bug#7112: 24.0.50; [PATCH] `ls-lisp-insert-directory' should be no-op for empty FILE

[Drew Adams]

> > You can call `dired' passing a cons arg that includes a list of file
> > names.  An empty file name causes this ugly error: 
> > (error "Args out of range: \"\", -1")
> > The reason is the following code near the end of
> > `ls-lisp-insert-directory':
> 
> I think this should most likely be fixed in the caller (i.e., in
> dired.el).

What does that mean?  dired.el is a file, not a caller.

> What's the backtrace for this bug?

Why not try it yourself, using the emacs -Q recipe:

M-: (dired '("foobar" "111.el" ""))

Anyway:

Debugger entered--Lisp error: (args-out-of-range "" -1)
  aref("" -1)
  (eq (aref file (1- (length file))) 47)
  (if (eq (aref file (1- (length file))) 47) (setq file (substring file 0 -1)))
  (if (or wildcard-regexp full-directory-p) (let* ((dir (file-name-as-directory
file)) (default-directory dir) (file-alist (directory-files-and-attributes dir
nil wildcard-regexp t (if (memq 110 switches) (quote integer) (quote string))))
(sum 0) (max-uid-len 0) (max-gid-len 0) (max-file-size 0) total-line files elt
short file-size attr fuid fgid uid-len gid-len) (cond ((memq 65 switches) (setq
file-alist (ls-lisp-delete-matching "^\\.\\.?$" file-alist))) ((not (memq 97
switches)) (setq file-alist (ls-lisp-delete-matching "^\\." file-alist)))) (setq
file-alist (ls-lisp-handle-switches file-alist switches)) (if (memq 67 switches)
(ls-lisp-column-format file-alist) (setq total-line (cons (point) (car-safe
file-alist))) (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 115 switches) (length (format
"%.0f" ...)) (length (format "%.0f" max-file-size))))) (setq
ls-lisp-filesize-f-fmt (format " %%%d.0f" (if (memq 115 switches) (length
(format "%.0f" ...)) (length (format "%.0f" max-file-size))))) (setq files
file-alist) (while files (setq elt (car files) files (cdr files) short (car elt)
attr (cdr elt) file-size (nth 7 attr)) (and attr (setq sum (+ file-size (if ...
sum ...))) (insert (ls-lisp-format short attr file-size switches time-index))))
(save-excursion (goto-char (car total-line)) (or (cdr total-line) (insert "(No
match)\n")) (insert (format "total %.0f\n" (fceiling (/ sum 1024.0)))))) (if
(memq 82 switches) (while file-alist (setq elt (car file-alist) file-alist (cdr
file-alist)) (when (and (eq (cadr elt) t) (not (string-match "\\`\\.\\.?/?\\'"
...))) (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 (file-name-absolute-p file) (setq file
(expand-file-name file))) (if (eq (aref file (1- (length file))) 47) (setq file
(substring file 0 -1))) (let ((fattr (file-attributes file (quote string)))) (if
fattr (insert (ls-lisp-format (if (memq 70 switches) (ls-lisp-classify-file file
fattr) file) fattr (nth 7 fattr) switches time-index)) (message "%s: doesn't
exist or is inaccessible" file) (ding) (sit-for 2))))
  ls-lisp-insert-directory("" (97 108) nil nil nil)
  (condition-case err (ls-lisp-insert-directory file switches
(ls-lisp-time-index switches) wildcard-regexp full-directory-p) (invalid-regexp
(if (equal (cadr err) "Unmatched [ or [^") (progn (setq wildcard-regexp (if
(memq 66 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)))))
  (if handler (funcall handler (quote insert-directory) file switches wildcard
full-directory-p) (if (string-match "--dired " switches) (setq switches
(replace-match "" nil nil switches))) (setq switches (delete 32 (delete 45
(append switches nil)))) (if (and ls-lisp-support-shell-wildcards (string-match
"[[?*]" file) (not (file-exists-p file))) (progn (or (not (eq (aref file (1-
...)) 47)) (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 66 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 (if (equal (cadr err) "Unmatched [ or [^") (progn (setq
wildcard-regexp (if (memq 66 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))))) (save-excursion
(goto-char (point-min)) (when (re-search-forward "^total" nil t) (let
((available (get-free-disk-space "."))) (when available (replace-match "total
used in directory") (end-of-line) (insert " available " available))))))
  (let ((handler (find-file-name-handler (expand-file-name file) (quote
insert-directory))) (orig-file file) wildcard-regexp) (if handler (funcall
handler (quote insert-directory) file switches wildcard full-directory-p) (if
(string-match "--dired " switches) (setq switches (replace-match "" nil nil
switches))) (setq switches (delete 32 (delete 45 (append switches nil)))) (if
(and ls-lisp-support-shell-wildcards (string-match "[[?*]" file) (not
(file-exists-p file))) (progn (or (not (eq (aref file ...) 47)) (setq file
(substring file 0 (1- ...)))) (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 66 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
(if (equal (cadr err) "Unmatched [ or [^") (progn (setq wildcard-regexp (if ...
"[^~]\\'") 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))))) (save-excursion (goto-char (point-min)) (when (re-search-forward
"^total" nil t) (let ((available (get-free-disk-space "."))) (when available
(replace-match "total used in directory") (end-of-line) (insert " available "
available)))))))
  (if ls-lisp-use-insert-directory-program (funcall original-insert-directory
file switches wildcard full-directory-p) (let ((handler (find-file-name-handler
(expand-file-name file) (quote insert-directory))) (orig-file file)
wildcard-regexp) (if handler (funcall handler (quote insert-directory) file
switches wildcard full-directory-p) (if (string-match "--dired " switches) (setq
switches (replace-match "" nil nil switches))) (setq switches (delete 32 (delete
45 (append switches nil)))) (if (and ls-lisp-support-shell-wildcards
(string-match "[[?*]" file) (not (file-exists-p file))) (progn (or (not (eq ...
47)) (setq file (substring file 0 ...))) (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 66 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
(if (equal (cadr err) "Unmatched [ or [^") (progn (setq wildcard-regexp ... file
...) (ls-lisp-insert-directory file switches ... nil full-directory-p)) (signal
(car err) (cdr err))))) (save-excursion (goto-char (point-min)) (when
(re-search-forward "^total" nil t) (let ((available ...)) (when available
(replace-match "total used in directory") (end-of-line) (insert " available "
available))))))))
  insert-directory("" "-al" nil nil)
  apply(insert-directory ("" "-al" nil nil))
  (let* ((inhibit-file-name-handlers (\` (tramp-completion-file-name-handler
cygwin-mount-name-hook-function cygwin-mount-map-drive-hook-function \, (and (eq
inhibit-file-name-operation operation) inhibit-file-name-handlers))))
(inhibit-file-name-operation operation)) (apply operation args))
  tramp-completion-run-real-handler(insert-directory ("" "-al" nil nil))
  (if (and fn tramp-mode (or (eq tramp-syntax (quote sep)) (featurep (quote
tramp)) (and (boundp (quote partial-completion-mode)) (symbol-value (quote
partial-completion-mode))) (featurep (quote ido)) (featurep (quote icicles))))
(save-match-data (apply (cdr fn) args)) (tramp-completion-run-real-handler
operation args))
  (let ((directory-sep-char 47) (fn (assoc operation
tramp-completion-file-name-handler-alist))) (if (and fn tramp-mode (or (eq
tramp-syntax (quote sep)) (featurep (quote tramp)) (and (boundp (quote
partial-completion-mode)) (symbol-value (quote partial-completion-mode)))
(featurep (quote ido)) (featurep (quote icicles)))) (save-match-data (apply (cdr
fn) args)) (tramp-completion-run-real-handler operation args)))
  tramp-completion-file-name-handler(insert-directory "" "-al" nil nil)
  funcall(tramp-completion-file-name-handler insert-directory "" "-al" nil nil)
  (if handler (funcall handler (quote insert-directory) file switches wildcard
full-directory-p) (if (string-match "--dired " switches) (setq switches
(replace-match "" nil nil switches))) (setq switches (delete 32 (delete 45
(append switches nil)))) (if (and ls-lisp-support-shell-wildcards (string-match
"[[?*]" file) (not (file-exists-p file))) (progn (or (not (eq (aref file (1-
...)) 47)) (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 66 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 (if (equal (cadr err) "Unmatched [ or [^") (progn (setq
wildcard-regexp (if (memq 66 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))))) (save-excursion
(goto-char (point-min)) (when (re-search-forward "^total" nil t) (let
((available (get-free-disk-space "."))) (when available (replace-match "total
used in directory") (end-of-line) (insert " available " available))))))
  (let ((handler (find-file-name-handler (expand-file-name file) (quote
insert-directory))) (orig-file file) wildcard-regexp) (if handler (funcall
handler (quote insert-directory) file switches wildcard full-directory-p) (if
(string-match "--dired " switches) (setq switches (replace-match "" nil nil
switches))) (setq switches (delete 32 (delete 45 (append switches nil)))) (if
(and ls-lisp-support-shell-wildcards (string-match "[[?*]" file) (not
(file-exists-p file))) (progn (or (not (eq (aref file ...) 47)) (setq file
(substring file 0 (1- ...)))) (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 66 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
(if (equal (cadr err) "Unmatched [ or [^") (progn (setq wildcard-regexp (if ...
"[^~]\\'") 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))))) (save-excursion (goto-char (point-min)) (when (re-search-forward
"^total" nil t) (let ((available (get-free-disk-space "."))) (when available
(replace-match "total used in directory") (end-of-line) (insert " available "
available)))))))
  (if ls-lisp-use-insert-directory-program (funcall original-insert-directory
file switches wildcard full-directory-p) (let ((handler (find-file-name-handler
(expand-file-name file) (quote insert-directory))) (orig-file file)
wildcard-regexp) (if handler (funcall handler (quote insert-directory) file
switches wildcard full-directory-p) (if (string-match "--dired " switches) (setq
switches (replace-match "" nil nil switches))) (setq switches (delete 32 (delete
45 (append switches nil)))) (if (and ls-lisp-support-shell-wildcards
(string-match "[[?*]" file) (not (file-exists-p file))) (progn (or (not (eq ...
47)) (setq file (substring file 0 ...))) (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 66 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
(if (equal (cadr err) "Unmatched [ or [^") (progn (setq wildcard-regexp ... file
...) (ls-lisp-insert-directory file switches ... nil full-directory-p)) (signal
(car err) (cdr err))))) (save-excursion (goto-char (point-min)) (when
(re-search-forward "^total" nil t) (let ((available ...)) (when available
(replace-match "total used in directory") (end-of-line) (insert " available "
available))))))))
  insert-directory("" "-al" nil nil)
  dired-insert-directory("c:/drews-lisp-20/foobar" "-al" ("111.el" "") nil t)
  dired-readin-insert()
  dired-readin()
  dired-internal-noselect(("c:/drews-lisp-20/foobar" "111.el" "") nil)
  dired-noselect(("foobar" "111.el" "") nil)
  dired(("foobar" "111.el" ""))
  eval((dired (quote ("foobar" "111.el" ""))) nil)
  eval-expression((dired (quote ("foobar" "111.el" ""))) nil)
  call-interactively(eval-expression nil nil)

But I already pointed you to the code that needs to be changed.
And I already provided the fix:

> `ls-lisp-insert-directory' should in fact do nothing at all (no-op) if
> FILE is "".  The entire body should be wrapped in this:
> (when (> (length file) 0) ...)

Simply wrap the body of `ls-lisp-insert-directory' with (when (> (length file)
0) ...), and the problem is fixed.  And that is the right way to fix it.