[yelp-tools] yelp-check: Fix validation for DocBook 5 with https redirects

[Shaun McCance <shaunm src gnome org>]

commit d08118955f2e29c7d263d79aff2580baaeabe576
Author: Shaun McCance <shaunm gnome org>
Date:   Fri Apr 26 12:11:13 2019 -0400

    yelp-check: Fix validation for DocBook 5 with https redirects
    
    At some point, docbook.org starting doing 301 redirects to send all
    requests thru https. Unfortunately, neither jing nor xmllint likes
    these redirects, and xmllint doesn't do https at all. So, we have
    to do some special casing depending on the validator and on whether
    we have local copies in the catalogs. Fun stuff.

 tools/yelp-check.in | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)
---
diff --git a/tools/yelp-check.in b/tools/yelp-check.in
index 526679d..d46e004 100755
--- a/tools/yelp-check.in
+++ b/tools/yelp-check.in
@@ -1060,11 +1060,29 @@ yelp_validate_db () {
     major=$(echo "$version" | cut -c1)
     if [ "x$major" = "x5" ]; then
         check_out_file=`mktemp "${TMPDIR:-/tmp}"/yelp-XXXXXXXX`
-        rng_uri="http://docbook.org/xml/$version/rng/docbook.rng";
+        # Canonical URIs are http, but they 301 redirect to https. jing can handle
+        # https fine, but not the redirect. And jing doesn't look at catalogs. So
+        # just always feed jing an https URI.
         if [ "x$check_jing" = "x1" ]; then
+            rng_uri="https://docbook.org/xml/$version/rng/docbook.rng";
             jing -i "$rng_uri" "$1" > "$check_out_file" 2>&1
         else
-            xmllint --noout --xinclude --noent --relaxng "$rng_uri" "$1" > "$check_out_file" 2>&1
+            # xmllint, on the other hand, does support catalogs. It also doesn't
+            # do the redirect, but it wouldn't matter if it did because it doesn't
+            # do https. So if the schema is available locally in the catalog, hand
+            # xmllint the http URI so it can use the local copy. Otherwise, we have
+            # to get curl involved to do https.
+            rng_uri="http://docbook.org/xml/$version/rng/docbook.rng";
+            incat=$(xmlcatalog /etc/xml/catalog "$rng_uri" | grep -c '^file:')
+            if [ "x$incat" != "x0" ]; then
+                xmllint --noout --xinclude --noent --relaxng "$rng_uri" "$1" > "$check_out_file" 2>&1
+            else
+                rng_uri="https://docbook.org/xml/$version/rng/docbook.rng";
+                check_rng_file=`mktemp "${TMPDIR:-/tmp}"/yelp-XXXXXXXX`
+                curl -sL -o "$check_rng_file" "$rng_uri"
+                xmllint --noout --xinclude --noent --relaxng "$check_rng_file" "$1" > "$check_out_file" 2>&1
+                rm "$check_rng_file"
+            fi
         fi
         yelp_check_retval="$?"
         cat "$check_out_file" | grep -v 'validates$'