44 lines
1.1 KiB
Go
44 lines
1.1 KiB
Go
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package net
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import (
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"internal/poll"
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"io"
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)
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// splice transfers data from r to c using the splice system call to minimize
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// copies from and to userspace. c must be a TCP connection. Currently, splice
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// is only enabled if r is a TCP or a stream-oriented Unix connection.
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//
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// If splice returns handled == false, it has performed no work.
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func splice(c *netFD, r io.Reader) (written int64, err error, handled bool) {
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var remain int64 = 1 << 62 // by default, copy until EOF
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lr, ok := r.(*io.LimitedReader)
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if ok {
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remain, r = lr.N, lr.R
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if remain <= 0 {
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return 0, nil, true
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}
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}
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var s *netFD
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if tc, ok := r.(*TCPConn); ok {
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s = tc.fd
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} else if uc, ok := r.(*UnixConn); ok {
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if uc.fd.net != "unix" {
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return 0, nil, false
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}
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s = uc.fd
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} else {
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return 0, nil, false
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}
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written, handled, sc, err := poll.Splice(&c.pfd, &s.pfd, remain)
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if lr != nil {
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lr.N -= written
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}
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return written, wrapSyscallError(sc, err), handled
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}
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