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...

This will allow us to poke character devices, and named pipes created
with mkfifo.