90 lines
2.6 KiB
Go
90 lines
2.6 KiB
Go
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// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
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// SPDX-License-Identifier: MIT
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package nfsfs
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import (
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"errors"
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)
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// ErrReadOnly marks an operation a read only export refuses, NFS4ERR_ROFS
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// on the wire.
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var ErrReadOnly = errors.New("nfsfs: the export is read only")
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// A roFS wraps an export and hides its mutating halves. The Writer half
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// is gone, so the dispatcher answers NFS4ERR_ROFS for every operation
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// that would change anything through it. The optional halves keep their
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// reads and refuse their writes with ErrReadOnly, so an export served
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// read only still reports its extended attributes, its holes and its
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// named attributes, and refuses to touch them.
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type roFS struct{ FS }
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// ReadOnly serves fs read only: the reads of every half pass through, the
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// writes of the mutating halves answer ErrReadOnly, and the mutating
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// Writer half disappears from the type.
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func ReadOnly(fs FS) FS {
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return roFS{fs}
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}
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// GetXattr reads one named attribute of the object.
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func (ro roFS) GetXattr(h Handle, name string, max int) ([]byte, error) {
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x, ok := ro.FS.(XattrFS)
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if !ok {
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return nil, ErrXattrNotSupp
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}
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return x.GetXattr(h, name, max)
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}
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// ListXattr names the attributes of the object.
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func (ro roFS) ListXattr(h Handle, max int) ([]string, error) {
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x, ok := ro.FS.(XattrFS)
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if !ok {
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return nil, ErrXattrNotSupp
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}
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return x.ListXattr(h, max)
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}
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// SetXattr refuses a write on a read only export.
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func (ro roFS) SetXattr(h Handle, name string, value []byte, mode uint32) error {
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return ErrReadOnly
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}
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// RemoveXattr refuses a write on a read only export.
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func (ro roFS) RemoveXattr(h Handle, name string) error {
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return ErrReadOnly
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}
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// SeekHole reports the first hole at or after the offset.
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func (ro roFS) SeekHole(h Handle, offset int64) (int64, bool, error) {
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s, ok := ro.FS.(interface {
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SeekHole(Handle, int64) (int64, bool, error)
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SeekData(Handle, int64) (int64, bool, error)
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})
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if !ok {
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return 0, false, ErrNoSparse
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}
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return s.SeekHole(h, offset)
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}
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// SeekData reports the first data byte at or after the offset.
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func (ro roFS) SeekData(h Handle, offset int64) (int64, bool, error) {
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s, ok := ro.FS.(interface {
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SeekHole(Handle, int64) (int64, bool, error)
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SeekData(Handle, int64) (int64, bool, error)
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})
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if !ok {
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return 0, false, ErrNoSparse
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}
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return s.SeekData(h, offset)
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}
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// Allocate refuses a space reservation on a read only export.
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func (ro roFS) Allocate(h Handle, offset, length int64) error {
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return ErrReadOnly
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}
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// Deallocate refuses a hole punch on a read only export.
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func (ro roFS) Deallocate(h Handle, offset, length int64) error {
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return ErrReadOnly
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}
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