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to that machine is no longer active.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


chroot(1M), chdir(2), privileges(5)

WARNINGS


The only use of fchroot() that is appropriate is to change back to the
system root.


January 20, 2003 CHROOT(2)