attr_get(3) — Linux manual page

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

ATTR_GET(3)               XFS Compatibility API              ATTR_GET(3)

NAME         top

       attr_get, attr_getf - get the value of a user attribute of a
       filesystem object

C SYNOPSIS         top

       #include <attr/attributes.h>

       int attr_get (const char *path, const char *attrname,
                     char *attrvalue, int *valuelength, int flags);

       int attr_getf (int fd, const char *attrname,
                      char *attrvalue, int *valuelength, int flags);

DESCRIPTION         top

       The attr_get and attr_getf functions provide a way to retrieve
       the value of an attribute.

       Path points to a path name for a filesystem object, and fd refers
       to the file descriptor associated with a file.  If the attribute
       attrname exists, the value associated with it will be copied into
       the attrvalue buffer.  The valuelength argument is an
       input/output argument that on the call to attr_get should contain
       the maximum size of attribute value the process is willing to
       accept.  On return, the valuelength will have been modified to
       show the actual size of the attribute value returned.  The flags
       argument can contain the following symbols bitwise OR'ed
       together:

       ATTR_ROOT
              Look for attrname in the root address space, not in the
              user address space.  (limited to use by super-user only)

       ATTR_DONTFOLLOW
              Do not follow symbolic links when resolving a path on an
              attr_get function call.  The default is to follow symbolic
              links.

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

       [ENOATTR]
              The attribute name given is not associated with the
              indicated filesystem object.

       [E2BIG]
              The value of the given attribute is too large to fit into
              the buffer.  The integer that the valuelength argument
              points to has been modified to show the actual number of
              bytes that would be required to store the value of that
              attribute.

       [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 was set in the flag argument that is not defined for
              this system call.

       [EFAULT]
              Path, attrname, attrvalue, or valuelength 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_getf will fail if:

       [ENOATTR]
              The attribute name given is not associated with the
              indicated filesystem object.

       [E2BIG]
              The value of the given attribute is too large to fit into
              the buffer.  The integer that the valuelength argument
              points to has been modified to show the actual number of
              bytes that would be required to store the value of that
              attribute.

       [EINVAL]
              A bit was set in the flag argument that is not defined for
              this system call, or fd refers to a socket, not a file.

       [EFAULT]
              Attrname, attrvalue, or valuelength 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.

SEE ALSO         top

       attr(1), attr_list(3), attr_multi(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 2021-08-27.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-04-19.)  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_GET(3)

Pages that refer to this page: attr(1)attr_multi(3)attr_remove(3)attr_set(3)