linux-kernel - Re: [PATCH v5 7/8] perf hists browser: Add option for runtime switching perf data file

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Date:	Wed, 31 Oct 2012 00:01:49 +0800
From:	Feng Tang <feng.tang@...el.com>
To:	Arnaldo Carvalho de Melo <acme@...hat.com>
Cc:	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>,
	Namhyung Kim <namhyung@...nel.org>,
	Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 7/8] perf hists browser: Add option for runtime
 switching perf data file

Hi Arnaldo,

Thanks for the review.

On Mon, Oct 29, 2012 at 12:06:20PM -0200, Arnaldo Carvalho de Melo wrote:
> Em Tue, Oct 30, 2012 at 11:56:08AM +0800, Feng Tang escreveu:
> > +	pwd_dir = opendir(pwd);
> > +	if (!pwd_dir)
> > +		return ret;
> > +
> > +	memset(options, 0, sizeof(options));
> > +	memset(options, 0, sizeof(abs_path));
> > +
> > +	while ((dent = readdir(pwd_dir))) {
> > +		char path[PATH_MAX];
> > +		u64 magic;
> > +		char *name = dent->d_name;
> > +		FILE *file;
> > +
> > +		if (!(dent->d_type == DT_REG))
> > +			continue;
> > +
> > +		snprintf(path, PATH_MAX, "%s/%s", pwd, name);
> > +
> > +		file = fopen(path, "r");
> > +		if (!file)
> > +			continue;
> > +
> > +		if (fread(&magic, 1, 8, file) < 8)
> > +			goto close_file_and_continue;
> > +
> > +		if (is_perf_magic(magic)) {
> > +			options[nr_options] = strdup(name);
> > +			if (!options[nr_options])
> > +				goto close_file_and_continue;
> 
> Silently not offering a valid file? At this point I think you should
> warn the user and bail out.

Yeah, we should give a warning message and go on with the valid data
files already got.
 
> > +
> > +			abs_path[nr_options] = strdup(path);
> > +			if (!abs_path[nr_options]) {
> > +				free(options[nr_options]);
> > +				goto close_file_and_continue;
> > +			}
> > +
> > +			nr_options++;
> > +		}
> > +
> > +close_file_and_continue:
> > +		fclose(file);
> > +		if (nr_options >= 256)
> > +			break;
> 
> Why is this? At the very least a warning has to be given to the user
> that way too many perf.data files are present, so only the first N are
> in the menu.

Ok. 

> > +	}
> > +	closedir(pwd_dir);
> > +
> > +	if (nr_options) {
> > +		choice = ui__popup_menu(nr_options, options);
> > +		if (choice < nr_options && choice >= 0) {
> > +			tmp = strdup(abs_path[choice]);
> > +			if (tmp) {
> > +				if (is_input_name_malloced)
> > +					free((void *)input_name);
> > +				input_name = tmp;
> > +				is_input_name_malloced = true;
> > +				ret = 0;
> > +			}
> 
> Here you return an error, but will the user get any warning on the
> caller of this function if it returns -1?
> 
> 
> > +		/* Switch to another data file */
> > +		else if (choice == switch_data) {
> > +do_data_switch:
> > +			if (!switch_data_file()) {
> > +				key = K_SWITCH_INPUT_DATA;
> > +				break;
> > +			}
> > +		}
> 
> ... no, so it will silently continue and the user will get confused.
>

Yes, I will add more ui_warning() in these error/problematic path

Thanks,
Feng
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