make PL_perlio an array of PerlIOl, not PerlIO *

Layers in PerlIO are implemented as a linked list of PerlIOl structs;
eaxch one has a 'next' field pointing to the next layer. Now here's the
clever bit: When PerlIO* pointers are passed around to refer to a
particular handle, these are actually pointers to the 'next' field of the
*parent* layer (so to access the flags field say of a PerlIOl, you have to
double-defref it, e.g. (*f)->flags). The big advantage of this is that
it's easy for a layer to pop itself; when you call PerlIO_pop(f), f is a
pointer to the parent's 'next' field, so pop(f) can just do
*f = (*f)->next.

This means that there has to be a fake 'next' field above the topmost
layer. This is where PL_perlio comes in: it's a pointer to an arena of
arrays of pointers, each one capable of pointing to a PerlIOl structure.
When  a new handle is created, a spare arena slot is grabbed, and the
address of that slot is returned. This also allows for a handle with no
layers.

What this commit does is change PL_perlio from being an array of
PerlIO* into an array of PerlIOl structures - i.e. each element in the
array goes from being a single pointer, to having several fields. These
will be made used of in follow-up commits.

1 files changed, 1 insertions, 1 deletions

diff --git a/perliol.h b/perliol.h
index 6b714bb6ef..d3053a1067 100644
--- a/perliol.h
+++ b/perliol.h
@@ -150,7 +150,7 @@ PERL_EXPORT_C PerlIO_funcs *PerlIO_layer_fetch(pTHX_ PerlIO_list_t *av, IV n, Pe
 
 
 PERL_EXPORT_C SV *PerlIO_sv_dup(pTHX_ SV *arg, CLONE_PARAMS *param);
-PERL_EXPORT_C void PerlIO_cleantable(pTHX_ PerlIO **tablep);
+PERL_EXPORT_C void PerlIO_cleantable(pTHX_ PerlIOl **tablep);
 PERL_EXPORT_C SV * PerlIO_tab_sv(pTHX_ PerlIO_funcs *tab);
 PERL_EXPORT_C void PerlIO_default_buffer(pTHX_ PerlIO_list_t *av);
 PERL_EXPORT_C void PerlIO_stdstreams(pTHX);