[libxslt] Backup XPath context node in xsltInitCtxtKey

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 5b0965010abf274f7a3a1291d16dde34c167e8a7
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Wed Jun 12 11:58:44 2019 +0200

    Backup XPath context node in xsltInitCtxtKey
    
    Regression caused by commit 029d0e96.
    
    Closes #66.

 libxslt/keys.c            |  3 +++
 tests/docs/bug-221.xml    |  9 +++++++++
 tests/general/bug-221.out |  2 ++
 tests/general/bug-221.xsl | 15 +++++++++++++++
 4 files changed, 29 insertions(+)
---
diff --git a/libxslt/keys.c b/libxslt/keys.c
index 2881056e..a1f150aa 100644
--- a/libxslt/keys.c
+++ b/libxslt/keys.c
@@ -629,6 +629,7 @@ xsltInitCtxtKey(xsltTransformContextPtr ctxt, xsltDocumentPtr idoc,
     xmlNodePtr oldContextNode;
     xsltDocumentPtr oldDocInfo;
     int        oldXPPos, oldXPSize;
+    xmlNodePtr oldXPNode;
     xmlDocPtr oldXPDoc;
     int oldXPNsNr;
     xmlNsPtr *oldXPNamespaces;
@@ -667,6 +668,7 @@ fprintf(stderr, "xsltInitCtxtKey %s : %d\n", keyDef->name, ctxt->keyInitLevel);
     oldDocInfo = ctxt->document;
     oldContextNode = ctxt->node;
 
+    oldXPNode = xpctxt->node;
     oldXPDoc = xpctxt->doc;
     oldXPPos = xpctxt->proximityPosition;
     oldXPSize = xpctxt->contextSize;
@@ -865,6 +867,7 @@ error:
     /*
     * Restore context state.
     */
+    xpctxt->node = oldXPNode;
     xpctxt->doc = oldXPDoc;
     xpctxt->nsNr = oldXPNsNr;
     xpctxt->namespaces = oldXPNamespaces;
diff --git a/tests/docs/bug-221.xml b/tests/docs/bug-221.xml
new file mode 100644
index 00000000..d9d4bacf
--- /dev/null
+++ b/tests/docs/bug-221.xml
@@ -0,0 +1,9 @@
+<model>
+    <resource>
+        <action name="one"/>
+    </resource>
+    <resource>
+        <action name="one"/>
+        <action name="two"/>
+    </resource>
+</model>
diff --git a/tests/general/bug-221.out b/tests/general/bug-221.out
new file mode 100644
index 00000000..96c105e2
--- /dev/null
+++ b/tests/general/bug-221.out
@@ -0,0 +1,2 @@
+<?xml version="1.0"?>
+<r>one</r><r>two</r>
diff --git a/tests/general/bug-221.xsl b/tests/general/bug-221.xsl
new file mode 100644
index 00000000..9b4af652
--- /dev/null
+++ b/tests/general/bug-221.xsl
@@ -0,0 +1,15 @@
+<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
+
+<xsl:key name="actions" match="/model/resource/action" use="@name"/>
+
+<xsl:template match="action">
+    <xsl:if test="generate-id(key('actions', @name)[1]) = generate-id(.)">
+        <r><xsl:value-of select="@name"/></r>
+    </xsl:if>
+</xsl:template>
+
+<xsl:template match="/">
+    <xsl:apply-templates select="model/resource/action"/>
+</xsl:template>
+
+</xsl:stylesheet>