From 29bb72f0432c7b89d2f7dec5022c582f8e10ada9 Mon Sep 17 00:00:00 2001
From: Tino Calancha <tino.calancha@gmail.com>
Date: Sat, 22 Aug 2020 17:39:16 +0200
Subject: [PATCH] Handle globstar in dired

Allow user to enable globstar when the shell support
it and disable it by default (e.g. bash).
* lisp/dired.el (dired-maybe-use-globstar): New user option.
(dired-enable-globstar-in-shell): New variable.
(dired-insert-directory): if `dired-maybe-use-globstar' is
non-nil and the shell supports globstar, then enable it.

* doc/emacs/dired.texi: Document feature.
; * etc/NEWS: Add entry.
---
 doc/emacs/dired.texi | 18 ++++++++++++++++++
 etc/NEWS             |  6 ++++++
 lisp/dired.el        | 27 +++++++++++++++++++++++++++
 3 files changed, 51 insertions(+)

diff --git a/doc/emacs/dired.texi b/doc/emacs/dired.texi
index de449e31c37..39caab086c2 100644
--- a/doc/emacs/dired.texi
+++ b/doc/emacs/dired.texi
@@ -79,6 +79,24 @@ The former lists all the files with extension @samp{.el} in directory
 @samp{foo}.  The latter lists the files with extension @samp{.el}
 in all the subdirectories of @samp{foo}.
 
+When the system shell supports globstar and it's enabled, then you
+can use recursive globbing:
+
+@example
+C-x d  ~/foo/**/*.el  @key{RET}
+@end example
+
+This command lists all the files with extension @samp{.el} descending
+recursively in all the subdirectories of @samp{foo}.  Note that there
+are small differences in the implementation of globstar between shells.
+Check your shell manual to know the expected behavior.
+
+@vindex dired-maybe-use-globstar
+@vindex dired-enable-globstar-in-shell
+If the shell supports globstar and disables it by default, you
+can still enable this feature with @code{dired-maybe-use-globstar} if
+the shell is included in @code{dired-enable-globstar-in-shell}.
+
 The usual history and completion commands can be used in the minibuffer;
 in particular, @kbd{M-n} puts the name of the visited file (if any) in
 the minibuffer (@pxref{Minibuffer History}).
diff --git a/etc/NEWS b/etc/NEWS
index b4833473ec6..a47b6e10b16 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -228,6 +228,12 @@ time zones will use a form like "+0100" instead of "CET".
 
 ** Dired
 
++++
+*** New user option 'dired-maybe-use-globstar'.
+If set, enables globstar in shells that support this feature.  The new
+variable 'dired-enable-globstar-in-shell' lists which shells can have
+globstar enabled.
+
 +++
 *** New user option 'dired-copy-dereference'.
 If set to non-nil, Dired will dereference symbolic links when copying.
diff --git a/lisp/dired.el b/lisp/dired.el
index 77bb6cfa9ca..d22d52ce627 100644
--- a/lisp/dired.el
+++ b/lisp/dired.el
@@ -77,6 +77,26 @@ If nil, `dired-listing-switches' is used."
    :type '(choice (const :tag "Use dired-listing-switches" nil)
                   (string :tag "Switches")))
 
+(defcustom dired-maybe-use-globstar nil
+  "If non-nil, enable globstar if the shell supports it.
+Some shells enable this feature by default (e.g. zsh or fish).
+
+See `dired-enable-globstar-in-shell' for a list of shells
+that support globstar and disable it by default.
+
+Note that the implementations of globstar have small differences
+between shells.  You must check your shell documentation to see
+what to expect."
+  :type 'boolean
+  :group 'dired)
+
+(defconst dired-enable-globstar-in-shell
+  '(("ksh" . "set -G")
+    ("bash" . "shopt -s globstar"))
+  "Alist of (SHELL . COMMAND), where COMMAND enables globstar in SHELL.
+If `dired-maybe-use-globstar' is non-nil, then `dired-insert-directory'
+checks this alist to enable globstar in the shell subprocess.")
+
 (defcustom dired-chown-program
   (purecopy (cond ((executable-find "chown") "chown")
                   ((file-executable-p "/usr/sbin/chown") "/usr/sbin/chown")
@@ -1470,6 +1490,13 @@ see `dired-use-ls-dired' for more details.")
                                  (executable-find explicit-shell-file-name))
                             (executable-find "sh")))
                     (switch (if remotep "-c" shell-command-switch)))
+               ;; Enable globstar
+               (when-let ((globstar dired-maybe-use-globstar)
+                          (enable-it
+                           (assoc-default
+                            (file-truename sh) dired-enable-globstar-in-shell
+                            (lambda (reg shell) (string-match reg shell)))))
+                 (setq script (format "%s; %s" enable-it script)))
                (unless
                    (zerop
                     (process-file sh nil (current-buffer) nil switch script))
-- 
2.39.2