Hi,
I don`t know if this is the right group to ask, but I would appreciate some help with the following.

The aim is to read a binary file from lisp.

The file contains a set of records, every record consists of the following data:
(cffi:defcstruct ppp
(nr :unsigned-int)
(name :char :count 32) ;; this is the problematic line 1
(alias :char :count 12) ;; this is the problematic line 2
(m :double)
(t :double)
(p :double)
(v :double))

Now the problematic line 1 should read 32 characters from an ascii-encoded file.
For that, I use the (defun test .....) (see below). The test converts the cstruct with-foreign-slots through (cffi:foreign-string-to-lisp name).
The output of (test) is:
(1 "ABC                             ABC         ÙÎ÷Só<@fffffŽ`@"
"ABC         ÙÎ÷Só<@fffffŽ`@" 28.9d0 132.4d0 3774.0d0 0.0d0)
where:
(length (second *))
>> 60
(length (third **))
>> 28
whereas I would expect the output to be:
(1 "ABC                             "
"ABC         " 28.9d0 132.4d0 3774.0d0 0.0d0)

with length second = 32 and length third = 12.

Am I missing something?
I tried:
(cffi:foreign-string-to-lisp name 32)
(cffi:foreign-string-to-lisp name 12)

this works, the correct output is presented. But how can I get the length of the char in the cstruct PPP?

Thank you very much,
best regards,
mosi

;;---- TEST.lisp ------
(in-package :cl-user)
(eval-when (:compile-toplevel :load-toplevel) (require :cffi))

(defpackage :test (:use :cl))

(in-package :test)

(cffi:defcfun "fopen" :pointer (path :string) (mode :string))

(cffi:defcfun "fread" :unsigned-long
(ptr :pointer)
(size :unsigned-long)
(nmemb :unsigned-long)
(stream :pointer))

(cffi:defcfun "fclose" :int (fp :pointer))

(cffi:defcstruct ppp
(nr :unsigned-int)
(name :char :count 32)
(alias :char :count 12)
(mw :double)
(tc :double)
(pc :double)
(vc :double))

(defparameter *file-path* "C://the-file.bin") ;;

(defun test ())
(let (file)
(unwind-protect
       (progn
    (setf file (fopen *file-path* "rb"))
    (cffi:with-foreign-object (struct 'ppp)
       (fread struct (cffi:foreign-type-size 'ppp) 1 file)
       (cffi:with-foreign-slots ((nr name alias m t p v)
                     struct
                     ppp)
         (list nr
           (cffi:foreign-string-to-lisp name)
           (cffi:foreign-string-to-lisp alias)
           mw
           tc
           pc
           vc))))
    (when file (fclose file))))

;; run this by (test)