76 lines
1.9 KiB
Go
76 lines
1.9 KiB
Go
/*
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Copyright 2017 the Heptio Ark contributors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package plugin
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import (
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"bytes"
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"io"
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)
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// ReceiveFunc is a function that either returns a slice
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// of an arbitrary number of bytes OR an error. Returning
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// an io.EOF means there is no more data to be read; any
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// other error is considered an actual error.
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type ReceiveFunc func() ([]byte, error)
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// CloseFunc is used to signal to the source of data that
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// the StreamReadCloser has been closed.
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type CloseFunc func() error
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// StreamReadCloser wraps a ReceiveFunc and a CloseSendFunc
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// to implement io.ReadCloser.
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type StreamReadCloser struct {
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buf *bytes.Buffer
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receive ReceiveFunc
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close CloseFunc
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}
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func (s *StreamReadCloser) Read(p []byte) (n int, err error) {
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for {
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// if buf exists and holds at least as much as we're trying to read,
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// read from the buffer
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if s.buf != nil && s.buf.Len() >= len(p) {
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return s.buf.Read(p)
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}
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// if buf is nil, create it
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if s.buf == nil {
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s.buf = new(bytes.Buffer)
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}
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// buf exists but doesn't hold enough data to fill p, so
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// receive again. If we get an EOF, return what's in the
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// buffer; else, write the new data to the buffer and
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// try another read.
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data, err := s.receive()
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if err == io.EOF {
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return s.buf.Read(p)
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}
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if err != nil {
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return 0, err
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}
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if _, err := s.buf.Write(data); err != nil {
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return 0, err
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}
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}
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}
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func (s *StreamReadCloser) Close() error {
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return s.close()
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}
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