Binary network communication appears broken

Binary network communication appears broken

[Harald Hanche-Olsen]

I discovered this because it breaks mew:

(This is with CVS emacs as of yesterday.
I spent many hours debugging my way to this simple test case.)

Define this function:

(defun test-net (coding)
  (interactive "SUse coding: ")
  (make-network-process
   :name "testproc"
   :host 'local :service 9898 :family 'ipv4
   :buffer "*testproc*"
   :coding coding
   :filter (lambda (proc string)
	     (setq *test* string ))
   :sentinel (lambda (proc string)
	       (delete-process proc))))

Set up a network service on port 9898 on localhost that just echos a
short string, then disconnect. The string should contain some
non-ASCII character. I used the string "målbar" (encoded as latin-1)
with a newline appended, total 7 bytes. (I used a one line shell
script under tcpserver. I suppose you could use inetd as well.)

Now run: M-x test-net RET binary RET

(Also tested with raw-text and no-conversion, same result.)

The string *test* now contains a string that appears to be 5
characters long: (insert *test*) certainly inserts 5 characters,
though (length *test*) returns 7. The string appears to be "m_ar\n",
where there is really a Chinese character in the position I indicated
with an underscore. (I am bending over backwards to avoid making this
a unicode encoded email. The character in question is #x5b22, if you
must know.) However, if I examine the characters of the text using
aref, it turns out to contain what I expected, except ?å is replaced
by #x5b22 again.

- Harald

PS. Please Cc me on replies, as I am not on the list. It appears
to be impossible to sign up for this list?

Re: Binary network communication appears broken

[Stefan Monnier]

> I discovered this because it breaks mew:
> (This is with CVS emacs as of yesterday.
> I spent many hours debugging my way to this simple test case.)

> Define this function:

> (defun test-net (coding)
>   (interactive "SUse coding: ")
>   (make-network-process
>    :name "testproc"
>    :host 'local :service 9898 :family 'ipv4
>    :buffer "*testproc*"
>    :coding coding
>    :filter (lambda (proc string)
> 	     (setq *test* string ))
>    :sentinel (lambda (proc string)
> 	       (delete-process proc))))

Thank you very much for your efforts.

Does the patch below help?


        Stefan


--- coding.c.~1.374.~	2008-03-25 11:59:11.000000000 -0400
+++ coding.c	2008-03-27 14:51:31.000000000 -0400
@@ -7030,10 +7030,10 @@
       || (! NILP (CODING_ATTR_POST_READ (attrs))
 	  && NILP (dst_object)))
     {
-      coding->dst_object = code_conversion_save (1, 1);
+      coding->dst_multibyte = !CODING_FOR_UNIBYTE (coding);
+      coding->dst_object = code_conversion_save (1, coding->dst_multibyte);
       coding->dst_pos = BEG;
       coding->dst_pos_byte = BEG_BYTE;
-      coding->dst_multibyte = !CODING_FOR_UNIBYTE (coding);
     }
   else if (BUFFERP (dst_object))
     {

Re: Binary network communication appears broken

[Harald Hanche-Olsen]

+ Stefan Monnier <monnier@iro.umontreal.ca>:

> Thank you very much for your efforts.

No problem. It still beats writing my own emacs from scratch, by quite
a few orders of magnitude.  8-)  A big part of the problem was that I
would get characters in a buffer that weren't really characters, and
then emacs would crash when trying to display this non-characters.  Or
at least that is how it seemed to me.

> Does the patch below help?

Yes indeed!  To prove it, I am responding from the patched emacs.
Thank you.

- Harald