bug#43318: Unable to open remote pdf directly with eww

bug#43318: Unable to open remote pdf directly with eww

[Stefan Kangas]

Steps to reproduce:

0. emacs -Q
1. M-x eww RET https://www.gnu.org/software/emacs/manual/pdf/emacs.pdf RET

Result: My external pdf reader (titled "Document Viewer", not sure what
it is, maybe some Gnome thing) opens with the message "Unable to open
file '/home/skangas/wip/emacs/-'".  It seems like it tried to open the
file "-" in the directory from which I run Emacs.

It would be useful if this would open the pdf doc-view-mode, or if the
pdf was downloaded to /tmp and opened using "Document Viewer" from there
or something.

bug#43318: Unable to open remote pdf directly with eww

[Lars Ingebrigtsen]

Stefan Kangas <stefan@marxist.se> writes:

> 0. emacs -Q
> 1. M-x eww RET https://www.gnu.org/software/emacs/manual/pdf/emacs.pdf RET
>
> Result: My external pdf reader (titled "Document Viewer", not sure what
> it is, maybe some Gnome thing) opens with the message "Unable to open
> file '/home/skangas/wip/emacs/-'".  It seems like it tried to open the
> file "-" in the directory from which I run Emacs.
>
> It would be useful if this would open the pdf doc-view-mode, or if the
> pdf was downloaded to /tmp and opened using "Document Viewer" from there
> or something.

When I open that link in eww, I get a *eww pdf* buffer which displays
the file (after a while; that's a big pdf) using DocView mode.

So perhaps this fails if whatever tools DocView mode uses isn't
installed?  It looks like it calls...  uhm...  gs?

In that case, it should try using a different pdf viewer, but I'm not
quite sure how that's handled.  mailcap should probably be consulted?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#43318: Unable to open remote pdf directly with eww

[Lars Ingebrigtsen]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> In that case, it should try using a different pdf viewer, but I'm not
> quite sure how that's handled.  mailcap should probably be consulted?

Oh, that is what it's doing:

(defun mailcap-view-mime (type)
  "View the data in the current buffer that has MIME type TYPE.
`mailcap--computed-mime-data' determines the method to use."
  (let ((method (mailcap-mime-info type)))
    (if (stringp method)
	(shell-command-on-region (point-min) (point-max)
				 ;; Use stdin as the "%s".
				 (format method "-")
				 (current-buffer)
				 t)
      (funcall method))))

eww puts the pdf data in a buffer and calls (for instance) "xpdf -" on
the data.

But this'll fail for most pdf viewers -- most of them don't read from
stdin, so this seems like a pretty gross hack...

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#43318: Unable to open remote pdf directly with eww

[Stefan Kangas]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Lars Ingebrigtsen <larsi@gnus.org> writes:
>
>> In that case, it should try using a different pdf viewer, but I'm not
>> quite sure how that's handled.  mailcap should probably be consulted?
>
> Oh, that is what it's doing:
>
> (defun mailcap-view-mime (type)
>   "View the data in the current buffer that has MIME type TYPE.
> `mailcap--computed-mime-data' determines the method to use."
>   (let ((method (mailcap-mime-info type)))
>     (if (stringp method)
> 	(shell-command-on-region (point-min) (point-max)
> 				 ;; Use stdin as the "%s".
> 				 (format method "-")
> 				 (current-buffer)
> 				 t)
>       (funcall method))))
>
> eww puts the pdf data in a buffer and calls (for instance) "xpdf -" on
> the data.
>
> But this'll fail for most pdf viewers -- most of them don't read from
> stdin, so this seems like a pretty gross hack...

Sounds like a good analysis.

In my case I'm using evince, because at some point I put this in my
"~/.mailcap":

    application/pdf; evince %s

And I guess evince doesn't read from stdin, as you say...

bug#43318: Unable to open remote pdf directly with eww

[Lars Ingebrigtsen]

Stefan Kangas <stefan@marxist.se> writes:

> In my case I'm using evince, because at some point I put this in my
> "~/.mailcap":
>
>     application/pdf; evince %s
>
> And I guess evince doesn't read from stdin, as you say...

I've now fixed this on the trunk to start the external viewer the
traditional way.  It starts it synchronously, though, which isn't ideal,
but having the deletion triggered from a process filter, for instance,
will leave the temporary file there upon crashes...

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#43318: Unable to open remote pdf directly with eww

[Stefan Kangas]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Stefan Kangas <stefan@marxist.se> writes:
>
>> In my case I'm using evince, because at some point I put this in my
>> "~/.mailcap":
>>
>>     application/pdf; evince %s
>>
>> And I guess evince doesn't read from stdin, as you say...
>
> I've now fixed this on the trunk to start the external viewer the
> traditional way.  It starts it synchronously, though, which isn't ideal,
> but having the deletion triggered from a process filter, for instance,
> will leave the temporary file there upon crashes...

I've now tested it and I can confirm that your fix works here.

bug#43318: Unable to open remote pdf directly with eww

[Lars Ingebrigtsen]

Stefan Kangas <stefan@marxist.se> writes:

> I've now tested it and I can confirm that your fix works here.

Thanks!

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no