How do you think about a time when selecting perf config file path ?

[taeung <treeze.taeung@gmail.com>]

Hi, Namhyung

How do you think about a time when selecting perf config file path ?

At this present, perfconfig file path can be selected as 
'/etc/perfconfig' or '$(HOME)/.perfconfig'.
And the config file path is selected when calling a function 
'perf_config()'.

If you see functions 1,2,3,4 as below, you can understand what I 
agonize. I think that the part which perf config path is selected must 
be separated as other function to also use the function in 
'cmd_config()' in new builtin-config.c.

For example,
If adding a option '--global' or '--local' for config file path,
the perf config file name have to selected in 'cmd_config()' before 
'perf_config()' is called.

How do you think about this ?

Thanks,
Taeung

1. a function 'perf_config()' in util/config.c

========
int perf_config(config_fn_t fn, void *data)
{
	int ret = 0, found = 0;
	const char *home = NULL;

	/* Setting $PERF_CONFIG makes perf read _only_ the given config file. */
	if (config_exclusive_filename)
		return perf_config_from_file(fn, config_exclusive_filename, data);
	if (perf_config_system() && !access(perf_etc_perfconfig(), R_OK)) {
		ret += perf_config_from_file(fn, perf_etc_perfconfig(),
					    data);
		found += 1;
	}

	home = getenv("HOME");
	if (perf_config_global() && home) {
		char *user_config = strdup(mkpath("%s/.perfconfig", home));
		struct stat st;

		if (user_config == NULL) {
			warning("Not enough memory to process %s/.perfconfig, "
				"ignoring it.", home);
			goto out;
		}

		if (stat(user_config, &st) < 0)
			goto out_free;

		if (st.st_uid && (st.st_uid != geteuid())) {
			warning("File %s not owned by current user or root, "
				"ignoring it.", user_config);
			goto out_free;
		}

		if (!st.st_size)
			goto out_free;

		ret += perf_config_from_file(fn, user_config, data);
		found += 1;
out_free:
		free(user_config);
	}
out:
	if (found == 0)
		return -1;
	return ret;
}
========

2. 'perf_config_from_file()' in util/config.c I modified

========
int perf_config_from_file(config_fn_t fn, const char *filename, void *data)
{
	int ret;
	FILE *f = fopen(filename, "r");

	ret = -1;
  	if (f) {
  		config_file = f;
-		config_file_name = filename;
+		config_file_name = strdup(filename);
  		config_linenr = 1;
  		config_file_eof = 0;
  		ret = perf_parse_file(fn, data);
  		fclose(f);
-		config_file_name = NULL;
  	}
	return ret;
}
========

3. 'perf_configset_write_in_full()' in util/config.c that I added as new 
a function because of new 'perf config' command. And this function use a 
global variable 'config_file_name' to rewrite config file with new 
config contents.
(To add new command 'perf-config', I try to modify this file 
'util/config.c')

========
+int perf_configset_write_in_full(void)
+{
+	struct config_section *section_node;
+	struct config_element *element_node;
+	const char *first_line = "# this file is auto-generated.";
+	FILE *fp = fopen(config_file_name, "w");
+
+	if (!fp)
+		return -1;
+
+	fprintf(fp, "%s\n", first_line);
+	/* overwrite configvariables */
+	list_for_each_entry(section_node, sections, list) {
+		fprintf(fp, "[%s]\n", section_node->name);
+		list_for_each_entry(element_node, &section_node->element_head, list) {
+			if (element_node->value)
+				fprintf(fp, "\t%s = %s\n",
+					element_node->subkey, element_node->value);
+		}
+	}
+	fclose(fp);
+
+	return 0;
+}
========

4. a new function 'cmd_config()' in new file builtin-config.c.
(If working a command as '$ perf config', cmd_config() is firstly 
called. This function is also added by me.)

========
+int cmd_config(int argc, const char **argv, const char *prefix 
__maybe_unused)
+{
+	int i, ret = 0;
+	int origin_argc = argc - 1;
+	char *value;
+	bool is_option;
+
+	argc = parse_options(argc, argv, config_options, config_usage,
+			     PARSE_OPT_STOP_AT_NON_OPTION);
+	if (origin_argc > argc)
+		is_option = true;
+	else
+		is_option = false;
+
+	if (!is_option && argc >= 0) {
+		switch (argc) {
+		case 0:
+			break;
+		default:
+			for (i = 0; argv[i]; i++) {
+				value = strrchr(argv[i], '=');
+				if (value == NULL || value == argv[i])
+					ret = perf_configset_with_option(show_spec_config, argv[i]);
+				else
+					ret = perf_configset_with_option(set_spec_config, argv[i]);
+				if (ret < 0)
+					break;
+			}
+			goto out;
+		}
+	}
+	if (params.list_action && argc == 0)
+		ret = perf_config(show_config, NULL);
+	else {
+		pr_warning("Error: Unknown argument.\n");
+		usage_with_options(config_usage, config_options);
+	}
+
+	return ret;
+}
========