listmount(2)                  System Calls Manual                 listmount(2)

NAME
       listmount - get a list of mount ID's

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <linux/mount.h>  /* Definition of struct mnt_id_req constants */
       #include <unistd.h>

       int syscall(SYS_listmount, struct mnt_id_req *req,
                   uint64_t *mnt_ids, size_t nr_mnt_ids,
                   unsigned long flags);

       #include <linux/mount.h>

       struct mnt_id_req {
           __u32  size;    /* sizeof(struct mnt_id_req) */
           __u64  mnt_id;  /* The parent mnt_id being searched */
           __u64  param;   /* The next mnt_id we want to find */
       };

       Note: glibc provides no wrapper for listmount(), necessitating the use
       of syscall(2).

DESCRIPTION
       To access the mounts in your namespace, you must have CAP_SYS_ADMIN in
       the user namespace.

       This function returns a list of mount IDs under the req.mnt_id.  This
       is meant to be used in conjuction with statmount(2) in order to provide
       a way to iterate and discover mounted file systems.

   The mnt_id_req structure
       req.size is used by the kernel to determine which struct mnt_id_req is
       being passed in, it should always be set to sizeof(struct mnt_id_req).

       req.mnt_id is the parent mnt_id that we will list from, which can
       either be LSMT_ROOT which means the root mount of the current mount
       namespace, or a mount ID obtained from either statx(2) using
       STATX_MNT_ID_UNIQUE or from listmount(2).

       req.param is used to tell the kernel what mount ID to start the list
       from.  This is useful if multiple calls to listmount(2) are required.
       This can be set to the last mount ID returned in order to resume from a
       previous spot in the list.

RETURN VALUE
       On success, the number of entries filled into mnt_ids is returned; 0 if
       there are no more mounts left.  On error, -1 is returned, and errno is
       set to indicate the error.

ERRORS
       EPERM  Permission is denied for accessing this mount.

       EFAULT req or mnt_ids points to a location outside the process's
              accessible address space.

       EINVAL Invalid flag specified in flags.

       EINVAL req is of insufficient size to be utilized.

       E2BIG  req is too large, the limit is the architectures page size.

       ENOENT The specified req.mnt_id doesn't exist.

       ENOMEM Out of memory (i.e., kernel memory).

STANDARDS
       Linux.

SEE ALSO
       statmount(2), statx(2)

Linux man-pages 6.10              2024-11-17                      listmount(2)