#include <unistd.h> int
chroot (const char *dirname);
is the address of the pathname of a directory, terminated by an ASCII NUL.
system call causes
to become the root directory,
that is, the starting point for path searches of pathnames
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
has no effect on the process's current directory.
This call is restricted to the super-user.
Depending on the setting of the
sysctl variable, open filedescriptors which reference directories
will make the
fail as follows:
is set to zero,
will always fail with
if there are any directories open.
is set to one (the default),
will fail with
if there are any directories open and the
process is already subject to the
Any other value for
will bypass the check for open directories
Upon successful completion, a value of 0 is returned.
a value of -1 is returned and
is set to indicate an error.
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
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