master 9b01bad: Allow Dired to dereference symbolic links when copying

[Lars Ingebrigtsen]

branch: master
commit 9b01badf7cf7bb6cd64bc8d39564b46ae74b889f
Author: Kaushal Modi <kaushal.modi@gmail.com>
Commit: Lars Ingebrigtsen <larsi@gnus.org>

    Allow Dired to dereference symbolic links when copying
    
    * doc/emacs/dired.texi (Operating on Files): Mention the new
    defcustom (bug#25075).
    * lisp/dired-aux.el (dired-do-copy): Invert the value of
    `dired-copy-dereference' in lexical scope when prefix argument is
    '(4). Update function documentation for the new defcustom.
    
    * lisp/dired-aux.el (dired-copy-file): Use `dired-copy-dereference' as
    the `dereference' argument to `dired-copy-file-recursive'.
    
    * lisp/dired-aux.el (dired-copy-file-recursive): Add new optional
    argument `dereference'.
    
    * lisp/dired.el (dired-copy-dereference): New defcustom, defaults to
    nil.
---
 doc/emacs/dired.texi |  8 ++++++++
 etc/NEWS             |  6 ++++++
 lisp/dired-aux.el    | 25 +++++++++++++++++++------
 lisp/dired.el        |  6 ++++++
 4 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/doc/emacs/dired.texi b/doc/emacs/dired.texi
index 4ff1dc1..de449e3 100644
--- a/doc/emacs/dired.texi
+++ b/doc/emacs/dired.texi
@@ -694,6 +694,14 @@ The variable @code{dired-recursive-copies} controls 
whether to copy
 directories recursively (like @samp{cp -r}).  The default is
 @code{top}, which means to ask before recursively copying a directory.
 
+@vindex dired-copy-dereference
+@cindex follow symbolic links
+@cindex dereference symbolic links
+The variable @code{dired-copy-dereference} controls whether to copy
+symbolic links as links or after dereferencing (like @samp{cp -L}).
+The default is @code{nil}, which means that the symbolic links are
+copied by creating new ones.
+
 @item D
 @findex dired-do-delete
 @kindex D @r{(Dired)}
diff --git a/etc/NEWS b/etc/NEWS
index ddb42fb..49c0b86 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -222,6 +222,12 @@ like "+0100" instead of "CET".
 
 ** Dired
 
++++
+*** New used option 'dired-copy-dereference'.
+If set, Dired will dereferences symbolic links when copying.  This can
+be switched off on a per-usage basis by providing 'dired-do-copy' with
+a 'C-u' prefix.
+
 *** New user option 'dired-mark-region' affects all Dired commands
 that mark files.  When non-nil and the region is active in Transient
 Mark mode, then Dired commands operate only on files in the active
diff --git a/lisp/dired-aux.el b/lisp/dired-aux.el
index 69b1753..c197ed0 100644
--- a/lisp/dired-aux.el
+++ b/lisp/dired-aux.el
@@ -1604,7 +1604,7 @@ Special value `always' suppresses confirmation."
 (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")
 
@@ -1627,7 +1627,8 @@ If `ask', ask for user confirmation."
         (dired-create-directory dir))))
 
 (defun dired-copy-file-recursive (from to ok-flag &optional
-                                      preserve-time top recursive)
+                                       preserve-time top recursive
+                                       dereference)
   (when (and (eq t (file-attribute-type (file-attributes from)))
             (file-in-directory-p to from))
     (error "Cannot copy `%s' into its subdirectory `%s'" from to))
@@ -1639,7 +1640,8 @@ If `ask', ask for user confirmation."
        (copy-directory from to preserve-time)
       (or top (dired-handle-overwrite to))
       (condition-case err
-         (if (stringp (file-attribute-type attrs))
+         (if (and (not dereference)
+                   (stringp (file-attribute-type attrs)))
              ;; It is a symlink
              (make-symbolic-link (file-attribute-type attrs) to ok-flag)
             (dired-maybe-create-dirs (file-name-directory to))
@@ -2165,6 +2167,9 @@ See HOW-TO argument for `dired-do-create-files'.")
 ;;;###autoload
 (defun dired-do-copy (&optional arg)
   "Copy all marked (or next ARG) files, or copy the current file.
+ARG has to be numeric for above functionality.  See
+`dired-get-marked-files' for more details.
+
 When operating on just the current file, prompt for the new name.
 
 When operating on multiple or marked files, prompt for a target
@@ -2178,10 +2183,18 @@ If `dired-copy-preserve-time' is non-nil, this command 
preserves
 the modification time of each old file in the copy, similar to
 the \"-p\" option for the \"cp\" shell command.
 
-This command copies symbolic links by creating new ones, similar
-to the \"-d\" option for the \"cp\" shell command."
+This command copies symbolic links by creating new ones,
+similar to the \"-d\" option for the \"cp\" shell command.
+But if `dired-copy-dereference' is non-nil, the symbolic
+links are dereferenced and then copied, similar to the \"-L\"
+option for the \"cp\" shell command.  If ARG is a cons with
+element 4 (`\\[universal-argument]'), the inverted value of
+`dired-copy-dereference' will be used."
   (interactive "P")
-  (let ((dired-recursive-copies dired-recursive-copies))
+  (let ((dired-recursive-copies dired-recursive-copies)
+        (dired-copy-dereference (if (equal arg '(4))
+                                    (not dired-copy-dereference)
+                                  dired-copy-dereference)))
     (dired-do-create-files 'copy #'dired-copy-file
                           "Copy"
                           arg dired-keep-marker-copy
diff --git a/lisp/dired.el b/lisp/dired.el
index d19d6d1..77bb6cf 100644
--- a/lisp/dired.el
+++ b/lisp/dired.el
@@ -216,6 +216,12 @@ The target is used in the prompt for file copy, rename 
etc."
   :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.
 (define-obsolete-variable-alias 'dired-free-space-program