Re: backup-buffer-copy loops if old backup can't be deleted

[Glenn Morris <rgm@gnu.org>]

How about this:


*** files.el	8 Aug 2007 14:06:01 -0000	1.896.2.15
--- files.el	21 Aug 2007 19:25:34 -0000
***************
*** 3120,3126 ****
  	    (file-error nil))))))
  
  (defun backup-buffer-copy (from-name to-name modes)
!   (let ((umask (default-file-modes)))
      (unwind-protect
  	(progn
  	  ;; Create temp files with strict access rights.  It's easy to
--- 3120,3131 ----
  	    (file-error nil))))))
  
  (defun backup-buffer-copy (from-name to-name modes)
!   (let ((umask (default-file-modes))
! 	(dir (or (file-name-directory to-name)
! 		 default-directory)))
!     ;; Can't delete or create files in a read-only directory.
!     (unless (file-writable-p dir)
!       (signal 'file-error (list "Directory is not writable" dir)))
      (unwind-protect
  	(progn
  	  ;; Create temp files with strict access rights.  It's easy to
***************
*** 3129,3142 ****
  	  (set-default-file-modes ?\700)
  	  (while (condition-case ()
  		     (progn
! 		       (condition-case nil
! 			   (delete-file to-name)
! 			 (file-error nil))
  		       (copy-file from-name to-name nil t)
  		       nil)
  		   (file-already-exists t))
  	    ;; The file was somehow created by someone else between
  	    ;; `delete-file' and `copy-file', so let's try again.
  	    nil))
        ;; Reset the umask.
        (set-default-file-modes umask)))
--- 3134,3149 ----
  	  (set-default-file-modes ?\700)
  	  (while (condition-case ()
  		     (progn
! 		       ;; Failure to delete an existing file is an error.
! 		       (if (file-exists-p to-name)
! 			   (delete-file to-name))
  		       (copy-file from-name to-name nil t)
  		       nil)
  		   (file-already-exists t))
  	    ;; The file was somehow created by someone else between
  	    ;; `delete-file' and `copy-file', so let's try again.
+ 	    ;; FIXME does that every actually happen in practice?
+ 	    ;; This is a potential infloop, which seems bad...
  	    nil))
        ;; Reset the umask.
        (set-default-file-modes umask)))