Initial commit

util/io.go

@@ -0,0 +1,36 @@
+package util
+
+import (
+	"io"
+)
+
+// A reader that waits for any unavailable bytes to become available for
+// reading.  This means that it will always wait until it can fill the entire
+// `[]byte` when `Read()` is called, as long as no error occurs.
+type WaitReader struct {
+	r io.Reader
+}
+
+func NewWaitReader(r io.Reader) WaitReader {
+	return WaitReader{
+		r: r,
+	}
+}
+
+func (r WaitReader) Read(p []byte) (int, error) {
+	var n int // Total number of bytes read.
+	for {
+		// Reattempt to read the unread bytes until we can fill `p` completely
+		// (or an error occurs).
+		nNew, err := r.r.Read(p[n:len(p)])
+		n += nNew
+		if err != nil {
+			return n, err
+		}
+		// Break when we have read enough bytes.
+		if n == len(p) {
+			break
+		}
+	}
+	return n, nil
+}