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// 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_v2[PATH_MAX + 1];
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
* the given subsystem. If we found v1, just use it. If not we can
* use v2 path as a fallback.
*/
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 (!strcmp(type, "cgroup")) {
token = strtok_r(tokens, ",", &saved_ptr);
while (token != NULL) {
if (subsys && !strcmp(token, subsys)) {
/* found */
fclose(fp);
if (strlen(mountpoint) < maxlen) {
strcpy(buf, mountpoint);
return 0;
}
return -1;
}
token = strtok_r(NULL, ",", &saved_ptr);
}
}
if (!strcmp(type, "cgroup2"))
strcpy(path_v2, mountpoint);
}
fclose(fp);
if (path_v2[0] && strlen(path_v2) < maxlen) {
strcpy(buf, path_v2);
return 0;
}
return -1;
}
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