ATTR_REMOVE(2) ATTR_REMOVE(2)
attr_remove, attr_removef - remove a user attribute of a filesystem
object
#include <sys/attributes.h>
int attr_remove (const char *path, const char *attrname, int flags);
int attr_removef (int fd, const char *attrname, int flags);
The attr group of system calls implement the ability for a user to attach
name/value pairs to objects within the filesystem.
They could be used to store meta-information about the file. For example
"character-set=kanji" could tell a document browser to use the Kanji
character set when displaying that document and "thumbnail=..." could
provide a reduced resolution overview of a high resolution graphic image.
The names can be up to MAXNAMELEN bytes in length, terminated by the
first 0 byte. The intent is that they be printable ASCII (or other
character set) names for the attribute.
The values can be up to ATTR_MAX_VALUELEN (currently 64KB) of arbitrary
binary data.
Attributes can be attached to all types of inodes: regular files,
directories, symbolic links, device nodes, etc.
There are 2 disjoint attribute name spaces associated with every
filesystem object. They are the root and user address spaces. The root
address space is accessible only to privileged users, and only then by
specifying a flag argument to the function call. A privileged user can
be either the superuser in an IRIX environment, or a user with
CAP_DEVICE_MGT capability. Other users will not see or be able to modify
attributes in the root address space. The user address space is
protected by the normal file permissions mechanism, so the owner of the
file can decide who is able to see and/or modify the value of attributes
on any particular file.
Attributes are currently fully supported only in the XFS and CXFS
filesystem types. Other filesystem types may provide a partial
implementation.
The attr_remove and attr_removef functions provide a way to remove
previously created attributes from filesystem objects.
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 attribute name and value will be removed from the fileystem
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ATTR_REMOVE(2) ATTR_REMOVE(2)
object. 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_remove
function call. The default is to follow symbolic links.
attr_remove will fail if one or more of the following are true:
[ENOATTR] The attribute name given is not associated with the
indicated filesystem object.
[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 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_removef will fail if:
[ENOATTR] The attribute name given is not associated with the
indicated filesystem object.
[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 points outside the allocated address space of the
process.
[EBADF] Fd does not refer to a valid descriptor.
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ATTR_REMOVE(2) ATTR_REMOVE(2)
attr(1),
attr_get(2), attr_getf(2),
attr_list(2), attr_list
attr_set(2), attr_setf(2),
Upon successful completion, a value of 0 is returned. Otherwise, a value
of -1 is returned and errno is set to indicate the error.
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