Adding upstream version 3.6.2.

Signed-off-by: Daniel Baumann <daniel@debian.org>

splitter.go

@@ -0,0 +1,65 @@
+package mailyak
+
+import (
+	"io"
+)
+
+const maxLineLen = 60
+
+// lineSplitter breaks the given input into lines of maxLineLen characters
+// before writing a "\r\n" newline
+type lineSplitter struct {
+	w      io.Writer
+	wrote  uint
+	maxLen int
+}
+
+type lineSplitterBuilder struct{}
+
+func (b lineSplitterBuilder) new(w io.Writer) io.Writer {
+	return &lineSplitter{w: w, maxLen: maxLineLen}
+}
+
+func (w *lineSplitter) Write(p []byte) (int, error) {
+	// Calculate the previously wrote line length
+	leftover := w.wrote % uint(w.maxLen)
+
+	// Calculate the amount of bytes remaining for this line
+	lineSize := w.maxLen - int(leftover)
+
+	// Break p into chunks
+	for i := 0; i < len(p); i += lineSize {
+
+		// Reset linesize
+		if i%w.maxLen != 0 && lineSize < w.maxLen {
+			lineSize = w.maxLen
+		}
+
+		// Calculate the end of the chunk offset
+		end := i + lineSize
+		if end > len(p) {
+			end = len(p)
+		}
+
+		// Slice chunk out of p
+		chunk := p[i:end]
+		// Increment the amount wrote so far by the chunk size
+		w.wrote += uint(len(chunk))
+
+		// Write the chunk
+		if n, err := w.w.Write(chunk); err != nil {
+			return i + n, err
+		}
+
+		// If this finishes a line, add linebreaks
+		if end == i+lineSize {
+			if _, err := w.w.Write([]byte("\r\n")); err != nil {
+				// If this errors, return the bytes wrote so far from the
+				// caller's perspective (it is unaware newlines are being added)
+				return i + len(chunk), err
+			}
+		}
+	}
+
+	return len(p), nil
+}