2 .\" Copyright (c) 2001 Dima Dorfman <dima@unixfreak.org>
3 .\" Copyright (c) 2003 Robert Watson <rwatson@FreeBSD.org>
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35 .Nm extattr_delete_fd ,
37 .Nm extattr_get_file ,
38 .Nm extattr_set_file ,
39 .Nm extattr_delete_file ,
40 .Nm extattr_list_file ,
41 .Nm extattr_get_link ,
42 .Nm extattr_set_link ,
43 .Nm extattr_delete_link ,
45 .Nd system calls to manipulate VFS extended attributes
52 .Fn extattr_get_fd "int fd" "int attrnamespace" "const char *attrname" "void *data" "size_t nbytes"
54 .Fn extattr_set_fd "int fd" "int attrnamespace" "const char *attrname" "const void *data" "size_t nbytes"
56 .Fn extattr_delete_fd "int fd" "int attrnamespace" "const char *attrname"
58 .Fn extattr_list_fd "int fd" "int attrnamespace" "void *data" "size_t nbytes"
60 .Fn extattr_get_file "const char *path" "int attrnamespace" "const char *attrname" "void *data" "size_t nbytes"
62 .Fn extattr_set_file "const char *path" "int attrnamespace" "const char *attrname" "const void *data" "size_t nbytes"
64 .Fn extattr_delete_file "const char *path" "int attrnamespace" "const char *attrname"
66 .Fn extattr_list_file "const char *path" "int attrnamespace" "void *data" "size_t nbytes"
68 .Fn extattr_get_link "const char *path" "int attrnamespace" "const char *attrname" "void *data" "size_t nbytes"
70 .Fn extattr_set_link "const char *path" "int attrnamespace" "const char *attrname" "const void *data" "size_t nbytes"
72 .Fn extattr_delete_link "const char *path" "int attrnamespace" "const char *attrname"
74 .Fn extattr_list_link "const char *path" "int attrnamespace" "void *data" "size_t nbytes"
76 Named extended attributes are meta-data associated with vnodes
77 representing files and directories.
80 pairs within a set of namespaces.
84 system call retrieves the value of the specified extended attribute into
85 a buffer pointed to by
91 system call sets the value of the specified extended attribute to the data
95 .Fn extattr_delete_file
96 system call deletes the extended attribute specified.
99 returns a list of attributes present in the requested namespace.
100 Each list entry consists of a single byte containing the length
101 of the attribute name, followed by the attribute name.
102 The attribute name is not terminated by ASCII 0 (nul).
104 .Fn extattr_get_file ,
106 .Fn extattr_list_file
111 arguments in the style of
114 consumes these arguments in the style of
124 .Fn extattr_list_file
125 then the size of defined extended attribute data will be returned, rather
126 than the quantity read, permitting applications to test the size of the
127 data without performing a read.
129 .Fn extattr_delete_link ,
130 .Fn extattr_get_link ,
133 system calls behave in the same way as their _file counterparts, except that
134 they do not follow symlinks.
139 .Fn extattr_delete_fd ,
141 .Fn extattr_list_fd ,
142 calls are identical to their
144 counterparts except for the first argument.
147 functions take a file descriptor, while the
149 functions take a path.
150 Both arguments describe a file associated with the extended attribute
151 that should be manipulated.
153 The following arguments are common to all the system calls described here:
154 .Bl -tag -width attrnamespace
156 the namespace in which the extended attribute resides; see
159 the name of the extended attribute
162 Named extended attribute semantics vary by file system implementing the call.
163 Not all operations may be supported for a particular attribute.
164 Additionally, the format of the data in
166 is attribute-specific.
168 For more information on named extended attributes, please see
171 This interface is under active development, and as such is subject to
172 change as applications are adapted to use it.
173 Developers are discouraged from relying on its stability.
176 .Fn extattr_get_file ,
177 .Fn extattr_set_file ,
179 .Fn extattr_list_file
180 calls return the number of bytes
181 that were read or written from the
190 .Fn extattr_list_file
191 return the number of bytes available to read.
192 If any of the calls are unsuccessful, the value \-1 is returned
193 and the global variable
195 is set to indicate the error.
197 .Rv -std extattr_delete_file
199 The following errors may be returned by the system calls themselves.
200 Additionally, the file system implementing the call may return any
201 other errors it desires.
209 or the memory range defined by
213 point outside the process's allocated address space.
214 .It Bq Er ENAMETOOLONG
215 The attribute name was longer than
216 .Dv EXTATTR_MAXNAMELEN .
222 .Fn extattr_delete_fd ,
225 system calls may also fail if:
228 The file descriptor referenced by
234 .Fn extattr_get_file ,
235 .Fn extattr_set_file ,
237 .Fn extattr_delete_file
238 calls may also fail due to the following errors:
241 The requested attribute was not defined for this file.
243 A component of the path prefix is not a directory.
244 .It Bq Er ENAMETOOLONG
245 A component of a pathname exceeded 255 characters,
246 or an entire path name exceeded 1023 characters.
248 A component of the path name that must exist does not exist.
250 Search permission is denied for a component of the path prefix.
251 .\" XXX are any missing?
258 .Xr VOP_GETEXTATTR 9 ,
261 Extended attribute support was developed as part of the
263 Project, and introduced in
265 It was developed to support security extensions requiring additional labels
266 to be associated with each file or directory.
268 In earlier versions of this API, passing an empty string for the
271 .Fn extattr_get_file ,
274 would return the list of attributes defined for the target object.
275 This interface has been deprecated in preference to using the explicit
276 list API, and should not be used.