forked from cerc-io/ipld-eth-server
78 lines
2.0 KiB
Go
78 lines
2.0 KiB
Go
// Copyright (c) 2013-2016 The btcsuite developers
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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package wire
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import (
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"bytes"
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"io"
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)
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// fixedWriter implements the io.Writer interface and intentially allows
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// testing of error paths by forcing short writes.
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type fixedWriter struct {
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b []byte
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pos int
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}
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// Write writes the contents of p to w. When the contents of p would cause
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// the writer to exceed the maximum allowed size of the fixed writer,
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// io.ErrShortWrite is returned and the writer is left unchanged.
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//
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// This satisfies the io.Writer interface.
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func (w *fixedWriter) Write(p []byte) (n int, err error) {
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lenp := len(p)
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if w.pos+lenp > cap(w.b) {
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return 0, io.ErrShortWrite
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}
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n = lenp
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w.pos += copy(w.b[w.pos:], p)
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return
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}
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// Bytes returns the bytes already written to the fixed writer.
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func (w *fixedWriter) Bytes() []byte {
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return w.b
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}
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// newFixedWriter returns a new io.Writer that will error once more bytes than
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// the specified max have been written.
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func newFixedWriter(max int) io.Writer {
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b := make([]byte, max)
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fw := fixedWriter{b, 0}
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return &fw
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}
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// fixedReader implements the io.Reader interface and intentially allows
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// testing of error paths by forcing short reads.
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type fixedReader struct {
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buf []byte
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pos int
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iobuf *bytes.Buffer
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}
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// Read reads the next len(p) bytes from the fixed reader. When the number of
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// bytes read would exceed the maximum number of allowed bytes to be read from
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// the fixed writer, an error is returned.
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//
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// This satisfies the io.Reader interface.
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func (fr *fixedReader) Read(p []byte) (n int, err error) {
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n, err = fr.iobuf.Read(p)
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fr.pos += n
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return
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}
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// newFixedReader returns a new io.Reader that will error once more bytes than
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// the specified max have been read.
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func newFixedReader(max int, buf []byte) io.Reader {
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b := make([]byte, max)
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if buf != nil {
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copy(b[:], buf)
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}
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iobuf := bytes.NewBuffer(b)
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fr := fixedReader{b, 0, iobuf}
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return &fr
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}
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