bug#25075: 26.0.50; [PATCH] Dired can now dereference symlinks when copying

[Kaushal Modi <kaushal.modi@gmail.com>]

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Hello,

Can you review and comment on the below patch. I came up with a necessity
to copy symlinks from one dired buffer to another dired buffer as a
dereferenced copy of that symlink.

In terminal, I would use the -L option of the cp command to do the same.

The current default behavior is unchanged as the new defcustom
dired-copy-dereference is set to nil.

From 4c4185b9d4df2dcbbb6e1e7fa8a21b75e84ca79f Mon Sep 17 00:00:00 2001
From: Kaushal Modi <kaushal.modi@gmail.com>
Date: Wed, 30 Nov 2016 12:52:42 -0500
Subject: [PATCH] Dired can now dereference symlinks when copying

* lisp/dired.el (dired-copy-dereference): New defcustom, defaults to
nil.

* lisp/dired-aux.el (dired-copy-file-recursive): Add new optional
argument `dereference'.

* lisp/dired-aux.el (dired-copy-file): Use `dired-copy-dereference' as
the `dereference' argument to `dired-copy-file-recursive'.
---
 lisp/dired-aux.el | 8 +++++---
 lisp/dired.el     | 6 ++++++
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/lisp/dired-aux.el b/lisp/dired-aux.el
index f94e053..149c540 100644
--- a/lisp/dired-aux.el
+++ b/lisp/dired-aux.el
@@ -1507,12 +1507,13 @@ dired-handle-overwrite
 (defun dired-copy-file (from to ok-flag)
   (dired-handle-overwrite to)
   (dired-copy-file-recursive from to ok-flag dired-copy-preserve-time t
-     dired-recursive-copies))
+     dired-recursive-copies dired-copy-dereference))

 (declare-function make-symbolic-link "fileio.c")

 (defun dired-copy-file-recursive (from to ok-flag &optional
-       preserve-time top recursive)
+       preserve-time top recursive
+                                       dereference)
   (when (and (eq t (car (file-attributes from)))
      (file-in-directory-p to from))
     (error "Cannot copy `%s' into its subdirectory `%s'" from to))
@@ -1524,7 +1525,8 @@ dired-copy-file-recursive
  (copy-directory from to preserve-time)
       (or top (dired-handle-overwrite to))
       (condition-case err
-  (if (stringp (car attrs))
+  (if (and (not dereference)
+                   (stringp (car attrs)))
       ;; It is a symlink
       (make-symbolic-link (car attrs) to ok-flag)
     (copy-file from to ok-flag preserve-time))
diff --git a/lisp/dired.el b/lisp/dired.el
index daa6d77..ca7ab28 100644
--- a/lisp/dired.el
+++ b/lisp/dired.el
@@ -191,6 +191,12 @@ dired-copy-preserve-time
   :type 'boolean
   :group 'dired)

+(defcustom dired-copy-dereference nil
+  "If non-nil, Dired dereferences symlinks when copying them.
+This is similar to the \"-L\" option for the \"cp\" shell command."
+  :type 'boolean
+  :group 'dired)
+                                        ;
 ; These variables were deleted and the replacements are on files.el.
 ; We leave aliases behind for back-compatibility.
 (defvaralias 'dired-free-space-program 'directory-free-space-program)
-- 
2.10.0

-- 

Kaushal Modi

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