bug#40127: 27.0.90; image-mode fails on all images with short EXIF tags

bug#40127: 27.0.90; image-mode fails on all images with short EXIF tags

[Juri Linkov]

I realized that the 4th problem reported in bug#39994 is not related to
image-converter.el, so here is a separate bug report.

The problem is that currently image-mode fails to open all image files
where one of EXIF tags is shorter than 4 bytes.  So none of the
images created by a device whose EXIF tag "Manufacturer" is "HTC"
can not be opened in Emacs 27.

Here's is the patch that at least allows opening any image
ignoring errors in EXIF parser implementation:

diff --git a/lisp/image-mode.el b/lisp/image-mode.el
index 22d7d91314..10900be33f 100644
--- a/lisp/image-mode.el
+++ b/lisp/image-mode.el
@@ -769,7 +769,7 @@ image-toggle-display-image
     ;; Get the rotation data from the file, if any.
     (setq image-transform-rotation
           (or (exif-orientation
-               (ignore-error exif-error
+               (ignore-errors
                  (exif-parse-buffer)))
               0.0))
 

bug#40127: 27.0.90; image-mode fails on all images with short EXIF tags

[Lars Ingebrigtsen]

Juri Linkov <juri@linkov.net> writes:

> I realized that the 4th problem reported in bug#39994 is not related to
> image-converter.el, so here is a separate bug report.
>
> The problem is that currently image-mode fails to open all image files
> where one of EXIF tags is shorter than 4 bytes.  So none of the
> images created by a device whose EXIF tag "Manufacturer" is "HTC"
> can not be opened in Emacs 27.

OK, fixed now in Emacs 27.  (Well, I did the fix on the trunk and then
cherry-picked it...  I was slightly unsure whether to also include the
new test cases and files, but I did so anyway -- they won't affect the
release anyway, I think?)

> Here's is the patch that at least allows opening any image
> ignoring errors in EXIF parser implementation:

[...]

> -               (ignore-error exif-error
> +               (ignore-errors
>                   (exif-parse-buffer)))

No, we should never wallpaper over bugs in the code -- we should fix the
bugs.

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