DragonFly On-Line Manual Pages

Search: Section:  

CHROOT(2)                DragonFly System Calls Manual               CHROOT(2)


NAME

     chroot, chroot_kernel -- change root directory


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <unistd.h>

     int
     chroot(const char *dirname);

     int
     chroot_kernel(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.

     It should be noted that chroot() has no effect on the process's current
     directory.

     This call is restricted to the super-user.

     Depending on the setting of the kern.chroot_allow_open_directories sysctl
     variable, open filedescriptors which reference directories will make the
     chroot() fail as follows:

     If kern.chroot_allow_open_directories is set to zero, chroot() will
     always fail with EPERM if there are any directories open.

     If kern.chroot_allow_open_directories is set to one (the default),
     chroot() will fail with EPERM if there are any directories open and the
     process is already subject to a chroot() call.

     Any other value for kern.chroot_allow_open_directories will bypass the
     check for open directories

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

     The chroot_kernel() system call adjusts the kernel's internal namecache
     and root vnode references to dirname.  If used in conjunction with
     chroot() during early boot, it allows for changing the root mount to any
     mount point available at that time.


ERRORS

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

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

     [EPERM]            The effective user ID is not the super-user, or one or
                        more filedescriptors are open directories.

     [ENAMETOOLONG]     A component of a pathname exceeded 255 characters, or
                        an entire path name exceeded 1023 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 translat-
                        ing 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.


SEE ALSO

     chdir(2), jail(2)


HISTORY

     The chroot() function call appeared in 4.2BSD.

DragonFly 3.5                   August 1, 2010                   DragonFly 3.5

Search: Section: