Libguestfs - Feb 2022 - [PATCH libnbd] golang: tests: Fix error handling

Like lot of the C examples, the aio copy test ignores read and write
errors in the completion callback, which can cause silent data
corruption. The failure in the test is not critical, but this is a bad
example that may be copied by developers to a real application.

The test panics now if completion callback fails, similar to other Go
examples.

Signed-off-by: Nir Soffer <nsoffer at redhat.com>
---
 golang/libnbd_590_aio_copy_test.go | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/golang/libnbd_590_aio_copy_test.go
b/golang/libnbd_590_aio_copy_test.go
index 570635c9..8be0ad2d 100644
--- a/golang/libnbd_590_aio_copy_test.go
+++ b/golang/libnbd_590_aio_copy_test.go
@@ -99,33 +99,41 @@ func asynch_copy(t *testing.T, src *Libnbd, dst *Libnbd) {
 		   source then do it now. */
 		if soff < size && src_in_flight < max_reads_in_flight {
 			n := bs
 			if n > size-soff {
 				n = size - soff
 			}
 			buf := MakeAioBuffer(uint(n))
 			soff_copy := soff
 			var optargs AioPreadOptargs
 			optargs.CompletionCallbackSet = true
-			optargs.CompletionCallback = func(*int) int {
+			optargs.CompletionCallback = func(error *int) int {
+				if *error != 0 {
+					err := syscall.Errno(*error).Error()
+					panic(err)
+				}
 				return read_completed(buf, soff_copy)
 			}
 			src.AioPread(buf, soff, &optargs)
 			soff += n
 		}
 
 		/* If there are any write commands waiting to
 		   be issued, send them now. */
 		for _, wb := range writes {
 			var optargs AioPwriteOptargs
 			optargs.CompletionCallbackSet = true
-			optargs.CompletionCallback = func(*int) int {
+			optargs.CompletionCallback = func(error *int) int {
+				if *error != 0 {
+					err := syscall.Errno(*error).Error()
+					panic(err)
+				}
 				return write_completed(wb.buf)
 			}
 			dst.AioPwrite(wb.buf, wb.offset, &optargs)
 		}
 		writes = writes[:0]
 
 		/* Now poll the file descriptors. */
 		nfd := 1
 		sfd, err := src.AioGetFd()
 		if err != nil {
-- 
2.34.1

On Thu, Feb 03, 2022 at 08:07:52PM +0200, Nir Soffer
wrote:
> Like lot of the C examples, the aio copy test ignores read and write
> errors in the completion callback, which can cause silent data
> corruption. The failure in the test is not critical, but this is a bad
> example that may be copied by developers to a real application.
> 
> The test panics now if completion callback fails, similar to other Go
> examples.
> 
> Signed-off-by: Nir Soffer <nsoffer at redhat.com>
> ---
>  golang/libnbd_590_aio_copy_test.go | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
ACK.

python/t/590-aio-copy.py and ocaml/tests/test_490_aio_copy.ml need the
same treatment.  I'll post that with my v2 of the CVE fix.

(It's nice that we've tried to share the same test numbers across
language bindings - it makes it a bit easier where we copy the same
coding paradigms across different languages)

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org