Libguestfs - Oct 2021 - [PATCH libnbd 1/2] golang/tests: Retry syscall.Select on EINTR

- Retry interrupted syscall.Select()
- Verify LibnbdError.Errno value

Nir Soffer (2):
  golang/tests: Retry syscall.Select on EINTR
  golang/tests: Test expected Errno

 .../src/libguestfs.org/libnbd/libnbd_590_aio_copy_test.go  | 7 ++++++-
 golang/src/libguestfs.org/libnbd/libnbd_610_error_test.go  | 7 +++----
 2 files changed, 9 insertions(+), 5 deletions(-)

-- 
2.31.1

Go syscall package does not handle EINTR like higher level packages, so
we need to handle it when using syscall.Select().

The test always fails when running:

    $ GOLANG=go pkg=libguestfs.org/libnbd ./run-tests.sh
    ...
    === RUN   Test590AioCopy
        libnbd_590_aio_copy_test.go:160: select: interrupted system call

Strangely, it never fails when running "make check".

Signed-off-by: Nir Soffer <nsoffer at redhat.com>
---
 .../src/libguestfs.org/libnbd/libnbd_590_aio_copy_test.go  | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/golang/src/libguestfs.org/libnbd/libnbd_590_aio_copy_test.go
b/golang/src/libguestfs.org/libnbd/libnbd_590_aio_copy_test.go
index d566e6b..ed7aed4 100644
--- a/golang/src/libguestfs.org/libnbd/libnbd_590_aio_copy_test.go
+++ b/golang/src/libguestfs.org/libnbd/libnbd_590_aio_copy_test.go
@@ -155,7 +155,12 @@ func asynch_copy(t *testing.T, src *Libnbd, dst *Libnbd) {
 		if dir_is_write(dst) {
 			fdset_set(&wfds, dfd)
 		}
-		_, err = syscall.Select(nfd, &rfds, &wfds, nil, nil)
+		for {
+			_, err = syscall.Select(nfd, &rfds, &wfds, nil, nil)
+			if err != syscall.EINTR {
+				break
+			}
+		}
 		if err != nil {
 			t.Fatalf("select: %s", err)
 		}
-- 
2.31.1

Use type assertion[1] to convert err to the concrete LibnbdError so we
can verify the expected Errno. The assertion will panic if err is not a
LibnbdError.

[1] https://tour.golang.org/methods/15

Signed-off-by: Nir Soffer <nsoffer at redhat.com>
---
 golang/src/libguestfs.org/libnbd/libnbd_610_error_test.go | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/golang/src/libguestfs.org/libnbd/libnbd_610_error_test.go
b/golang/src/libguestfs.org/libnbd/libnbd_610_error_test.go
index 27540ce..0f81e76 100644
--- a/golang/src/libguestfs.org/libnbd/libnbd_610_error_test.go
+++ b/golang/src/libguestfs.org/libnbd/libnbd_610_error_test.go
@@ -18,7 +18,7 @@
 
 package libnbd
 
-import "fmt"
+import "syscall"
 import "testing"
 
 func Test610Error(t *testing.T) {
@@ -34,8 +34,7 @@ func Test610Error(t *testing.T) {
 	err = h.Pread(buf, 0, nil)
 	if err == nil {
 		t.Fatalf("expected an error from operation")
+	} else if err.(*LibnbdError).Errno != syscall.ENOTCONN {
+		t.Fatalf("unexpected error: %s", err)
 	}
-	fmt.Printf("error = %s\n", err)
-	/* XXX We expect the errno to be ENOTCONN, but I couldn't work
-	   out how to test it. */
 }
-- 
2.31.1