popen and exit code on Windows

[Giovanni Bajo]

iker.arizmendi at gmail.com wrote:

> On UNIX one can use popen* to get a pipe for reading, a pipe for
> writing, and the exit code of the child process via a call to close()
> on the last pipe. Is there any way, in principle, to simulate such
> behaviour on Windows? Some googling reveals that direct use of the
> popen* functions on Windows will not do the trick, but are there
> indirect ways?

This is well-tested:

def launch(cmd, split_lines=True):
    """Launch a sub-process. Return its output (both stdout and stderr),
    optionally split by lines (if split_lines is True). Raise a LaunchError
    exception if the exit code of the process is non-zero (failure)."""
    if os.name not in ['nt', 'os2']:
        p = popen2.Popen4(cmd)
        p.tochild.close()
        if split_lines:
            out = p.fromchild.readlines()
        else:
            out = p.fromchild.read()
        ret = p.wait()
        if ret == 0:
            ret = None
        else:
            ret >>= 8
    else:
        i,k = os.popen4(cmd)
        i.close()
        if split_lines:
            out = k.readlines()
        else:
            out = k.read()
        ret = k.close()

    if ret is None:
        return out
    raise LaunchError(ret, cmd, out)

-- 
Giovanni Bajo