bug#61326: [DRAFT PATCH v2] Work around zip's filename extension limitation (was: Adding --no-add-suffix to zip patch)

[Ruijie Yu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

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Eli Zaretskii <eliz@gnu.org> writes:

>> From: Ruijie Yu <ruijie@netyu.xyz>
>> Cc: Eli Zaretskii <eliz@gnu.org>, asjo@koldfront.dk
>> Date: Thu, 09 Feb 2023 00:48:15 +0800
>>
>> Here is a preliminary patch that contains some "REVIEW" comments where I
>> need inputs.
>
> Thanks, but could you perhaps post diffs disregarding the whitespace
> changes?  That would make it easier to review the real changes.

Thanks, done.

>> -(defun archive-*-write-file-member (archive descr command)
>> +;; REVIEW: is there a better name than AVOID-EXTLESS-P?
>> +(defun archive-*-write-file-member (archive descr command
>> +                                            &optional avoid-extless-p)
>
> ensure-extension?

That sounds better, and I have renamed the variable in this iteration.

>> +    ;; REVIEW: the diff here is because the previous code had TAB's
>> +    ;; (while assuming each TAB is 4 spaces), and my Emacs replaced
>> +    ;; them with spaces.  What is the status quo on this kind of diff?
>> +    ;; I can remove them if we consider this change excessive and/or
>> +    ;; intrusive.
>
> TABs in Emacs are by default 8 columns, not 4.
>
> It is OK to convert TABs to spaces when changing the code in Lisp, but
> please do that only for the last commit, to make the review process
> easier.  For all the draft versions, please use "git diff" options
> that cause Git to ignore changes in whitespace.
>
> Thanks.

Thanks, I will keep that in mind.  I have also made some rearrangements
in the code to minimize delta.

In addition, I fixed an issue from the first iteration: in the first
iteration, the user would be prompted to revert buffer from disk if the
rename was in action; in this iteration this should no longer be the
case -- that is, the user should expect no difference between filenames
with extensions and without.

As pointed out in the commit message, two things remain: to ensure that
all write operations to extensionless zip archives behave correctly, and
to have some way to test that things continue to work in the future.


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From bc56c17082ea3ff2a76308f14310908853e3a2d1 Mon Sep 17 00:00:00 2001
From: Ruijie Yu <ruijie+git@netyu.xyz>
Date: Thu, 9 Feb 2023 00:45:19 +0800
Subject: [PATCH] lisp/arc-mode.el Work around zip's filename limitations on
 extension

[DRAFT PATCH]

Fixes 61326.  The "zip" executable requires that the named archive must have
an extension, else it attaches ".zip" to the supplied file name, causing
incorrect behaviors.  This patch looks for such scenarios and temporarily
rename extension-less archives so that "zip" would function correctly.

TODO:

1. Make sure other write operations, in addition to zip-write-member, are
fixed.
2. Tests? (I might need some pointers as to where existing tests are and how
to write them.)
---
 lisp/arc-mode.el | 38 +++++++++++++++++++++++++++++---------
 1 file changed, 29 insertions(+), 9 deletions(-)

diff --git a/lisp/arc-mode.el b/lisp/arc-mode.el
index 6f3e922880d..cd7f4ca1134 100644
--- a/lisp/arc-mode.el
+++ b/lisp/arc-mode.el
@@ -1350,14 +1350,23 @@ archive-write-file-member
       (setq last-coding-system-used archive-member-coding-system))
   t)

-(defun archive-*-write-file-member (archive descr command)
+(defun archive-*-write-file-member
+    (archive descr command &optional ensure-extension)
   (let* ((archive (expand-file-name archive))
+         (real-archive archive)
+         (archive (if ensure-extension
+                      (make-temp-name
+                       (expand-file-name (concat archive "_tmp.")))
+                    archive))
          (ename (archive--file-desc-ext-file-name descr))
          (tmpfile (expand-file-name ename archive-tmpdir))
          (top (directory-file-name (file-name-as-directory archive-tmpdir)))
     (default-directory (file-name-as-directory top)))
     (unwind-protect
-        (progn
+        (cl-flet ((maybe-rename (newname)
+                    (when ensure-extension
+                      (with-current-buffer archive-superior-buffer
+                        (rename-visited-file newname)))))
           (make-directory (file-name-directory tmpfile) t)
      ;; If the member is itself an archive, write it without
      ;; the dired-like listing we created.
@@ -1376,16 +1385,20 @@ archive-*-write-file-member
      (setq ename
        (encode-coding-string ename archive-file-name-coding-system))
           (let* ((coding-system-for-write 'no-conversion)
-        (default-directory (file-name-as-directory archive-tmpdir))
-        (exitcode (apply #'call-process
-                 (car command)
-                 nil
-                 nil
-                 nil
+        (default-directory (file-name-as-directory archive-tmpdir)))
+            (unwind-protect
+                (progn
+                  (maybe-rename archive)
+                  (let ((exitcode
+                         (apply #'call-process (car command)
+                                nil nil nil
                  (append (cdr command)
                      (list archive ename)))))
             (or (zerop exitcode)
        (error "Updating was unsuccessful (%S)" exitcode))))
+              (progn (maybe-rename real-archive)
+                     (with-current-buffer archive-superior-buffer
+                       (revert-buffer nil t))))))
       (archive-delete-local tmpfile))))

 (defun archive-write-file (&optional file)
@@ -2048,12 +2061,19 @@ archive--file-desc-case-fiddled
   (not (eq (archive--file-desc-int-file-name fd)
            (archive--file-desc-ext-file-name fd))))

+(defun archive--file-name-zip-extless-p (fname)
+  ;; zip's rule: if the filename contains "." anywhere in the name
+  ;; (including obscure names like ".foo" and "bar."), then this
+  ;; filename is considered to have an extension.
+  (not (seq-contains-p (file-name-nondirectory fname) ?. #'eq)))
+
 (defun archive-zip-write-file-member (archive descr)
   (archive-*-write-file-member
    archive
    descr
    (if (archive--file-desc-case-fiddled descr)
-       archive-zip-update-case archive-zip-update)))
+       archive-zip-update-case archive-zip-update)
+   (archive--file-name-zip-extless-p archive)))

 (defun archive-zip-chmod-entry (newmode files)
   (save-restriction
--
2.39.1


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Best,


RY