CHROOT(2)                 OpenBSD Programmer's Manual                CHROOT(2)

NAME
     chroot - change root directory

SYNOPSIS
     #include <unistd.h>

     int
     chroot(const char *dirname);

DESCRIPTION
     dirname is the address of the pathname of a directory, terminated by an
     ASCII NUL.  chroot() causes dirname to become the root directory, that
     is, the starting point for path searches of pathnames beginning with `/'.

     In order for a directory to become the root directory a process must have
     execute (search) access for that directory.

     If the program is not currently running with an altered root directory,
     it should be noted that chroot() has no effect on the process's current
     directory.

     If the program is already running with an altered root directory, the
     process's current directory is changed to the same new root directory.
     This prevents the current directory from being further up the directory
     tree than the altered root directory.

     This call is restricted to the superuser.

RETURN VALUES
     Upon successful completion, a value of 0 is returned.  Otherwise, a value
     of -1 is returned and errno is set to indicate an error.

EXAMPLES
     The following example changes the root directory to newroot, sets the
     current directory to the new root, and drops any setuid privileges.

           #include <err.h>
           #include <unistd.h>

           if (chroot(newroot) != 0 || chdir("/") != 0)
                   err(1, "%s", newroot);
           seteuid(getuid());
           setuid(getuid());

ERRORS
     chroot() will fail and the root directory will be unchanged if:

     [ENOTDIR]     A component of the path name is not a directory.

     [ENAMETOOLONG]
                   A component of a pathname exceeded {NAME_MAX} characters,
                   or an entire path name exceeded {PATH_MAX} characters.

     [ENOENT]      The named directory does not exist.

     [EACCES]      Search permission is denied for any component of the path
                   name.

     [ELOOP]       Too many symbolic links were encountered in translating the
                   pathname.

     [EFAULT]      dirname points outside the process's allocated address
                   space.

     [EIO]         An I/O error occurred while reading from or writing to the
                   file system.

     [EPERM]       The caller is not the superuser.

SEE ALSO
     chdir(2)

WARNINGS
     There are ways for a root process to escape from the chroot jail.

HISTORY
     The chroot() function call appeared in 4.2BSD.

OpenBSD 4.0                      June 4, 1993                                2
