bug#37922: 26.3; move-file-to-trash puts wrong trash file name at name collision

[Shingo Tanaka <shingo.fg8@gmail.com>]

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Hi,

When delete-by-moving-to-trash is t and system-move-file-to-trash is not
defined, move-file-to-trash moves the deleted file to system trash can
following freedesktop.org trash can specification.

In this condition, when a file is deleted and it has the same name as the
one of an already deleted file in trash can, move-file-to-trash generates
another file name by using make-temp-file to avoid the name collision.
Unfortunately, it does put a wrong name with suffix ".trashinfo".

For example, when 2 "hoge.txt" are deleted, expected files are like:

/home/myusername/.local/share/Trash/files:
-rw-rw-rw- 1 myusername  10 2019-10-25 20:00 hoge.txt
-rw-rw-rw- 1 myusername  10 2019-10-25 20:00 hoge.txtwmWP0h

/home/myusername/.local/share/Trash/info:
-rw-rw-rw- 1 myusername  75 2019-10-25 20:00 hoge.txt.trashinfo
-rw------- 1 myusername  75 2019-10-25 20:00 hoge.txtwmWP0h.trashinfo

However, the reality is the 2nd trash file in files directory is named
wrongly with ".trashinfo" suffix like:

/home/myusername/.local/share/Trash/files:
-rw-rw-rw- 1 myusername  10 2019-10-25 20:00 hoge.txt
-rw-rw-rw- 1 myusername  10 2019-10-25 20:00 hoge.txtwmWP0h.trashinfo
                                                            ^^^^^^^^^
/home/myusername/.local/share/Trash/info:
-rw-rw-rw- 1 myusername  75 2019-10-25 20:00 hoge.txt.trashinfo
-rw------- 1 myusername  75 2019-10-25 20:00 hoge.txtwmWP0h.trashinfo

Here is a potential patch.

--- files.el.original 2019-09-17 05:14:45.000000000 +0900
+++ files.el 2019-10-25 20:52:13.899138800 +0900
@@ -7408,7 +7408,8 @@
     (setq info-fn (make-temp-file
    (expand-file-name files-base trash-info-dir)
    nil ".trashinfo"))
-    (setq files-base (file-name-nondirectory info-fn))
+    (setq files-base (substring (file-name-nondirectory info-fn)
+ 0 (- (length ".trashinfo"))))
     (write-region nil nil info-fn nil 'quiet info-fn)))
  ;; Finally, try to move the file to the trashcan.
  (let ((delete-by-moving-to-trash nil)

---
Shingo Tanaka

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