[PATCH] docs-rst: automatically convert Graphviz and SVG images

[Daniel Vetter]

On Thu, Mar 02, 2017 at 08:06:39PM +0100, Markus Heiser wrote:
> Hi Mauro,
> 
> > Tested here with the enclosed patch.
> 
> great, big step forward making /media/Makefile smaller ...  thanks a lot!!!!
> 
> > It crashed:
> > Exception occurred:
> >  File "/devel/v4l/patchwork/Documentation/sphinx/kfigure.py", line 222, in dot2format
> >    sys.stderr.write(err)
> > TypeError: write() argument must be str, not bytes
> > The full traceback has been saved in /tmp/sphinx-err-_1vahbmg.log, if you want to report the issue to the developers.
> > Please also report this if it was a user error, so that a better error message can be provided next time.
> > A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!
> > Documentation/Makefile.sphinx:69: recipe for target 'htmldocs' failed
> > make[1]: *** [htmldocs] Error 1
> > Makefile:1450: recipe for target 'htmldocs' failed
> > make: *** [htmldocs] Error 2
> > 
> > Weird enough, it produced a Documentation/output/media/uapi/v4l/pipeline.svg file.
> 
> I guess that the dot command writes something to stderr. This is captured 
> by the extension and printed to stderr ...
> 
> +def dot2format(dot_fname, out_fname):
> ...
> +    exit_code = 42
> +    with open(out_fname, "w") as out:
> +        p = subprocess.Popen(
> +            cmd, stdout = out, stderr = subprocess.PIPE )
> +        nil, err = p.communicate()
> +
> +        sys.stderr.write(err)
> +
> +        exit_code = p.returncode
> +        out.flush()
> +    return bool(exit_code == 0)
> 
> >  File "/devel/v4l/patchwork/Documentation/sphinx/kfigure.py", line 222, in dot2format
> >    sys.stderr.write(err)
> > TypeError: write() argument must be str, not bytes
> 
> Do we need this stderr output? For a first test, uncomment the 
> "sys.stderr.write(err)“ in line 222. Or, if we really need the
> stderr, try:
> 
> -        sys.stderr.write(err)
> +        sys.stderr.write(str(err))
> 
> I this fixes, there is another "sys.stderr.write(err)" in 
> func svg2pdf(..) which should also fixed ….
>  
> +def svg2pdf(svg_fname, pdf_fname):
> ...
> +    cmd = [convert_cmd, svg_fname, pdf_fname]
> +    p = subprocess.Popen(
> +        cmd, stdout = out, stderr = subprocess.PIPE )
> +    nil, err = p.communicate()
> +
> -        sys.stderr.write(err)
> +        sys.stderr.write(str(err))
> +
> +    exit_code = p.returncode
> +    return bool(exit_code == 0)

Yes, I very much want stderr to be forward. Without that you don't see
error output from dot or convert, and that makes it impossible to debug
anything. If I want a direct forwarding of the bytes, how should I do this
in python? Capturing stderr and then re-dumping it is kinda silly ...

Note that I copied this pattern from the kernel-doc extension, seems to
have worked there.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch