helper: export internal stub functions for cross-package testing

Signed-off-by: Ophestra Umiker <cat@ophivana.moe>

1 files changed, 90 insertions, 0 deletions

diff --git a/helper/stub.go b/helper/stub.go
new file mode 100644
index 00000000..32dc11e9
--- /dev/null
+++ b/helper/stub.go
@@ -0,0 +1,90 @@
+package helper
+
+import (
+	"io"
+	"os"
+	"os/exec"
+	"strconv"
+	"syscall"
+	"testing"
+)
+
+// InternalChildStub is an internal function but exported because it is cross-package;
+// it is part of the implementation of the helper stub.
+func InternalChildStub() {
+	// this test mocks the helper process
+	if os.Getenv(FortifyHelper) != "1" {
+		return
+	}
+
+	// simulate args pipe behaviour
+	func() {
+		f := os.NewFile(3, "|0")
+		if f == nil {
+			panic("attempted to start helper without args pipe")
+		}
+
+		if _, err := io.Copy(os.Stdout, f); err != nil {
+			panic("cannot read args: " + err.Error())
+		}
+	}()
+
+	var wait chan struct{}
+
+	// simulate status pipe behaviour
+	if os.Getenv(FortifyStatus) == "1" {
+		wait = make(chan struct{})
+		go func() {
+			f := os.NewFile(4, "|1")
+			if f == nil {
+				panic("attempted to start with status reporting without status pipe")
+			}
+
+			if _, err := f.Write([]byte{'x'}); err != nil {
+				panic("cannot write to status pipe: " + err.Error())
+			}
+
+			// wait for status pipe close
+			var epoll int
+			if fd, err := syscall.EpollCreate1(0); err != nil {
+				panic("cannot open epoll fd: " + err.Error())
+			} else {
+				defer func() {
+					if err = syscall.Close(fd); err != nil {
+						panic("cannot close epoll fd: " + err.Error())
+					}
+				}()
+				epoll = fd
+			}
+			if err := syscall.EpollCtl(epoll, syscall.EPOLL_CTL_ADD, int(f.Fd()), &syscall.EpollEvent{}); err != nil {
+				panic("cannot add status pipe to epoll: " + err.Error())
+			}
+			events := make([]syscall.EpollEvent, 1)
+			if _, err := syscall.EpollWait(epoll, events, -1); err != nil {
+				panic("cannot poll status pipe: " + err.Error())
+			}
+			if events[0].Events != syscall.EPOLLERR {
+				panic(strconv.Itoa(int(events[0].Events)))
+
+			}
+			close(wait)
+		}()
+	}
+
+	if wait != nil {
+		<-wait
+	}
+}
+
+// InternalReplaceExecCommand is an internal function but exported because it is cross-package;
+// it is part of the implementation of the helper stub.
+func InternalReplaceExecCommand(t *testing.T) {
+	t.Cleanup(func() {
+		execCommand = exec.Command
+	})
+
+	// replace execCommand to have the resulting *exec.Cmd launch TestHelperChildStub
+	execCommand = func(name string, arg ...string) *exec.Cmd {
+		return exec.Command(os.Args[0], append([]string{"-test.run=TestHelperChildStub", "--", name}, arg...)...)
+	}
+}