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

[Mauro Carvalho Chehab <mchehab@s-opensource.com>]

Em Thu, 2 Mar 2017 16:34:22 -0300
Mauro Carvalho Chehab <mchehab@s-opensource.com> escreveu:

> Em Thu, 2 Mar 2017 20:06:39 +0100
> Markus Heiser <markus.heiser@darmarit.de> escreveu:
> 
> > 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))
> 
> Yes, this fixed. I actually did:
> 
> -        sys.stderr.write(err)
> +        sys.stderr.write(str(err))
> +        sys.stderr.write("\n")
> 
> It is now printing:
> 	b''
> 
> I added the \n print to avoid it to be mixed with the "writing output"
> prints.
> 
> No idea how to make sense from it - but clearly, the error report
> logic require some care ;-)

I'm not a Python programmer, but googling about the right syntax for
p.communicate(), I suspect that the fix should be similar to this code
snippet below.

Without the if, this code:

	sys.stderr.write("Error:" + repr(p.communicate()[0]) + "\n")

prints:
	Error:None

So, I guess the code below is ok.

Markus, please check. 

Daniel, Feel free to merge it with the original patch if OK.

diff --git a/Documentation/sphinx/kfigure.py b/Documentation/sphinx/kfigure.py
index 32eab0f4cfba..b154c5f17752 100644
--- a/Documentation/sphinx/kfigure.py
+++ b/Documentation/sphinx/kfigure.py
@@ -217,11 +217,12 @@ def dot2format(dot_fname, out_fname):
     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
+
+        if exit_code == 0:
+            sys.stderr.write("Error:" + repr(p.communicate()[0]) + "\n")
+
         out.flush()
     return bool(exit_code == 0)
 
@@ -239,11 +240,12 @@ 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)
 
     exit_code = p.returncode
+
+    if exit_code == 0:
+        sys.stderr.write("Error:" + repr(p.communicate()[0]) + "\n")
+
     return bool(exit_code == 0)