[nongnu] elpa/undo-fu-session 27b688e02d: Add option to skip saving undo information for temporary files

[ELPA Syncer]

branch: elpa/undo-fu-session
commit 27b688e02d5f5bb7a939f3e312b0219aebe24afc
Author: Campbell Barton <ideasman42@gmail.com>
Commit: Campbell Barton <ideasman42@gmail.com>

    Add option to skip saving undo information for temporary files
    
    Bump to version 0.6 as this feature addresses security implications
    for utilities that extract encrypted files into a temporary directory
    for editing.
    
    Resolves #6.
---
 changelog.rst      |  3 ++-
 readme.rst         |  3 +++
 undo-fu-session.el | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 64 insertions(+), 2 deletions(-)

diff --git a/changelog.rst b/changelog.rst
index 6d33f3265d..34cbc57e30 100644
--- a/changelog.rst
+++ b/changelog.rst
@@ -3,8 +3,9 @@
 Change Log
 ##########
 
-- In development.
+- Version 0.6 (2023-05-20)
 
+  - Add ``undo-fu-session-ignore-temp-files`` to ignore files in temporary 
directories.
   - The ``undo-fu-session-incompatible-files`` match is now case insensitive 
for case insensitive file-systems.
 
 - Version 0.5 (2023-04-05)
diff --git a/readme.rst b/readme.rst
index 322c4afa78..451dc3f19a 100644
--- a/readme.rst
+++ b/readme.rst
@@ -80,6 +80,9 @@ Customization
    List of major-modes in which saving undo session should not be performed.
 ``undo-fu-session-ignore-encrypted-files`` (``t``)
    Ignore saving/recovering undo session for encrypted files (matching 
``epa-file-name-regexp``).
+``undo-fu-session-ignore-temp-files`` (``t``)
+   Ignore saving/recovering undo session for files under 
``temporary-file-directory``
+   (as well as ``/tmp`` & ``/dev/shm/``).
 ``undo-fu-session-file-limit`` (``nil``)
    Number of files to store, nil to disable limiting entirely.
 
diff --git a/undo-fu-session.el b/undo-fu-session.el
index 158538dbc3..30443466fc 100755
--- a/undo-fu-session.el
+++ b/undo-fu-session.el
@@ -8,7 +8,7 @@
 
 ;; URL: https://codeberg.com/ideasman42/emacs-undo-fu-session
 ;; Keywords: convenience
-;; Version: 0.5
+;; Version: 0.6
 ;; Package-Requires: ((emacs "28.1"))
 
 ;;; Commentary:
@@ -64,6 +64,10 @@
   "Ignore encrypted files for undo session."
   :type 'boolean)
 
+(defcustom undo-fu-session-ignore-temp-files t
+  "Ignore temporary files for undo session."
+  :type 'boolean)
+
 (defcustom undo-fu-session-compression 'gz
   "The type of compression to use or nil.
 
@@ -101,6 +105,30 @@ Enforcing removes the oldest files."
   `(let ((inhibit-message t))
      (message ,str ,@args)))
 
+(defun undo-fu-session--canonicalize-path (path)
+  "Return the canonical PATH.
+
+This is done without adjusting trailing slashes or following links."
+  ;; Some pre-processing on `path' since it may contain the user path
+  ;; or be relative to the default directory.
+  ;;
+  ;; Notes:
+  ;; - This is loosely based on `f-same?'` from the `f' library.
+  ;;   However it's important this only runs on the user directory and NOT 
trusted directories
+  ;;   since there should never be any ambiguity (which could be caused by 
expansion)
+  ;;   regarding which path is trusted.
+  ;; - Avoid `file-truename' since this follows symbolic-links,
+  ;;   `expand-file-name' handles `~` and removing `/../' from paths.
+  (let ((file-name-handler-alist nil))
+    ;; Expand user `~' and default directory.
+    (expand-file-name path)))
+
+(defun undo-fu-session--ensure-trailing-slash (dir)
+  "Return DIR with exactly one trailing slash."
+  ;; Both "/tmp" and "/tmp//" result in "/tmp/"
+  (file-name-as-directory (directory-file-name dir)))
+
+
 ;; ---------------------------------------------------------------------------
 ;; Undo List Make Linear
 ;;
@@ -449,6 +477,34 @@ Argument PENDING-LIST an `pending-undo-list' compatible 
list."
                 (funcall matcher filename)))
           (throw 'found t))))))
 
+(defun undo-fu-session--temp-file-check (filename)
+  "Return t if FILENAME is in a temporary directory."
+  (let ((temp-dirs (list))
+        (is-temp nil))
+    (when temporary-file-directory
+      ;; Ensure a single slash so `string-prefix-p' can be used.
+      (push (undo-fu-session--ensure-trailing-slash temporary-file-directory) 
temp-dirs))
+
+    ;; Even if this directory doesn't exist, the check is relatively harmless.
+    (cond
+     ((memq system-type (list 'ms-dos 'windows-nt))
+      nil)
+     (t
+      (push "/tmp/" temp-dirs)
+      (push "/dev/shm/" temp-dirs)))
+
+    (setq temp-dirs (delete-dups temp-dirs))
+
+    (when temp-dirs
+      ;; Canonicalized in case the default directory happens to be TEMP.
+      (let ((filename-canonical (undo-fu-session--canonicalize-path filename)))
+        (while temp-dirs
+          (let ((dir (pop temp-dirs)))
+            (when (string-prefix-p dir filename-canonical 
(file-name-case-insensitive-p dir))
+              (setq is-temp t)
+              (setq temp-dirs nil))))))
+    is-temp))
+
 (defun undo-fu-session--directory-ensure ()
   "Ensure the undo directory has been created."
   (unless (file-directory-p undo-fu-session-directory)
@@ -469,6 +525,8 @@ Argument PENDING-LIST an `pending-undo-list' compatible 
list."
            epa-file-handler
            (string-match-p (car epa-file-handler) filename))
       nil)
+     ((and undo-fu-session-ignore-temp-files (undo-fu-session--temp-file-check 
filename))
+      nil)
      ((and test-files (undo-fu-session--match-file-name filename test-files))
       nil)
      ((and test-modes (memq (buffer-local-value 'major-mode buffer) 
test-modes))