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+.\" Copyright (c) 1983, 1991, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 4. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"     @(#)chroot.2	8.1 (Berkeley) 6/4/93
+.\" $FreeBSD$
+.\"
+.Dd June 4, 1993
+.Dt CHROOT 2
+.Os
+.Sh NAME
+.Nm chroot
+.Nd change root directory
+.Sh LIBRARY
+.Lb libc
+.Sh SYNOPSIS
+.In unistd.h
+.Ft int
+.Fn chroot "const char *dirname"
+.Sh DESCRIPTION
+The
+.Fa dirname
+argument
+is the address of the pathname of a directory, terminated by an ASCII NUL.
+The
+.Fn chroot
+system call causes
+.Fa dirname
+to become the root directory,
+that is, the starting point for path searches of pathnames
+beginning with
+.Ql / .
+.Pp
+In order for a directory to become the root directory
+a process must have execute (search) access for that directory.
+.Pp
+It should be noted that
+.Fn chroot
+has no effect on the process's current directory.
+.Pp
+This call is restricted to the super-user.
+.Pp
+Depending on the setting of the
+.Ql kern.chroot_allow_open_directories
+sysctl variable, open filedescriptors which reference directories
+will make the
+.Fn chroot
+fail as follows:
+.Pp
+If
+.Ql kern.chroot_allow_open_directories
+is set to zero,
+.Fn chroot
+will always fail with
+.Er EPERM
+if there are any directories open.
+.Pp
+If
+.Ql kern.chroot_allow_open_directories
+is set to one (the default),
+.Fn chroot
+will fail with
+.Er EPERM
+if there are any directories open and the
+process is already subject to the
+.Fn chroot
+system call.
+.Pp
+Any other value for
+.Ql kern.chroot_allow_open_directories
+will bypass the check for open directories
+.Pp
+Upon successful completion, a value of 0 is returned.
+Otherwise,
+a value of -1 is returned and
+.Va errno
+is set to indicate an error.
+.Sh ERRORS
+The
+.Fn chroot
+system call
+will fail and the root directory will be unchanged if:
+.Bl -tag -width Er
+.It Bq Er ENOTDIR
+A component of the path name is not a directory.
+.It Bq Er EPERM
+The effective user ID is not the super-user, or one or more
+filedescriptors are open directories.
+.It Bq Er ENAMETOOLONG
+A component of a pathname exceeded 255 characters,
+or an entire path name exceeded 1023 characters.
+.It Bq Er ENOENT
+The named directory does not exist.
+.It Bq Er EACCES
+Search permission is denied for any component of the path name.
+.It Bq Er ELOOP
+Too many symbolic links were encountered in translating the pathname.
+.It Bq Er EFAULT
+The
+.Fa dirname
+argument
+points outside the process's allocated address space.
+.It Bq Er EIO
+An I/O error occurred while reading from or writing to the file system.
+.El
+.Sh SEE ALSO
+.Xr chdir 2 ,
+.Xr jail 2
+.Sh HISTORY
+The
+.Fn chroot
+system call appeared in
+.Bx 4.2 .
+.Sh BUGS
+If the process is able to change its working directory to the target
+directory, but another access control check fails (such as a check for
+open directories, or a MAC check), it is possible that this system
+call may return an error, with the working directory of the process
+left changed.