Hi all,
I'm trying to develop a CFFI binding for librrd, but I'm stuck right at the begining.
The function signature I'm trying to call is
int rrd_create(int, char **);
My test C code look's like this
#include <stdio.h> #include <stdlib.h> #include <string.h>
#include <rrd.h>
int main(int argc, char** argv) { char* c[6];
c[0] = "create"; c[1] = "test.rrd"; c[2] = "--step=300"; c[3] = "DS:a:GAUGE:600:U:U"; c[4] = "DS:b:GAUGE:600:U:U"; c[5] = "RRA:AVERAGE:0.5:1:300";
if (rrd_create(6, c) < 0) (void) fprintf(stderr, "librrd call failed: %s\n", rrd_get_error());
return (0); }
Using SBCL 0.9.9 and CFFI 0.9.0 on x86 I came up with the following LISP code (after doing the necessary housekeeping to load librrd)
(defvar *cmd* (list "test.rrd" "--step=300" "DS:a:GAUGE:600:U:U" "DS:b:GAUGE:600:U:U" "RRA:AVERAGE:0.5:1:300"))
(cffi:defcfun "rrd_create" :int (argcount :int) (args :pointer))
(cffi:with-foreign-pointer (ptr (+ (reduce #'+ (map 'vector #'length *cmd*)) (length *cmd*) 6)) (cffi:lisp-string-to-foreign "dummy" ptr 6) ; librrd needs a dummy fst arg (let ((curptr (cffi:inc-pointer ptr 6))) (dolist (param *cmd*) (let ((size (1+ (length param)))) (cffi:lisp-string-to-foreign param curptr size) (setf curptr (cffi:inc-pointer curptr size))))) (rrd-create 6 ptr))
But I get this error
memory fault [Condition of type SB-KERNEL::MEMORY-FAULT-ERROR]
Restarts: 0: [ABORT-REQUEST] Abort handling SLIME request. 1: [ABORT] Exit debugger, returning to top level.
Backtrace: 0: (SB-KERNEL::MEMORY-FAULT-ERROR) 1: ("foreign function: call_into_lisp") 2: ("foreign function: post_signal_tramp") 3: ("foreign function: getsubopt") 4: ("foreign function: getopt_long") 5: ("foreign function: rrd_create") 6: (RRD-CREATE 6 #.(SB-SYS:INT-SAP #X08269100)) 7: (NIL) 8: (SB-INT:EVAL-IN-LEXENV (CFFI-SYS:WITH-FOREIGN-POINTER (PTR (+ # # 6)) (CFFI:LISP-STRING-TO-FOREIGN "dummy" PTR 6) (LET (#) (DOLIST # #)) (RRD-CREATE 6 PTR)) #<NULL-LEXENV>) --more--
I tried various other ways but did not suceed and now I'm stuck.
TIA
Nikolai