Class Local

invoke/runners.py:1234–1431

Execute a command on the local system in a subprocess. .. note:: When Invoke itself is executed without a controlling terminal (e.g. when ``sys.stdin`` lacks a useful ``fileno``), it's not possible to present a handle on our PTY to local subprocesses. In such situat

class Local(Runner):
    """
    Execute a command on the local system in a subprocess.

    .. note::
        When Invoke itself is executed without a controlling terminal (e.g.
        when ``sys.stdin`` lacks a useful ``fileno``), it's not possible to
        present a handle on our PTY to local subprocesses. In such situations,
        `Local` will fallback to behaving as if ``pty=False`` (on the theory
        that degraded execution is better than none at all) as well as printing
        a warning to stderr.

        To disable this behavior, say ``fallback=False``.

    .. versionadded:: 1.0
    """

    def __init__(self, context: "Context") -> None:
        super().__init__(context)
        # Bookkeeping var for pty use case
        self.status = 0

    def should_use_pty(self, pty: bool = False, fallback: bool = True) -> bool:
        use_pty = False
        if pty:
            use_pty = True
            # TODO: pass in & test in_stream, not sys.stdin
            if not has_fileno(sys.stdin) and fallback:
                if not self.warned_about_pty_fallback:
                    err = "WARNING: stdin has no fileno; falling back to non-pty execution!\n"  # noqa
                    sys.stderr.write(err)
                    self.warned_about_pty_fallback = True
                use_pty = False
        return use_pty

    def read_proc_stdout(self, num_bytes: int) -> Optional[bytes]:
        # Obtain useful read-some-bytes function
        if self.using_pty:
            # Need to handle spurious OSErrors on some Linux platforms.
            try:
                data = os.read(self.parent_fd, num_bytes)
            except OSError as e:
                # Only eat I/O specific OSErrors so we don't hide others
                stringified = str(e)
                io_errors = (
                    # The typical default
                    "Input/output error",
                    # Some less common platforms phrase it this way
                    "I/O error",
                )
                if not any(error in stringified for error in io_errors):
                    raise
                # The bad OSErrors happen after all expected output has
                # appeared, so we return a falsey value, which triggers the
                # "end of output" logic in code using reader functions.
                data = None
        elif self.process and self.process.stdout:
            data = os.read(self.process.stdout.fileno(), num_bytes)