infinite loop from unwriteable backup files

infinite loop from unwriteable backup files

[Ken Olum]

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In GNU Emacs 22.1.1 (x86_64-mandrake-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2007-09-19 on deborah.mandriva.com, modified by Mandriva

If you try to modify a file in a write-protected directory in which
there is already a backup file for the file you are editing, then
emacs goes into an infinite loop when you attempt to save the modified
buffer.  To reproduce this bug:

    mkdir test
    touch test/foo.bar
    touch test/foo.bar~
    chmod ugo-w test
    emacs test/foo.bar

Modify the buffer, type C-x C-s.  Emacs runs forever.

Enclosed below is a backtrace obtained by (previously) setting debug-on-quit and
typing C-g as it tries to save the file.

                                        Ken

----------------------------------------------------------------------

 delete-file("/home/kdo/test/foo.bar~")
  byte-code("ÂÃďˆÅ\b	ÂÆ$ˆÂ‡" [from-name to-name nil (delete-file to-name) ((file-error)) copy-file t] 5)
  backup-buffer-copy("/home/kdo/test/foo.bar" "/home/kdo/test/foo.bar~" 420)
  byte-code("\b„c

Re: infinite loop from unwriteable backup files

[Glenn Morris]

Ken Olum wrote:

> If you try to modify a file in a write-protected directory in which
> there is already a backup file for the file you are editing, then
> emacs goes into an infinite loop when you attempt to save the modified
> buffer.

Thanks for the report. This is already fixed. The fix will be in Emacs
22.2.