perf symbols: Use lsdir() for the search in kcore cache directory

Use lsdir() to search in kcore cache directory. This also avoids
checking hidden dot directory entries, because kcore cache directories
must always have the name from timestamps when taking the kcore
snapshots, and it never start with dot.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160511135208.23943.68071.stgit@devboxSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/symbol.c

@@ -1608,25 +1608,27 @@ int dso__load_vmlinux_path(struct dso *dso, struct map *map,
 	return err;
 }
 
+static bool visible_dir_filter(const char *name, struct dirent *d)
+{
+	if (d->d_type != DT_DIR)
+		return false;
+	return lsdir_no_dot_filter(name, d);
+}
+
 static int find_matching_kcore(struct map *map, char *dir, size_t dir_sz)
 {
 	char kallsyms_filename[PATH_MAX];
-	struct dirent *dent;
 	int ret = -1;
-	DIR *d;
+	struct strlist *dirs;
+	struct str_node *nd;
 
-	d = opendir(dir);
-	if (!d)
+	dirs = lsdir(dir, visible_dir_filter);
+	if (!dirs)
 		return -1;
 
-	while (1) {
-		dent = readdir(d);
-		if (!dent)
-			break;
-		if (dent->d_type != DT_DIR)
-			continue;
+	strlist__for_each(nd, dirs) {
 		scnprintf(kallsyms_filename, sizeof(kallsyms_filename),
-			  "%s/%s/kallsyms", dir, dent->d_name);
+			  "%s/%s/kallsyms", dir, nd->s);
 		if (!validate_kcore_addresses(kallsyms_filename, map)) {
 			strlcpy(dir, kallsyms_filename, dir_sz);
 			ret = 0;
@@ -1634,7 +1636,7 @@ static int find_matching_kcore(struct map *map, char *dir, size_t dir_sz)
 		}
 	}
 
-	closedir(d);
+	strlist__delete(dirs);
 
 	return ret;
 }