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iotests.py: Do not wait() before communicate()

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Waiting on a process for which we have a pipe will stall if the process
outputs more data than fits into the OS-provided buffer.  We must use
communicate() before wait(), and in fact, communicate() perfectly
replaces wait() already.

We have to drop the stderr=subprocess.STDOUT parameter from
subprocess.Popen() in qemu_nbd_early_pipe(), because stderr is passed on
to the child process, so if we do not drop this parameter, communicate()
will hang (because the pipe is not closed).

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200630083711.40567-1-mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Max Reitz 2020-06-30 10:37:11 +02:00 committed by Kevin Wolf
parent 3dfa23b9ef
commit 49438972b8
1 changed files with 17 additions and 17 deletions
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34
tests/qemu-iotests/iotests.py
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@ -146,11 +146,12 @@ def qemu_img_pipe(*args):
stdout=subprocess.PIPE,
stderr=subprocess.STDOUT,
universal_newlines=True)
exitcode = subp.wait()
if exitcode < 0:
output = subp.communicate()[0]
if subp.returncode < 0:
sys.stderr.write('qemu-img received signal %i: %s\n'
% (-exitcode, ' '.join(qemu_img_args + list(args))))
return subp.communicate()[0]
% (-subp.returncode,
' '.join(qemu_img_args + list(args))))
return output
def qemu_img_log(*args):
result = qemu_img_pipe(*args)
@ -177,11 +178,11 @@ def qemu_io(*args):
subp = subprocess.Popen(args, stdout=subprocess.PIPE,
stderr=subprocess.STDOUT,
universal_newlines=True)
exitcode = subp.wait()
if exitcode < 0:
output = subp.communicate()[0]
if subp.returncode < 0:
sys.stderr.write('qemu-io received signal %i: %s\n'
% (-exitcode, ' '.join(args)))
return subp.communicate()[0]
% (-subp.returncode, ' '.join(args)))
return output
def qemu_io_log(*args):
result = qemu_io(*args)
@ -257,15 +258,14 @@ def qemu_nbd_early_pipe(*args):
and its output in case of an error'''
subp = subprocess.Popen(qemu_nbd_args + ['--fork'] + list(args),
stdout=subprocess.PIPE,
stderr=subprocess.STDOUT,
universal_newlines=True)
exitcode = subp.wait()
if exitcode < 0:
output = subp.communicate()[0]
if subp.returncode < 0:
sys.stderr.write('qemu-nbd received signal %i: %s\n' %
(-exitcode,
(-subp.returncode,
' '.join(qemu_nbd_args + ['--fork'] + list(args))))
return exitcode, subp.communicate()[0] if exitcode else ''
return subp.returncode, output if subp.returncode else ''
def qemu_nbd_popen(*args):
'''Run qemu-nbd in daemon mode and return the parent's exit code'''
@ -1062,11 +1062,11 @@ def qemu_pipe(*args):
subp = subprocess.Popen(args, stdout=subprocess.PIPE,
stderr=subprocess.STDOUT,
universal_newlines=True)
exitcode = subp.wait()
if exitcode < 0:
output = subp.communicate()[0]
if subp.returncode < 0:
sys.stderr.write('qemu received signal %i: %s\n' %
(-exitcode, ' '.join(args)))
return subp.communicate()[0]
(-subp.returncode, ' '.join(args)))
return output
def supported_formats(read_only=False):
'''Set 'read_only' to True to check ro-whitelist