Distinguish between the end of the top-level BSON object and an error so that parameter loading can complete.

apps/systemlib/bson/tinybson.c

@@ -45,13 +45,13 @@
 
 
 #if 1
-# define debug(fmt, args...)		do { warnx("BSON:" fmt, ##args); } while(0)
+# define debug(fmt, args...)		do { warnx("BSON: " fmt, ##args); } while(0)
 #else
 # define debug(fmt, args...)		do { } while(0)
 #endif
 
 #define CODER_CHECK(_c)		do { if (_c->fd == -1) return -1; } while(0)
-#define CODER_KILL(_c, _reason)	do { debug("killed:%s", _reason); _c->fd = -1; return -1; } while(0)
+#define CODER_KILL(_c, _reason)	do { debug("killed: %s", _reason); _c->fd = -1; return -1; } while(0)
 
 static int
 read_int8(bson_decoder_t decoder, int8_t *b)
@@ -105,8 +105,12 @@ bson_decoder_next(bson_decoder_t decoder)
 			decoder->nesting--;
 
 		/* if the nesting level is now zero, the top-level document is done */
-		if (decoder->nesting == 0)
+		if (decoder->nesting == 0) {
 			CODER_KILL(decoder, "nesting is zero, document is done");
+
+			/* return end-of-file to the caller */
+			return 0;
+		}
 	}
 
 	/* if there are unread bytes pending in the stream, discard them */
@@ -247,7 +251,7 @@ bson_encoder_fini(bson_encoder_t encoder)
 {
 	CODER_CHECK(encoder);
 
-	if (write_int8(encoder, 0))
+	if (write_int8(encoder, BSON_EOO))
 		CODER_KILL(encoder, "write error on document terminator");
 
 	return 0;

apps/systemlib/bson/tinybson.h

@@ -108,21 +108,35 @@ struct bson_decoder_s
 
 /**
  * Initialise the decoder.
+ *
+ * @param decoder		Decoder state structure to be initialised.
+ * @param fd			File to read BSON data from.
+ * @param callback		Callback to be invoked by bson_decoder_next
+ * @param private		Callback private data, stored in node.
+ * @return			Zero on success.
  */
 __EXPORT int bson_decoder_init(bson_decoder_t decoder, int fd, bson_decoder_callback callback, void *private);
 
 /**
  * Process the next node from the stream and invoke the callback.
+ *
+ * @param decoder		Decoder state, must have been initialised with bson_decoder_init.
+ * @return			-1 if parsing encountered an error, 0 if the BSON stream has ended,
+ *				otherwise the return value from the callback.
  */
 __EXPORT int bson_decoder_next(bson_decoder_t decoder);
 
 /**
  * Copy node data.
+ *
+ * @param decoder		Decoder state, must have been initialised with bson_decoder_init.
  */
 __EXPORT int bson_decoder_copy_data(bson_decoder_t decoder, void *buf);
 
 /**
  * Report copyable data size.
+ *
+ * @param decoder		Decoder state, must have been initialised with bson_decoder_init.
  */
 __EXPORT size_t bson_decoder_data_pending(bson_decoder_t decoder);
 

apps/systemlib/param/param.c

@@ -479,14 +479,14 @@ param_export(int fd, bool only_unsaved)
 		}
 	}
 
-	if (bson_encoder_fini(&encoder))
-		goto out;
-
 	result = 0;
 
 out:
 	param_unlock();
 
+	if (result == 0)
+		result = bson_encoder_fini(&encoder);
+
 	return result;
 }
 
@@ -499,7 +499,8 @@ param_import_callback(bson_decoder_t decoder, void *private, bson_node_t node)
 	int result = -1;
 
 	/*
-	 * EOO means the end of the parameter object.
+	 * EOO means the end of the parameter object. (Currently not supporting
+	 * nested BSON objects).
 	 */
 	if (node->type == BSON_EOO) {
 		*(bool *)private = true;
@@ -513,8 +514,10 @@ param_import_callback(bson_decoder_t decoder, void *private, bson_node_t node)
 	 */
 	param_t param = param_find(node->name);
 
-	if (param == PARAM_INVALID)
-		return 0;
+	if (param == PARAM_INVALID) {
+		debug("ignoring unrecognised parameter '%s'", node->name);
+		return 1;
+	}
 
 	/*
 	 * Handle setting the parameter from the node
@@ -583,7 +586,8 @@ param_import_callback(bson_decoder_t decoder, void *private, bson_node_t node)
 		tmp = NULL;
 	}
 
-	result = 0;
+	/* don't return zero, that means EOF */
+	result = 1;
 
 out:
 
@@ -607,16 +611,14 @@ param_import(int fd)
 
 	done = false;
 
-	while (!done) {
+	do {
 		result = bson_decoder_next(&decoder);
 
-		if (result != 0) {
-			debug("error during BSON decode");
-			break;
-		}
-	}
+	} while(result > 0);
 
 out:
+	if (result < 0)
+		debug("BSON error decoding parameters");
 	return result;
 }