More param command related improvements

src/modules/systemlib/bson/tinybson.c

@@ -407,6 +407,9 @@ bson_encoder_fini(bson_encoder_t encoder)
 		memcpy(encoder->buf, &len, sizeof(len));
 	}
 
+	/* sync file */
+	fsync(encoder->fd);
+
 	return 0;
 }
 

src/modules/systemlib/param/param.c

@@ -61,7 +61,7 @@
 #include "uORB/uORB.h"
 #include "uORB/topics/parameter_update.h"
 
-#if 1
+#if 0
 # define debug(fmt, args...)		do { warnx(fmt, ##args); } while(0)
 #else
 # define debug(fmt, args...)		do { } while(0)
@@ -514,19 +514,25 @@ param_save_default(void)
 	const char *filename = param_get_default_file();
 
 	/* write parameters to temp file */
-	fd = open(filename, O_WRONLY);
+	fd = open(filename, O_WRONLY | O_CREAT);
 
 	if (fd < 0) {
 		warn("failed to open param file: %s", filename);
-		res = ERROR;
+		return ERROR;
 	}
 
 	if (res == OK) {
 		res = param_export(fd, false);
+
+	        if (res != OK) {
+	            warnx("failed to write parameters to file: %s", filename);
+	        }
 	}
 
 	close(fd);
 
+	return res;
+
 #if 0
 	const char *filename_tmp = malloc(strlen(filename) + 5);
 	sprintf(filename_tmp, "%s.tmp", filename);
@@ -579,9 +585,9 @@ param_save_default(void)
 	}
 
 	free(filename_tmp);
-#endif
 
 	return res;
+#endif
 }
 
 /**

src/systemcmds/param/param.c

@@ -72,7 +72,12 @@ param_main(int argc, char *argv[])
 			if (argc >= 3) {
 				do_save(argv[2]);
 			} else {
-				do_save(param_get_default_file());
+				if (param_save_default()) {
+					warnx("Param export failed.");
+					exit(1);
+				} else {
+					exit(0);
+				}
 			}
 		}
 
@@ -133,11 +138,8 @@ param_main(int argc, char *argv[])
 static void
 do_save(const char* param_file_name)
 {
-	/* delete the parameter file in case it exists */
-	unlink(param_file_name);
-
 	/* create the file */
-	int fd = open(param_file_name, O_WRONLY | O_CREAT | O_EXCL);
+	int fd = open(param_file_name, O_WRONLY | O_CREAT);
 
 	if (fd < 0)
 		err(1, "opening '%s' failed", param_file_name);
@@ -146,7 +148,7 @@ do_save(const char* param_file_name)
 	close(fd);
 
 	if (result < 0) {
-		unlink(param_file_name);
+		(void)unlink(param_file_name);
 		errx(1, "error exporting to '%s'", param_file_name);
 	}