config input handling improvements

This commit changes a few things in the config handling:

* When reading the configuration from multiple sources, a source can now
  override settings already set by a preceding source for settings that
  are not lists.  Previously, trying to change the value of a setting in a
  subsequence file would be considered an error, just like trying to set
  the value of a particular setting multiple times in a single
  configuration file.

* A configuration fragment in CYCLONEDDS_URI now no longer requires the
  CycloneDDS top-level tag to be specified.  If it is missing it will be
  assumed.  This is only true for configuration fragments contained in
  CYCLONEDDS_URI, not for data read from a file.

* A configuration fragment in CYCLONEDDS_URI no longer requires that all
  elements are properly closed: a missing close tag is treated as-if it
  is the end of the fragment and any elements are implicitly closed.
  Again this does not apply to files.

* The configuration dump now lists explicitly which sources affected
  each setting, with a default value indicated by an empty set.

The result of the latter two is that one can almost pretend that it is a
sane format instead of XML.  For example, if one would like to override
tracing settings, one could just write:

  CYCLONEDDS_URI="$CYCLONEDDS_URI,<Tracing><Verbosity>finest"

Signed-off-by: Erik Boasson <eb@ilities.com>

src/core/ddsi/include/dds/ddsi/q_config.h

@@ -238,7 +238,7 @@ struct config
   char *tracingOutputFileName;
   int tracingTimestamps;
   int tracingAppendToFile;
-  unsigned allowMulticast;
+  uint32_t allowMulticast;
   enum transport_selector transport_selector;
   enum boolean_default compat_use_ipv6;
   enum boolean_default compat_tcp_enable;
@@ -413,6 +413,7 @@ struct cfgst;
 
 struct cfgst *config_init (const char *configfile);
 void config_print_cfgst (struct cfgst *cfgst);
+void config_free_source_info (struct cfgst *cfgst);
 void config_fini (struct cfgst *cfgst);
 
 #ifdef DDSI_INCLUDE_NETWORK_PARTITIONS

src/core/ddsi/src/q_init.c

@@ -584,8 +584,10 @@ int rtps_config_prep (struct cfgst *cfgst)
     thread_states_init (max_threads);
   }
 
-  /* Now the per-thread-log-buffers are set up, so print the configuration */
+  /* Now the per-thread-log-buffers are set up, so print the configuration.  After this there
+     is no value to the source information for the various configuration elements, so free those. */
   config_print_cfgst (cfgst);
+  config_free_source_info (cfgst);
   return 0;
 
 err_config_late_error:

src/ddsrt/include/dds/ddsrt/xmlparser.h

@@ -38,7 +38,7 @@ extern "C" {
 
 #define DDSRT_XMLP_REQUIRE_EOF          1u /* set by default; if not set, junk may follow top-level closing tag */
 #define DDSRT_XMLP_ANONYMOUS_CLOSE_TAG  2u /* clear by default; if set allow closing an element with </> instead of </name> */
-
+#define DDSRT_XMLP_MISSING_CLOSE_AS_EOF 4u /* clear by default; if set, treat missing close tag as EOF */
     DDS_EXPORT struct ddsrt_xmlp_state *ddsrt_xmlp_new_file (FILE *fp, void *varg, const struct ddsrt_xmlp_callbacks *cb);
     DDS_EXPORT struct ddsrt_xmlp_state *ddsrt_xmlp_new_string (const char *string, void *varg, const struct ddsrt_xmlp_callbacks *cb);
     DDS_EXPORT void ddsrt_xmlp_set_options (struct ddsrt_xmlp_state *st, unsigned options);

src/ddsrt/src/xmlparser.c

@@ -35,6 +35,7 @@ struct ddsrt_xmlp_state {
     size_t cbufn; /* number of bytes in cbuf (cbufp <= cbufn) */
     size_t cbufmax; /* allocated size of cbuf (cbufn <= cbufmax) */
     size_t cbufmark; /* NORMARKER or marker position (cbufmark <= cbufp) for rewinding */
+    int eof; /* fake EOF (for treating missing close tags as EOF) */
     char *cbuf; /* parser input buffer */
     FILE *fp; /* file to refill cbuf from, or NULL if parsing a string */
     int line; /* current line number */
@@ -97,6 +98,7 @@ static void ddsrt_xmlp_new_common (struct ddsrt_xmlp_state *st)
 {
     st->cbufp = 0;
     st->cbufmark = NOMARKER;
+    st->eof = 0;
     st->tpp = 0;
     st->tpescp = 0;
     st->tpsz = 1024;
@@ -170,6 +172,9 @@ void ddsrt_xmlp_free (struct ddsrt_xmlp_state *st)
 static int make_chars_available (struct ddsrt_xmlp_state *st, size_t nmin)
 {
     size_t n, pos;
+    if (st->eof) {
+        return 0;
+    }
     pos = (st->cbufmark != NOMARKER) ? st->cbufmark : st->cbufp;
     assert (st->cbufn >= st->cbufp);
     assert (st->cbufmax >= st->cbufn);
@@ -215,6 +220,11 @@ static void discard_input_marker (struct ddsrt_xmlp_state *st)
     st->linemark = 0;
 }
 
+static int have_input_marker (struct ddsrt_xmlp_state *st)
+{
+    return (st->cbufmark != NOMARKER);
+}
+
 static void rewind_to_input_marker (struct ddsrt_xmlp_state *st)
 {
     assert (st->cbufmark != NOMARKER);
@@ -680,12 +690,22 @@ static int parse_element (struct ddsrt_xmlp_state *st, uintptr_t parentinfo)
                 }
             }
             st->nest--;
+            set_input_marker (st);
             if (((tok = next_token (st, &ename)) != TOK_CLOSE_TAG && tok != TOK_SHORTHAND_CLOSE_TAG) || next_char (st) != '>') {
+                if (!(st->options & DDSRT_XMLP_MISSING_CLOSE_AS_EOF)) {
                   PE_LOCAL_ERROR ("expecting closing tag", name);
+                } else {
+                    rewind_to_input_marker (st);
+                    st->eof = 1;
+                    tok = TOK_SHORTHAND_CLOSE_TAG;
+                }
             }
             if (tok != TOK_SHORTHAND_CLOSE_TAG && strcmp (name, ename) != 0) {
                 PE_LOCAL_ERROR ("open/close tag mismatch", ename);
             }
+            if (have_input_marker (st)) {
+                discard_input_marker (st);
+            }
             ret = st->cb.elem_close (st->varg, eleminfo);
             goto ok;
         default: