transcode.py 文件源码

def run_pipeline(cmds):
    # The Python executable (and its children) ignore SIGPIPE. (See
    # http://bugs.python.org/issue1652) Our subprocesses need to see
    # it.
    sigpipe_handler = signal.signal(signal.SIGPIPE, signal.SIG_DFL)
    stdin = None
    last_proc = None
    procs = []
    try:
        for cmd in cmds:
            proc = subprocess.Popen(shlex.split(cmd), stdin=stdin, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
            if last_proc:
                # Ensure last_proc receives SIGPIPE if proc exits first
                last_proc.stdout.close()
            procs.append(proc)
            stdin = proc.stdout
            last_proc = proc
    finally:
        signal.signal(signal.SIGPIPE, sigpipe_handler)

    last_stderr = last_proc.communicate()[1]

    results = []
    for (cmd, proc) in zip(cmds[:-1], procs[:-1]):
        # wait() is OK here, despite use of PIPE above; these procs
        # are finished.
        proc.wait()
        results.append((proc.returncode, proc.stderr.read()))
    results.append((last_proc.returncode, last_stderr))
    return results