go mod tidy

go.mod

@@ -1,7 +1,8 @@
 module github.com/mazrean/formstream
 
-go 1.21.5
-toolchain go1.22.5
+go 1.22
+
+toolchain go1.23.0
 
 require go.uber.org/mock v0.5.0
 

multipart/processor.go

@@ -0,0 +1,78 @@
+package multipart
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"mime/multipart"
+	"strings"
+	"sync"
+)
+
+type processor struct {
+	*multipart.Reader
+	valueMap map[string][]string
+	fileMap  map[string][]*FileHeader
+}
+
+func newProcessor(r *multipart.Reader) *processor {
+	return &processor{
+		Reader:   r,
+		valueMap: make(map[string][]string),
+	}
+}
+
+var bufPool = sync.Pool{
+	New: func() interface{} {
+		return new(bytes.Buffer)
+	},
+}
+
+func (p *processor) readValue(name string) []string {
+	if values, ok := p.valueMap[name]; ok {
+		return values
+	}
+
+	part, err := p.readUntilField(name)
+	if err != nil {
+		return nil
+	}
+	defer part.Close()
+
+	if part == nil {
+		return nil
+	}
+
+	sb := strings.Builder{}
+	if _, err := io.Copy(&sb, part); err != nil {
+		return nil
+	}
+
+	return []string{sb.String()}
+}
+
+func (p *processor) readUntilField(name string) (*multipart.Part, error) {
+	buf, ok := bufPool.Get().(*bytes.Buffer)
+	if !ok {
+		buf = new(bytes.Buffer)
+	}
+	buf.Reset()
+
+	for {
+		part, err := p.NextPart()
+		if err != nil {
+			if errors.Is(err, io.EOF) {
+				return nil, nil
+			}
+			return nil, err
+		}
+
+		if part.FormName() == name {
+			return part, nil
+		}
+
+		if _, err := buf.ReadFrom(part); err != nil {
+			return nil, err
+		}
+	}
+}

multipart/reader.go

@@ -0,0 +1,48 @@
+package multipart
+
+import (
+	"io"
+	"mime/multipart"
+	"net/textproto"
+)
+
+type Reader struct {
+	*multipart.Reader
+}
+
+func NewReader(r io.Reader, boundary string) *Reader {
+	return &Reader{
+		Reader: multipart.NewReader(r, boundary),
+	}
+}
+
+func (r *Reader) ReadForm(maxMemory int64) (*Form, error) {
+	return &Form{
+		processor: newProcessor(r.Reader),
+	}, nil
+}
+
+type Form struct {
+	processor *processor
+}
+
+func (f *Form) Value(name string) ([]string, bool) {
+	return f.processor.readValue(name)
+}
+
+func (f *Form) File(name string) []*FileHeader
+
+type FileHeader struct {
+	Filename string
+	Header   textproto.MIMEHeader
+	Size     int64
+}
+
+func (fh *FileHeader) Open() (File, error)
+
+type File interface {
+	io.Reader
+	io.ReaderAt
+	io.Seeker
+	io.Closer
+}