Add directory-empty-p and new argument COUNT for directory-files-*

* doc/lispref/files.texi (Contents of Directories): Mention COUNT
argument of directory-files.  Add directory-empty-p.

* etc/NEWS: Mention directory-empty-p and directory-files changes.

* lisp/dired.el (directory-empty-p): New defun.

* lisp/net/ange-ftp.el (ange-ftp-directory-files)
(ange-ftp-directory-files-and-attributes):
* lisp/net/tramp.el (tramp-handle-directory-files)
(tramp-handle-directory-files-and-attributes):
* lisp/net/tramp-adb.el
(tramp-adb-handle-directory-files-and-attributes):
* lisp/net/tramp-rclone.el (tramp-rclone-handle-directory-files):
* lisp/net/tramp-sh.el (tramp-sh-handle-directory-files-and-attributes):
* lisp/net/tramp-smb.el (tramp-smb-handle-directory-files): Add new COUNT
argument.

* src/dired.c (directory_files_internal): Implement new
RETURN_COUNT argument.
(Fdirectory_files, Fdirectory_files_and_attributes): Add new COUNT
argument.

* src/lisp.h (directory_files_internal): Add RETURN_COUNT to declaration.

* src/sysdep.c (list_system_processes): Add Qnil to
directory_files_internal call.

* test/src/dired-tests.el (directory-files-and-attributes-tests):
New file.

1 files changed, 20 insertions, 0 deletions

diff --git a/doc/lispref/files.texi b/doc/lispref/files.texi
index fc66d1c085d..f707fde88a8 100644
--- a/doc/lispref/files.texi
+++ b/doc/lispref/files.texi
@@ -2937,6 +2937,10 @@ you want the utmost possible speed and don't care what order the files
 are processed in.  If the order of processing is visible to the user,
 then the user will probably be happier if you do sort the names.
 
+If @var{count} is non-@code{nil}, the function will return names of
+first @var{count} number of files, or names of all files, whichever
+occurs first.  @var{count} has to be an integer greater than zero.
+
 @example
 @group
 (directory-files "~lewis")
@@ -2950,6 +2954,22 @@ An error is signaled if @var{directory} is not the name of a directory
 that can be read.
 @end defun
 
+@defun directory-empty-p filename
+This utility function returns t if given @var{filename} is an
+accessible directory and it does not contain any files, i.e. is an
+empty directory.  It will ignore '.' and '..' on systems that returns
+them as files in a directory.
+
+As a special case, this function will also return t if
+FILENAME is the empty string ("").  This quirk is due to Emacs
+interpreting the empty string (in some cases) as the current
+directory.
+
+Symbolic links to directories count as directories.
+See @var{file-symlink-p} to distinguish symlinks.
+
+@end defun
+
 @cindex recursive traverse of directory tree
 @defun directory-files-recursively directory regexp &optional include-directories predicate follow-symlinks
 Return all files under @var{directory} whose names match @var{regexp}.