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package ioutils
import (
"crypto/sha256"
"encoding/hex"
"io"
"golang.org/x/net/context"
)
type readCloserWrapper struct {
io.Reader
closer func() error
}
func (r *readCloserWrapper) Close() error {
return r.closer()
}
// NewReadCloserWrapper returns a new io.ReadCloser.
func NewReadCloserWrapper(r io.Reader, closer func() error) io.ReadCloser {
return &readCloserWrapper{
Reader: r,
closer: closer,
}
}
type readerErrWrapper struct {
reader io.Reader
closer func()
}
func (r *readerErrWrapper) Read(p []byte) (int, error) {
n, err := r.reader.Read(p)
if err != nil {
r.closer()
}
return n, err
}
// NewReaderErrWrapper returns a new io.Reader.
func NewReaderErrWrapper(r io.Reader, closer func()) io.Reader {
return &readerErrWrapper{
reader: r,
closer: closer,
}
}
// HashData returns the sha256 sum of src.
func HashData(src io.Reader) (string, error) {
h := sha256.New()
if _, err := io.Copy(h, src); err != nil {
return "", err
}
return "sha256:" + hex.EncodeToString(h.Sum(nil)), nil
}
// OnEOFReader wraps an io.ReadCloser and a function
// the function will run at the end of file or close the file.
type OnEOFReader struct {
Rc io.ReadCloser
Fn func()
}
func (r *OnEOFReader) Read(p []byte) (n int, err error) {
n, err = r.Rc.Read(p)
if err == io.EOF {
r.runFunc()
}
return
}
// Close closes the file and run the function.
func (r *OnEOFReader) Close() error {
err := r.Rc.Close()
r.runFunc()
return err
}
func (r *OnEOFReader) runFunc() {
if fn := r.Fn; fn != nil {
fn()
r.Fn = nil
}
}
// cancelReadCloser wraps an io.ReadCloser with a context for cancelling read
// operations.
type cancelReadCloser struct {
cancel func()
pR *io.PipeReader // Stream to read from
pW *io.PipeWriter
}
// NewCancelReadCloser creates a wrapper that closes the ReadCloser when the
// context is cancelled. The returned io.ReadCloser must be closed when it is
// no longer needed.
func NewCancelReadCloser(ctx context.Context, in io.ReadCloser) io.ReadCloser {
pR, pW := io.Pipe()
// Create a context used to signal when the pipe is closed
doneCtx, cancel := context.WithCancel(context.Background())
p := &cancelReadCloser{
cancel: cancel,
pR: pR,
pW: pW,
}
go func() {
_, err := io.Copy(pW, in)
select {
case <-ctx.Done():
// If the context was closed, p.closeWithError
// was already called. Calling it again would
// change the error that Read returns.
default:
p.closeWithError(err)
}
in.Close()
}()
go func() {
for {
select {
case <-ctx.Done():
p.closeWithError(ctx.Err())
case <-doneCtx.Done():
return
}
}
}()
return p
}
// Read wraps the Read method of the pipe that provides data from the wrapped
// ReadCloser.
func (p *cancelReadCloser) Read(buf []byte) (n int, err error) {
return p.pR.Read(buf)
}
// closeWithError closes the wrapper and its underlying reader. It will
// cause future calls to Read to return err.
func (p *cancelReadCloser) closeWithError(err error) {
p.pW.CloseWithError(err)
p.cancel()
}
// Close closes the wrapper its underlying reader. It will cause
// future calls to Read to return io.EOF.
func (p *cancelReadCloser) Close() error {
p.closeWithError(io.EOF)
return nil
}
|
