linux-kernel - Re: [PATCH] perf: report: don't allow empty argument for '-t'.

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Date:	Mon, 16 Mar 2015 11:20:35 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Wang Nan <wangnan0@...wei.com>
Cc:	acme@...nel.org, jolsa@...nel.org, linux-kernel@...r.kernel.org,
	mingo@...hat.com, lizefan@...wei.com, pi3orama@....com
Subject: Re: [PATCH] perf: report: don't allow empty argument for '-t'.

On Fri, Mar 13, 2015 at 12:51:54PM +0000, Wang Nan wrote:
> Without this patch, perf report cause segfault if pass "" as '-t':
> 
>   $ perf report -t ""
> 
>    # To display the perf.data header info, please use --header/--header-only options.
>    #
>    # Samples: 37  of event 'syscalls:sys_enter_write'
>    # Event count (approx.): 37
>    #
>    # Children    SelfCommand   Shared Object         Symbol
>    Segmentation fault
> 
> Since -t is used to add field-separator for generate table, -t "" is
> actually meanless. This patch defines a new OPT_STRING_NOEMPTY() option
> generator to ensure user never pass empty string to that option.
> 
> Signed-off-by: Wang Nan <wangnan0@...wei.com>
> ---
>  tools/perf/builtin-report.c     |  2 +-

I think perf 'diff' and 'mem' commands also have same problem..

Thanks,
Namhyung


>  tools/perf/util/parse-options.c | 21 +++++++++++++++++++--
>  tools/perf/util/parse-options.h |  2 ++
>  3 files changed, 22 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
> index fb35034..2652e52 100644
> --- a/tools/perf/builtin-report.c
> +++ b/tools/perf/builtin-report.c
> @@ -676,7 +676,7 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
>  	OPT_STRING('w', "column-widths", &symbol_conf.col_width_list_str,
>  		   "width[,width...]",
>  		   "don't try to adjust column width, use these fixed values"),
> -	OPT_STRING('t', "field-separator", &symbol_conf.field_sep, "separator",
> +	OPT_STRING_NOEMPTY('t', "field-separator", &symbol_conf.field_sep, "separator",
>  		   "separator for columns, no spaces will be added between "
>  		   "columns '.' is reserved."),
>  	OPT_BOOLEAN('U', "hide-unresolved", &report.hide_unresolved,
> diff --git a/tools/perf/util/parse-options.c b/tools/perf/util/parse-options.c
> index 1457d66..01626be 100644
> --- a/tools/perf/util/parse-options.c
> +++ b/tools/perf/util/parse-options.c
> @@ -37,6 +37,7 @@ static int get_value(struct parse_opt_ctx_t *p,
>  {
>  	const char *s, *arg = NULL;
>  	const int unset = flags & OPT_UNSET;
> +	int err;
>  
>  	if (unset && p->opt)
>  		return opterror(opt, "takes no value", flags);
> @@ -114,13 +115,29 @@ static int get_value(struct parse_opt_ctx_t *p,
>  		return 0;
>  
>  	case OPTION_STRING:
> +		err = 0;
>  		if (unset)
>  			*(const char **)opt->value = NULL;
>  		else if (opt->flags & PARSE_OPT_OPTARG && !p->opt)
>  			*(const char **)opt->value = (const char *)opt->defval;
>  		else
> -			return get_arg(p, opt, flags, (const char **)opt->value);
> -		return 0;
> +			err = get_arg(p, opt, flags, (const char **)opt->value);
> +
> +		/* PARSE_OPT_NOEMPTY: Allow NULL but disallow empty string. */
> +		if (opt->flags & PARSE_OPT_NOEMPTY) {
> +			const char *val = *(const char **)opt->value;
> +
> +			if (!val)
> +				return err;
> +
> +			/* Similar to unset if we are given an empty string. */
> +			if (val[0] == '\0') {
> +				*(const char **)opt->value = NULL;
> +				return 0;
> +			}
> +		}
> +
> +		return err;
>  
>  	case OPTION_CALLBACK:
>  		if (unset)
> diff --git a/tools/perf/util/parse-options.h b/tools/perf/util/parse-options.h
> index 97b153f..59561fd 100644
> --- a/tools/perf/util/parse-options.h
> +++ b/tools/perf/util/parse-options.h
> @@ -40,6 +40,7 @@ enum parse_opt_option_flags {
>  	PARSE_OPT_LASTARG_DEFAULT = 16,
>  	PARSE_OPT_DISABLED = 32,
>  	PARSE_OPT_EXCLUSIVE = 64,
> +	PARSE_OPT_NOEMPTY  = 128,
>  };
>  
>  struct option;
> @@ -122,6 +123,7 @@ struct option {
>  #define OPT_LONG(s, l, v, h)        { .type = OPTION_LONG, .short_name = (s), .long_name = (l), .value = check_vtype(v, long *), .help = (h) }
>  #define OPT_U64(s, l, v, h)         { .type = OPTION_U64, .short_name = (s), .long_name = (l), .value = check_vtype(v, u64 *), .help = (h) }
>  #define OPT_STRING(s, l, v, a, h)   { .type = OPTION_STRING,  .short_name = (s), .long_name = (l), .value = check_vtype(v, const char **), (a), .help = (h) }
> +#define OPT_STRING_NOEMPTY(s, l, v, a, h)   { .type = OPTION_STRING,  .short_name = (s), .long_name = (l), .value = check_vtype(v, const char **), (a), .help = (h), .flags = PARSE_OPT_NOEMPTY}
>  #define OPT_DATE(s, l, v, h) \
>  	{ .type = OPTION_CALLBACK, .short_name = (s), .long_name = (l), .value = (v), .argh = "time", .help = (h), .callback = parse_opt_approxidate_cb }
>  #define OPT_CALLBACK(s, l, v, a, h, f) \
> -- 
> 1.8.3.4
> 
> --
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