bug#65305: 29.1; archive-mode can not handle subfile names encoded with utf-8

[awrhygty]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: awrhygty@outlook.com
>> Cc: 65305@debbugs.gnu.org
>> Date: Tue, 15 Aug 2023 22:53:01 +0900
>> 
>> Eli Zaretskii <eliz@gnu.org> writes:
>> 
>> > Is there any way of distinguishing these Python-created ZIP archives
>> > from ZIP archives created by other Windows programs?
>> >
>> > Emacs by default assumes that file names in a ZIP archive created by a
>> > Windows program are encoded in the console codepage, and it enforces
>> > using that encoding for file names when the "creator" of the ZIP
>> > archive indicates the archive was created by Windows programs such as
>> > InfoZip's zip.exe and the File Explorer.  In my testing, zip archives
>> > created by Python as above record the "creator" as number 0 (zero),
>> > which is identical to what InfoZip does.  So, unless someone explains
>> > how to distinguish these zip archives from those created by InfoZip, I
>> > don't see how can Emacs know whether to use the InfoZip heuristics or
>> > the Python heuristics.  Without the InfoZip/File Explorer heuristics
>> > we have in arc-mode.el today, Emacs on Windows would be completely
>> > unable to support non-ASCII file names in ZIP archives.
>> 
>> There is a bit flag indicating that the subfile name is encoded with
>> utf-8. Bytes 6-7 in local file header or bytes 8-9 in central directory
>> header are general purpose bit flag. And bit 11 of the flag represents
>> file encoding flag(1 for utf-8 encoding).
>
> Thanks, please try the patch below.  If it gives good results, I will
> install it.
>
>> I guess unzip.exe does not support utf-8 encoded subfile name.
>> Writing batch file with utf-8 encoding:
>>   c:\Emacs\emacs-29.1\bin\unzip.exe test.zip 一.txt
>> and run with chcp 932, 荳\200.txt is extracted.
>> With chcp 65001, extraction failed.
>> 
>> Writing batch file with cp932 encoding:(same as above)
>>   c:\Emacs\emacs-29.1\bin\unzip.exe test.zip 一.txt
>> and run with chcp 65001, 荳\200.txt is extracted.
>> With chcp 932, extraction failed.
>> This is not an ideal behavior, but extraction to STDOUT may work.
>> 
>> To the contrary, 7z.exe extracts 一.txt correctly.
>> If batch file is encoded with utf-8, it works with chcp 65001.
>> If batch file is encoded with cp932, it works with chcp 932.
>
> Like I said: support for UTF-8 encoded file names on Windows is
> sporadic and incomplete.  It will remain so until Windows file-related
> APIs support UTF-8 encoded file names.
>
> diff --git a/lisp/arc-mode.el b/lisp/arc-mode.el
> index 5e696c0..05a71fb 100644
> --- a/lisp/arc-mode.el
> +++ b/lisp/arc-mode.el
> @@ -1990,6 +1990,7 @@ archive-zip-summarize
>      (setq p (+ p (point-min)))
>      (while (string= "PK\001\002" (buffer-substring p (+ p 4)))
>        (let* ((creator (get-byte (+ p 5)))
> +             (gpflags (archive-l-e (+ p 8) 2))
>            ;; (method  (archive-l-e (+ p 10) 2))
>               (modtime (archive-l-e (+ p 12) 2))
>               (moddate (archive-l-e (+ p 14) 2))
> @@ -2001,7 +2002,12 @@ archive-zip-summarize
>               (efnname (let ((str (buffer-substring (+ p 46) (+ p 46 fnlen))))
>                       (decode-coding-string
>                        str
> -                         (or (if (and w32-fname-encoding
> +                         ;; Bit 11 of general purpose bit flags (bytes
> +                         ;; 8-9) of Central Directory: 1 means UTF-8
> +                         ;; encoded file names.
> +                         (or (if (/= 0 (logand gpflags #x0800))
> +                                 'utf-8-unix)
> +                             (if (and w32-fname-encoding
>                                        (memq creator
>                                              ;; This should be just 10 and
>                                              ;; 14, but InfoZip uses 0 and

The patch works to list entries, and the contents can be extracted with
7z.exe. unzip.exe does not work well.

I tried the settings below, but rewriting entries does not work.
(archive-zip-* variables' values are default if archive-7z-program is set
and zip.exe/unzip.exe are non-existent)

(setq archive-7z-program "c:/Program Files/7-Zip/7z.exe"
      archive-zip-extract '("c:/Program Files/7-Zip/7z.exe" "x" "-so")
      archive-zip-expunge '("c:/Program Files/7-Zip/7z.exe" "d")
      archive-zip-update  '("c:/Program Files/7-Zip/7z.exe" "u")
      archive-zip-update-case archive-zip-update)

It is because update command needs "-si" option followed by an entry
name. It should be one argument like (format "-si%s" name).