attr_multi(3) — Linux manual page

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), 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 2020-12-18.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2020-11-03.)  If you discover 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)

Pages that refer to this page: attr(1)attr_get(3)attr_list(3)attr_remove(3)attr_set(3)handle(3)