang Public License,
* Version 1.1, (the "License"); you may not use this file except in
* compliance with the License. You should have received a copy of the
* Erlang Public License along with this software. If not, it can be
* retrieved via the world wide web at http://www.erlang.org/.
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* The Initial Developer of the Original Code is Ericsson Utvecklings AB.
* Portions created by Ericsson are Copyright 1999, Ericsson Utvecklings
* AB. All Rights Reserved.''
*
* $Id$
*/
/*
* Purpose: A driver using libpq to connect to Postgres
* from erlang, a sample for the driver documentation
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <libpq-fe.h>
#include <erl_driver.h>
#include <ei.h>
#include "pg_encode.h"
/* Driver interface declarations */
static ErlDrvData start(ErlDrvPort port, char *command);
static void stop(ErlDrvData drv_data);
static int control(ErlDrvData drv_data, unsigned int command, char *buf,
int len, char **rbuf, int rlen);
static ErlDrvEntry pq_driver_entry = {
NULL, /* init */
start,
stop,
NULL, /* output */
NULL, /* ready_input */
NULL, /* ready_output */
"pg_sync", /* the name of the driver */
NULL, /* finish */
NULL, /* handle */
control,
NULL, /* timeout */
NULL, /* outputv */
NULL, /* ready_async */
NULL, /* flush */
NULL, /* call */
NULL /* event */
};
typedef struct our_data_t {
PGconn* conn;
} our_data_t;
/* Keep the following definitions in alignment with the
* defines in erl_pq_sync.erl
*/
#define DRV_CONNECT 'C'
#define DRV_DISCONNECT 'D'
#define DRV_SELECT 'S'
/* INITIALIZATION AFTER LOADING */
/*
* This is the init function called after this driver has been loaded.
* It must *not* be declared static. Must return the address to
* the driver entry.
*/
DRIVER_INIT(pq_drv)
{
return &pq_driver_entry;
}
/* DRIVER INTERFACE */
static ErlDrvData start(ErlDrvPort port, char *command)
{
our_data_t* data;
data = (our_data_t*)driver_alloc(sizeof(our_data_t));
data->conn = NULL;
set_port_control_flags(port, PORT_CONTROL_FLAG_BINARY);
return (ErlDrvData)data;
}
static int do_disconnect(our_data_t* data, ei_x_buff* x);
static void stop(ErlDrvData drv_data)
{
do_disconnect((our_data_t*)drv_data, NULL);
}
static ErlDrvBinary* ei_x_to_new_binary(ei_x_buff* x)
{
ErlDrvBinary* bin = driver_alloc_binary(x->index);
if (bin != NULL)
memcpy(&bin->orig_bytes[0], x->buff, x->index);
return bin;
}
static char* get_s(const char* buf, int len);
static int do_connect(const char *s, our_data_t* data, ei_x_buff* x);
static int do_select(const char* s, our_data_t* data, ei_x_buff* x);
/* Since we are operating in binary mode, the return value from control
* is irrelevant, as long as it is not negative.
*/
static int control(ErlDrvData drv_data, unsigned int command, char *buf,
int len, char **rbuf, int rlen)
{
int r;
ei_x_buff x;
our_data_t* data = (our_data_t*)drv_data;
char* s = get_s(buf, len);
ei_x_new_with_version(&x);
switch (command) {
case DRV_CONNECT: r = do_connect(s, data, &x); break;
case DRV_DISCONNECT: r = do_disconnect(data, &x); break;
case DRV_SELECT: r = do_select(s, data, &x); break;
default: r = -1; break;
}
*rbuf = (char*)ei_x_to_new_binary(&x);
ei_x_free(&x);
driver_free(s);
return r;
}
static int do_connect(const char *s, our_data_t* data, ei_x_buff* x)
{
PGconn* conn = PQconnectdb(s);
if (PQstatus(conn) != CONNECTION_OK) {
encode_error(x, conn);
PQfinish(conn);
conn = NULL;
} else {
encode_ok(x);
}
data->conn = conn;
return 0;
}
static int do_disconnect(our_data_t* data, ei_x_buff* x)
{
if (data->conn == NULL)
return 0;
PQfinish(data->conn);
data->conn = NULL;
if (x != NULL)
encode_ok(x);
return 0;
}
static int do_select(const char* s, our_data_t* data, ei_x_buff* x)
{
PGresult* res = PQexec(data->conn, s);
encode_result(x, res, data->conn);
PQclear(res);
return 0;
}
/* utilities */
static char* get_s(const char* buf, int len)
{
char* result;
if (len < 1 || len > 10000) return NULL;
result = driver_alloc(len+1);
memcpy(result, buf, len);
result[len] = '\0';
return result;
}
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