bug#26011: 26.0.50; tramp should respect large-file-warning-threshold

[Michael Albinus <michael.albinus@gmx.de>]

Robert Marshall <robert.marshall@codethink.co.uk> writes:

Hi Robert,

> If from dired you attempt to copy a file to a tramp ssh dired (I have
> dired-dwim-target set to t) and that file is very large, emacs will pause
> for some time and eventually stop with:
>
> tramp-file-name-handler: Memory exhausted--use C-x s then exit and
> restart Emacs
>
> If tramp is going to open the file and it is large I think it should
> warn the user (respecting large-file-warning-threshold?) rather than
> going ahead without confirmation and erroring with an alarming message!

Well, this happens in case Tramp inserts the file into a temporary
buffer.  What about this patch:

--8<---------------cut here---------------start------------->8---
diff --git a/lisp/tramp-sh.el b/lisp/tramp-sh.el
index 071ef79..8561962 100644
--- a/lisp/tramp-sh.el
+++ b/lisp/tramp-sh.el
@@ -2147,6 +2147,11 @@ file names."
 First arg OP is either `copy' or `rename' and indicates the operation.
 FILENAME is the source file, NEWNAME the target file.
 KEEP-DATE is non-nil if NEWNAME should have the same timestamp as FILENAME."
+  ;; Check, whether file is too large.  Emacs checks in `insert-file-1'
+  ;; and `find-file-noselect', but that's not called here.
+  (abort-if-file-too-large
+   (tramp-compat-file-attribute-size (file-attributes (file-truename filename)))
+   (symbol-name op) filename)
   ;; We must disable multibyte, because binary data shall not be
   ;; converted.  We don't want the target file to be compressed, so we
   ;; let-bind `jka-compr-inhibit' to t.  `epa-file-handler' shall not
--8<---------------cut here---------------end--------------->8---

> Robert

Best regards, Michael.