[PATCH v2] Re: [BUG] org-attach-id-ts-folder-format fails on customized IDs [9.6 (9.6-??-2e9999783)]

[Ihor Radchenko]

Ihor Radchenko <yantar92@gmail.com> writes:

>> Ihor, I am afraid of collisions due to short input to md5. Long hash 
>> value gives false impression of high entropy but actually there are not 
>> so many variants for 1 or 2 characters strings. Either there is no point 
>> in making long name from short id or random string of appropriate length 
>> should be used instead.
>
> Random is not an option. If we use random string, how will we get the
> right attachment path on a second call? This function must return the
> same value given the same input.
>
> Having said that, I do agree (taking into account the other comment)
> that md5 may not be a very good idea. Maybe simply something like
> "__/id". Ideally, we should be able to recover the original id from the
> path to attachment.

I have updated the patch to use "__/id" when id is too short.
Any objections?

>From 7ca5fe66c53a1399943a2e2d4a1675ca8cd14194 Mon Sep 17 00:00:00 2001
Message-Id: 
<7ca5fe66c53a1399943a2e2d4a1675ca8cd14194.1660131747.git.yantar92@gmail.com>
From: Ihor Radchenko <yantar92@gmail.com>
Date: Sat, 23 Jul 2022 13:13:24 +0800
Subject: [PATCH v2] org-attach-dir-from-id: Do not rely on ID being over 6
 chars long

* lisp/org-attach.el (org-attach-id-uuid-folder-format): Fall back to
"--/ID" when the ID contains 2 chars or less and cannot be split into
the "xy/z...." path.
(org-attach-id-ts-folder-format): Fall back to "unknown/ID" path
format when the ID contains less than 7 chars and cannot be split into
the "YYYYMM/rest" path.

Fixes 
https://orgmode.org/list/KC8PcypJapBpJQtJxM0kX5N7Z0THL2Lq6EQjBMzpw1-vgQf72egZ2JOIlTbPYiqAVD4MdSBhrhBZr2Ykf5DN1mocm1ANvvuKKZShlkgzKYM=@pm.me
---
 lisp/org-attach.el | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/lisp/org-attach.el b/lisp/org-attach.el
index fe49af6f3..bb7c787f7 100644
--- a/lisp/org-attach.el
+++ b/lisp/org-attach.el
@@ -159,19 +159,28 @@ (defcustom org-attach-archive-delete nil
 (defun org-attach-id-uuid-folder-format (id)
   "Translate an UUID ID into a folder-path.
 Default format for how Org translates ID properties to a path for
-attachments.  Useful if ID is generated with UUID."
-  (format "%s/%s"
-         (substring id 0 2)
-         (substring id 2)))
+attachments.  Useful if ID is generated with UUID.
+
+When ID is too short (less than 3 chars), use its md5 hash to create
+the path."
+  (if (< (length id) 3)
+      (format "--/%s" id)
+    (format "%s/%s"
+           (substring id 0 2)
+           (substring id 2))))
 
 (defun org-attach-id-ts-folder-format (id)
   "Translate an ID based on a timestamp to a folder-path.
 Useful way of translation if ID is generated based on ISO8601
 timestamp.  Splits the attachment folder hierarchy into
-year-month, the rest."
-  (format "%s/%s"
-         (substring id 0 6)
-         (substring id 6)))
+year-month, the rest.
+
+When ID is too short (less than 7 chars), return \"unknown/ID\"."
+  (if (< (length id) 7)
+      (format "unknown/%s" id)
+    (format "%s/%s"
+           (substring id 0 6)
+           (substring id 6))))
 
 (defcustom org-attach-id-to-path-function-list 
'(org-attach-id-uuid-folder-format
                                                 org-attach-id-ts-folder-format)
-- 
2.35.1


-- 
Ihor Radchenko,
Org mode contributor,
Learn more about Org mode at https://orgmode.org/.
Support Org development at https://liberapay.com/org-mode,
or support my work at https://liberapay.com/yantar92