Commit 49438972 authored by Max Reitz's avatar Max Reitz Committed by Kevin Wolf
Browse files

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



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: default avatarMax Reitz <mreitz@redhat.com>
Message-Id: <20200630083711.40567-1-mreitz@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 3dfa23b9

tests/qemu-iotests/iotests.py

+17 −17
Original line number Diff line number Diff line
@@ -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