54 lines
1.3 KiB
Go
54 lines
1.3 KiB
Go
// Copyright 2016 the Go-FUSE 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 splice
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import (
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"fmt"
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"log"
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"os"
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"syscall"
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)
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func (p *Pair) LoadFromAt(fd uintptr, sz int, off int64) (int, error) {
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n, err := syscall.Splice(int(fd), &off, p.w, nil, sz, 0)
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return int(n), err
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}
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func (p *Pair) LoadFrom(fd uintptr, sz int) (int, error) {
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if sz > p.size {
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return 0, fmt.Errorf("LoadFrom: not enough space %d, %d",
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sz, p.size)
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}
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n, err := syscall.Splice(int(fd), nil, p.w, nil, sz, 0)
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if err != nil {
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err = os.NewSyscallError("Splice load from", err)
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}
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return int(n), err
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}
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func (p *Pair) WriteTo(fd uintptr, n int) (int, error) {
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m, err := syscall.Splice(p.r, nil, int(fd), nil, int(n), 0)
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if err != nil {
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err = os.NewSyscallError("Splice write", err)
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}
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return int(m), err
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}
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const _SPLICE_F_NONBLOCK = 0x2
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func (p *Pair) discard() {
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_, err := syscall.Splice(p.r, nil, int(devNullFD), nil, int(p.size), _SPLICE_F_NONBLOCK)
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if err == syscall.EAGAIN {
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// all good.
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} else if err != nil {
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errR := syscall.Close(p.r)
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errW := syscall.Close(p.w)
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// This can happen if something closed our fd
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// inadvertently (eg. double close)
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log.Panicf("splicing into /dev/null: %v (close R %d '%v', close W %d '%v')", err, p.r, errR, p.w, errW)
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}
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}
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