196 lines
5 KiB
Groff
196 lines
5 KiB
Groff
.\"
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.\" Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
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.\"
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.\" @APPLE_LICENSE_HEADER_START@
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.\"
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.\" This file contains Original Code and/or Modifications of Original Code
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.\" as defined in and that are subject to the Apple Public Source License
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.\" Version 2.0 (the 'License'). You may not use this file except in
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.\" compliance with the License. Please obtain a copy of the License at
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.\" http://www.opensource.apple.com/apsl/ and read it before using this
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.\" file.
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.\"
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.\" The Original Code and all software distributed under the License are
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.\" distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
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.\" EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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.\" INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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.\" FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
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.\" Please see the License for the specific language governing rights and
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.\" limitations under the License.
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.\"
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.\" @APPLE_LICENSE_HEADER_END@
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.\"
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.Dd Oct 19, 2004
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.Dt SETXATTR 2
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.Os "Mac OS X"
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.Sh NAME
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.Nm setxattr,
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.Nm fsetxattr
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.Nd set an extended attribute value
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.Sh SYNOPSIS
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.Fd #include <sys/xattr.h>
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.Ft int
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.Fn setxattr "const char *path" "const char *name" "void *value" "size_t size" "u_int32_t position" "int options"
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.Ft int
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.Fn fsetxattr "int fd" "const char *name" "void *value" "size_t size" "u_int32_t position" "int options"
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.Sh DESCRIPTION
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Extended attributes extend the basic attributes associated with files and
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directories in the file system. They are stored as name:data pairs
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associated with file system objects (files, directories, symlinks, etc).
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.Pp
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.Fn setxattr
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associates
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.Fa name
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and
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.Fa data
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together as an attribute of
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.Fa path .
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.Pp
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An extended attribute's
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.Fa name
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is a simple NULL-terminated UTF-8 string.
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.Fa Value
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is a pointer to a data buffer of
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.Fa size
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bytes containing textual or binary data to be associated with the
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extended attribute.
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.Fa Position
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specifies the offset within the extended attribute. In the current
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implementation, only the resource fork extended attribute makes use of
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this argument. For all others,
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.Fa position
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is reserved and should be
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set to zero.
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.Pp
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.Fa options
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controls how the attribute is set:
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.Pp
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.Bl -tag -width XATTR_NOFOLLOW
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.It Dv XATTR_NOFOLLOW
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do not follow symbolic links.
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.Fn setxattr
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normally sets attributes on the target of
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.Fa path
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if it is a symbolic link.
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With this option,
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.Fn setxattr
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will act on the link itself.
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.It Dv XATTR_CREATE
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fail if the named attribute already exists.
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.It Dv XATTR_REPLACE
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fail if the named attribute does not exist. Failure to specify
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.Dv XATTR_REPLACE
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or
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.Dv XATTR_CREATE
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allows creation and replacement.
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.El
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.Pp
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.Fn fsetxattr
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is identical to
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.Fn setxattr ,
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except that it sets an extended attribute on an open file referenced by
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file descriptor
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.Fa fd .
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.Sh NOTES
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On some filesystems, such as
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.Dv HFS+ ,
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setting the extended attribute
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.Dv com.apple.ResourceFork
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will update the modification time (``mtime'') of
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the file.
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.Pp
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Due to historical reasons, the
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.Dv XATTR_FINDERINFO_NAME
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(defined to be
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.Dq com.apple.FinderInfo )
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extended attribute must be 32 bytes; see the
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.Dv ATTR_CMN_FNDRINFO
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section in
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.Xr getattrlist 2 .
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.Pp
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The maximum supported size of extended attribute can be found out using
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.Xr pathconf 2
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with _PC_XATTR_SIZE_BITS option.
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.Sh RETURN VALUES
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On success, 0 is returned. On failure, -1 is returned and the global
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variable
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.Va errno
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is set as follows.
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.Sh ERRORS
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.Bl -tag -width Er
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.It Bq Er EEXIST
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.Fa options
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contains
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.Em XATTR_CREATE
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and the named attribute already exists.
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.It Bq Er ENOATTR
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.Fa options
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is set to
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.Em XATTR_REPLACE
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and the named attribute does not exist.
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.It Bq Er ENOTSUP
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The file system does not support extended attributes or has them disabled.
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.It Bq Er EROFS
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The file system is mounted read-only.
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.It Bq Er ERANGE
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The data size of the attribute is out of range (some attributes have size
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restrictions).
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.It Bq Er EPERM
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.\" EFTYPE could be more specific but isn't POSIX
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Attributes cannot be associated with this type of object. For example,
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attributes are not allowed for resource forks.
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.It Bq Er EINVAL
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.Fa name
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or
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.Fa options
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is invalid.
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.Fa name
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must be valid UTF-8 and
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.Fa options
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must make sense.
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.It Bq Er ENOTDIR
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A component of
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.Fa path
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is not a directory.
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.It Bq Er ENAMETOOLONG
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.Fa name
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exceeded
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.Dv XATTR_MAXNAMELEN
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UTF-8 bytes, or a component of
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.Fa path
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exceeded
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.Dv NAME_MAX
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characters, or the entire
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.Fa path
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exceeded
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.Dv PATH_MAX
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characters.
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.It Bq Er EACCES
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Search permission is denied for a component of
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.Fa path
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or permission to set the attribute is denied.
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.It Bq Er ELOOP
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Too many symbolic links were encountered resolving
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.Fa path .
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.It Bq Er EFAULT
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.Fa path
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or
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.Fa name
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points to an invalid address.
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.It Bq Er EIO
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An I/O error occurred while reading from or writing to the file system.
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.It Bq Er E2BIG
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The data size of the extended attribute is too large.
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.It Bq Er ENOSPC
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Not enough space left on the file system.
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.El
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.Sh SEE ALSO
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.Xr getxattr 2 ,
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.Xr listxattr 2 ,
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.Xr removexattr 2 ,
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.Xr pathconf 2
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.Sh HISTORY
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.Fn setxattr
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and
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.Fn fsetxattr
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first appeared in Mac OS X 10.4.
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