Fix permissions handling (CVE-2010-0825).

[emacs.git] / lisp / ls-lisp.el

;;; ls-lisp.el --- emulate insert-directory completely in Emacs Lisp

;; Copyright (C) 1992, 1994, 2000, 2001, 2002, 2003, 2004,
;;   2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.

;; Author: Sebastian Kremer <sk@thp.uni-koeln.de>
;; Modified by: Francis J. Wright <F.J.Wright@maths.qmw.ac.uk>
;; Maintainer: FSF
;; Keywords: unix, dired

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; OVERVIEW ==========================================================

;; This file redefines the function `insert-directory' to implement it
;; directly from Emacs lisp, without running ls in a subprocess.  It
;; is useful if you cannot afford to fork Emacs on a real memory UNIX,
;; or other non-UNIX platforms if you don't have the ls
;; program, or if you want a different format from what ls offers.

;; This function can use regexps instead of shell wildcards.  If you
;; enter regexps remember to double each $ sign.  For example, to
;; include files *.el, enter `.*\.el$$', resulting in the regexp
;; `.*\.el$'.

;; RESTRICTIONS ======================================================

;; * A few obscure ls switches are still ignored: see the docstring of
;; `insert-directory'.

;; TO DO =============================================================

;; Complete handling of F switch (if/when possible).

;; FJW: May be able to sort much faster by consing the sort key onto
;; the front of each list element, sorting and then stripping the key
;; off again!

;;; History:

;; Written originally by Sebastian Kremer <sk@thp.uni-koeln.de>
;; Revised by Andrew Innes and Geoff Volker (and maybe others).

;; Modified by Francis J. Wright <F.J.Wright@maths.qmw.ac.uk>, mainly
;; to support many more ls options, "platform emulation" and more
;; robust sorting.

;;; Code:

(eval-when-compile (require 'cl))

(defgroup ls-lisp nil
  "Emulate the ls program completely in Emacs Lisp."
  :version "21.1"
  :group 'dired)

(defcustom ls-lisp-emulation
  (cond ;; ((eq system-type 'windows-nt) 'MS-Windows)
        ((memq system-type
               '(hpux usg-unix-v irix berkeley-unix))
         'UNIX))                        ; very similar to GNU
  ;; Anything else defaults to nil, meaning GNU.
  "Platform to emulate: GNU (default), MacOS, MS-Windows, UNIX.
Corresponding value is one of the atoms: nil, MacOS, MS-Windows, UNIX.
Sets default values for: `ls-lisp-ignore-case', `ls-lisp-dirs-first',
`ls-lisp-verbosity'.  Need not match actual platform.  Changing this
option will have no effect until you restart Emacs."
  :type '(choice (const :tag "GNU" nil)
                 (const MacOS)
                 (const MS-Windows)
                 (const UNIX))
  :group 'ls-lisp)

(defcustom ls-lisp-ignore-case
  ;; Name change for consistency with other option names.
  (or (memq ls-lisp-emulation '(MS-Windows MacOS))
      (and (boundp 'ls-lisp-dired-ignore-case) ls-lisp-dired-ignore-case))
  "Non-nil causes ls-lisp alphabetic sorting to ignore case."
  :type 'boolean
  :group 'ls-lisp)

(defcustom ls-lisp-dirs-first (eq ls-lisp-emulation 'MS-Windows)
  "Non-nil causes ls-lisp to sort directories first in any ordering.
\(Or last if it is reversed.)  Follows Microsoft Windows Explorer."
  ;; Functionality suggested by Chris McMahan <cmcmahan@one.net>
  :type 'boolean
  :group 'ls-lisp)

(defcustom ls-lisp-verbosity
  (cond ((eq ls-lisp-emulation 'MacOS) nil)
        ((eq ls-lisp-emulation 'MS-Windows)
         (if (and (fboundp 'w32-using-nt) (w32-using-nt))
             '(links)))                 ; distinguish NT/2K from 9x
        ((eq ls-lisp-emulation 'UNIX) '(links uid)) ; UNIX ls
        (t '(links uid gid)))           ; GNU ls
  "A list of optional file attributes that ls-lisp should display.
It should contain none or more of the symbols: links, uid, gid.
A value of nil (or an empty list) means display none of them.

Concepts come from UNIX: `links' means count of names associated with
the file\; `uid' means user (owner) identifier\; `gid' means group
identifier.

If emulation is MacOS then default is nil\;
if emulation is MS-Windows then default is `(links)' if platform is
Windows NT/2K, nil otherwise\;
if emulation is UNIX then default is `(links uid)'\;
if emulation is GNU then default is `(links uid gid)'."
  ;; Functionality suggested by Howard Melman <howard@silverstream.com>
  :type '(set (const :tag "Show Link Count" links)
              (const :tag "Show User" uid)
              (const :tag "Show Group" gid))
  :group 'ls-lisp)

(defcustom ls-lisp-use-insert-directory-program
  (not (memq system-type '(ms-dos windows-nt)))
  "Non-nil causes ls-lisp to revert back to using `insert-directory-program'.
This is useful on platforms where ls-lisp is dumped into Emacs, such as
Microsoft Windows, but you would still like to use a program to list
the contents of a directory."
  :type 'boolean
  :group 'ls-lisp)

;;; Autoloaded because it is let-bound in `recover-session', `mail-recover-1'.
;;;###autoload
(defcustom ls-lisp-support-shell-wildcards t
  "Non-nil means ls-lisp treats file patterns as shell wildcards.
Otherwise they are treated as Emacs regexps (for backward compatibility)."
  :type 'boolean
  :group 'ls-lisp)

(defcustom ls-lisp-format-time-list
  '("%b %e %H:%M"
    "%b %e  %Y")
  "List of `format-time-string' specs to display file time stamps.
These specs are used ONLY if a valid locale can not be determined.

If `ls-lisp-use-localized-time-format' is non-nil, these specs are used
regardless of whether the locale can be determined.

Syntax:  (EARLY-TIME-FORMAT OLD-TIME-FORMAT)

The EARLY-TIME-FORMAT is used if file has been modified within the
current year. The OLD-TIME-FORMAT is used for older files.  To use ISO
8601 dates, you could set:

\(setq ls-lisp-format-time-list
       '(\"%Y-%m-%d %H:%M\"
         \"%Y-%m-%d      \"))"
  :type '(list (string :tag "Early time format")
               (string :tag "Old time format"))
  :group 'ls-lisp)

(defcustom ls-lisp-use-localized-time-format nil
  "Non-nil causes ls-lisp to use `ls-lisp-format-time-list' even if
a valid locale is specified.

WARNING: Using localized date/time format might cause Dired columns
to fail to lign up, e.g. if month names are not all of the same length."
  :type 'boolean
  :group 'ls-lisp)

(defvar original-insert-directory nil
  "This holds the original function definition of `insert-directory'.")

(defvar ls-lisp-uid-d-fmt "-%d"
  "Format to display integer UIDs.")
(defvar ls-lisp-uid-s-fmt "-%s"
  "Format to display user names.")
(defvar ls-lisp-gid-d-fmt "-%d"
  "Format to display integer GIDs.")
(defvar ls-lisp-gid-s-fmt "-%s"
  "Format to display user group names.")
(defvar ls-lisp-filesize-d-fmt "%d"
  "Format to display integer file sizes.")
(defvar ls-lisp-filesize-f-fmt "%.0f"
  "Format to display float file sizes.")

;; Remember the original insert-directory function
(or (featurep 'ls-lisp)  ; FJW: unless this file is being reloaded!
    (setq original-insert-directory (symbol-function 'insert-directory)))

\f
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun insert-directory (file switches &optional wildcard full-directory-p)
  "Insert directory listing for FILE, formatted according to SWITCHES.
Leaves point after the inserted text.
SWITCHES may be a string of options, or a list of strings.
Optional third arg WILDCARD means treat FILE as shell wildcard.
Optional fourth arg FULL-DIRECTORY-P means file is a directory and
switches do not contain `d', so that a full listing is expected.

This version of the function comes from `ls-lisp.el'.
If the value of `ls-lisp-use-insert-directory-program' is non-nil then
it works exactly like the version from `files.el' and runs a directory
listing program whose name is in the variable
`insert-directory-program'; if also WILDCARD is non-nil then it runs
the shell specified by `shell-file-name'.  If the value of
`ls-lisp-use-insert-directory-program' is nil then it runs a Lisp
emulation.

The Lisp emulation does not run any external programs or shells.  It
supports ordinary shell wildcards if `ls-lisp-support-shell-wildcards'
is non-nil; otherwise, it interprets wildcards as regular expressions
to match file names.  It does not support all `ls' switches -- those
that work are: A a c i r S s t u U X g G B C R n and F partly."
  (if ls-lisp-use-insert-directory-program
      (funcall original-insert-directory
               file switches wildcard full-directory-p)
    ;; We need the directory in order to find the right handler.
    (let ((handler (find-file-name-handler (expand-file-name file)
                                           'insert-directory))
          (orig-file file)
          wildcard-regexp)
      (if handler
          (funcall handler 'insert-directory file switches
                   wildcard full-directory-p)
        ;; Remove --dired switch
        (if (string-match "--dired " switches)
            (setq switches (replace-match "" nil nil switches)))
        ;; Convert SWITCHES to a list of characters.
        (setq switches (delete ?- (append switches nil)))
        ;; Sometimes we get ".../foo*/" as FILE.  While the shell and
        ;; `ls' don't mind, we certainly do, because it makes us think
        ;; there is no wildcard, only a directory name.
        (if (and ls-lisp-support-shell-wildcards
                 (string-match "[[?*]" file)
                 ;; Prefer an existing file to wildcards, like
                 ;; dired-noselect does.
                 (not (file-exists-p file)))
            (progn
              (or (not (eq (aref file (1- (length file))) ?/))
                  (setq file (substring file 0 (1- (length file)))))
              (setq wildcard t)))
        (if wildcard
            (setq wildcard-regexp
                  (if ls-lisp-support-shell-wildcards
                      (wildcard-to-regexp (file-name-nondirectory file))
                    (file-name-nondirectory file))
                  file (file-name-directory file))
          (if (memq ?B switches) (setq wildcard-regexp "[^~]\\'")))
        (condition-case err
            (ls-lisp-insert-directory
             file switches (ls-lisp-time-index switches)
             wildcard-regexp full-directory-p)
          (invalid-regexp
           ;; Maybe they wanted a literal file that just happens to
           ;; use characters special to shell wildcards.
           (if (equal (cadr err) "Unmatched [ or [^")
               (progn
                 (setq wildcard-regexp (if (memq ?B switches) "[^~]\\'")
                       file (file-relative-name orig-file))
                 (ls-lisp-insert-directory
                  file switches (ls-lisp-time-index switches)
                  nil full-directory-p))
             (signal (car err) (cdr err)))))
        ;; Try to insert the amount of free space.
        (save-excursion
          (goto-char (point-min))
          ;; First find the line to put it on.
          (when (re-search-forward "^total" nil t)
            (let ((available (get-free-disk-space ".")))
              (when available
                ;; Replace "total" with "total used", to avoid confusion.
                (replace-match "total used in directory")
                (end-of-line)
                (insert " available " available)))))))))

(defun ls-lisp-insert-directory
  (file switches time-index wildcard-regexp full-directory-p)
  "Insert directory listing for FILE, formatted according to SWITCHES.
Leaves point after the inserted text.  This is an internal function
optionally called by the `ls-lisp.el' version of `insert-directory'.
It is called recursively if the -R switch is used.
SWITCHES is a *list* of characters.  TIME-INDEX is the time index into
file-attributes according to SWITCHES.  WILDCARD-REGEXP is nil or an *Emacs
regexp*.  FULL-DIRECTORY-P means file is a directory and SWITCHES does
not contain `d', so that a full listing is expected."
  (if (or wildcard-regexp full-directory-p)
      (let* ((dir (file-name-as-directory file))
             (default-directory dir)    ; so that file-attributes works
             (file-alist
              (directory-files-and-attributes dir nil wildcard-regexp t
                                              (if (memq ?n switches)
                                                  'integer
                                                'string)))
             (now (current-time))
             (sum 0)
             (max-uid-len 0)
             (max-gid-len 0)
             (max-file-size 0)
             ;; do all bindings here for speed
             total-line files elt short file-size fil attr
             fuid fgid uid-len gid-len)
        (cond ((memq ?A switches)
               (setq file-alist
                     (ls-lisp-delete-matching "^\\.\\.?$" file-alist)))
              ((not (memq ?a switches))
               ;; if neither -A  nor -a, flush . files
               (setq file-alist
                     (ls-lisp-delete-matching "^\\." file-alist))))
        (setq file-alist
              (ls-lisp-handle-switches file-alist switches))
        (if (memq ?C switches)          ; column (-C) format
            (ls-lisp-column-format file-alist)
          (setq total-line (cons (point) (car-safe file-alist)))
          ;; Find the appropriate format for displaying uid, gid, and
          ;; file size, by finding the longest strings among all the
          ;; files we are about to display.
          (dolist (elt file-alist)
            (setq attr (cdr elt)
                  fuid (nth 2 attr)
                  uid-len (if (stringp fuid) (string-width fuid)
                            (length (format "%d" fuid)))
                  fgid (nth 3 attr)
                  gid-len (if (stringp fgid) (string-width fgid)
                            (length (format "%d" fgid)))
                  file-size (nth 7 attr))
            (if (> uid-len max-uid-len)
                (setq max-uid-len uid-len))
            (if (> gid-len max-gid-len)
                (setq max-gid-len gid-len))
            (if (> file-size max-file-size)
                (setq max-file-size file-size)))
          (setq ls-lisp-uid-d-fmt (format " %%-%dd" max-uid-len))
          (setq ls-lisp-uid-s-fmt (format " %%-%ds" max-uid-len))
          (setq ls-lisp-gid-d-fmt (format " %%-%dd" max-gid-len))
          (setq ls-lisp-gid-s-fmt (format " %%-%ds" max-gid-len))
          (setq ls-lisp-filesize-d-fmt
                (format " %%%dd"
                        (if (memq ?s switches)
                            (length (format "%.0f"
                                            (fceiling (/ max-file-size 1024.0))))
                          (length (format "%.0f" max-file-size)))))
          (setq ls-lisp-filesize-f-fmt
                (format " %%%d.0f"
                        (if (memq ?s switches)
                            (length (format "%.0f"
                                            (fceiling (/ max-file-size 1024.0))))
                          (length (format "%.0f" max-file-size)))))
          (setq files file-alist)
          (while files                  ; long (-l) format
            (setq elt (car files)
                  files (cdr files)
                  short (car elt)
                  attr (cdr elt)
                  file-size (nth 7 attr))
            (and attr
                 (setq sum (+ file-size
                              ;; Even if neither SUM nor file's size
                              ;; overflow, their sum could.
                              (if (or (< sum (- 134217727 file-size))
                                      (floatp sum)
                                      (floatp file-size))
                                  sum
                                (float sum))))
                 (insert (ls-lisp-format short attr file-size
                                         switches time-index now))))
          ;; Insert total size of all files:
          (save-excursion
            (goto-char (car total-line))
            (or (cdr total-line)
                ;; Shell says ``No match'' if no files match
                ;; the wildcard; let's say something similar.
                (insert "(No match)\n"))
            (insert (format "total %.0f\n" (fceiling (/ sum 1024.0))))))
        (if (memq ?R switches)
            ;; List the contents of all directories recursively.
            ;; cadr of each element of `file-alist' is t for
            ;; directory, string (name linked to) for symbolic
            ;; link, or nil.
            (while file-alist
              (setq elt (car file-alist)
                    file-alist (cdr file-alist))
              (when (and (eq (cadr elt) t) ; directory
                         ;; Under -F, we have already decorated all
                         ;; directories, including "." and "..", with
                         ;; a /, so allow for that as well.
                         (not (string-match "\\`\\.\\.?/?\\'" (car elt))))
                (setq elt (expand-file-name (car elt) dir))
                (insert "\n" elt ":\n")
                (ls-lisp-insert-directory
                 elt switches time-index wildcard-regexp full-directory-p)))))
    ;; If not full-directory-p, FILE *must not* end in /, as
    ;; file-attributes will not recognize a symlink to a directory,
    ;; so must make it a relative filename as ls does:
    (if (file-name-absolute-p file) (setq file (expand-file-name file)))
    (if (eq (aref file (1- (length file))) ?/)
        (setq file (substring file 0 -1)))
    (let ((fattr (file-attributes file 'string)))
      (if fattr
          (insert (ls-lisp-format file fattr (nth 7 fattr)
                                  switches time-index (current-time)))
        (message "%s: doesn't exist or is inaccessible" file)
        (ding) (sit-for 2)))))          ; to show user the message!

(defun ls-lisp-column-format (file-alist)
  "Insert the file names (only) in FILE-ALIST into the current buffer.
Format in columns, sorted vertically, following GNU ls -C.
Responds to the window width as ls should but may not!"
  (let (files fmt ncols collen (nfiles 0) (colwid 0))
    ;; Count number of files as `nfiles', build list of filenames as
    ;; `files', and find maximum filename length as `colwid':
    (let (file len)
      (while file-alist
        (setq nfiles (1+ nfiles)
              file (caar file-alist)
              files (cons file files)
              file-alist (cdr file-alist)
              len (length file))
        (if (> len colwid) (setq colwid len))))
    (setq files (nreverse files)
          colwid (+ 2 colwid)           ; 2 character column gap
          fmt (format "%%-%ds" colwid)  ; print format
          ncols (/ (window-width) colwid) ; no of columns
          collen (/ nfiles ncols))      ; floor of column length
    (if (> nfiles (* collen ncols)) (setq collen (1+ collen)))
    ;; Output the file names in columns, sorted vertically:
    (let ((i 0) j)
      (while (< i collen)
        (setq j i)
        (while (< j nfiles)
          (insert (format fmt (nth j files)))
          (setq j (+ j collen)))
        ;; FJW: This is completely unnecessary, but I don't like
        ;; trailing white space...
        (delete-region (point) (progn (skip-chars-backward " \t") (point)))
        (insert ?\n)
        (setq i (1+ i))))))

(defun ls-lisp-delete-matching (regexp list)
  "Delete all elements matching REGEXP from LIST, return new list."
  ;; Should perhaps use setcdr for efficiency.
  (let (result)
    (while list
      (or (string-match regexp (caar list))
          (setq result (cons (car list) result)))
      (setq list (cdr list)))
    result))

(defsubst ls-lisp-string-lessp (s1 s2)
  "Return t if string S1 is less than string S2 in lexicographic order.
Case is significant if `ls-lisp-ignore-case' is nil.
Unibyte strings are converted to multibyte for comparison."
  (let ((u (compare-strings s1 0 nil s2 0 nil ls-lisp-ignore-case)))
    (and (numberp u) (< u 0))))

(defun ls-lisp-handle-switches (file-alist switches)
  "Return new FILE-ALIST sorted according to SWITCHES.
SWITCHES is a list of characters.  Default sorting is alphabetic."
  ;; FILE-ALIST's elements are (FILE . FILE-ATTRIBUTES).
  (or (memq ?U switches)                ; unsorted
      ;; Catch and ignore unexpected sorting errors
      (condition-case err
          (setq file-alist
                (let (index)
                  ;; Copy file-alist in case of error
                  (sort (copy-sequence file-alist) ; modifies its argument!
                        (cond ((memq ?S switches)
                               (lambda (x y) ; sorted on size
                                 ;; 7th file attribute is file size
                                 ;; Make largest file come first
                                 (< (nth 7 (cdr y))
                                    (nth 7 (cdr x)))))
                              ((setq index (ls-lisp-time-index switches))
                               (lambda (x y) ; sorted on time
                                 (ls-lisp-time-lessp (nth index (cdr y))
                                                     (nth index (cdr x)))))
                              ((memq ?X switches)
                               (lambda (x y) ; sorted on extension
                                 (ls-lisp-string-lessp
                                  (ls-lisp-extension (car x))
                                  (ls-lisp-extension (car y)))))
                              (t
                               (lambda (x y) ; sorted alphabetically
                                 (ls-lisp-string-lessp (car x) (car y))))))))
        (error (message "Unsorted (ls-lisp sorting error) - %s"
                        (error-message-string err))
               (ding) (sit-for 2))))    ; to show user the message!
  (if (memq ?F switches)                ; classify switch
      (setq file-alist (mapcar 'ls-lisp-classify file-alist)))
  (if ls-lisp-dirs-first
  ;; Re-sort directories first, without otherwise changing the
  ;; ordering, and reverse whole list.  cadr of each element of
  ;; `file-alist' is t for directory, string (name linked to) for
  ;; symbolic link, or nil.
      (let (el dirs files)
        (while file-alist
          (if (or (eq (cadr (setq el (car file-alist))) t) ; directory
                  (and (stringp (cadr el))
                       (file-directory-p (cadr el)))) ; symlink to a directory
              (setq dirs (cons el dirs))
            (setq files (cons el files)))
          (setq file-alist (cdr file-alist)))
        (setq file-alist
              (if (memq ?U switches)    ; unsorted order is reversed
                  (nconc dirs files)
                (nconc files dirs)
                ))))
  ;; Finally reverse file alist if necessary.
  ;; (eq below MUST compare `(not (memq ...))' to force comparison of
  ;; `t' or `nil', rather than list tails!)
  (if (eq (eq (not (memq ?U switches))  ; unsorted order is reversed
              (not (memq ?r switches))) ; reversed sort order requested
          ls-lisp-dirs-first)           ; already reversed
      (nreverse file-alist)
    file-alist))

(defun ls-lisp-classify (filedata)
  "Append a character to each file name indicating the file type.
Also, for regular files that are executable, append `*'.
The file type indicators are `/' for directories, `@' for symbolic
links, `|' for FIFOs, `=' for sockets, and nothing for regular files.
\[But FIFOs and sockets are not recognized.]
FILEDATA has the form (filename . `file-attributes').  Its `cadr' is t
for directory, string (name linked to) for symbolic link, or nil."
  (let ((file-name (car filedata))
        (type (cadr filedata)))
    (cond (type
           (cons
            (concat (propertize file-name 'dired-filename t)
                    (if (eq type t) "/" "@"))
            (cdr filedata)))
          ((string-match "x" (nth 9 filedata))
           (cons
            (concat (propertize file-name 'dired-filename t) "*")
            (cdr filedata)))
          (t
           (cons
            (propertize file-name 'dired-filename t)
            (cdr filedata))))))

(defun ls-lisp-extension (filename)
  "Return extension of FILENAME (ignoring any version extension)
FOLLOWED by null and full filename, SOLELY for full alpha sort."
  ;; Force extension sort order: `no ext' then `null ext' then `ext'
  ;; to agree with GNU ls.
  (concat
   (let* ((i (length filename)) end)
     (if (= (aref filename (1- i)) ?.) ; null extension
         "\0"
       (while (and (>= (setq i (1- i)) 0)
                   (/= (aref filename i) ?.)))
       (if (< i 0) "\0\0"               ; no extension
         (if (/= (aref filename (1+ i)) ?~)
             (substring filename (1+ i))
           ;; version extension found -- ignore it
           (setq end i)
           (while (and (>= (setq i (1- i)) 0)
                       (/= (aref filename i) ?.)))
           (if (< i 0) "\0\0"   ; no extension
             (substring filename (1+ i) end))))
       )) "\0" filename))

;; From Roland McGrath.  Can use this to sort on time.
(defun ls-lisp-time-lessp (time0 time1)
  "Return t if time TIME0 is earlier than time TIME1."
  (let ((hi0 (car time0)) (hi1 (car time1)))
    (or (< hi0 hi1)
        (and (= hi0 hi1)
             (< (cadr time0) (cadr time1))))))

(defun ls-lisp-format (file-name file-attr file-size switches time-index now)
  "Format one line of long ls output for file FILE-NAME.
FILE-ATTR and FILE-SIZE give the file's attributes and size.
SWITCHES, TIME-INDEX and NOW give the full switch list and time data."
  (let ((file-type (nth 0 file-attr))
        ;; t for directory, string (name linked to)
        ;; for symbolic link, or nil.
        (drwxrwxrwx (nth 8 file-attr))) ; attribute string ("drwxrwxrwx")
    (concat (if (memq ?i switches)      ; inode number
                (let ((inode (nth 10 file-attr)))
                  (if (consp inode)
                      (if (consp (cdr inode))
                          ;; 2^(24+16) = 1099511627776.0, but
                          ;; multiplying by it and then adding the
                          ;; other members of the cons cell in one go
                          ;; loses precision, since a double does not
                          ;; have enough significant digits to hold a
                          ;; full 64-bit value.  So below we split
                          ;; 1099511627776 into high 13 and low 5
                          ;; digits and compute in two parts.
                          (let ((p1 (* (car inode) 10995116.0))
                                (p2 (+ (* (car inode) 27776.0)
                                       (* (cadr inode) 65536.0)
                                       (cddr inode))))
                            (format " %13.0f%05.0f "
                                    ;; Use floor to emulate integer
                                    ;; division.
                                    (+ p1 (floor p2 100000.0))
                                    (mod p2 100000.0)))
                        (format " %18.0f "
                                (+ (* (car inode) 65536.0)
                                   (cdr inode))))
                    (format " %18d " inode))))
            ;; nil is treated like "" in concat
            (if (memq ?s switches)      ; size in K
                (format ls-lisp-filesize-f-fmt
                        (fceiling (/ file-size 1024.0))))
            drwxrwxrwx                  ; attribute string
            (if (memq 'links ls-lisp-verbosity)
                (format "%3d" (nth 1 file-attr))) ; link count
            ;; Numeric uid/gid are more confusing than helpful;
            ;; Emacs should be able to make strings of them.
            ;; They tend to be bogus on non-UNIX platforms anyway so
            ;; optionally hide them.
            (if (memq 'uid ls-lisp-verbosity)
                ;; uid can be a sting or an integer
                (let ((uid (nth 2 file-attr)))
                  (format (if (stringp uid)
                              ls-lisp-uid-s-fmt
                            ls-lisp-uid-d-fmt)
                          uid)))
            (if (not (memq ?G switches)) ; GNU ls -- shows group by default
                (if (or (memq ?g switches) ; UNIX ls -- no group by default
                        (memq 'gid ls-lisp-verbosity))
                    (let ((gid (nth 3 file-attr)))
                      (format (if (stringp gid)
                                  ls-lisp-gid-s-fmt
                                ls-lisp-gid-d-fmt)
                              gid))))
            (ls-lisp-format-file-size file-size (memq ?h switches))
            " "
            (ls-lisp-format-time file-attr time-index now)
            " "
            (if (not (memq ?F switches)) ; ls-lisp-classify already did that
                (propertize file-name 'dired-filename t)
              file-name)
            (if (stringp file-type)     ; is a symbolic link
                (concat " -> " file-type))
            "\n"
            )))

(defun ls-lisp-time-index (switches)
  "Return time index into file-attributes according to ls SWITCHES list.
Return nil if no time switch found."
  ;; FJW: Default of nil is IMPORTANT and used in `ls-lisp-handle-switches'!
  (cond ((memq ?c switches) 6)          ; last mode change
        ((memq ?t switches) 5)          ; last modtime
        ((memq ?u switches) 4)))        ; last access

(defun ls-lisp-time-to-seconds (time)
  "Convert TIME to a floating point number."
  (+ (* (car time) 65536.0)
     (cadr time)
     (/ (or (nth 2 time) 0) 1000000.0)))

(defun ls-lisp-format-time (file-attr time-index now)
  "Format time for file with attributes FILE-ATTR according to TIME-INDEX.
Use the same method as ls to decide whether to show time-of-day or year,
depending on distance between file date and NOW.
All ls time options, namely c, t and u, are handled."
  (let* ((time (nth (or time-index 5) file-attr)) ; default is last modtime
         (diff (- (ls-lisp-time-to-seconds time)
                  (ls-lisp-time-to-seconds now)))
         ;; Consider a time to be recent if it is within the past six
         ;; months.  A Gregorian year has 365.2425 * 24 * 60 * 60 ==
         ;; 31556952 seconds on the average, and half of that is 15778476.
         ;; Write the constant explicitly to avoid roundoff error.
         (past-cutoff -15778476)) ; half a Gregorian year
    (condition-case nil
        ;; Use traditional time format in the C or POSIX locale,
        ;; ISO-style time format otherwise, so columns line up.
        (let ((locale system-time-locale))
          (if (not locale)
              (let ((vars '("LC_ALL" "LC_TIME" "LANG")))
                (while (and vars (not (setq locale (getenv (car vars)))))
                  (setq vars (cdr vars)))))
          (if (member locale '("C" "POSIX"))
              (setq locale nil))
          (format-time-string
           (if (and (<= past-cutoff diff) (<= diff 0))
               (if (and locale (not ls-lisp-use-localized-time-format))
                   "%m-%d %H:%M"
                 (nth 0 ls-lisp-format-time-list))
             (if (and locale (not ls-lisp-use-localized-time-format))
                 "%Y-%m-%d "
               (nth 1 ls-lisp-format-time-list)))
           time))
      (error "Unk  0  0000"))))

(defun ls-lisp-format-file-size (file-size human-readable)
  (if (not human-readable)
      (format (if (floatp file-size)
                  ls-lisp-filesize-f-fmt
                ls-lisp-filesize-d-fmt)
              file-size)
    (if (< file-size 1024)
        (format " %4d" file-size)
      (do ((file-size (/ file-size 1024.0) (/ file-size 1024.0))
           ;; kilo, mega, giga, tera, peta, exa
           (post-fixes (list "k" "M" "G" "T" "P" "E") (cdr post-fixes)))
          ((< file-size 1024)
           (format " %3.0f%s"  file-size (car post-fixes)))))))

(provide 'ls-lisp)

;; arch-tag: e55f399b-05ec-425c-a6d5-f5e349c35ab4
;;; ls-lisp.el ends here