If SGML_CATALOG_FILES is in the environment, pass --catalogs to xmllint and
xsltproc. Also pass --nonet to xsltproc to detect future missing stylesheet
problems.

An earlier version of this patch was filed upstream at
https://github.com/asciidoc/asciidoc-py3/issues/61 so depending on how that goes
this could get merged.

Upstream-Status: Inappropriate
Signed-off-by: Ross Burton <ross.burton@intel.com>

diff --git a/a2x.py b/a2x.py
index 2d7699a..582d809 100755
--- a/a2x.py
+++ b/a2x.py
@@ -57,6 +57,10 @@ LYNX_OPTS = '-dump'
 W3M_OPTS = '-dump -cols 70 -T text/html -no-graph'
 XSLTPROC_OPTS = ''
 
+if "SGML_CATALOG_FILES" in os.environ:
+  XMLLINT += " --catalogs"
+  XSLTPROC += " --catalogs"
+
 ######################################################################
 # End of configuration file parameters.
 ######################################################################
@@ -298,7 +302,7 @@ def exec_xsltproc(xsl_file, xml_file, dst_dir, opts = ''):
     cwd = os.getcwd()
     shell_cd(dst_dir)
     try:
-        shell('"%s" %s "%s" "%s"' % (XSLTPROC, opts, xsl_file, xml_file))
+        shell('%s %s "%s" "%s"' % (XSLTPROC, opts, xsl_file, xml_file))
     finally:
         shell_cd(cwd)
 
@@ -483,7 +487,7 @@ class A2X(AttrDict):
             self.asciidoc_opts += ' --doctype %s' % self.doctype
         for attr in self.attributes:
             self.asciidoc_opts += ' --attribute "%s"' % attr
-#        self.xsltproc_opts += ' --nonet'
+        self.xsltproc_opts += ' --nonet'
         if self.verbose:
             self.asciidoc_opts += ' --verbose'
             self.dblatex_opts += ' -V'
@@ -634,7 +638,7 @@ class A2X(AttrDict):
         shell('"%s" --backend docbook -a "a2x-format=%s" %s --out-file "%s" "%s"' %
              (self.asciidoc, self.format, self.asciidoc_opts, docbook_file, self.asciidoc_file))
         if not self.no_xmllint and XMLLINT:
-            shell('"%s" --nonet --noout --valid "%s"' % (XMLLINT, docbook_file))
+            shell('%s --nonet --noout --valid "%s"' % (XMLLINT, docbook_file))
 
     def to_xhtml(self):
         self.to_docbook()