tools lib traceevent: Make plugin options either string or boolean

When a plugin option is defined, by default it is a boolean (true or false).

If the option is something else, then it needs to set its "value" field to
a default string other than NULL (can be just "").

If the value is not set then the option is considered boolean, and the
updating of the option value will be handled accordingly.

Signed-off-by: Steven Rostedt <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/lib/traceevent/event-parse.h

···
 	char				*name;
 	char				*plugin_alias;
 	char				*description;
-	char				*value;
+	const char			*value;
 	void				*priv;
 	int				set;
 };
···
  *
  *   .plugin_alias is used to give a shorter name to access
  *   the vairable. Useful if a plugin handles more than one event.
+ *
+ *   If .value is not set, then it is considered a boolean and only
+ *   .set will be processed. If .value is defined, then it is considered
+ *   a string option and .set will be ignored.
  *
  * PEVENT_PLUGIN_ALIAS: (optional)
  *   The name to use for finding options (uses filename if not defined)

tools/lib/traceevent/event-plugin.c

···
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  */
 
+#include <ctype.h>
 #include <stdio.h>
 #include <string.h>
 #include <dlfcn.h>
···
 	char			*name;
 	void			*handle;
 };
+
+static void lower_case(char *str)
+{
+	if (!str)
+		return;
+	for (; *str; str++)
+		*str = tolower(*str);
+}
+
+static int update_option_value(struct pevent_plugin_option *op, const char *val)
+{
+	char *op_val;
+
+	if (!val) {
+		/* toggle, only if option is boolean */
+		if (op->value)
+			/* Warn? */
+			return 0;
+		op->set ^= 1;
+		return 0;
+	}
+
+	/*
+	 * If the option has a value then it takes a string
+	 * otherwise the option is a boolean.
+	 */
+	if (op->value) {
+		op->value = val;
+		return 0;
+	}
+
+	/* Option is boolean, must be either "1", "0", "true" or "false" */
+
+	op_val = strdup(val);
+	if (!op_val)
+		return -1;
+	lower_case(op_val);
+
+	if (strcmp(val, "1") == 0 || strcmp(val, "true") == 0)
+		op->set = 1;
+	else if (strcmp(val, "0") == 0 || strcmp(val, "false") == 0)
+		op->set = 0;
+	free(op_val);
+
+	return 0;
+}
 
 /**
  * traceevent_plugin_list_options - get list of plugin options
···
 {
 	struct trace_plugin_options *op;
 	char *plugin;
+	int ret = 0;
 
 	if (option->plugin_alias) {
 		plugin = strdup(option->plugin_alias);
···
 		if (strcmp(op->option, option->name) != 0)
 			continue;
 
-		option->value = op->value;
-		option->set ^= 1;
-		goto out;
+		ret = update_option_value(option, op->value);
+		if (ret)
+			goto out;
+		break;
 	}
 
 	/* first look for unnamed options */
···
 		if (strcmp(op->option, option->name) != 0)
 			continue;
 
-		option->value = op->value;
-		option->set ^= 1;
+		ret = update_option_value(option, op->value);
 		break;
 	}
 
  out:
 	free(plugin);
-	return 0;
+	return ret;
 }
 
 /**