#include <unistd.h> int
chroot (const char *dirname);
DESCRIPTION
The
Fa dirname
argument
is the address of the pathname of a directory, terminated by an ASCII NUL.
The
chroot ();
system call causes
Fa 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
Er EPERM
if there are any directories open.
If
`kern.chroot_allow_open_directories'
is set to one (the default),
chroot ();
will fail with
Er EPERM
if there are any directories open and the
process is already subject to the
chroot ();
system 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.
ERRORS
The
chroot ();
system call
will fail and the root directory will be unchanged if:
Bq Er ENOTDIR
A component of the path name is not a directory.
Bq Er EPERM
The effective user ID is not the super-user, or one or more
filedescriptors are open directories.
Bq Er ENAMETOOLONG
A component of a pathname exceeded 255 characters,
or an entire path name exceeded 1023 characters.
Bq Er ENOENT
The named directory does not exist.
Bq Er EACCES
Search permission is denied for any component of the path name.
Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
Bq Er EFAULT
The
Fa dirname
argument
points outside the process's allocated address space.
Bq Er EIO
An I/O error occurred while reading from or writing to the file system.
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.
