* Added nsc parameter to xml2xpath() and ensured the xpath uses prefixes.

* Old code: add `NULL` as second parameter

CHANGELOG.md

@@ -136,6 +136,8 @@ Users may have to change how they access the system
 
 Developers may need to change their code
 
+* Added `nsc` parameter to `xml2xpath()` and ensured the xpath uses prefixes.
+  * Old code: add `NULL` as second parameter
 * Added `eof` parameter to `clicon_rpc()` and `clicon_rpc1()` and error handling modified
 
 ## 5.6.0

lib/clixon/clixon_xml_map.h

@@ -68,7 +68,7 @@ int xml_nopresence_default(cxobj *xt);
 int xml_nopresence_default_mark(cxobj *x, void *arg);
 int xml_sanity(cxobj *x, void  *arg);
 int xml_non_config_data(cxobj *xt, cxobj **xerr);
-int xml2xpath(cxobj *x, char **xpath);
+int xml2xpath(cxobj *x, cvec *nsc, char **xpath);
 int assign_namespace_element(cxobj *x0, cxobj *x1, cxobj *x1p);
 int assign_namespace_body(cxobj *x0, cxobj *x1);
 int xml_merge(cxobj *x0, cxobj *x1, yang_stmt *yspec, char **reason);

lib/src/clixon_netconf_lib.c

@@ -1375,7 +1375,7 @@ netconf_minmax_elements_xml(cxobj **xret,
 	goto done;
     }
     if (xml_parent(xp)){ /* Dont include root, eg <config> */
-	if (xml2xpath(xp, &path) < 0)
+	if (xml2xpath(xp, NULL, &path) < 0)
 	    goto done;
 	if (path)
 	    cprintf(cb, "%s", path);

lib/src/clixon_xml_map.c

@@ -1291,12 +1291,16 @@ xml_non_config_data(cxobj  *xt,
     return retval;
 }
 
-/*! Given an XML node, build an xpath to root, internal function
+/*! Given an XML node, build an xpath  recursively to root, internal function
+ * @param[in]  x      XML object
+ * @param[in]  nsc    Namespace context
+ * @param[out] cb     XPath string as cbuf.
  * @retval     0      OK
  * @retval    -1      Error. eg XML malformed
  */
 static int
 xml2xpath1(cxobj *x,
+	   cvec  *nsc,
 	   cbuf  *cb)
 {
     int           retval = -1;
@@ -1309,12 +1313,30 @@ xml2xpath1(cxobj *x,
     cxobj        *xb;
     char         *b;
     enum rfc_6020 keyword;
+    char         *prefix = NULL;
+    char         *namespace;
     
     if ((xp = xml_parent(x)) == NULL)
 	goto ok;
-    xml2xpath1(xp, cb);
+    if (xml2xpath1(xp, nsc, cb) < 0)
+	goto done;
+    if (nsc){
+	if (xml2ns(x, xml_prefix(x), &namespace) < 0)
+	    goto done;
+	if (namespace){
+	    if (xml_nsctx_get_prefix(nsc, namespace, &prefix) == 0)
+		; /* maybe NULL? */
+	}
+	else
+	    prefix = xml_prefix(x); /* maybe NULL? */
+    }
+    else
+	prefix = xml_prefix(x);
     /* XXX: sometimes there should be a /, sometimes not */
-    cprintf(cb, "/%s", xml_name(x));
+    cprintf(cb, "/");
+    if (prefix)
+	cprintf(cb, "%s:", prefix);
+    cprintf(cb, "%s", xml_name(x));
     if ((y = xml_spec(x)) != NULL){
 	keyword = yang_keyword_get(y);
 	switch (keyword){
@@ -1334,7 +1356,10 @@ xml2xpath1(cxobj *x,
 		if ((xb = xml_find(x, keyname)) == NULL)
 		    goto done;
 		b = xml_body(xb);
-		cprintf(cb, "[%s=\"%s\"]", keyname, b?b:"");
+		cprintf(cb, "[");
+		if (prefix)
+		    cprintf(cb, "%s:", prefix);
+		cprintf(cb, "%s=\"%s\"]", keyname, b?b:"");
 	    }
 	    break;
 	default:
@@ -1348,8 +1373,14 @@ xml2xpath1(cxobj *x,
 }
 
 /*! Given an XML node, build an xpath to root
- * Builds only unqualified xpaths, ie no predicates []
+ *
+ * Creates an XPath from an XML node with some limitations, see notes below.
+ * The prefixes used are from the given namespace context if any, otherwise the native prefixes are used, if any.
+ * Note that this means that prefixes may be translated such as if the XML namespace mapping is different than the once used
+ * in the XML.
+ * Therefore, if nsc is "canonical", the returned xpath is also "canonical", even though the XML is not.
  * @param[in]  x      XML object
+ * @param[in]  nsc    Namespace context
  * @param[out] xpath  Malloced xpath string. Need to free() after use
  * @retval     0      OK
  * @retval    -1      Error. (eg XML malformed)
@@ -1357,6 +1388,7 @@ xml2xpath1(cxobj *x,
  */
 int
 xml2xpath(cxobj *x,
+	  cvec  *nsc,
 	  char **xpathp)
 {
     int   retval = -1;
@@ -1367,7 +1399,7 @@ xml2xpath(cxobj *x,
 	clicon_err(OE_XML, errno, "cbuf_new");
 	goto done;
     }
-    if (xml2xpath1(x, cb) < 0)
+    if (xml2xpath1(x, nsc, cb) < 0)
 	goto done;
     /* XXX: see xpath in test statement,.. */
     xpath = cbuf_get(cb);

test/test_xpath_inverse.sh

@@ -0,0 +1,91 @@
+#!/usr/bin/env bash
+# Test xpath inverse function.
+# That is, given an xml + xpath -> specific node x in xml -> xml2xpath(x)
+
+# Magic line must be first in script (see README.md)
+s="$_" ; . ./lib.sh || if [ "$s" = $0 ]; then exit 0; else return 0; fi
+
+: ${clixon_util_xpath:=clixon_util_xpath}
+
+ydir=$dir/yang
+xml1=$dir/xml1.xml
+xml2=$dir/xml2.xml
+
+if [ ! -d $ydir ]; then
+    mkdir $ydir
+fi
+
+# canonical namespace xpath tests
+# need yang modules
+cat <<EOF > $ydir/a.yang
+module a{
+  namespace "urn:example:a";
+  prefix a;
+  container x{
+    leaf y{
+      type string;
+    }
+    list z {
+      key k;
+      leaf k{
+         type string;
+      }
+    }
+  }
+}
+EOF
+
+# Default prefix
+cat <<EOF > $xml1
+<x xmlns="urn:example:a">
+   <y>foo</y>
+   <z>
+     <k>1</k>
+   </z>
+   <z>
+     <k>2</k>
+   </z>
+</x>
+EOF
+
+# Explicit indexes
+cat <<EOF > $xml2
+<a:x xmlns:a="urn:example:a">
+   <a:y>foo</a:y>
+   <a:z>
+     <a:k>1</a:k>
+   </a:z>
+   <a:z>
+     <a:k>2</a:k>
+   </a:z>
+</a:x>
+EOF
+
+new "xpath leaf default ns"
+expectpart "$($clixon_util_xpath -If $xml1 -y $ydir -p /x/y)" 0 'Inverse: /x/y'
+
+new "xpath leaf explicit prefix"
+expectpart "$($clixon_util_xpath -If $xml2 -y $ydir -p /a:x/a:y)" 0 'Inverse: /a:x/a:y'
+
+new "xpath leaf explicit prefix"
+expectpart "$($clixon_util_xpath -If $xml2 -y $ydir -p /a:x/a:y -n a:urn:example:a)" 0 'Inverse: /a:x/a:y'
+
+new "xpath leaf no prefix"
+expectpart "$($clixon_util_xpath -If $xml1 -y $ydir -p /x/y -n a:urn:example:a)" 0 'Inverse: /a:x/a:y'
+
+new "xpath leaf other nsc"
+expectpart "$($clixon_util_xpath -If $xml1 -y $ydir -p /a:x/a:y -n b:urn:example:a)" 0 'Inverse: /b:x/b:y' --not-- /a:x/a:y
+
+new "xpath list same nsc"
+expectpart "$($clixon_util_xpath -If $xml1 -y $ydir -p /a:x/a:z[a:k='2'] -n a:urn:example:a)" 0 'Inverse: /a:x/a:z\[a:k="2"\]'
+
+new "xpath list same nsc"
+expectpart "$($clixon_util_xpath -If $xml1 -y $ydir -p /a:x/a:z[a:k='2'] -n b:urn:example:a)" 0 'Inverse: /b:x/b:z\[b:k="2"\]' --not-- '/a:x/a:z'
+
+rm -rf $dir
+
+# unset conditional parameters 
+unset clixon_util_xpath
+
+new "endtest"
+endtest

util/clixon_util_xpath.c

@@ -60,7 +60,7 @@ See https://www.w3.org/TR/xpath/
 #include "clixon/clixon.h"
 
 /* Command line options to be passed to getopt(3) */
-#define XPATH_OPTS "hD:f:p:i:n:cl:y:Y:"
+#define XPATH_OPTS "hD:f:p:i:In:cl:y:Y:"
 
 static int
 usage(char *argv0)
@@ -72,6 +72,7 @@ usage(char *argv0)
 	    "\t-f <file>  \tXML file\n"
 	    "\t-p <xpath> \tPrimary XPATH string\n"
 	    "\t-i <xpath0>\t(optional) Initial XPATH string\n"
+            "\t-I \t\tCheck inverse, map back xml result to xpath and check if equal\n"
 	    "\t-n <pfx:id>\tNamespace binding (pfx=NULL for default)\n"
 	    "\t-c \t\tMap xpath to canonical form\n"
 	    "\t-l <s|e|o|f<file>> \tLog on (s)yslog, std(e)rr, std(o)ut or (f)ile (stderr is default)\n"
@@ -120,7 +121,6 @@ main(int    argc,
     int         retval = -1;
     char       *argv0 = argv[0];
     int         i;
-    cxobj     **xv = NULL;
     cxobj      *x0 = NULL;
     cxobj      *x;
     int         c;
@@ -144,6 +144,7 @@ main(int    argc,
     cxobj      *xerr = NULL; /* malloced must be freed */
     int         logdst = CLICON_LOG_STDERR;
     int         dbg = 0;
+    int         xpath_inverse = 0;
 
     /* In the startup, logs to stderr & debug flag set later */
     clicon_log_init("xpath", LOG_DEBUG, logdst); 
@@ -180,6 +181,9 @@ main(int    argc,
 	case 'i': /* Optional initial XPATH string */
 	    xpath0 = optarg;
 	    break;
+	case 'I': /* Check inverse */
+	    xpath_inverse++;
+	    break;
 	case 'n':{ /* Namespace binding */
 	    char *prefix;
 	    char *id;
@@ -307,7 +311,7 @@ main(int    argc,
      */
     if (clixon_xml_parse_file(fp, YB_NONE, NULL, &x0, NULL) < 0){
 	fprintf(stderr, "Error: parsing: %s\n", clicon_err_reason);
-	return -1;
+	goto done;
     }
 
     /* Validate XML as well */
@@ -361,6 +365,23 @@ main(int    argc,
 	x = x0;
     if (xpath_vec_ctx(x, nsc, xpath, 0, &xc) < 0)
 	return -1;
+    /* Check inverse, eg XML back to xpath and compare with original, only if nodes */
+    if (xpath_inverse && xc->xc_type == XT_NODESET){
+	cxobj *xi;
+	char  *xpathi = NULL;
+	for (i=0; i<xc->xc_size; i++){
+	    xi = xc->xc_nodeset[i];
+	    if (xml2xpath(xi, nsc, &xpathi) < 0)
+		goto done;
+	    fprintf(stdout, "Inverse: %s\n", xpathi);
+	    if (xpathi){
+		free(xpathi);
+		xpathi = NULL;
+	    }
+	}
+	goto ok;
+    }
+
     /* Print results */
     cb = cbuf_new();
     ctx_print2(cb, xc);
@@ -376,8 +397,6 @@ main(int    argc,
 	ctx_free(xc);
     if (xcfg)
 	xml_free(xcfg);
-    if (xv)
-	free(xv);
     if (buf)
 	free(buf);
     if (x0)