97 lines
1.7 KiB
Go
97 lines
1.7 KiB
Go
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package sys
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import (
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"fmt"
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"math"
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"os"
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"runtime"
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"strconv"
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"github.com/cilium/ebpf/internal/unix"
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)
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var ErrClosedFd = unix.EBADF
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type FD struct {
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raw int
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}
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func newFD(value int) *FD {
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fd := &FD{value}
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runtime.SetFinalizer(fd, (*FD).Close)
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return fd
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}
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// NewFD wraps a raw fd with a finalizer.
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//
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// You must not use the raw fd after calling this function, since the underlying
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// file descriptor number may change. This is because the BPF UAPI assumes that
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// zero is not a valid fd value.
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func NewFD(value int) (*FD, error) {
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if value < 0 {
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return nil, fmt.Errorf("invalid fd %d", value)
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}
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fd := newFD(value)
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if value != 0 {
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return fd, nil
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}
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dup, err := fd.Dup()
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_ = fd.Close()
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return dup, err
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}
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func (fd *FD) String() string {
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return strconv.FormatInt(int64(fd.raw), 10)
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}
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func (fd *FD) Int() int {
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return fd.raw
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}
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func (fd *FD) Uint() uint32 {
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if fd.raw < 0 || int64(fd.raw) > math.MaxUint32 {
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// Best effort: this is the number most likely to be an invalid file
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// descriptor. It is equal to -1 (on two's complement arches).
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return math.MaxUint32
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}
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return uint32(fd.raw)
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}
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func (fd *FD) Close() error {
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if fd.raw < 0 {
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return nil
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}
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value := int(fd.raw)
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fd.raw = -1
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fd.Forget()
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return unix.Close(value)
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}
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func (fd *FD) Forget() {
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runtime.SetFinalizer(fd, nil)
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}
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func (fd *FD) Dup() (*FD, error) {
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if fd.raw < 0 {
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return nil, ErrClosedFd
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}
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// Always require the fd to be larger than zero: the BPF API treats the value
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// as "no argument provided".
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dup, err := unix.FcntlInt(uintptr(fd.raw), unix.F_DUPFD_CLOEXEC, 1)
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if err != nil {
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return nil, fmt.Errorf("can't dup fd: %v", err)
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}
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return newFD(dup), nil
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}
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func (fd *FD) File(name string) *os.File {
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fd.Forget()
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return os.NewFile(uintptr(fd.raw), name)
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}
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