confirmed-commit fixes, tests

- fixed typo preventing evaluation of confirmed-commit logic in backend_startup
- fixed uninitialized variable warnings
- added details to CHANGELOG.MD
- added capabilities advertisement for confirmed-commit 1.0 and 1.1
- added xml hello message that uses only eom framing, for simplicity in asynch tests
- add stty restore after wait_restconf to fix console corruption in tests
- adjust test_confirmed_commit to drop perms and run as the invoking user.  This will require running user to have permissions on /usr/local/var/example
- added CLI tests

lib/src/clixon_datastore.c

@@ -418,7 +418,8 @@ xmldb_delete(clicon_handle h,
     if (xmldb_db2file(h, db, &filename) < 0)
 	goto done;
     if (lstat(filename, &sb) == 0)
-        // TODO this had been changed from unlink to truncate some time ago.  It was changed back for confirmed-commit
+        // TODO this had been changed from unlink to truncate some time ago, likely related to dropping privileges.
+        // It was changed back for confirmed-commit, and test_confirmed_commit.sh drops privileges.
         // as the presence of the rollback_db at startup triggers loading of the rollback rather than the startup
         // configuration.  It might not be sufficient to check for a truncated file.  Needs more review, switching back
         // to unlink temporarily.
@@ -619,7 +620,7 @@ xmldb_rename(clicon_handle h,
              const char    *suffix)
 {
     char *old;
-    char *fname;
+    char *fname = NULL;
     int retval = -1;
 
     if ((xmldb_db2file(h, db, &old)) < 0) {

lib/src/clixon_netconf_lib.c

@@ -1765,6 +1765,7 @@ netconf_hello_server(clicon_handle h,
     char *module_set_id;
     char *ietf_yang_library_revision;
     char *encstr = NULL;
+    yang_stmt *yspec = clicon_dbspec_yang(h);
 
     module_set_id = clicon_option_str(h, "CLICON_MODULE_SET_ID");
     cprintf(cb, "<hello xmlns=\"%s\">", NETCONF_BASE_NAMESPACE);
@@ -1799,6 +1800,13 @@ netconf_hello_server(clicon_handle h,
     cprintf(cb, "<capability>");
     xml_chardata_cbuf_append(cb, "urn:ietf:params:netconf:capability:with-defaults:1.0?basic-mode=explicit&also-supported=report-all,trim,report-all-tagged");
     cprintf(cb, "</capability>");
+
+    /* rfc 4741 and 6241 confirmed-commit capabilities */
+    if (if_feature(yspec, "ietf-netconf", "confirmed-commit")) {
+        cprintf(cb, "<capability>urn:ietf:params:netconf:capability:confirmed-commit:1.0</capability>");
+        cprintf(cb, "<capability>urn:ietf:params:netconf:capability:confirmed-commit:1.1</capability>");
+    }
+
     cprintf(cb, "</capabilities>");
     if (session_id) 
 	cprintf(cb, "<session-id>%lu</session-id>", (long unsigned int)session_id);