linux-kernel - Re: [PATCH v2 1/1] perf tools: remove sscanf extension %as

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Date:	Fri, 21 Sep 2012 08:29:05 -0700
From:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
To:	irina.tirdea@...il.com
Cc:	mingo@...hat.com, a.p.zijlstra@...llo.nl, rostedt@...dmis.org,
	paulus@...ba.org, dsahern@...il.com, namhyung.kim@....com,
	linux-kernel@...r.kernel.org, masami.hiramatsu.pt@...achi.com,
	Irina Tirdea <irina.tirdea@...el.com>
Subject: Re: [PATCH v2 1/1] perf tools: remove sscanf extension %as

Em Thu, Sep 20, 2012 at 11:37:50PM +0300, irina.tirdea@...il.com escreveu:
> From: Irina Tirdea <irina.tirdea@...el.com>
> 
> perf uses sscanf extension %as to read and allocate a
> string in the same step. This is a non-standard extension
> only present in new versions of glibc.
> 
> Replacing the use of sscanf and %as with strtok_r calls
> in order to parse a given string into its components.
> This is needed in Android since bionic does not support
> %as extension for sscanf.

Masami, can I have your Acked-by or even a Tested-by?

- Arnaldo
 
> Signed-off-by: Irina Tirdea <irina.tirdea@...el.com>
> ---
>  tools/perf/util/probe-event.c       |   36 ++++++++++++++++++++++++++++-------
>  tools/perf/util/trace-event-parse.c |   18 ++++++++----------
>  2 files changed, 37 insertions(+), 17 deletions(-)
> 
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index 4ce04c2..49a256e 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -1100,6 +1100,7 @@ static int parse_probe_trace_command(const char *cmd,
>  	struct probe_trace_point *tp = &tev->point;
>  	char pr;
>  	char *p;
> +	char *argv0_str = NULL, *fmt, *fmt1_str, *fmt2_str, *fmt3_str;
>  	int ret, i, argc;
>  	char **argv;
>  
> @@ -1116,14 +1117,27 @@ static int parse_probe_trace_command(const char *cmd,
>  	}
>  
>  	/* Scan event and group name. */
> -	ret = sscanf(argv[0], "%c:%a[^/ \t]/%a[^ \t]",
> -		     &pr, (float *)(void *)&tev->group,
> -		     (float *)(void *)&tev->event);
> -	if (ret != 3) {
> +	argv0_str = strdup(argv[0]);
> +	if (argv0_str == NULL) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +	fmt1_str = strtok_r(argv0_str, ":", &fmt);
> +	fmt2_str = strtok_r(NULL, "/", &fmt);
> +	fmt3_str = strtok_r(NULL, " \t", &fmt);
> +	if (fmt1_str == NULL || strlen(fmt1_str) != 1 || fmt2_str == NULL
> +	    || fmt3_str == NULL) {
>  		semantic_error("Failed to parse event name: %s\n", argv[0]);
>  		ret = -EINVAL;
>  		goto out;
>  	}
> +	pr = fmt1_str[0];
> +	tev->group = strdup(fmt2_str);
> +	tev->event = strdup(fmt3_str);
> +	if (tev->group == NULL || tev->event == NULL) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
>  	pr_debug("Group:%s Event:%s probe:%c\n", tev->group, tev->event, pr);
>  
>  	tp->retprobe = (pr == 'r');
> @@ -1135,10 +1149,17 @@ static int parse_probe_trace_command(const char *cmd,
>  		p++;
>  	} else
>  		p = argv[1];
> -	ret = sscanf(p, "%a[^+]+%lu", (float *)(void *)&tp->symbol,
> -		     &tp->offset);
> -	if (ret == 1)
> +	fmt1_str = strtok_r(p, "+", &fmt);
> +	tp->symbol = strdup(fmt1_str);
> +	if (tp->symbol == NULL) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +	fmt2_str = strtok_r(NULL, "", &fmt);
> +	if (fmt2_str == NULL)
>  		tp->offset = 0;
> +	else
> +		tp->offset = strtoul(fmt2_str, NULL, 10);
>  
>  	tev->nargs = argc - 2;
>  	tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
> @@ -1162,6 +1183,7 @@ static int parse_probe_trace_command(const char *cmd,
>  	}
>  	ret = 0;
>  out:
> +	free(argv0_str);
>  	argv_free(argv);
>  	return ret;
>  }
> diff --git a/tools/perf/util/trace-event-parse.c b/tools/perf/util/trace-event-parse.c
> index aa4c860..3aabcd6 100644
> --- a/tools/perf/util/trace-event-parse.c
> +++ b/tools/perf/util/trace-event-parse.c
> @@ -229,24 +229,22 @@ void parse_proc_kallsyms(struct pevent *pevent,
>  	char *next = NULL;
>  	char *addr_str;
>  	char *mod;
> -	char ch;
> +	char *fmt;
>  
>  	line = strtok_r(file, "\n", &next);
>  	while (line) {
>  		mod = NULL;
> -		sscanf(line, "%as %c %as\t[%as",
> -		       (float *)(void *)&addr_str, /* workaround gcc warning */
> -		       &ch, (float *)(void *)&func, (float *)(void *)&mod);
> +		addr_str = strtok_r(line, " ", &fmt);
>  		addr = strtoull(addr_str, NULL, 16);
> -		free(addr_str);
> -
> -		/* truncate the extra ']' */
> +		/* skip character */
> +		strtok_r(NULL, " ", &fmt);
> +		func = strtok_r(NULL, "\t", &fmt);
> +		mod = strtok_r(NULL, "]", &fmt);
> +		/* truncate the extra '[' */
>  		if (mod)
> -			mod[strlen(mod) - 1] = 0;
> +			mod = mod + 1;
>  
>  		pevent_register_function(pevent, func, addr, mod);
> -		free(func);
> -		free(mod);
>  
>  		line = strtok_r(NULL, "\n", &next);
>  	}
> -- 
> 1.7.9.5
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