NAME | C SYNOPSIS | DESCRIPTION | DIAGNOSTICS | SEE ALSO | COLOPHON

ATTR_MULTI(3)               XFS Compatibility API              ATTR_MULTI(3)

NAME         top

       attr_multi,  attr_multif  -  manipulate multiple user attributes on a
       filesystem object at once

C SYNOPSIS         top

       #include <attr/attributes.h>

       int attr_multi (const char *path, attr_multiop_t *oplist,
                       int count, int flags);

       int attr_multif (int fd, attr_multiop_t *oplist,
                        int count, int flags);

DESCRIPTION         top

       The attr_multi and attr_multif functions provide a way to operate on
       multiple attributes of a filesystem object at once.

       Path points to a path name for a filesystem object, and fd refers to
       the file descriptor associated with a file.  The oplist is an array
       of attr_multiop_t structures.  Each element in that array describes a
       single attribute operation and provides all the information required
       to carry out that operation and to check for success or failure of
       that operation.  Count tells how many elements are in the oplist
       array.

       The contents of an attr_multiop_t structure include the following
       members:

          int am_opcode; /* which operation to perform (see below) */
          int am_error; /* [out arg] result of this sub-op (an errno) */
          char *am_attrname; /* attribute name to work with */
          char *am_attrvalue; /* [in/out arg] attribute value (raw bytes) */
          int am_length; /* [in/out arg] length of value */
          int am_flags; /* flags (bit-wise OR of #defines below) */

       The am_opcode field defines how the remaining fields are to be
       interpreted and can take on one of the following values:

          ATTR_OP_GET /* return the indicated attr's value */
          ATTR_OP_SET /* set/create the indicated attr/value pair */
          ATTR_OP_REMOVE /* remove the indicated attr */

       The am_error field will contain the appropriate error result code if
       that sub-operation fails.  The result codes for a given sub-operation
       are a subset of the result codes that are possible from the
       corresponding single-attribute function call.  For example, the
       result code possible from an ATTR_OP_GET sub-operation are a subset
       of those that can be returned from an attr_get function call.

       The am_attrname field is a pointer to a NULL terminated string giving
       the attribute name that the sub-operation should operate on.

       The am_attrvalue, am_length and am_flags fields are used to store the
       value of the named attribute, and some control flags for that sub-
       operation, respectively.  Their use varies depending on the value of
       the am_opcode field.

       ATTR_OP_GET
              The am_attrvalue field is a pointer to a empty buffer that
              will be overwritten with the value of the named attribute.
              The am_length field is initially the total size of the memory
              buffer that the am_attrvalue field points to.  After the
              operation, the am_length field contains the actual size of the
              attribute´s value.  The am_flags field may be set to the
              ATTR_ROOT flag.  If the process has appropriate priviledges,
              the ROOT namespace will be searched for the named attribute,
              otherwise the USER namespace will be searched.

       ATTR_OP_SET
              The am_attrvalue and am_length fields contain the new value
              for the given attribute name and its length.  The ATTR_ROOT
              flag may be set in the am_flags field.  If the process has
              appropriate priviledges, the ROOT namespace will be searched
              for the named attribute, otherwise the USER namespace will be
              searched.  The ATTR_CREATE and the ATTR_REPLACE flags may also
              be set in the am_flags field (but not simultaneously).  If the
              ATTR_CREATE flag is set, the sub-operation will set the
              am_error field to EEXIST if the named attribute already
              exists.  If the ATTR_REPLACE flag is set, the sub-operation
              will set the am_error field to ENOATTR if the named attribute
              does not already exist.  If neither of those two flags are set
              and the attribute does not exist, then the attribute will be
              created with the given value.  If neither of those two flags
              are set and the attribute already exists, then the value will
              be replaced with the given value.

       ATTR_OP_REMOVE
              The am_attrvalue and am_length fields are not used and are
              ignored.  The am_flags field may be set to the ATTR_ROOT flag.
              If the process has appropriate priviledges, the ROOT namespace
              will be searched for the named attribute, otherwise the USER
              namespace will be searched.

       The flags argument to the attr_multi call is used to control
       following of symbolic links in the path argument.  The default is to
       follow symbolic links, flags should be set to ATTR_DONTFOLLOW to not
       follow symbolic links.

       attr_multi will fail if one or more of the following are true:

       [ENOENT]         The named file does not exist.

       [EPERM]          The effective user ID does not match the owner of
                        the file and the effective user ID is not super-
                        user.

       [ENOTDIR]        A component of the path prefix is not a directory.

       [EACCES]         Search permission is denied on a component of the
                        path prefix.

       [EINVAL]         A bit other than ATTR_DONTFOLLOW was set in the flag
                        argument.

       [EFAULT]         Path, or oplist points outside the allocated address
                        space of the process.

       [ELOOP]          A path name lookup involved too many symbolic links.

       [ENAMETOOLONG]   The length of path exceeds {MAXPATHLEN}, or a
                        pathname component is longer than {MAXNAMELEN}.

       attr_multif will fail if:

       [EINVAL]       A bit was set in the flag argument, or fd refers to a
                      socket, not a file.

       [EFAULT]       Oplist points outside the allocated address space of
                      the process.

       [EBADF]        Fd does not refer to a valid descriptor.

DIAGNOSTICS         top

       On success, zero is returned.  On error, -1 is returned, and errno is
       set appropriately.  Note that the individual operations listed in the
       oplist array each have their own error return fields.  The errno
       variable only records the result of the attr_multi call itself, not
       the result of any of the sub-operations.

SEE ALSO         top

       attr(1), attr_get(3), attr_list(3), attr_remove(3), and attr_set(3).

COLOPHON         top

       This page is part of the attr (manipulating filesystem extended
       attributes) project.  Information about the project can be found at
       ⟨http://savannah.nongnu.org/projects/attr⟩.  If you have a bug report
       for this manual page, see 
       ⟨http://savannah.nongnu.org/bugs/?group=attr⟩.  This page was obtained
       from the project's upstream Git repository 
       ⟨git://git.savannah.nongnu.org/attr.git⟩ on 2017-03-13.  If you dis‐
       cover any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page, or
       you have corrections or improvements to the information in this
       COLOPHON (which is not part of the original manual page), send a mail
       to man-pages@man7.org

Dec 2001                     Extended Attributes               ATTR_MULTI(3)