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44 lines
1.3 KiB
Go
44 lines
1.3 KiB
Go
// Copyright 2023 sigma
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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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package reader
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import "io"
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// LimitReader returns a Reader that reads from r
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// but stops with EOF after n bytes.
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// The underlying implementation is a *LimitedReader.
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func LimitReader(r io.Reader, n int64) io.Reader { return &LimitedReader{r, n} }
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// A LimitedReader reads from R but limits the amount of
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// data returned to just N bytes. Each call to Read
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// updates N to reflect the new amount remaining.
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// Read returns EOF when N <= 0 or when the underlying R returns EOF.
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type LimitedReader struct {
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R io.Reader // underlying reader
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N int64 // max bytes remaining
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}
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func (l *LimitedReader) Read(p []byte) (n int, err error) {
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if l.N <= 0 {
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return 0, io.EOF
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}
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if int64(len(p)) > l.N {
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p = p[0:l.N]
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}
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n, err = l.R.Read(p)
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l.N -= int64(n)
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return
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}
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