restructured the project to comply community guideline, for others check release note

internal/utils/io.go

@@ -0,0 +1,127 @@
+package utils
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"io"
+	"os"
+	"syscall"
+
+	E "github.com/yusing/go-proxy/internal/error"
+)
+
+// TODO: move to "utils/io"
+type (
+	FileReader struct {
+		Path string
+	}
+
+	ContextReader struct {
+		ctx context.Context
+		io.Reader
+	}
+
+	ContextWriter struct {
+		ctx context.Context
+		io.Writer
+	}
+
+	Pipe struct {
+		r      ContextReader
+		w      ContextWriter
+		ctx    context.Context
+		cancel context.CancelFunc
+	}
+
+	BidirectionalPipe struct {
+		pSrcDst *Pipe
+		pDstSrc *Pipe
+	}
+)
+
+func (r *ContextReader) Read(p []byte) (int, error) {
+	select {
+	case <-r.ctx.Done():
+		return 0, r.ctx.Err()
+	default:
+		return r.Reader.Read(p)
+	}
+}
+
+func (w *ContextWriter) Write(p []byte) (int, error) {
+	select {
+	case <-w.ctx.Done():
+		return 0, w.ctx.Err()
+	default:
+		return w.Writer.Write(p)
+	}
+}
+
+func NewPipe(ctx context.Context, r io.ReadCloser, w io.WriteCloser) *Pipe {
+	_, cancel := context.WithCancel(ctx)
+	return &Pipe{
+		r:      ContextReader{ctx: ctx, Reader: r},
+		w:      ContextWriter{ctx: ctx, Writer: w},
+		ctx:    ctx,
+		cancel: cancel,
+	}
+}
+
+func (p *Pipe) Start() (err error) {
+	err = Copy(&p.w, &p.r)
+	switch {
+	case
+		// NOTE: ignoring broken pipe and connection reset by peer
+		errors.Is(err, syscall.EPIPE),
+		errors.Is(err, syscall.ECONNRESET):
+		return nil
+	}
+	return err
+}
+
+func NewBidirectionalPipe(ctx context.Context, rw1 io.ReadWriteCloser, rw2 io.ReadWriteCloser) BidirectionalPipe {
+	return BidirectionalPipe{
+		pSrcDst: NewPipe(ctx, rw1, rw2),
+		pDstSrc: NewPipe(ctx, rw2, rw1),
+	}
+}
+
+func NewBidirectionalPipeIntermediate(ctx context.Context, listener io.ReadCloser, client io.ReadWriteCloser, target io.ReadWriteCloser) *BidirectionalPipe {
+	return &BidirectionalPipe{
+		pSrcDst: NewPipe(ctx, listener, client),
+		pDstSrc: NewPipe(ctx, client, target),
+	}
+}
+
+func (p BidirectionalPipe) Start() error {
+	errCh := make(chan error, 2)
+	go func() {
+		errCh <- p.pSrcDst.Start()
+	}()
+	go func() {
+		errCh <- p.pDstSrc.Start()
+	}()
+	return E.JoinE("bidirectional pipe error", <-errCh, <-errCh).Error()
+}
+
+func Copy(dst *ContextWriter, src *ContextReader) error {
+	_, err := io.Copy(dst, src)
+	return err
+}
+
+func LoadJson[T any](path string, pointer *T) E.NestedError {
+	data, err := E.Check(os.ReadFile(path))
+	if err.HasError() {
+		return err
+	}
+	return E.From(json.Unmarshal(data, pointer))
+}
+
+func SaveJson[T any](path string, pointer *T, perm os.FileMode) E.NestedError {
+	data, err := E.Check(json.Marshal(pointer))
+	if err.HasError() {
+		return err
+	}
+	return E.From(os.WriteFile(path, data, perm))
+}