Re: [PATCH] [RFC V1]s390/perf: fix 'start' address of module's map

[Jiri Olsa <jolsa@redhat.com>]

On Thu, Jul 07, 2016 at 09:49:36AM +0800, Song Shan Gong wrote:

SNIP

> +	char *line = NULL;
> +	size_t n;
> +	char *sep;
> +
> +	module_name[len - 1] = '\0';
> +	module_name += 1;
> +	snprintf(path, PATH_MAX, "%s/sys/module/%s/sections/.text",
> +				machine->root_dir, module_name);
> +	file = fopen(path, "r");
> +	if (file == NULL)
> +		return -1;
> +
> +	len = getline(&line, &n, file);
> +	if (len < 0) {
> +		err = -1;
> +		goto out;
> +	}
> +	line[--len] = '\0'; /* \n */
> +	sep = strrchr(line, 'x');
> +	if (sep == NULL) {
> +		err = -1;
> +		goto out;
> +	}
> +	hex2u64(sep + 1, &text_start);

we have following functions in tools/lib/api/fs to read
single number from file, which I assume you do above:

int sysfs__read_int(const char *entry, int *value);
int sysfs__read_ull(const char *entry, unsigned long long *value);

please check if you could use some of them,
we could add some more generic one if needed

thanks,
jirka