107 lines
2.6 KiB
Go
107 lines
2.6 KiB
Go
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// +build !windows
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// TODO: windows now has pipes, verify if it maybe works
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// TODO: extract from filecoin
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package bytesink
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import (
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"fmt"
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"io/ioutil"
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"os"
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"syscall"
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"github.com/pkg/errors"
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)
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// FifoByteSink is not safe for concurrent access, as writes to underlying pipe are atomic only
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// if len(buf) is less than the OS-specific PIPE_BUF value.
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type FifoByteSink struct {
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file *os.File
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path string
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}
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// Open prepares the sink for writing by opening the backing FIFO file. Open
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// will block until someone opens the FIFO file for reading.
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func (s *FifoByteSink) Open() error {
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file, err := os.OpenFile(s.path, os.O_WRONLY, os.ModeNamedPipe)
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if err != nil {
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return errors.Wrap(err, "failed to open pipe")
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}
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s.file = file
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return nil
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}
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// Write writes the provided buffer to the underlying pipe. Write will block
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// until the provided buffer's bytes have been read from the read end of the
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// pipe.
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//
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// Warning: Writes are atomic only if len(buf) is less than the OS-specific
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// PIPE_BUF value. For more information, see:
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//
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// http://pubs.opengroup.org/onlinepubs/9699919799/functions/write.html
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func (s *FifoByteSink) Write(buf []byte) (int, error) {
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return s.file.Write(buf)
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}
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// Close ensures that the underlying file is closed and removed.
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func (s *FifoByteSink) Close() (retErr error) {
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cerr := s.file.Close()
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if cerr != nil {
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return cerr
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}
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defer func() {
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rerr := os.Remove(s.path)
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if retErr == nil {
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retErr = rerr
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}
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}()
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return
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}
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// ID produces a string-identifier for this byte sink. For now, this is just the
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// path of the FIFO file. This string may get more structured in the future.
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func (s *FifoByteSink) ID() string {
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return s.path
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}
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// NewFifo creates a FIFO pipe and returns a pointer to a FifoByteSink, which
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// satisfies the ByteSink interface. The FIFO pipe is used to stream bytes to
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// rust-fil-proofs from Go during the piece-adding flow. Writes to the pipe are
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// buffered automatically by the OS; the size of the buffer varies.
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func NewFifo() (*FifoByteSink, error) {
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path, err := createTmpFifoPath()
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if err != nil {
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return nil, errors.Wrap(err, "creating FIFO path failed")
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}
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err = syscall.Mkfifo(path, 0600)
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if err != nil {
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return nil, errors.Wrap(err, "mkfifo failed")
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}
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return &FifoByteSink{
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path: path,
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}, nil
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}
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// createTmpFifoPath creates a path with which a temporary FIFO file may be
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// created.
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func createTmpFifoPath() (string, error) {
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file, err := ioutil.TempFile("", "")
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if err != nil {
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return "", err
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}
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err = file.Close()
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if err != nil {
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return "", err
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}
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return fmt.Sprintf("%s.fifo", file.Name()), nil
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}
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