NAME    [Toc]    [Back]

     chroot - change root directory

LIBRARY    [Toc]    [Back]

     Standard C Library (libc, -lc)

SYNOPSIS    [Toc]    [Back]

     #include <unistd.h>

     int
     chroot(const char *dirname);

     int
     fchroot(int fd);

DESCRIPTION    [Toc]    [Back]

     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 current working directory is not at or under the new root directory,
 it is silently set to the new root directory.  It should be noted
     that, on most other systems, chroot() has no effect on the process's current
 directory.

     This call is restricted to the super-user.

     The fchroot() function performs the same operation on an open directory
     file known by the file descriptor fd.

RETURN VALUES    [Toc]    [Back]

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

ERRORS    [Toc]    [Back]

     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.

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

     [EACCES]           Search permission is denied for the directory referenced
 by the file descriptor.

     [EBADF]            The argument fd is not a valid file descriptor.

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

     [ENOTDIR]          The argument fd does not reference a directory.

SEE ALSO    [Toc]    [Back]

     chdir(2)

HISTORY    [Toc]    [Back]

     The chroot() function call appeared in 4.2BSD.  Working directory handling
 was changed in NetBSD 1.4 to prevent one way a process could use a
     second chroot() call to a different directory to "escape" from the
     restricted subtree.  The fchroot() function appeared in NetBSD 1.4.

BSD                             April 18, 2001                             BSD