qemu_nbd_pipe() currently unconditionally reads qemu-nbd's output. That
is not ideal because qemu-nbd may keep stderr open after the parent
process has exited.
Currently, the only user of qemu_nbd_pipe() is 147, which discards the
whole output if the parent process returned success and only evaluates
it on error. Therefore, we can replace qemu_nbd_pipe() by
qemu_nbd_early_pipe() that does the same: Discard the output on success,
and return it on error.
Signed-off-by: Max Reitz
---
tests/qemu-iotests/147| 4 ++--
tests/qemu-iotests/iotests.py | 9 ++---
2 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/tests/qemu-iotests/147 b/tests/qemu-iotests/147
index 82513279b0..2d84fddb01 100755
--- a/tests/qemu-iotests/147
+++ b/tests/qemu-iotests/147
@@ -24,7 +24,7 @@ import socket
import stat
import time
import iotests
-from iotests import cachemode, imgfmt, qemu_img, qemu_nbd, qemu_nbd_pipe
+from iotests import cachemode, imgfmt, qemu_img, qemu_nbd, qemu_nbd_early_pipe
NBD_PORT_START = 32768
NBD_PORT_END= NBD_PORT_START + 1024
@@ -93,7 +93,7 @@ class QemuNBD(NBDBlockdevAddBase):
pass
def _try_server_up(self, *args):
-status, msg = qemu_nbd_pipe('-f', imgfmt, test_img, *args)
+status, msg = qemu_nbd_early_pipe('-f', imgfmt, test_img, *args)
if status == 0:
return True
if 'Address already in use' in msg:
diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index f811f69135..ce21d83182 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -204,9 +204,9 @@ def qemu_nbd(*args):
'''Run qemu-nbd in daemon mode and return the parent's exit code'''
return subprocess.call(qemu_nbd_args + ['--fork'] + list(args))
-def qemu_nbd_pipe(*args):
+def qemu_nbd_early_pipe(*args):
'''Run qemu-nbd in daemon mode and return both the parent's exit code
- and its output'''
+ and its output in case of an error'''
subp = subprocess.Popen(qemu_nbd_args + ['--fork'] + list(args),
stdout=subprocess.PIPE,
stderr=subprocess.STDOUT,
@@ -216,7 +216,10 @@ def qemu_nbd_pipe(*args):
sys.stderr.write('qemu-nbd received signal %i: %s\n' %
(-exitcode,
' '.join(qemu_nbd_args + ['--fork'] + list(args
-return exitcode, subp.communicate()[0]
+if exitcode == 0:
+return exitcode, ''
+else:
+return exitcode, subp.communicate()[0]
def compare_images(img1, img2, fmt1=imgfmt, fmt2=imgfmt):
'''Return True if two image files are identical'''
--
2.20.1
