diff options
Diffstat (limited to 'erts/example/pg_sync.c')
| -rw-r--r-- | erts/example/pg_sync.c | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/erts/example/pg_sync.c b/erts/example/pg_sync.c new file mode 100644 index 0000000000..6eaa6138e6 --- /dev/null +++ b/erts/example/pg_sync.c @@ -0,0 +1,180 @@ +/* + * %CopyrightBegin% + * + * Copyright Ericsson AB 2006-2009. All Rights Reserved. + * + * 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 online 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. + * + * %CopyrightEnd% + */ +/* + * 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; +} |