Python errno 模块，ESPIPE 实例源码

def __init__(self, input, size=None, **args):
        if not hasattr(input, "seek"):
            if size is None:
                input = InputPipe(input, self._setSize)
            else:
                input = InputPipe(input)
        elif size is None:
            try:
                input.seek(0, 2)
                size = input.tell() * 8
            except IOError as err:
                if err.errno == ESPIPE:
                    input = InputPipe(input, self._setSize)
                else:
                    source = args.get("source", "<inputio:%r>" % input)
                    raise InputStreamError(
                        "Unable to get size of %s: %s" % (source, err))
        self._input = input
        InputStream.__init__(self, size=size, **args)

def __init__(self, input, size=None, **args):
        if not hasattr(input, "seek"):
            if size is None:
                input = InputPipe(input, self._setSize)
            else:
                input = InputPipe(input)
        elif size is None:
            try:
                input.seek(0, 2)
                size = input.tell() * 8
            except IOError, err:
                if err.errno == ESPIPE:
                    input = InputPipe(input, self._setSize)
                else:
                    charset = getTerminalCharset()
                    errmsg = unicode(str(err), charset)
                    source = args.get("source", "<inputio:%r>" % input)
                    raise InputStreamError(_("Unable to get size of %s: %s") % (source, errmsg))
        self._input = input
        InputStream.__init__(self, size=size, **args)

def try_seek(fd, offset):
    try:
        if offset is None:
            os.lseek(fd, 0, os.SEEK_END)
        elif offset >= 0:
            os.lseek(fd, offset, os.SEEK_SET)
        else:
            os.lseek(fd, offset, os.SEEK_END)
    except OSError as ose:
        if ose.args[0] != errno.ESPIPE:
            raise

def seekable(self):
        if self._seekable is None:
            try:
                _original_os.lseek(self._fileno, 0, _original_os.SEEK_CUR)
            except IOError as e:
                if get_errno(e) == errno.ESPIPE:
                    self._seekable = False
                else:
                    raise
            else:
                self._seekable = True

        return self._seekable

def seekable(self):
        if self._seekable is None:
            try:
                _original_os.lseek(self._fileno, 0, _original_os.SEEK_CUR)
            except IOError as e:
                if get_errno(e) == errno.ESPIPE:
                    self._seekable = False
                else:
                    raise
            else:
                self._seekable = True

        return self._seekable

def _get_file_size(self, obj):
        """Analyze file-like object and attempt to determine its size.

        :param obj: file-like object, typically redirected from stdin.
        :retval The file's size or None if it cannot be determined.
        """
        # For large images, we need to supply the size of the
        # image file. See LP Bugs #827660 and #845788.
        if hasattr(obj, 'seek') and hasattr(obj, 'tell'):
            try:
                obj.seek(0, os.SEEK_END)
                obj_size = obj.tell()
                obj.seek(0)
                return obj_size
            except IOError as e:
                if e.errno == errno.ESPIPE:
                    # Illegal seek. This means the user is trying
                    # to pipe image data to the client, e.g.
                    # echo testdata | bin/glance add blah..., or
                    # that stdin is empty, or that a file-like
                    # object which doesn't support 'seek/tell' has
                    # been supplied.
                    return None
                else:
                    raise
        else:
            # Cannot determine size of input image
            return None