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package tarlog
import (
"io"
"sync"
"github.com/sirupsen/logrus"
"github.com/vbatts/tar-split/archive/tar"
)
type tarLogger struct {
writer *io.PipeWriter
closeMutex *sync.Mutex
closed bool
}
// NewLogger returns a writer that, when a tar archive is written to it, calls
// `logger` for each file header it encounters in the archive.
func NewLogger(logger func(*tar.Header)) (io.WriteCloser, error) {
reader, writer := io.Pipe()
t := &tarLogger{
writer: writer,
closeMutex: new(sync.Mutex),
closed: false,
}
tr := tar.NewReader(reader)
t.closeMutex.Lock()
go func() {
hdr, err := tr.Next()
for err == nil {
logger(hdr)
hdr, err = tr.Next()
}
// Make sure to avoid writes after the reader has been closed.
if err := reader.Close(); err != nil {
logrus.Errorf("error closing tarlogger reader: %v", err)
}
// Unblock the Close().
t.closeMutex.Unlock()
}()
return t, nil
}
func (t *tarLogger) Write(b []byte) (int, error) {
if t.closed {
// We cannot use os.Pipe() as this alters the tar's digest. Using
// io.Pipe() requires this workaround as it does not allow for writes
// after close.
return len(b), nil
}
n, err := t.writer.Write(b)
if err == io.ErrClosedPipe {
// The pipe got closed. Track it and avoid to call Write in future.
t.closed = true
return len(b), nil
}
return n, err
}
func (t *tarLogger) Close() error {
err := t.writer.Close()
// Wait for the reader to finish.
t.closeMutex.Lock()
return err
}
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