Re: "Args out of range:" error when opening existing files

[Glenn Morris <gmorris+news@ast.cam.ac.uk>]

Joseph Shraibman wrote:

> I keep getting errors like this when opening existing files:
[...]
> string-equal: Args out of range: "/etc/hosts", 0, 18

I think you could solve this pretty easily:

i) Does it happen if you start Emacs with -q?

No, so it's something caused by your .emacs file.

ii) Maybe look for "string-equal" in .emacs? Oh look, there it is, with a
"0" and an "18" too:

> ; this prevents the creating of ~ backup files in the jsp directory, bec.
> ; the ~ files are visible to anyone who accesses them with a web browser
> (setq backup-enable-predicate
>       (lambda (name)
>         (or (< (length name) 5)
>             (and
>              (not (string-equal "/tmp/" (substring name 0 5)))
>              (not (string-equal "/local/www/htdocs/"
>                                 (substring name 0 18)))))))

Comment this out and your problems will go away.

(substring name 0 18)

is clearly going to give an error when you visit a file whose full name has
less than 18 characters.

So you want to have no backups for files beneath "/local/www/htdocs/".
I use something like this:

(defun my-backup-enable-predicate (name)
  "Function to use for `backup-enable-predicate'.
Runs `normal-backup-enable-predicate', but checks further if that is non-nil."
  (when (normal-backup-enable-predicate name)
    (let* ((dir "/local/www/htdocs/")
           (comp (compare-strings dir 0 nil name 0 nil)))
      ;; Directory is under dir.
      (not (and (not (eq comp t))
                (< comp (- (length dir))))))))

(setq backup-enable-predicate 'my-backup-enable-predicate)

Or, as you say you are using Emacs 21, you could use the variable
backup-directory-alist to keep the backups for your htdocs somewhere else.
For example:

(setq backup-directory-alist
      '(("^/local/www/htdocs/" . "/path/to/secure/directory")))