Subject: bug#77898: 31.0.50; arc-mode: Split PKZIP archive signature not recognized

From: Jens Schmidt <[email-masked]>
Date: Sat, 19 Apr 2025 14:31:27 +0200

On 2025-04-18  14:51, Eli Zaretskii wrote:

> Please add comments describing the possible signatures, with pointers
> to specific sections of APPNOTE.txt.

As an aside, how would you add a comment to the first branch of a
`cond' if you would like to keep the branches aligned to the *end*
of the `cond' keyword?  I usually do these as follows:

    (cond ;; See APPNOTE.txt (version 6.3.10) from PKWARE for the zip
          ;; file signatures:
          ;; - PK\003\004 == 0x04034b50: local file header signature
          ;;   (section 4.3.7)
          ;; - PK\007\010 == 0x08074b50 (followed by local header):
          ;;   spanned/split archive signature (section 8.5.3)
          ;; - PK00 == 0x30304b50 (followed by local header): temporary
          ;;   spanned/split archive signature (section 8.5.4)
          ((looking-at "\\(?:PK\007\010\\|PK00\\)?[P]K\003\004") 'zip)

But the Emacs indentation machinery clearly disagrees on that and
I'm not sure to what extent Emacs's indentation is normative in its
own sources.

Thanks.