CHROOT(2) System Calls CHROOT(2)
NAME
chroot, fchroot - change root directory
SYNOPSIS
#include <unistd.h>
int chroot(
const char *path);
int fchroot(
int fildes);
DESCRIPTION
The
chroot() and
fchroot() functions cause a directory to become the
root directory, the starting point for path searches for path names
beginning with
/ (slash). The user's working directory is unaffected
by the
chroot() and
fchroot() functions.
The
path argument points to a path name naming a directory. The
fildes argument to
fchroot() is the open file descriptor of the
directory which is to become the root.
The privilege {
PRIV_PROC_CHROOT} must be asserted in the effective
set of the process to change the root directory. While it is always
possible to change to the system root using the
fchroot() function,
it is not guaranteed to succeed in any other case, even if
fildes is
valid in all respects.
The ".." entry in the root directory is interpreted to mean the root
directory itself. Therefore, ".." cannot be used to access files
outside the subtree rooted at the root directory. Instead,
fchroot() can be used to reset the root to a directory that was opened before
the root directory was changed.
RETURN VALUES
Upon successful completion,
0 is returned. Otherwise,
-1 is returned,
the root directory remains unchanged, and
errno is set to indicate
the error.
ERRORS
The
chroot() function will fail if:
EACCES Search permission is denied for a component of the
path prefix of
dirname, or search permission is
denied for the directory referred to by
dirname.
EBADF The descriptor is not valid.
EFAULT The
path argument points to an illegal address.
EINVAL The
fchroot() function attempted to change to a
directory the is not the system root and external
circumstances do not allow this.
EINTR A signal was caught during the execution of the
chroot() function.
EIO An I/O error occurred while reading from or writing
to the file system.
ELOOP Too many symbolic links were encountered in
translating
path.
ENAMETOOLONG The length of the
path argument exceeds
PATH_MAX, or
the length of a
path component exceeds
NAME_MAX while
_POSIX_NO_TRUNC is in effect.
ENOENT The named directory does not exist or is a null
pathname.
ENOLINK The
path argument points to a remote machine and the
link to that machine is no longer active.
ENOTDIR Any component of the path name is not a directory.
EPERM The {
PRIV_PROC_CHROOT} privilege is not asserted in
the effective set of the calling process.
SEE ALSO
chdir(2),
privileges(7),
chroot(8)WARNINGS
The only use of
fchroot() that is appropriate is to change back to
the system root.
January 20, 2003 CHROOT(2)
