1ATTR_MULTI(3) XFS Compatibility API ATTR_MULTI(3)
2
6 attr_multi, attr_multif - manipulate multiple user attributes on a
7 filesystem object at once
8
10 #include <attr/attributes.h>
11 int attr_multi (const char *path, attr_multiop_t *oplist,
13 int count, int flags);
14 int attr_multif (int fd, attr_multiop_t *oplist,
16 int count, int flags);
17
19 The attr_multi and attr_multif functions provide a way to operate on
20 multiple attributes of a filesystem object at once.
21 Path points to a path name for a filesystem object, and fd refers to
23 the file descriptor associated with a file. The oplist is an array of
24 attr_multiop_t structures. Each element in that array describes a sin‐
25 gle attribute operation and provides all the information required to
26 carry out that operation and to check for success or failure of that
27 operation. Count tells how many elements are in the oplist array.
28 The contents of an attr_multiop_t structure include the following mem‐
30 bers:
31 int am_opcode; /* which operation to perform (see below) */
33 int am_error; /* [out arg] result of this sub-op (an errno) */
34 char *am_attrname; /* attribute name to work with */
35 char *am_attrvalue; /* [in/out arg] attribute value (raw bytes) */
36 int am_length; /* [in/out arg] length of value */
37 int am_flags; /* flags (bit-wise OR of #defines below) */
38 The am_opcode field defines how the remaining fields are to be inter‐
40 preted and can take on one of the following values:
41 ATTR_OP_GET /* return the indicated attr's value */
43 ATTR_OP_SET /* set/create the indicated attr/value pair */
44 ATTR_OP_REMOVE /* remove the indicated attr */
45 The am_error field will contain the appropriate error result code if
47 that sub-operation fails. The result codes for a given sub-operation
48 are a subset of the result codes that are possible from the correspond‐
49 ing single-attribute function call. For example, the result code pos‐
50 sible from an ATTR_OP_GET sub-operation are a subset of those that can
51 be returned from an attr_get function call.
52 The am_attrname field is a pointer to a NULL terminated string giving
54 the attribute name that the sub-operation should operate on.
55 The am_attrvalue, am_length and am_flags fields are used to store the
57 value of the named attribute, and some control flags for that sub-oper‐
58 ation, respectively. Their use varies depending on the value of the
59 am_opcode field.
60 ATTR_OP_GET
62 The am_attrvalue field is a pointer to a empty buffer that will
63 be overwritten with the value of the named attribute. The
64 am_length field is initially the total size of the memory buffer
65 that the am_attrvalue field points to. After the operation, the
66 am_length field contains the actual size of the attribute´s
67 value. The am_flags field may be set to the ATTR_ROOT flag. If
68 the process has appropriate priviledges, the ROOT namespace will
69 be searched for the named attribute, otherwise the USER name‐
70 space will be searched.
71 ATTR_OP_SET
73 The am_attrvalue and am_length fields contain the new value for
74 the given attribute name and its length. The ATTR_ROOT flag may
75 be set in the am_flags field. If the process has appropriate
76 priviledges, the ROOT namespace will be searched for the named
77 attribute, otherwise the USER namespace will be searched. The
78 ATTR_CREATE and the ATTR_REPLACE flags may also be set in the
79 am_flags field (but not simultaneously). If the ATTR_CREATE
80 flag is set, the sub-operation will set the am_error field to
81 EEXIST if the named attribute already exists. If the ATTR_RE‐
82 PLACE flag is set, the sub-operation will set the am_error field
83 to ENOATTR if the named attribute does not already exist. If
84 neither of those two flags are set and the attribute does not
85 exist, then the attribute will be created with the given value.
86 If neither of those two flags are set and the attribute already
87 exists, then the value will be replaced with the given value.
88 ATTR_OP_REMOVE
90 The am_attrvalue and am_length fields are not used and are ig‐
91 nored. The am_flags field may be set to the ATTR_ROOT flag. If
92 the process has appropriate priviledges, the ROOT namespace will
93 be searched for the named attribute, otherwise the USER name‐
94 space will be searched.
95 The flags argument to the attr_multi call is used to control following
97 of symbolic links in the path argument. The default is to follow sym‐
98 bolic links, flags should be set to ATTR_DONTFOLLOW to not follow sym‐
99 bolic links.
100 attr_multi will fail if one or more of the following are true:
102 [ENOENT] The named file does not exist.
104 [EPERM] The effective user ID does not match the owner of the
106 file and the effective user ID is not super-user.
107 [ENOTDIR] A component of the path prefix is not a directory.
109 [EACCES] Search permission is denied on a component of the path
111 prefix.
112 [EINVAL] A bit other than ATTR_DONTFOLLOW was set in the flag
114 argument.
115 [EFAULT] Path, or oplist points outside the allocated address
117 space of the process.
118 [ELOOP] A path name lookup involved too many symbolic links.
120 [ENAMETOOLONG] The length of path exceeds {MAXPATHLEN}, or a pathname
122 component is longer than {MAXNAMELEN}.
123 attr_multif will fail if:
125 [EINVAL] A bit was set in the flag argument, or fd refers to a
127 socket, not a file.
128 [EFAULT] Oplist points outside the allocated address space of the
130 process.
131 [EBADF] Fd does not refer to a valid descriptor.
133
135 On success, zero is returned. On error, -1 is returned, and errno is
136 set appropriately. Note that the individual operations listed in the
137 oplist array each have their own error return fields. The errno vari‐
138 able only records the result of the attr_multi call itself, not the re‐
139 sult of any of the sub-operations.
140
142 attr(1), attr_get(3), attr_list(3), attr_remove(3), attr_set(3)
143Dec 2001 Extended Attributes ATTR_MULTI(3)