.\" .\" Copyright (c) 2004 Apple Computer, Inc. All rights reserved. .\" .\" @APPLE_LICENSE_HEADER_START@ .\" .\" This file contains Original Code and/or Modifications of Original Code .\" as defined in and that are subject to the Apple Public Source License .\" Version 2.0 (the 'License'). You may not use this file except in .\" compliance with the License. Please obtain a copy of the License at .\" http://www.opensource.apple.com/apsl/ and read it before using this .\" file. .\" .\" The Original Code and all software distributed under the License are .\" distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER .\" EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, .\" INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, .\" FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. .\" Please see the License for the specific language governing rights and .\" limitations under the License. .\" .\" @APPLE_LICENSE_HEADER_END@ .\" .Dd Oct 19, 2004 .Dt GETXATTR 2 .Os "Mac OS X" .Sh NAME .Nm getxattr, .Nm fgetxattr .Nd get an extended attribute value .Sh SYNOPSIS .Fd #include <sys/xattr.h> .Ft ssize_t .Fn getxattr "const char *path" "const char *name" "void *value" "size_t size" "u_int32_t position" "int options" .Ft ssize_t .Fn fgetxattr "int fd" "const char *name" "void *value" "size_t size" "u_int32_t position" "int options" .Sh DESCRIPTION Extended attributes extend the basic attributes of files and directories in the file system. They are stored as name:data pairs associated with file system objects (files, directories, symlinks, etc). .Pp The .Fn getxattr function retrieves up to .Fa size bytes of data from the extended attribute identified by .Fa name associated with .Fa path into the pre-allocated buffer pointed to by .Fa value . The function returns the number of bytes of data retrieved. .Pp An extended attribute's .Fa name is a simple NULL-terminated UTF-8 string. .Fa position specifies an offset within the extended attribute. In the current implementation, this argument is only used with the resource fork attribute. For all other extended attributes, this parameter is reserved and should be zero. .Pp On success, .Fa value contains the data associated with .Fa name . When .Fa value is set to NULL, .Fn getxattr returns current size of the named attribute. This facility can be used to determine the size of a buffer sufficiently large to hold the data currently associated with the attribute. .Pp .Fa options specify options for retrieving extended attributes: .Pp .Bl -tag -width XATTR_NOFOLLOW .It Dv XATTR_NOFOLLOW do not follow symbolic links. .Fn getxattr normally returns information from the target of .Fa path if it is a symbolic link. With this option, .Fn getxattr will return extended attribute data from the symbolic link instead. .It Dv XATTR_SHOWCOMPRESSION .Fn getxattr and .Fn fgetxattr will return HFS Plus Compression extended attribute .Fa name (if present) for the file referred to by .Fa path or .Fa fd . .El .Pp .Fn fgetxattr is identical to .Fn getxattr , except that it retrieves extended attribute data from the open file referenced by the file descriptor .Fa fd . .Sh RETURN VALUES On success, the size of the extended attribute data is returned. On failure, -1 is returned and the global variable .Va errno is set as follows. .Sh ERRORS .Bl -tag -width Er .It Bq Er ENOATTR The extended attribute does not exist. .It Bq Er ENOTSUP The file system does not support extended attributes or has the feature disabled. .It Bq Er ERANGE .Fa value (as indicated by .Fa size ) is too small to hold the extended attribute data. .It Bq Er EPERM The named attribute is not permitted for this type of object. .It Bq Er EINVAL .Fa name is invalid or .Fa options has an unsupported bit set. .It Bq Er EISDIR .Fa path or .Fa fd do not refer to a regular file and the attribute in question is only applicable to files. Similar to EPERM. .It Bq Er ENOTDIR A component of .Fa path 's prefix is not a directory. .It Bq Er ENAMETOOLONG The length of .Fa name exceeds .Dv XATTR_MAXNAMELEN UTF-8 bytes, or a component of .Fa path exceeds .Dv NAME_MAX characters, or the entire .Fa path exceeds .Dv PATH_MAX characters. .It Bq Er EACCES Search permission is denied for a component of .Fa path or the attribute is not allowed to be read (e.g. an ACL prohibits reading the attributes of this file). .It Bq Er ELOOP Too many symbolic links were encountered in translating the pathname. .It Bq Er EFAULT .Fa path or .Fa name points to an invalid address. .It Bq Er EIO An I/O error occurred while reading from or writing to the file system. .El .Sh SEE ALSO .Xr listxattr 2 , .Xr removexattr 2 , .Xr setxattr 2 .Sh HISTORY .Fn getxattr and .Fn fgetxattr first appeared in Mac OS X 10.4.