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61 lines
1.7 KiB
61 lines
1.7 KiB
/*
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* Minio Cloud Storage, (C) 2017 Minio, Inc.
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*
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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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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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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 ioutil implements some I/O utility functions which are not covered
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// by the standard library.
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package ioutil
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import (
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"io"
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)
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// WriteOnCloser implements io.WriteCloser and always
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// exectues at least one write operation if it is closed.
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//
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// This can be useful within the context of HTTP. At least
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// one write operation must happen to send the HTTP headers
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// to the peer.
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type WriteOnCloser struct {
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io.Writer
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hasWritten bool
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}
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func (w *WriteOnCloser) Write(p []byte) (int, error) {
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w.hasWritten = true
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return w.Writer.Write(p)
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}
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// Close closes the WriteOnCloser. It behaves like io.Closer.
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func (w *WriteOnCloser) Close() error {
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if !w.hasWritten {
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_, err := w.Write(nil)
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if err != nil {
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return err
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}
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}
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if closer, ok := w.Writer.(io.Closer); ok {
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return closer.Close()
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}
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return nil
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}
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// HasWritten returns true if at least one write operation was performed.
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func (w *WriteOnCloser) HasWritten() bool { return w.hasWritten }
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// WriteOnClose takes an io.Writer and returns an ioutil.WriteOnCloser.
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func WriteOnClose(w io.Writer) *WriteOnCloser {
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return &WriteOnCloser{w, false}
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}
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