Remove the arbitrary limit on the path to the default parameter file. Add a verb to the param command to set the default parameter file.

apps/systemcmds/param/param.c

@@ -62,8 +62,6 @@ static void	do_import(const char* param_file_name);
 static void	do_show(void);
 static void	do_show_print(void *arg, param_t param);
 
-static const char *param_file_name_default = "/eeprom/parameters";
-
 int
 param_main(int argc, char *argv[])
 {
@@ -72,7 +70,7 @@ param_main(int argc, char *argv[])
 			if (argc >= 3) {
 				do_save(argv[2]);
 			} else {
-				do_save(param_file_name_default);
+				do_save(param_get_default_file());
 			}
 		}
 
@@ -80,7 +78,7 @@ param_main(int argc, char *argv[])
 			if (argc >= 3) {
 				do_load(argv[2]);
 			} else {
-				do_load(param_file_name_default);
+				do_load(param_get_default_file());
 			}
 		}
 
@@ -88,17 +86,26 @@ param_main(int argc, char *argv[])
 			if (argc >= 3) {
 				do_import(argv[2]);
 			} else {
-				do_import(param_file_name_default);
+				do_import(param_get_default_file());
 			}
 		}
 
+		if (!strcmp(argv[1], "select")) {
+			if (argc >= 3) {
+				param_set_default_file(argv[2]);
+			} else {
+				param_set_default_file(NULL);
+			}
+			warnx("selected parameter file %s", param_get_default_file());
+		}
+
 		if (!strcmp(argv[1], "show")) {
 			do_show();
 		}
 			
 	}
-
-	errx(1, "expected a command, try 'load', 'import', 'show' or 'save'\n");
+	
+	errx(1, "expected a command, try 'load', 'import', 'show', 'select' or 'save'");
 }
 
 static void

apps/systemlib/param/param.c

@@ -481,38 +481,38 @@ param_reset_all(void)
 	param_notify_changes();
 }
 
-static char param_default_file_name[50] = "/eeprom/parameters";
+static const char *param_default_file = "/eeprom/parameters";
+static char *param_user_file;
 
 int
 param_set_default_file(const char* filename)
 {
-	if (filename) {
-		if (strlen(filename) < sizeof(param_default_file_name))
-		{
-			strcpy(param_default_file_name, filename);
-		} else {
-			warnx("param file name too long");
-			return 1;
-		}
-		return 0;
-	} else {
-		warnx("no valid param file name");
-		return 1;
+	if (param_user_file != NULL) {
+		free(param_user_file);
+		param_user_file = NULL;
 	}
+	if (filename)
+		param_user_file = strdup(filename);
 	return 0;
 }
 
+const char *
+param_get_default_file(void)
+{
+	return (param_user_file != NULL) ? param_user_file : param_default_file;
+}
+
 int
 param_save_default(void)
 {
 	/* delete the file in case it exists */
-	unlink(param_default_file_name);
+	unlink(param_get_default_file());
 
 	/* create the file */
-	int fd = open(param_default_file_name, O_WRONLY | O_CREAT | O_EXCL);
+	int fd = open(param_get_default_file(), O_WRONLY | O_CREAT | O_EXCL);
 
 	if (fd < 0) {
-		warn("opening '%s' for writing failed", param_default_file_name);
+		warn("opening '%s' for writing failed", param_get_default_file());
 		return -1;
 	}
 
@@ -522,8 +522,8 @@ param_save_default(void)
 	close(fd);
 
 	if (result != 0) {
-		unlink(param_default_file_name);
-		warn("error exporting parameters to '%s'", param_default_file_name);
+		unlink(param_get_default_file());
+		warn("error exporting parameters to '%s'", param_get_default_file());
 		return -2;
 	}
 
@@ -536,12 +536,12 @@ param_save_default(void)
 int
 param_load_default(void)
 {
-	int fd = open(param_default_file_name, O_RDONLY);
+	int fd = open(param_get_default_file(), O_RDONLY);
 
 	if (fd < 0) {
 		/* no parameter file is OK, otherwise this is an error */
 		if (errno != ENOENT) {
-			warn("open '%s' for reading failed", param_default_file_name);
+			warn("open '%s' for reading failed", param_get_default_file());
 			return -1;
 		}
 		return 1;
@@ -551,7 +551,7 @@ param_load_default(void)
 	close(fd);
 
 	if (result != 0) {
-		warn("error reading parameters from '%s'", param_default_file_name);
+		warn("error reading parameters from '%s'", param_get_default_file());
 		return -2;
 	}
 

apps/systemlib/param/param.h

@@ -234,25 +234,40 @@ __EXPORT int		param_load(int fd);
  */
 __EXPORT void		param_foreach(void (*func)(void *arg, param_t param), void *arg, bool only_changed);
 
-/**
- * Export parameters to the default file name.
- *
- *
- * @param 
- */
-__EXPORT int 		param_save_default(void);
-
 /**
  * Set the default parameter file name.
+ *
+ * @param filename	Path to the default parameter file.  The file is not require to
+ *			exist.
+ * @return		Zero on success.
  */
 __EXPORT int 		param_set_default_file(const char* filename);
 
 /**
- * Import parameters from the default file name.
+ * Get the default parameter file name.
+ *
+ * @return		The path to the current default parameter file; either as
+ *			a result of a call to param_set_default_file, or the 
+ *			built-in default.
+ */
+__EXPORT const char 	*param_get_default_file(void);
+
+/**
+ * Save parameters to the default file.
+ *
+ * This function saves all parameters with non-default values.
+ *
+ * @return		Zero on success.
+ */
+__EXPORT int 		param_save_default(void);
+
+/**
+ * Load parameters from the default parameter file.
+ *
+ * @return		Zero on success.
  */
 __EXPORT int 		param_load_default(void);
 
-
 /*
  * Macros creating static parameter definitions.
  *