[Libguestfs] [libnbd PATCH v2 1/5] python: tests: Fix error handling

Like a 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 dies with an assertion failure now if completion callback fails. Tested with the temporary patch of: | diff --git i/python/t/590-aio-copy.py w/python/t/590-aio-copy.py | index 861fa6c8..4cd64d83 100644 | --- i/python/t/590-aio-copy.py | +++ w/python/t/590-aio-copy.py | @@ -117,7 +117,8 @@ src.set_handle_name("src") | dst = nbd.NBD() | dst.set_handle_name("dst") | src.connect_command(["nbdkit", "-s", "--exit-with-parent", "-r", | - "pattern", "size=%d" % disk_size]) | + "--filter=error", "pattern", "error-pread-rate=1", | + "size=%d" % disk_size]) | dst.connect_command(["nbdkit", "-s", "--exit-with-parent", | "memory", "size=%d" % disk_size]) | asynch_copy(src, dst) --- python/t/590-aio-copy.py | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/python/t/590-aio-copy.py b/python/t/590-aio-copy.py index 6cde5934..861fa6c8 100644 --- a/python/t/590-aio-copy.py +++ b/python/t/590-aio-copy.py @@ -1,5 +1,5 @@ # libnbd Python bindings -# Copyright (C) 2010-2019 Red Hat Inc. +# Copyright (C) 2010-2022 Red Hat Inc. # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by @@ -36,6 +36,7 @@ def asynch_copy(src, dst): # This callback is called when any pread from the source # has completed. def read_completed(buf, offset, error): + assert not error global bytes_read bytes_read += buf.size() wr = (buf, offset) @@ -46,6 +47,7 @@ def asynch_copy(src, dst): # This callback is called when any pwrite to the destination # has completed. def write_completed(buf, error): + assert not error global bytes_written bytes_written += buf.size() # By returning 1 here we auto-retire the pwrite command. -- 2.34.1