Re: [PATCH 2/2] ios: Introduce IO stream device for stdin, stdout, stderr.

[Jose E. Marchesi]

    >      +static char *
    >      +ios_dev_stream_handler_normalize (const char *handler)
    >      +{
    >      +  if (strcmp (handler, "stdin")
    >      +      && strcmp (handler, "stdout")
    >      +      && strcmp (handler, "stderr"))
    >      +    return NULL;
    >      +
    >      +  return strdup (handler);
    >      +}
    >
    > I think we should introduce a new flag to use in ios_open,
    > IOS_F_STREAM.  This way, ios_open can do the following:
    >
    > - If IOS_M_RDONLY & IOS_F_STREAM -> Use the stream IOD to open the given
    >    filename.
    >
    > - If IOS_M_WRONLY & IOS_F_STREAM -> Use the stream IOD to open the given
    >    filename.
    >
    > At the Poke level this translates to:
    >
    > open ("foo/bar", IOS_F_STREAM & IOS_M_RDONLY)
    >   -> Open the file foo/bar as a read-only stream.
    >
    > open ("foo/bar", IOS_F_STREAM & IOS_M_WRONLY)
    >   -> Open the file foo/bar as a write-only stream.
    >
    > open ("foo/bar", IOS_F_STREAM & IOS_M_RDWR)
    >   -> ERROR.  Not possible to open a stream for both read and write.
    >
    > This means that handler of the stream IOD won't ever be used, so it can
    > just return NULL in all cases...
    
    The filename is the handler, right? So "foo/bar" in this case. Plus,
    it is used in .info ios too.
    Also, if handler_normalize returns NULL, that is a rejection of the
    handler by that IO device. It would eventually be opened as a regular
    file.

Yeah, the filename is the handler.  I forgot the interface.

Since the stream IOD operates on files reachable in the filesystem, I
would use exactly the same normalization than ios-dev-file.  So we need
to factor the code currently in ios_dev_file_handler_normalize into a
function that can be also used by ios_dev_stream_handler_normalize...
    
    > This will allow us to poke character devices, and named pipes created
    > with mkfifo.
    
    Right, I can add the flag IOS_F_STREAM. I need to check if they are
    read and written to differently. Assuming it wouldn't be too
    complicated, I can add the support for them too.

Thanks!