vendor: add gomega/gbytes and gomega/gexec

vendor/github.com/onsi/gomega/gexec/prefixed_writer.go

@@ -0,0 +1,53 @@
+package gexec
+
+import (
+	"io"
+	"sync"
+)
+
+/*
+PrefixedWriter wraps an io.Writer, emiting the passed in prefix at the beginning of each new line.
+This can be useful when running multiple gexec.Sessions concurrently - you can prefix the log output of each
+session by passing in a PrefixedWriter:
+
+gexec.Start(cmd, NewPrefixedWriter("[my-cmd] ", GinkgoWriter), NewPrefixedWriter("[my-cmd] ", GinkgoWriter))
+*/
+type PrefixedWriter struct {
+	prefix        []byte
+	writer        io.Writer
+	lock          *sync.Mutex
+	atStartOfLine bool
+}
+
+func NewPrefixedWriter(prefix string, writer io.Writer) *PrefixedWriter {
+	return &PrefixedWriter{
+		prefix:        []byte(prefix),
+		writer:        writer,
+		lock:          &sync.Mutex{},
+		atStartOfLine: true,
+	}
+}
+
+func (w *PrefixedWriter) Write(b []byte) (int, error) {
+	w.lock.Lock()
+	defer w.lock.Unlock()
+
+	toWrite := []byte{}
+
+	for _, c := range b {
+		if w.atStartOfLine {
+			toWrite = append(toWrite, w.prefix...)
+		}
+
+		toWrite = append(toWrite, c)
+
+		w.atStartOfLine = c == '\n'
+	}
+
+	_, err := w.writer.Write(toWrite)
+	if err != nil {
+		return 0, err
+	}
+
+	return len(b), nil
+}