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FANOTIFY_MARK(2) Linux Programmer's Manual FANOTIFY_MARK(2)

NAME

     fanotify_mark - add, remove, or modify an fanotify mark on a filesystem
     object

SYNOPSIS

     #include <sys/fanotify.h>

     int fanotify_mark(int fanotify_fd, unsigned int flags,
                       uint64_t mask, int dirfd, const char *pathname);

DESCRIPTION

     For an overview of the fanotify API, see fanotify(7).

     fanotify_mark() adds, removes,  or  modifies  an  fanotify  mark  on  a
     filesystem  object.   The  caller  must  have  read  permission  on the
     filesystem object that is to be marked.

     The  fanotify_fd  argument  is  a  file  descriptor  returned  by  fan-
     otify_init(2).

     flags  is  a  bit mask describing the modification to perform.  It must
     include exactly one of the following values:

     FAN_MARK_ADD
            The events in mask will be added to the mark  mask  (or  to  the
            ignore  mask).   mask  must be nonempty or the error EINVAL will
            occur.

     FAN_MARK_REMOVE
            The events in argument mask will be removed from the  mark  mask
            (or  from  the ignore mask).  mask must be nonempty or the error
            EINVAL will occur.

     FAN_MARK_FLUSH
            Remove either all mount or all non-mount marks from the fanotify
            group.   If  flags contains FAN_MARK_MOUNT, all marks for mounts
            are removed from the group.  Otherwise, all marks  for  directo-
            ries  and  files are removed.  No flag other than FAN_MARK_MOUNT
            can  be  used  in  conjunction  with  FAN_MARK_FLUSH.   mask  is
            ignored.

     If  none  of  the values above is specified, or more than one is speci-
     fied, the call fails with the error EINVAL.

     In addition, zero or more of the following  values  may  be  ORed  into
     flags:

     FAN_MARK_DONT_FOLLOW
            If  pathname  is  a  symbolic link, mark the link itself, rather
            than the file to which it refers.  (By default,  fanotify_mark()
            dereferences pathname if it is a symbolic link.)

     FAN_MARK_ONLYDIR
            If  the  filesystem  object to be marked is not a directory, the
            error ENOTDIR shall be raised.

     FAN_MARK_MOUNT
            Mark the mount point specified by pathname.  If pathname is  not
            itself  a  mount point, the mount point containing pathname will
            be marked.  All directories, subdirectories, and  the  contained
            files of the mount point will be monitored.

     FAN_MARK_IGNORED_MASK
            The  events in mask shall be added to or removed from the ignore
            mask.

     FAN_MARK_IGNORED_SURV_MODIFY
            The ignore mask shall survive modify events.  If  this  flag  is
            not  set,  the ignore mask is cleared when a modify event occurs
            for the ignored file or directory.

     mask defines which events shall be listened  for  (or  which  shall  be
     ignored).  It is a bit mask composed of the following values:

     FAN_ACCESS
            Create  an  event  when  a  file  or directory (but see BUGS) is
            accessed (read).

     FAN_MODIFY
            Create an event when a file is modified (write).

     FAN_CLOSE_WRITE
            Create an event when a writable file is closed.

     FAN_CLOSE_NOWRITE
            Create an event when a read-only file or directory is closed.

     FAN_OPEN
            Create an event when a file or directory is opened.

     FAN_Q_OVERFLOW
            Create an event when an overflow of the event queue occurs.  The
            size  of  the  event  queue  is  limited  to  16384  entries  if
            FAN_UNLIMITED_QUEUE is not set in fanotify_init(2).

     FAN_OPEN_PERM
            Create an event when a permission to open a file or directory is
            requested.    An   fanotify   file   descriptor   created   with
            FAN_CLASS_PRE_CONTENT or FAN_CLASS_CONTENT is required.

     FAN_ACCESS_PERM
            Create an event when a permission to read a file or directory is
            requested.    An   fanotify   file   descriptor   created   with
            FAN_CLASS_PRE_CONTENT or FAN_CLASS_CONTENT is required.

     FAN_ONDIR
            Create events for  directories--for  example,  when  opendir(3),
            readdir(3)  (but see BUGS), and closedir(3) are called.  Without
            this flag, only events for files are created.

     FAN_EVENT_ON_CHILD
            Events for the immediate children of marked directories shall be
            created.  The flag has no effect when marking mounts.  Note that
            events are not generated for children of the  subdirectories  of
            marked  directories.   To monitor complete directory trees it is
            necessary to mark the relevant mount.

     The following composed value is defined:

     FAN_CLOSE
            A file is closed (FAN_CLOSE_WRITE|FAN_CLOSE_NOWRITE).

     The filesystem object to be marked is determined by the file descriptor
     dirfd and the pathname specified in pathname:

If pathname is NULL, dirfd defines the filesystem object to be

marked.

If pathname is NULL, and dirfd takes the special value AT_FDCWD, the

current working directory is to be marked.

If pathname is absolute, it defines the filesystem object to be

marked, and dirfd is ignored.

If pathname is relative, and dirfd does not have the value AT_FDCWD,

then the filesystem object to be marked is determined by interpret-

        ing pathname relative the directory referred to by dirfd.

If pathname is relative, and dirfd has the value AT_FDCWD, then the

filesystem object to be marked is determined by interpreting path-

        name relative the current working directory.

RETURN VALUE

     On success, fanotify_mark() returns 0.  On error, -1 is  returned,  and
     errno is set to indicate the error.

ERRORS

     EBADF  An invalid file descriptor was passed in fanotify_fd.

     EINVAL An invalid value was passed in flags or mask, or fanotify_fd was
            not an fanotify file descriptor.

     EINVAL The fanotify file descriptor was opened with FAN_CLASS_NOTIF and
            mask  contains  a  flag  for permission events (FAN_OPEN_PERM or
            FAN_ACCESS_PERM).

     ENOENT The filesystem object indicated by dirfd and pathname  does  not
            exist.  This error also occurs when trying to remove a mark from
            an object which is not marked.

     ENOMEM The necessary memory could not be allocated.

     ENOSPC The number of marks exceeds the limit of 8192 and the FAN_UNLIM-
            ITED_MARKS  flag  was  not  specified  when  the  fanotify  file
            descriptor was created with fanotify_init(2).

     ENOSYS This kernel does not implement  fanotify_mark().   The  fanotify
            API  is  available  only  if the kernel was configured with CON-
            FIG_FANOTIFY.

     ENOTDIR
            flags contains FAN_MARK_ONLYDIR, and dirfd and pathname  do  not
            specify a directory.

VERSIONS

     fanotify_mark()  was  introduced  in version 2.6.36 of the Linux kernel
     and enabled in version 2.6.37.

CONFORMING TO

     This system call is Linux-specific.

BUGS

     The following bugs were present in Linux kernels before version 3.16:

If flags contains FAN_MARK_FLUSH, dirfd and pathname must specify a

valid filesystem object, even though this object is not used.

readdir(2) does not generate a FAN_ACCESS event.

If fanotify_mark() is called with FAN_MARK_FLUSH, flags is not

checked for invalid values.