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

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Fri, May 15, 2015 at 09:40:53PM +0900, Namhyung Kim escreveu:
> Hi Taeung,
> 
> Please Cc Arnaldo and Jiri at least you want to talk about the perf
> tools develeopment.  But I guess they already subscribed to this list
> though. :)
> 
> On Thu, May 14, 2015 at 03:29:44PM +0900, taeung wrote:
> > Hi, Namhyung
> > 
> > How do you think about a time when selecting perf config file path ?

Couldn't parse the above phrase :-\

> > 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()'.
> 
> Yes, as far as I can see that it reads from both of global and local
> config file and local setting overwrites the global one.
> 
> > 
> > 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.
> 
> Please don't agonize. :)
> 
> I think you can extend perf_config_system() and perf_config_global() -
> they need to be renamed IMHO - to select which config to be used.

Yeah, all this came from .git, some stuff was ok, some is rather
confusing, please suggest patches with an explanation of the current
problem and your proposed solution.
 
> 
> > 
> > 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 ?

Well. since this came from git land, maybe they have documentation about
the decisions they made in the order of processing those files, and that
may help us understand possible issues we may not be considering in this
discussion.

It may be in their docs or buried in the changelog for the git git tree,
or maybe the investigation may show that at some point we made a mistake
and introduced a bug in our copy of their code.

- Arnaldo
 
> Yes, you can add a variable like config_src to select it..
> 
> enum {
>   BOTH,
>   GLOBAL_ONLY,
>   LOCAL_ONLY,
> } config_src = BOTH;
> 
> cmd_config() {
>   ...
> 
>   if (global)
>     config_src = GLOBAL_ONLY;
>   else if (local)
>     config_src = LOCAL_ONLY;
> 
>   ...
> 
>   perf_config()
> }
> 
> perf_config_system()
> {
>   return config_src != LOCAL_ONLY && ...;
> }
> 
> perf_config_global()
> {
>   return config_src != GLOBAL_ONLY && ...;
> }
> 
> Thanks,
> Namhyung
> 
> 
> > 
> > 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;
> > +}
> > ========
> --
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