nfs/internal/nfs4/xattr.go

// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: MIT

// The extended attribute operations of RFC 8276: four narrow operations
// over named opaque values.

package nfs4

import (
	"sourcedock.dev/petrbalvin/nfs/internal/xdr"
)

// SETXATTR modes of the setxattr4mode4 enum.
const (
	SetXattrUnchecked = 0
	SetXattrCreate    = 1
	SetXattrReplace   = 2
)

// AppendGetXattrArgs appends the GETXATTR argop: the name alone, the
// whole argument RFC 8276 defines.
func AppendGetXattrArgs(b []byte, name string) []byte {
	b = xdr.AppendUint32(b, OpGetxattr)
	return xdr.AppendString(b, name)
}

// AppendGetXattrRes appends a successful GETXATTR result: the value as
// one opaque.
func AppendGetXattrRes(b []byte, value []byte) []byte {
	return xdr.AppendVarOpaque(b, value)
}

// DecodeGetXattrRes decodes a successful GETXATTR result.
func DecodeGetXattrRes(body []byte) ([]byte, error) {
	return xdr.NewDecoder(body).VarOpaque()
}

// AppendSetXattrArgs appends the SETXATTR argop: the create mode, the
// name and the value.
func AppendSetXattrArgs(b []byte, mode uint32, name string, value []byte) []byte {
	b = xdr.AppendUint32(b, OpSetxattr)
	b = xdr.AppendUint32(b, mode)
	b = xdr.AppendString(b, name)
	return xdr.AppendVarOpaque(b, value)
}

// AppendListXattrArgs appends the LISTXATTR argop: the cookie the last
// reply returned and the response size budget.
func AppendListXattrArgs(b []byte, cookie uint64, maxcount uint32) []byte {
	b = xdr.AppendUint32(b, OpListxattr)
	b = xdr.AppendUint64(b, cookie)
	return xdr.AppendUint32(b, maxcount)
}

// AppendListXattrRes appends a successful LISTXATTR result: the cookie
// of the last name, the names and the end of list flag.
func AppendListXattrRes(b []byte, cookie uint64, names []string, eof bool) []byte {
	b = xdr.AppendUint64(b, cookie)
	b = xdr.AppendUint32(b, uint32(len(names)))
	for _, n := range names {
		b = xdr.AppendString(b, n)
	}
	return xdr.AppendBool(b, eof)
}

// AppendRemoveXattrArgs appends the REMOVEXATTR argop: the name.
func AppendRemoveXattrArgs(b []byte, name string) []byte {
	b = xdr.AppendUint32(b, OpRemovexattr)
	return xdr.AppendString(b, name)
}