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NetBSD 6.1.5 - man page for fchroot (netbsd section 2)

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CHROOT(2)			     BSD System Calls Manual				CHROOT(2)

NAME
     chroot -- 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:

     [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.

     [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.

BSD					  April 18, 2001				      BSD
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