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freebsd/lib/libc/sys/chflags.2
Julian Elischer 50dab48a5b Submitted by: Whistle Communications (archie Cobbs)
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
1997-06-02 06:24:52 +00:00

167 lines
4.8 KiB
Groff

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.\" @(#)chflags.2 8.3 (Berkeley) 5/2/95
.\"
.Dd May 2, 1995
.Dt CHFLAGS 2
.Os
.Sh NAME
.Nm chflags ,
.Nm fchflags
.Nd set file flags
.Sh SYNOPSIS
.Fd #include <sys/stat.h>
.Fd #include <unistd.h>
.Ft int
.Fn chflags "const char *path" "u_long flags"
.Ft int
.Fn fchflags "int fd" "u_long flags"
.Sh DESCRIPTION
The file whose name
is given by
.Fa path
or referenced by the descriptor
.Fa fd
has its flags changed to
.Fa flags .
.Pp
The flags specified are formed by
.Em or Ns 'ing
the following values
.Pp
.Bl -tag -width "SF_IMMUTABLE" -compact -offset indent
.It UF_NODUMP
Do not dump the file.
.It UF_IMMUTABLE
The file may not be changed.
.It UF_APPEND
The file may only be appended to.
.It UF_NOUNLINK
The file may not be renamed or deleted.
.It UF_OPAQUE
The directory is opaque when viewed through a union stack.
.\".It ARCHIVED
.\"File is archived.
.It SF_IMMUTABLE
The file may not be changed.
.It SF_APPEND
The file may only be appended to.
.It SF_NOUNLINK
The file may not be renamed or deleted.
.El
.Pp
The
.Dq UF_IMMUTABLE
,
.Dq UF_APPEND
and
.Dq UF_NOUNLINK
flags may be set or unset by either the owner of a file or the super-user.
.Pp
The
.Dq SF_IMMUTABLE
,
.Dq SF_APPEND
and
.Dq SF_NOUNLINK
flags may only be set or unset by the super-user.
Attempts by the non-super-user to set the super-user only flags
are silently ignored.
These flags may be set at any time, but normally may only be unset when
the system is in single-user mode.
(See
.Xr init 8
for details.)
.Sh RETURN VALUES
Upon successful completion, a value of 0 is returned.
Otherwise, -1 is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn Chflags
will fail if:
.Bl -tag -width Er
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded 255 characters,
or an entire path name exceeded 1023 characters.
.It Bq Er ENOENT
The named file does not exist.
.It Bq Er EACCES
Search permission is denied for a component of the path prefix.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er EPERM
The effective user ID does not match the owner of the file and
the effective user ID is not the super-user.
.It Bq Er EROFS
The named file resides on a read-only file system.
.It Bq Er EFAULT
.Fa Path
points outside the process's allocated address space.
.It Bq Er EIO
An
.Tn I/O
error occurred while reading from or writing to the file system.
.El
.Pp
.Fn Fchflags
will fail if:
.Bl -tag -width Er
.It Bq Er EBADF
The descriptor is not valid.
.It Bq Er EINVAL
.Fa Fd
refers to a socket, not to a file.
.It Bq Er EPERM
The effective user ID does not match the owner of the file and
the effective user ID is not the super-user.
.It Bq Er EROFS
The file resides on a read-only file system.
.It Bq Er EIO
An
.Tn I/O
error occurred while reading from or writing to the file system.
.El
.Sh SEE ALSO
.Xr chflags 1 ,
.Xr init 8 ,
.Xr mount_union 8
.Sh HISTORY
The
.Nm chflags
and
.Nm fchflags
functions first appeared in
.Bx 4.4 .