#316: catch "broken pipe" OSErrors when communicating with graphviz; get stdout/stderr anyway. This happens e.g. when dot does not support the selected output format.

CHANGES

@@ -1,6 +1,9 @@
 Release 0.6.4 (in development)
 ==============================
 
+* #316: Catch OSErrors occurring when calling graphviz with
+  arguments it doesn't understand.
+
 * Restore compatibility with Pygments >= 1.2.
 
 * #295: Fix escaping of hyperref targets in LaTeX output.

sphinx/ext/graphviz.py

@@ -22,7 +22,7 @@ except ImportError:
 from docutils import nodes
 
 from sphinx.errors import SphinxError
-from sphinx.util import ensuredir, ENOENT
+from sphinx.util import ensuredir, ENOENT, EPIPE
 from sphinx.util.compat import Directive
 
 
@@ -102,6 +102,10 @@ def render_dot(self, code, options, format, prefix='graphviz'):
 
     ensuredir(path.dirname(outfn))
 
+    # graphviz expects UTF-8 by default
+    if isinstance(code, unicode):
+        code = code.encode('utf-8')
+
     dot_args = [self.builder.config.graphviz_dot]
     dot_args.extend(self.builder.config.graphviz_dot_args)
     dot_args.extend(options)
@@ -118,10 +122,17 @@ def render_dot(self, code, options, format, prefix='graphviz'):
                           self.builder.config.graphviz_dot)
         self.builder._graphviz_warned_dot = True
         return None, None
-    # graphviz expects UTF-8 by default
-    if isinstance(code, unicode):
-        code = code.encode('utf-8')
+    try:
+        # Graphviz may close standard input when an error occurs,
+        # resulting in a broken pipe on communicate()
         stdout, stderr = p.communicate(code)
+    except OSError, err:
+        if err.errno != EPIPE:
+            raise
+        # in this case, read the standard output and standard error streams
+        # directly, to get the error message(s)
+        stdout, stderr = p.stdout.read(), p.stderr.read()
+        p.wait()
     if p.returncode != 0:
         raise GraphvizError('dot exited with error:\n[stderr]\n%s\n'
                             '[stdout]\n%s' % (stderr, stdout))
@@ -131,7 +142,7 @@ def render_dot(self, code, options, format, prefix='graphviz'):
 def render_dot_html(self, node, code, options, prefix='graphviz',
                     imgcls=None, alt=None):
     try:
-        fname, outfn = render_dot(self, code, options, 'png', prefix)
+        fname, outfn = render_dot(self, code, options, 'pnf', prefix)
     except GraphvizError, exc:
         self.builder.warn('dot code %r: ' % code + str(exc))
         raise nodes.SkipNode

sphinx/util/__init__.py

@@ -29,6 +29,7 @@ import sphinx
 # Errnos that we need.
 EEXIST = getattr(errno, 'EEXIST', 0)
 ENOENT = getattr(errno, 'ENOENT', 0)
+EPIPE  = getattr(errno, 'EPIPE', 0)
 
 # Generally useful regular expressions.
 ws_re = re.compile(r'\s+')