// SPDX-License-Identifier: GPL-2.0#include <linux/stringify.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include "fs.h" int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys){	FILE *fp;	char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];	char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;	char *token, *saved_ptr = NULL; 	fp = fopen("/proc/mounts", "r");	if (!fp)		return -1; 	/*	 * in order to handle split hierarchy, we need to scan /proc/mounts	 * and inspect every cgroupfs mount point to find one that has	 * perf_event subsystem	 */	path_v1[0] = '\0';	path_v2[0] = '\0'; 	while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"				__stringify(PATH_MAX)"s %*d %*d\n",				mountpoint, type, tokens) == 3) { 		if (!path_v1[0] && !strcmp(type, "cgroup")) { 			token = strtok_r(tokens, ",", &saved_ptr); 			while (token != NULL) {				if (subsys && !strcmp(token, subsys)) {					strcpy(path_v1, mountpoint);					break;				}				token = strtok_r(NULL, ",", &saved_ptr);			}		} 		if (!path_v2[0] && !strcmp(type, "cgroup2"))			strcpy(path_v2, mountpoint); 		if (path_v1[0] && path_v2[0])			break;	}	fclose(fp); 	if (path_v1[0])		path = path_v1;	else if (path_v2[0])		path = path_v2;	else		return -1; 	if (strlen(path) < maxlen) {		strcpy(buf, path);		return 0;	}	return -1;}