CHROOT(2)                     System Calls Manual                    CHROOT(2)

NAME
     chroot, fchroot - change root directory

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <unistd.h>

     int
     chroot(const char *dirname);

     int
     fchroot(int fd);

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

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

     [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.

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

     [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.

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

     [EPERM]            The effective user ID of the calling process is not
                        the super-user.

     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.

     [EPERM]            The effective user ID of the calling process is not
                        the super-user.

SEE ALSO
     chdir(2)

STANDARDS
     The chroot() function conforms to X/Open System Interfaces and Headers
     Issue 5 ("XSH5"), with the restriction that the calling process' working
     directory must be at or under the new root directory.  Otherwise, the
     working directory is silently set to the new root directory; this is an
     extension to the standard.

     chroot() was declared a legacy interface, and subsequently removed in
     IEEE Std 1003.1-2001 ("POSIX.1").

HISTORY
     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.

NetBSD 10.0                     April 18, 2001                     NetBSD 10.0