Update vendor/

vendor/github.com/emersion/go-imap/backend/backendutil/body.go

@@ -0,0 +1,68 @@
+package backendutil
+
+import (
+	"bytes"
+	"errors"
+	"io"
+
+	"github.com/emersion/go-imap"
+	"github.com/emersion/go-message"
+)
+
+var errNoSuchPart = errors.New("backendutil: no such message body part")
+
+// FetchBodySection extracts a body section from a message.
+func FetchBodySection(e *message.Entity, section *imap.BodySectionName) (imap.Literal, error) {
+	// First, find the requested part using the provided path
+	for i := len(section.Path) - 1; i >= 0; i-- {
+		n := section.Path[i]
+
+		mr := e.MultipartReader()
+		if mr == nil {
+			return nil, errNoSuchPart
+		}
+
+		for j := 1; j <= n; j++ {
+			p, err := mr.NextPart()
+			if err == io.EOF {
+				return nil, errNoSuchPart
+			} else if err != nil {
+				return nil, err
+			}
+
+			if j == n {
+				e = p
+				break
+			}
+		}
+	}
+
+	// Then, write the requested data to a buffer
+	b := new(bytes.Buffer)
+
+	// Write the header
+	mw, err := message.CreateWriter(b, e.Header)
+	if err != nil {
+		return nil, err
+	}
+	defer mw.Close()
+
+	// If the header hasn't been requested, discard it
+	if section.Specifier == imap.TextSpecifier {
+		b.Reset()
+	}
+
+	// Write the body, if requested
+	switch section.Specifier {
+	case imap.EntireSpecifier, imap.TextSpecifier:
+		if _, err := io.Copy(mw, e.Body); err != nil {
+			return nil, err
+		}
+	}
+
+	var l imap.Literal = b
+	if section.Partial != nil {
+		l = bytes.NewReader(section.ExtractPartial(b.Bytes()))
+	}
+	return l, nil
+}