[20.10] Revert "Ignore SIGURG on Linux."

This reverts commit 3c87f01.

This commit introduced two regressions;

- spurious "Unsupported signal: <nil>. Discarding."
- docker start --attach hanging if the container does not
  have a TTY attached

Reverting for now, while we dug deeper into what's causing
the regression.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/command/container/attach.go

@@ -97,8 +97,7 @@ func runAttach(dockerCli command.Cli, opts *attachOptions) error {
 	}
 
 	if opts.proxy && !c.Config.Tty {
-		sigc := notfiyAllSignals()
-		go ForwardAllSignals(ctx, dockerCli, opts.container, sigc)
+		sigc := ForwardAllSignals(ctx, dockerCli, opts.container)
 		defer signal.StopCatch(sigc)
 	}
 

cli/command/container/client_test.go

@@ -32,7 +32,6 @@ type fakeClient struct {
 	containerExportFunc     func(string) (io.ReadCloser, error)
 	containerExecResizeFunc func(id string, options types.ResizeOptions) error
 	containerRemoveFunc     func(ctx context.Context, container string, options types.ContainerRemoveOptions) error
-	containerKillFunc       func(ctx context.Context, container, signal string) error
 	Version                 string
 }
 
@@ -155,10 +154,3 @@ func (f *fakeClient) ContainerExecResize(_ context.Context, id string, options t
 	}
 	return nil
 }
-
-func (f *fakeClient) ContainerKill(ctx context.Context, container, signal string) error {
-	if f.containerKillFunc != nil {
-		return f.containerKillFunc(ctx, container, signal)
-	}
-	return nil
-}

cli/command/container/run.go

@@ -131,8 +131,7 @@ func runContainer(dockerCli command.Cli, opts *runOptions, copts *containerOptio
 		return runStartContainerErr(err)
 	}
 	if opts.sigProxy {
-		sigc := notfiyAllSignals()
-		go ForwardAllSignals(ctx, dockerCli, createResponse.ID, sigc)
+		sigc := ForwardAllSignals(ctx, dockerCli, createResponse.ID)
 		defer signal.StopCatch(sigc)
 	}
 

cli/command/container/start.go

@@ -74,8 +74,7 @@ func runStart(dockerCli command.Cli, opts *startOptions) error {
 
 		// We always use c.ID instead of container to maintain consistency during `docker start`
 		if !c.Config.Tty {
-			sigc := notfiyAllSignals()
-			ForwardAllSignals(ctx, dockerCli, c.ID, sigc)
+			sigc := ForwardAllSignals(ctx, dockerCli, c.ID)
 			defer signal.StopCatch(sigc)
 		}
 

cli/command/container/tty.go

@@ -95,3 +95,32 @@ func MonitorTtySize(ctx context.Context, cli command.Cli, id string, isExec bool
 	}
 	return nil
 }
+
+// ForwardAllSignals forwards signals to the container
+func ForwardAllSignals(ctx context.Context, cli command.Cli, cid string) chan os.Signal {
+	sigc := make(chan os.Signal, 128)
+	signal.CatchAll(sigc)
+	go func() {
+		for s := range sigc {
+			if s == signal.SIGCHLD || s == signal.SIGPIPE {
+				continue
+			}
+			var sig string
+			for sigStr, sigN := range signal.SignalMap {
+				if sigN == s {
+					sig = sigStr
+					break
+				}
+			}
+			if sig == "" {
+				fmt.Fprintf(cli.Err(), "Unsupported signal: %v. Discarding.\n", s)
+				continue
+			}
+
+			if err := cli.Client().ContainerKill(ctx, cid, sig); err != nil {
+				logrus.Debugf("Error sending signal: %s", err)
+			}
+		}
+	}()
+	return sigc
+}