Improve APIv2 support for Attach

A few major fixes here:
- Support for attaching to Configured containers, to match Docker
  behavior.
- Support for stream parameter has been improved (we now properly
  handle cases where it is not set).
- Initial support for logs parameter has been added.
- Setting attach streams when the container has a terminal is now
  supported.
- Errors are properly reported once the hijack has begun.

Signed-off-by: Matthew Heon <mheon@redhat.com>

1 files changed, 27 insertions, 4 deletions

diff --git a/libpod/util.go b/libpod/util.go
index e9d234bbe..6457dac1c 100644
--- a/libpod/util.go
+++ b/libpod/util.go
@@ -2,6 +2,7 @@ package libpod
 
 import (
 	"bufio"
+	"encoding/binary"
 	"fmt"
 	"io"
 	"os"
@@ -239,11 +240,22 @@ func checkDependencyContainer(depCtr, ctr *Container) error {
 // hijackWriteErrorAndClose writes an error to a hijacked HTTP session and
 // closes it. Intended to HTTPAttach function.
 // If error is nil, it will not be written; we'll only close the connection.
-func hijackWriteErrorAndClose(toWrite error, cid string, httpCon io.Closer, httpBuf *bufio.ReadWriter) {
+func hijackWriteErrorAndClose(toWrite error, cid string, terminal bool, httpCon io.Closer, httpBuf *bufio.ReadWriter) {
 	if toWrite != nil {
-		if _, err := httpBuf.Write([]byte(toWrite.Error())); err != nil {
-			logrus.Errorf("Error writing error %q to container %s HTTP attach connection: %v", toWrite, cid, err)
-		} else if err := httpBuf.Flush(); err != nil {
+		errString := []byte(fmt.Sprintf("%v\n", toWrite))
+		if !terminal {
+			// We need a header.
+			header := makeHTTPAttachHeader(2, uint32(len(errString)))
+			if _, err := httpBuf.Write(header); err != nil {
+				logrus.Errorf("Error writing header for container %s attach connection error: %v", cid, err)
+			}
+			// TODO: May want to return immediately here to avoid
+			// writing garbage to the socket?
+		}
+		if _, err := httpBuf.Write(errString); err != nil {
+			logrus.Errorf("Error writing error to container %s HTTP attach connection: %v", cid, err)
+		}
+		if err := httpBuf.Flush(); err != nil {
 			logrus.Errorf("Error flushing HTTP buffer for container %s HTTP attach connection: %v", cid, err)
 		}
 	}
@@ -252,3 +264,14 @@ func hijackWriteErrorAndClose(toWrite error, cid string, httpCon io.Closer, http
 		logrus.Errorf("Error closing container %s HTTP attach connection: %v", cid, err)
 	}
 }
+
+// makeHTTPAttachHeader makes an 8-byte HTTP header for a buffer of the given
+// length and stream. Accepts an integer indicating which stream we are sending
+// to (STDIN = 0, STDOUT = 1, STDERR = 2).
+func makeHTTPAttachHeader(stream byte, length uint32) []byte {
+	headerBuf := []byte{stream, 0, 0, 0}
+	lenBuf := []byte{0, 0, 0, 0}
+	binary.BigEndian.PutUint32(lenBuf, length)
+	headerBuf = append(headerBuf, lenBuf...)
+	return headerBuf
+}