50dab48a5b
These changes add the ability to specify that a UFS file/directory cannot be unlinked. This is basically a scaled back version of the IMMUTABLE flag. The reason is to allow an administrator to create a directory hierarchy that a group of users can arbitrarily add/delete files from, but that the hierarchy itself is safe from removal by them. If the NOUNLINK definition is set to 0 then this results in no change to what happens normally. (and results in identical binary (in the kernel)). It can be proven that if this bit is never set by the admin, no new behaviour is introduced.. Several "good idea" comments from reviewers plus one grumble about creeping featurism. This code is in production in 2.2 based systems
167 lines
4.8 KiB
Groff
167 lines
4.8 KiB
Groff
.\" Copyright (c) 1989, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)chflags.2 8.3 (Berkeley) 5/2/95
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.\"
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.Dd May 2, 1995
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.Dt CHFLAGS 2
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.Os
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.Sh NAME
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.Nm chflags ,
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.Nm fchflags
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.Nd set file flags
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.Sh SYNOPSIS
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.Fd #include <sys/stat.h>
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.Fd #include <unistd.h>
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.Ft int
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.Fn chflags "const char *path" "u_long flags"
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.Ft int
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.Fn fchflags "int fd" "u_long flags"
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.Sh DESCRIPTION
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The file whose name
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is given by
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.Fa path
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or referenced by the descriptor
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.Fa fd
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has its flags changed to
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.Fa flags .
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.Pp
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The flags specified are formed by
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.Em or Ns 'ing
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the following values
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.Pp
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.Bl -tag -width "SF_IMMUTABLE" -compact -offset indent
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.It UF_NODUMP
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Do not dump the file.
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.It UF_IMMUTABLE
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The file may not be changed.
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.It UF_APPEND
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The file may only be appended to.
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.It UF_NOUNLINK
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The file may not be renamed or deleted.
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.It UF_OPAQUE
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The directory is opaque when viewed through a union stack.
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.\".It ARCHIVED
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.\"File is archived.
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.It SF_IMMUTABLE
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The file may not be changed.
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.It SF_APPEND
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The file may only be appended to.
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.It SF_NOUNLINK
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The file may not be renamed or deleted.
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.El
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.Pp
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The
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.Dq UF_IMMUTABLE
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,
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.Dq UF_APPEND
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and
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.Dq UF_NOUNLINK
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flags may be set or unset by either the owner of a file or the super-user.
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.Pp
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The
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.Dq SF_IMMUTABLE
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,
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.Dq SF_APPEND
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and
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.Dq SF_NOUNLINK
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flags may only be set or unset by the super-user.
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Attempts by the non-super-user to set the super-user only flags
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are silently ignored.
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These flags may be set at any time, but normally may only be unset when
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the system is in single-user mode.
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(See
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.Xr init 8
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for details.)
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.Sh RETURN VALUES
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Upon successful completion, a value of 0 is returned.
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Otherwise, -1 is returned and the global variable
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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.Fn Chflags
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will fail if:
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.Bl -tag -width Er
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.It Bq Er ENOTDIR
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A component of the path prefix is not a directory.
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.It Bq Er ENAMETOOLONG
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A component of a pathname exceeded 255 characters,
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or an entire path name exceeded 1023 characters.
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.It Bq Er ENOENT
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The named file does not exist.
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.It Bq Er EACCES
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Search permission is denied for a component of the path prefix.
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.It Bq Er ELOOP
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Too many symbolic links were encountered in translating the pathname.
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.It Bq Er EPERM
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The effective user ID does not match the owner of the file and
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the effective user ID is not the super-user.
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.It Bq Er EROFS
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The named file resides on a read-only file system.
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.It Bq Er EFAULT
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.Fa Path
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points outside the process's allocated address space.
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.It Bq Er EIO
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An
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.Tn I/O
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error occurred while reading from or writing to the file system.
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.El
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.Pp
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.Fn Fchflags
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EBADF
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The descriptor is not valid.
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.It Bq Er EINVAL
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.Fa Fd
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refers to a socket, not to a file.
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.It Bq Er EPERM
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The effective user ID does not match the owner of the file and
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the effective user ID is not the super-user.
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.It Bq Er EROFS
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The file resides on a read-only file system.
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.It Bq Er EIO
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An
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.Tn I/O
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error occurred while reading from or writing to the file system.
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.El
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.Sh SEE ALSO
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.Xr chflags 1 ,
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.Xr init 8 ,
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.Xr mount_union 8
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.Sh HISTORY
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The
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.Nm chflags
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and
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.Nm fchflags
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functions first appeared in
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.Bx 4.4 .
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