json null string error

lib/src/clixon_json_parse.y

@@ -259,6 +259,7 @@ valuelist     : value
 
 /* quoted string */
 string        : J_DQ ustring J_DQ {  clicon_debug(2,"string->\" ustring \"");$$=$2; }
+              | J_DQ J_DQ {  clicon_debug(2,"string->\" ustring \"");$$=strdup(""); }
               ;
 
 /* unquoted string */

lib/src/json_xpath.c

@@ -0,0 +1,126 @@
+/*
+ * Utility debug tool
+ * Static Compile:  gcc -Wall json_xpath.c -o json_xpath -l clixon
+gcc -O2 -o json_xpath json_xpath.c clixon_log.o clixon_err.o clixon_json.o clixon_xml.o clixon_xsl.o clixon_json_parse.tab.o clixon_xml_parse.tab.o lex.clixon_json_parse.o lex.clixon_xml_parse.o ../../../cligen/cligen_buf.o ../../../cligen/cligen_var.o ../../../cligen/cligen_gen.o ../../../cligen/cligen_cvec.o ../../../cligen/cligen_handle.o ../../../cligen/getline.o ../../../cligen/cligen_read.o ../../../cligen/cligen_match.o ../../../cligen/cligen_expand.o  ../../../cligen/cligen_print.o
+ */
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+/* cligen */
+#include <cligen/cligen.h>
+
+/* clicon */
+#include <clixon/clixon.h>
+
+static int
+usage(char *argv0)
+{
+    fprintf(stderr, "usage:%s <xpath> # XML/JSON expected on stdin\n"
+	    "\t-h    Help\n"
+    	    "\t-b    Strip to body value (eg \"<a>val</a>\" --> \"val\"\n"
+	    "\t-j    json input (not xml)\n",
+	    argv0);
+    exit(0);
+}
+
+int
+main(int argc, char **argv)
+{
+    int i;
+    cxobj     **xv;
+    cxobj      *x;
+    cxobj      *xn;
+    cxobj      *xb;
+    char       *xpath;
+    int         body = 0;
+    int         json = 0;
+    size_t      xlen = 0;
+    size_t      len;
+    size_t      buflen = 128;
+    char       *buf;
+    char       *p;
+    int         retval;
+    char        c;
+
+    while ((c = getopt(argc, argv, "?hbj")) != -1)
+      switch (c) {
+      case '?':
+      case 'h':
+	usage(argv[0]);
+	break;
+      case 'b':
+	body++;
+	break;
+      case 'j':
+	json++;
+	break;
+      default:
+	usage(argv[0]);
+      }
+    if (optind >= argc)
+      usage(argv[0]);
+    xpath=argv[optind];
+
+    clicon_log_init("xpath", 0, CLICON_LOG_STDERR);
+    if ((buf = malloc(buflen)) == NULL){
+	perror("malloc");
+	return -1;
+    }
+    /* |---------------|-------------| 
+     * buf             p             buf+buflen
+     */
+    p = buf;
+    memset(p, 0, buflen);
+    while (1){
+	if ((retval = read(0, p, buflen-(p-buf))) < 0){
+	    perror("read");
+	    return -1;
+	}
+	if (retval == 0)
+	    break;
+	p += retval; 
+	len = p-buf;
+
+	if (buf+buflen-p < 10){ /* allocate more */
+	    buflen *= 2;
+	    if ((buf = realloc(buf, buflen)) == NULL){
+		perror("realloc");
+		return -1;
+	    }
+	    p = buf+len;
+	    memset(p, 0, (buf+buflen)-p);
+	}
+    }
+    if (json){
+      if (json_parse_str(buf, &x) < 0)
+	return -1;
+    }
+    else
+      if (clicon_xml_parse_str(buf, &x) < 0)
+	return -1;
+
+    if (xpath_vec(x, xpath, &xv, &xlen) < 0)
+	return -1;
+    if (xv){
+	for (i=0; i<xlen; i++){
+	    xn = xv[i];
+	    if (body)
+	      xb = xml_find(xn, "body");
+	    else
+	      xb = xn;
+	    if (xb){
+	      //	      xml2json(stdout, xb, 0);
+	      clicon_xml2file(stdout, xb, 0, 0);
+	      fprintf(stdout,"\n");
+	    }
+	}
+	free(xv);
+    }
+    if (x)
+	xml_free(x);
+    if (buf)
+	free(buf);
+    return 0;
+}