Make Win32 errors visible to callers

This makes hcsError public so that callers can inspect the internal
error and check it against certain known Win32 error codes.

createprocess.go

@@ -48,10 +48,9 @@ func makeOpenFiles(hs []syscall.Handle) (_ []io.ReadWriteCloser, err error) {
 // CreateProcessInComputeSystem starts a process in a container. This is invoked, for example,
 // as a result of docker run, docker exec, or RUN in Dockerfile. If successful,
 // it returns the PID of the process.
-func CreateProcessInComputeSystem(id string, useStdin bool, useStdout bool, useStderr bool, params CreateProcessParams) (_ uint32, _ io.WriteCloser, _ io.ReadCloser, _ io.ReadCloser, hr uint32, err error) {
+func CreateProcessInComputeSystem(id string, useStdin bool, useStdout bool, useStderr bool, params CreateProcessParams) (_ uint32, _ io.WriteCloser, _ io.ReadCloser, _ io.ReadCloser, err error) {
 	title := "HCSShim::CreateProcessInComputeSystem"
 	logrus.Debugf(title+" id=%s", id)
-	hr = 0xFFFFFFFF
 
 	// If we are not emulating a console, ignore any console size passed to us
 	if !params.EmulateConsole {
@@ -82,14 +81,13 @@ func CreateProcessInComputeSystem(id string, useStdin bool, useStdout bool, useS
 
 	err = createProcessWithStdHandlesInComputeSystem(id, string(paramsJson), &pid, stdinParam, stdoutParam, stderrParam)
 	if err != nil {
-		winerr := makeErrorf(err, title, "id=%s params=%v", id, params)
-		hr = winerr.HResult()
+		herr := makeErrorf(err, title, "id=%s params=%v", id, params)
+		err = herr
 		// Windows TP4: Hyper-V Containers may return this error with more than one
 		// concurrent exec. Do not log it as an error
-		if hr != Win32InvalidArgument {
-			logrus.Error(winerr)
+		if herr.Err != WSAEINVAL {
+			logrus.Error(err)
 		}
-		err = winerr
 		return
 	}
 
@@ -99,5 +97,5 @@ func CreateProcessInComputeSystem(id string, useStdin bool, useStdout bool, useS
 	}
 
 	logrus.Debugf(title+" - succeeded id=%s params=%s pid=%d", id, paramsJson, pid)
-	return pid, pipes[0], pipes[1], pipes[2], 0, nil
+	return pid, pipes[0], pipes[1], pipes[2], nil
 }

hcsshim.go

@@ -43,47 +43,52 @@ const (
 	// Specific user-visible exit codes
 	WaitErrExecFailed = 32767
 
-	// Known Win32 RC values which should be trapped
-	Win32PipeHasBeenEnded                 = 0x8007006d // WaitForProcessInComputeSystem: The pipe has been ended
-	Win32SystemShutdownIsInProgress       = 0x8007045B // ShutdownComputeSystem: A system shutdown is in progress
-	Win32SpecifiedPathInvalid             = 0x800700A1 // ShutdownComputeSystem: The specified path is invalid
-	Win32SystemCannotFindThePathSpecified = 0x80070003 // ShutdownComputeSystem: The system cannot find the path specified
-	Win32InvalidArgument                  = 0x80072726 // CreateProcessInComputeSystem: An invalid argument was supplied
-	EFail                                 = 0x80004005
+	ERROR_GEN_FAILURE          = syscall.Errno(31)
+	ERROR_SHUTDOWN_IN_PROGRESS = syscall.Errno(1115)
+	WSAEINVAL                  = syscall.Errno(10022)
 
 	// Timeout on wait calls
 	TimeoutInfinite = 0xFFFFFFFF
 )
 
-type hcsError struct {
+type HcsError struct {
 	title string
 	rest  string
-	err   error
+	Err   error
 }
 
-type Win32Error interface {
-	error
-	HResult() uint32
+func makeError(err error, title, rest string) *HcsError {
+	if hr, ok := err.(syscall.Errno); ok {
+		// Convert the HRESULT to a Win32 error code so that it better matches
+		// error codes returned from go and other packages.
+		err = syscall.Errno(win32FromHresult(uint32(hr)))
+	}
+	return &HcsError{title, rest, err}
 }
 
-func makeError(err error, title, rest string) Win32Error {
-	return &hcsError{title, rest, err}
+func makeErrorf(err error, title, format string, a ...interface{}) *HcsError {
+	return makeError(err, title, fmt.Sprintf(format, a...))
 }
 
-func makeErrorf(err error, title, format string, a ...interface{}) Win32Error {
-	return makeError(err, title, fmt.Sprintf(format, a...))
+func win32FromError(err error) uint32 {
+	if herr, ok := err.(*HcsError); ok {
+		return win32FromError(herr.Err)
+	}
+	if code, ok := err.(syscall.Errno); ok {
+		return win32FromHresult(uint32(code))
+	}
+	return uint32(ERROR_GEN_FAILURE)
 }
 
-func (e *hcsError) HResult() uint32 {
-	if hr, ok := e.err.(syscall.Errno); ok {
-		return uint32(hr)
-	} else {
-		return EFail
+func win32FromHresult(hr uint32) uint32 {
+	if hr&0x1fff0000 == 0x00070000 {
+		return hr & 0xffff
 	}
+	return hr
 }
 
-func (e *hcsError) Error() string {
-	return fmt.Sprintf("%s- Win32 API call returned error r1=0x%x err=%s%s", e.title, e.HResult(), e.err, e.rest)
+func (e *HcsError) Error() string {
+	return fmt.Sprintf("%s- Win32 API call returned error r1=0x%x err=%s%s", e.title, win32FromError(e.Err), e.Err, e.rest)
 }
 
 func convertAndFreeCoTaskMemString(buffer *uint16) string {

shutdownterminatecomputesystem.go

@@ -3,19 +3,19 @@ package hcsshim
 import "github.com/Sirupsen/logrus"
 
 // TerminateComputeSystem force terminates a container.
-func TerminateComputeSystem(id string, timeout uint32, context string) (uint32, error) {
+func TerminateComputeSystem(id string, timeout uint32, context string) error {
 	return shutdownTerminate(false, id, timeout, context)
 }
 
 // ShutdownComputeSystem shuts down a container by requesting a shutdown within
 // the container operating system.
-func ShutdownComputeSystem(id string, timeout uint32, context string) (uint32, error) {
+func ShutdownComputeSystem(id string, timeout uint32, context string) error {
 	return shutdownTerminate(true, id, timeout, context)
 }
 
 // shutdownTerminate is a wrapper for ShutdownComputeSystem and TerminateComputeSystem
 // which have very similar calling semantics
-func shutdownTerminate(shutdown bool, id string, timeout uint32, context string) (uint32, error) {
+func shutdownTerminate(shutdown bool, id string, timeout uint32, context string) error {
 
 	var (
 		title = "HCSShim::"
@@ -35,10 +35,9 @@ func shutdownTerminate(shutdown bool, id string, timeout uint32, context string)
 	}
 
 	if err != nil {
-		err := makeErrorf(err, title, "id=%s context=%s", id, context)
-		return err.HResult(), err
+		return makeErrorf(err, title, "id=%s context=%s", id, context)
 	}
 
 	logrus.Debugf(title+" succeeded id=%s context=%s", id, context)
-	return 0, nil
+	return nil
 }

waitprocess.go

@@ -3,19 +3,18 @@ package hcsshim
 import "github.com/Sirupsen/logrus"
 
 // WaitForProcessInComputeSystem waits for a process ID to terminate and returns
-// the exit code. Returns exitcode, errno, error
-func WaitForProcessInComputeSystem(id string, processid uint32, timeout uint32) (int32, uint32, error) {
+// the exit code. Returns exitcode, error
+func WaitForProcessInComputeSystem(id string, processid uint32, timeout uint32) (int32, error) {
 
 	title := "HCSShim::WaitForProcessInComputeSystem"
 	logrus.Debugf(title+" id=%s processid=%d", id, processid)
 
 	var exitCode uint32
 	err := waitForProcessInComputeSystem(id, processid, timeout, &exitCode)
 	if err != nil {
-		err := makeErrorf(err, title, "id=%s", id)
-		return 0, err.HResult(), err
+		return 0, makeErrorf(err, title, "id=%s", id)
 	}
 
 	logrus.Debugf(title+" succeeded id=%s processid=%d exitcode=%d", id, processid, exitCode)
-	return int32(exitCode), 0, nil
+	return int32(exitCode), nil
 }