Perhaps someone with a bit more familiarity with the Parrot IO subsystem
could give me some guidance here. I'm currently trying to get a new
'peek' opcode working, and I'm having difficulties getting the io_unix
layer implemented correctly.
As far as I know, I'd get a call down into the io_unix layer when the
ParrotIO object isn't buffered. What I want to be able to do is to
read()/fread() a character off of the io->fd filedescriptor, copy it into
the buffer, then ungetc() it back onto the stream. Unfortunately,
however, ungetc requires a (FILE *), while the ParrotIO object carries
around only a raw file descriptor (I think).
I've seen some instances where people will cast the raw descriptor to a
(FILE *), however the man page for ungetc warns ominously in its BUGS
section that:
It is not advisable to mix calls to input functions from
the stdio library with low - level calls to read() for the
file descriptor associated with the input stream; the
results will be undefined and very probably not what you
want.
Numerous segfaults would seem to confirm that this is indeed very probably
not what I want.
That being said, what is the best course for buffering such characters at
the io_unix layer? I apparently am not able to use the standard library
functions to do so (additionally, they only guarantee that you can peek
and replace a single character).
-c
