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/*
Copyright (C) 2023 Pasha <pasha@bell01.com>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "cgroup_file_handle.h"
#include <errno.h>
#include <fcntl.h>
#include <linux/magic.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/vfs.h>
#ifndef CGROUP_SUPER_MAGIC
#define CGROUP_SUPER_MAGIC 0x27e0eb
#endif
#ifndef CGROUP2_SUPER_MAGIC
#define CGROUP2_SUPER_MAGIC 0x63677270
#endif
int get_cgroup_file_handle(const char *pathname, char *cgroupfhp) {
struct statfs sfs;
int mount_id, fhsize, flags, dirfd, ret, err;
struct file_handle *fhp;
err = 1;
ret = 0;
err = statfs(pathname, &sfs);
if (err != 0) {
fprintf(stderr, "statfs on %s failed: %s\n", pathname, strerror(errno));
return ret;
}
if ((sfs.f_type != (typeof(sfs.f_type))CGROUP2_SUPER_MAGIC)) {
fprintf(stderr, "%s is not cgroup2 mount.\n", pathname);
return ret;
}
fhsize = sizeof(*fhp);
fhp = malloc(fhsize);
if (!fhp) {
fprintf(stderr, "Cannot allocate memory for get_cgroup_file_handle(...)\n");
return ret;
}
flags = 0;
dirfd = AT_FDCWD;
fhp->handle_bytes = CGROUP_FILE_HANDLE_BYTES;
err = name_to_handle_at(dirfd, pathname, (struct file_handle *)fhp, &mount_id,
flags);
if (err != 0) {
fprintf(stderr, "name_to_handle_at failed: %s\n", strerror(errno));
goto clean_exit;
}
if (fhp->handle_bytes != CGROUP_FILE_HANDLE_BYTES) {
fprintf(stderr, "Unexpected handle size: %d. \n", fhp->handle_bytes);
goto clean_exit;
}
memcpy(cgroupfhp, fhp->f_handle, CGROUP_FILE_HANDLE_BYTES);
ret = 1;
clean_exit:
free(fhp);
return ret;
}
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