Hi,
I'm having a problem wrapping the Rabbit MQ C client
library (https://github.com/alanxz/rabbitmq-c) using the ffi. My
problem is with the amqp_queue_declare function. The C
declaration is:
amqp_queue_declare_ok_t *
amqp_queue_declare(amqp_connection_state_t state,
amqp_channel_t channel,
amqp_bytes_t queue,
amqp_boolean_t passive,
amqp_boolean_t durable,
amqp_boolean_t exclusive,
amqp_boolean_t auto_delete,
amqp_table_t arguments);
It seems to run successfully when wrapped to return an opaque
pointer:
(define _amqp-queue-declare-ok-pointer (_cpointer 'QUEUE-DECLARE-OK))
(define-amqp amqp_queue_declare
(_fun _amqp-connection-state-pointer
_amqp_channel_t _pointer _int _int _int _int _pointer
-> _amqp-queue-declare-ok-pointer))
> #<cpointer:QUEUE-DECLARE-OK>
Wrapping it to return a cstruct pointer fails with a SEGV.
> SIGSEGV MAPERR si_code 1 fault on addr (nil)
The wrapping code for the c structs is as follows:
(define _size_t _uint32)
(define _amqp_channel_t _uint16)
(define-cstruct _amqp_bytes_t
([len _size_t]
[bytes _pointer]))
;; c definition of amqp_bytes_t is:
;; typedef struct amqp_bytes_t_ {
;; size_t len;
;; void *bytes;
;; } amqp_bytes_t;
(define-cstruct _amqp_queue_declare_ok_t
([queue _amqp_bytes_t]
[message_count _uint32]
[consumer_count _uint32]))
;; typedef struct amqp_queue_declare_ok_t_ {
;; amqp_bytes_t queue;
;; uint32_t message_count;
;; uint32_t consumer_count;
;; } amqp_queue_declare_ok_t;
(define-amqp amqp_queue_declare
(_fun _amqp-connection-state-pointer
_amqp_channel_t _pointer _int _int _int _int _pointer
-> _amqp_queue_declare_ok_t))
Any ideas what I'm doing wrong here?
The full code so far is below:
#lang racket/base
(require ffi/unsafe
ffi/unsafe/define)
(define lib-rabbit-mq (ffi-lib "librabbitmq"))
(define-ffi-definer define-amqp lib-rabbit-mq)
;; C types
(define _size_t _uint32)
(define _amqp_channel_t _uint16)
(define-cstruct _amqp_bytes_t
([len _size_t]
[bytes _pointer]))
(define-cstruct _amqp_queue_declare_ok_t
([queue _amqp_bytes_t]
[message_count _uint32]
[consumer_count _uint32]))
(define-cstruct _amqp_method_t
([id _uint32]
[decoded _pointer]))
(define-cstruct _amqp_rpc_reply_t
([reply_type _int]
[reply _amqp_method_t]
[library_error _int]))
(define _amqp-connection-state-pointer (_cpointer 'CONNECTION-STATE))
(define _amqp-channel-open_ok-pointer (_cpointer 'CHANNEL-OPEN-OK))
;; C functions
(define-amqp amqp_error_string (_fun _int -> _string))
(define-amqp amqp_get_rpc_reply (_fun _amqp-connection-state-pointer ->
_amqp_rpc_reply_t))
(define-amqp amqp_new_connection (_fun -> _amqp-connection-state-pointer))
(define-amqp amqp_open_socket (_fun _string _int -> _int))
(define-amqp amqp_set_sockfd (_fun _amqp-connection-state-pointer
_int -> _int))
(define-amqp amqp_login (_fun _amqp-connection-state-pointer
_string _int _int _int _int _string _string ->
_amqp_rpc_reply_t))
(define-amqp amqp_channel_open (_fun _amqp-connection-state-pointer
_amqp_channel_t ->
_amqp-channel-open_ok-pointer))
;; *** THIS DOES NOT WORK
(define-amqp amqp_queue_declare
(_fun _amqp-connection-state-pointer
_amqp_channel_t _pointer _int _int _int _int _pointer
-> _amqp_queue_declare_ok_t))
;; *** THIS SEEMS TO WORK
(define _amqp-queue-declare-ok-pointer (_cpointer 'QUEUE-DECLARE-OK))
(define-amqp amqp_queue_declare
(_fun _amqp-connection-state-pointer
_amqp_channel_t _pointer _int _int _int _int _pointer
-> _amqp-queue-declare-ok-pointer))
;; main
(define conn (amqp_new_connection))
(define sockfd (amqp_open_socket "localhost" 5672))
(when (< sockfd 0) (amqp_error_string (* -1 sockfd)))
(amqp_set_sockfd conn sockfd)
(define *AMQP_SASL_METHOD_PLAIN* 0)
(define resp (amqp_login conn "/" 0 131072 0
*AMQP_SASL_METHOD_PLAIN* "user" "pwd"))
(amqp_channel_open conn 1)
(amqp_queue_declare conn 1 #f 0 0 0 1 #f)
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