получить значение пользовательского атрибута объекта файловой системы (get the value of a user attribute of a filesystem object)
Имя (Name)
attr_get, attr_getf - get the value of a user attribute of a
filesystem object
Синопсис C (C Synopsis)
#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);
Описание (Description)
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.
Диагностика (Diagnostic)
On success, zero is returned. On error, -1 is returned, and
errno is set appropriately.
Смотри также (See also)
attr(1), attr_list(3), attr_multi(3), attr_remove(3), attr_set(3)
