[PATCH 4/3] docs: sphinx/kfigure.py: Add check of 'dot -Tpdf'

[Akira Yokosawa <akiyks@gmail.com>]

To prevent any regression on existing build systems, limit the
fallback of converting DOT -> raster PDF only when all of the
following conditions are met.

 o dot(1) doesn't support -Tpdf
 o rsvg-convert(1) is not found
 o inkscape(1) is not found

Suggested-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
---
 Documentation/sphinx/kfigure.py | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/Documentation/sphinx/kfigure.py b/Documentation/sphinx/kfigure.py
index d5802e3975e5..dbe75ee8ae61 100644
--- a/Documentation/sphinx/kfigure.py
+++ b/Documentation/sphinx/kfigure.py
@@ -113,6 +113,8 @@ def pass_handle(self, node):           # pylint: disable=W0613
 
 # Graphviz's dot(1) support
 dot_cmd = None
+# dot(1) -Tpdf should be used
+dot_Tpdf = False
 
 # ImageMagick' convert(1) support
 convert_cmd = None
@@ -175,7 +177,7 @@ def setupTools(app):
 
     This function is called once, when the builder is initiated.
     """
-    global dot_cmd, convert_cmd, rsvg_convert_cmd   # pylint: disable=W0603
+    global dot_cmd, dot_Tpdf, convert_cmd, rsvg_convert_cmd   # pylint: disable=W0603
     global inkscape_cmd, inkscape_ver_one, inkscape_show_warn  # pylint: disable=W0603
     kernellog.verbose(app, "kfigure: check installed tools ...")
 
@@ -186,6 +188,16 @@ def setupTools(app):
 
     if dot_cmd:
         kernellog.verbose(app, "use dot(1) from: " + dot_cmd)
+
+        try:
+            dot_Thelp_list = subprocess.check_output([dot_cmd, '-Thelp'],
+                                    stderr=subprocess.STDOUT)
+        except subprocess.CalledProcessError as err:
+            dot_Thelp_list = err.output
+            pass
+
+        dot_Tpdf_ptn = b'pdf'
+        dot_Tpdf = re.search(dot_Tpdf_ptn, dot_Thelp_list)
     else:
         kernellog.warn(app, "dot(1) not found, for better output quality install "
                        "graphviz from https://www.graphviz.org")
@@ -197,6 +209,7 @@ def setupTools(app):
         inkscape_ver_one = re.search(ver_one_ptn, inkscape_ver)
         convert_cmd = None
         rsvg_convert_cmd = None
+        dot_Tpdf = False
 
         try:
             if os.environ['SPHINX_SHOW_INKSCAPE_WARN']:
@@ -216,6 +229,7 @@ def setupTools(app):
 
         if rsvg_convert_cmd:
             kernellog.verbose(app, "use rsvg-convert(1) from: " + rsvg_convert_cmd)
+            dot_Tpdf = False
         else:
             kernellog.verbose(app, "rsvg-convert(1) not found, "
                               "falling back to raster image conversion")
@@ -308,11 +322,12 @@ def convert_image(img_node, translator, src_fname=None):
 
             if in_ext == '.dot':
                 kernellog.verbose(app, 'convert DOT to: {out}/' + _name)
-                if translator.builder.format == 'latex':
+                if translator.builder.format == 'latex' and not dot_Tpdf:
                     svg_fname = path.join(translator.builder.outdir, fname + '.svg')
                     ok1 = dot2format(app, src_fname, svg_fname)
                     ok2 = svg2pdf_by_rsvg(app, svg_fname, dst_fname)
                     ok = ok1 and ok2
+
                 else:
                     ok = dot2format(app, src_fname, dst_fname)
 
-- 
2.17.1