[PATCH] bindat and multibyte string RAW-DATA

[PATCH] bindat and multibyte string RAW-DATA

[Thien-Thi Nguyen]

i am having difficulty imagining how a multibyte string RAW-DATA to
`bindat-pack' and `bindat-unpack' could be anything less than latent
confusion and bugs cultivation.  so i propose the change below.  WDYT?

here is an example of the problem (silent weirdness):

;; unibyte ok
(bindat-unpack '((one u8) (two u8)) (string 40 41))
     => ((two . 41) (one . 40))

;; multibyte -- big "bytes"!
(bindat-unpack '((one u8) (two u8)) (string 53450 53451))
     => ((two . 53451) (one . 53450))

there was variability over "size of byte" a while back, but these
days the above behavior would probably be considered buggy.

apparently, there are other problems as well:

;; vector -- more big bytes
(bindat-unpack '((one u8) (two u8)) (vector 53450 53451))
     => ((two . 53451) (one . 53450))

however, the patch does not address this last problem.  a check:

  (when (vectorp raw-data)
    (let ((i 0) (len (length raw-data)) value)
      (while (< i len)
        (setq value (aref raw-data i))
        (unless (and (<= 0 value) (<= value 255))
          (error "Array element out of range")))))

inserted into `bindat-unpack' would work, but it seems heavy...

thi

__________________________________________________________
*** bindat.el	23 May 2006 11:21:59 -0000	1.10
--- bindat.el	23 May 2006 23:11:32 -0000
***************
*** 345,352 ****
  
  (defun bindat-unpack (spec raw-data &optional pos)
    "Return structured data according to SPEC for binary data in RAW-DATA.
! RAW-DATA is a string or vector.  Optional third arg POS specifies the
! starting offset in RAW-DATA."
    (unless pos (setq pos 0))
    (bindat--unpack-group spec))
  
--- 345,354 ----
  
  (defun bindat-unpack (spec raw-data &optional pos)
    "Return structured data according to SPEC for binary data in RAW-DATA.
! RAW-DATA is a unibyte string or vector.  Optional third arg POS specifies
! the starting offset in RAW-DATA."
!   (when (multibyte-string-p raw-data)
!     (error "String is multibyte"))
    (unless pos (setq pos 0))
    (bindat--unpack-group spec))
  
***************
*** 581,590 ****
  
  (defun bindat-pack (spec struct &optional raw-data pos)
    "Return binary data packed according to SPEC for structured data STRUCT.
! Optional third arg RAW-DATA is a pre-allocated string or vector to pack into.
! Optional fourth arg POS is the starting offset into RAW-DATA.
! Note: The result is a multibyte string; use `string-make-unibyte' on it
! to make it unibyte if necessary."
    (let ((no-return raw-data))
      (unless pos (setq pos 0))
      (unless raw-data
--- 583,592 ----
  
  (defun bindat-pack (spec struct &optional raw-data pos)
    "Return binary data packed according to SPEC for structured data STRUCT.
! Optional third arg RAW-DATA is a pre-allocated unibyte string or vector to
! pack into.  Optional fourth arg POS is the starting offset into RAW-DATA."
!   (when (multibyte-string-p raw-data)
!     (error "Pre-allocated string is multibyte"))
    (let ((no-return raw-data))
      (unless pos (setq pos 0))
      (unless raw-data

Re: [PATCH] bindat and multibyte string RAW-DATA

[Kim F. Storm]

Thien-Thi Nguyen <ttn@gnu.org> writes:

> i am having difficulty imagining how a multibyte string RAW-DATA to
> `bindat-pack' and `bindat-unpack' could be anything less than latent
> confusion and bugs cultivation.  so i propose the change below.  WDYT?

Your changes looks ok.  Please install them.

-- 
Kim F. Storm <storm@cua.dk> http://www.cua.dk