98 lines
2.3 KiB
Go
98 lines
2.3 KiB
Go
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package nfs
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import (
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"bytes"
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"context"
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"errors"
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"io"
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"os"
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"github.com/willscott/go-nfs-client/nfs/xdr"
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)
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type nfsReadArgs struct {
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Handle []byte
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Offset uint64
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Count uint32
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}
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type nfsReadResponse struct {
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Count uint32
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EOF uint32
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Data []byte
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}
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// MaxRead is the advertised largest buffer the server is willing to read
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const MaxRead = 1 << 24
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// CheckRead is a size where - if a request to read is larger than this,
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// the server will stat the file to learn it's actual size before allocating
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// a buffer to read into.
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const CheckRead = 1 << 15
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func onRead(ctx context.Context, w *response, userHandle Handler) error {
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w.errorFmt = opAttrErrorFormatter
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var obj nfsReadArgs
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err := xdr.Read(w.req.Body, &obj)
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if err != nil {
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return &NFSStatusError{NFSStatusInval, err}
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}
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fs, path, err := userHandle.FromHandle(obj.Handle)
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if err != nil {
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return &NFSStatusError{NFSStatusStale, err}
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}
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fh, err := fs.Open(ctx, fs.Join(path...))
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if err != nil {
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if os.IsNotExist(err) {
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return &NFSStatusError{NFSStatusNoEnt, err}
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}
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if errors.Is(err, context.DeadlineExceeded) {
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return &NFSStatusError{NFSStatusJukebox, err}
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}
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return &NFSStatusError{NFSStatusAccess, err}
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}
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resp := nfsReadResponse{}
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if obj.Count > CheckRead {
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info, err := fs.Stat(ctx, fs.Join(path...))
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if err != nil {
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return &NFSStatusError{NFSStatusAccess, err}
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}
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if info.Size()-int64(obj.Offset) < int64(obj.Count) {
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obj.Count = uint32(uint64(info.Size()) - obj.Offset)
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}
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}
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if obj.Count > MaxRead {
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obj.Count = MaxRead
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}
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resp.Data = make([]byte, obj.Count)
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// todo: multiple reads if size isn't full
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cnt, err := fh.ReadAt(ctx, resp.Data, int64(obj.Offset))
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if err != nil && !errors.Is(err, io.EOF) {
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return &NFSStatusError{NFSStatusIO, err}
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}
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resp.Count = uint32(cnt)
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resp.Data = resp.Data[:resp.Count]
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if errors.Is(err, io.EOF) {
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resp.EOF = 1
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}
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writer := bytes.NewBuffer([]byte{})
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if err := xdr.Write(writer, uint32(NFSStatusOk)); err != nil {
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return &NFSStatusError{NFSStatusServerFault, err}
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}
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if err := WritePostOpAttrs(writer, tryStat(ctx, fs, path)); err != nil {
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return &NFSStatusError{NFSStatusServerFault, err}
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}
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if err := xdr.Write(writer, resp); err != nil {
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return &NFSStatusError{NFSStatusServerFault, err}
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}
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if err := w.Write(writer.Bytes()); err != nil {
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return &NFSStatusError{NFSStatusServerFault, err}
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}
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return nil
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}
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