PerlIO Layer implementation future proofing.

 - Inspired by Nick C's suggestion add size of function table to the table
   as a validation check.
 - also optimize pseudo-layer code to avoid malloc/link of something
   destined to be immediately popped & freed.
 - Minor addition to pod/perliol.pod

p4raw-id: //depot/perlio@17330

1 files changed, 4 insertions, 3 deletions

diff --git a/perliol.h b/perliol.h
index 76d74a7abb..fa399e6f50 100644
--- a/perliol.h
+++ b/perliol.h
@@ -14,10 +14,11 @@ struct PerlIO_list_s {
 };
 
 struct _PerlIO_funcs {
+    Size_t fsize;
     char *name;
     Size_t size;
     U32 kind;
-    IV (*Pushed) (pTHX_ PerlIO *f, const char *mode, SV *arg);
+    IV (*Pushed) (pTHX_ PerlIO *f, const char *mode, SV *arg, PerlIO_funcs *tab);
     IV (*Popped) (pTHX_ PerlIO *f);
     PerlIO *(*Open) (pTHX_ PerlIO_funcs *tab,
 		     PerlIO_list_t *layers, IV n,
@@ -124,7 +125,7 @@ extern SV *PerlIO_arg_fetch(PerlIO_list_t *av, IV n);
 
 extern IV PerlIOBase_fileno(pTHX_ PerlIO *f);
 extern PerlIO *PerlIOBase_dup(pTHX_ PerlIO *f, PerlIO *o, CLONE_PARAMS *param, int flags);
-extern IV PerlIOBase_pushed(pTHX_ PerlIO *f, const char *mode, SV *arg);
+extern IV PerlIOBase_pushed(pTHX_ PerlIO *f, const char *mode, SV *arg, PerlIO_funcs *tab);
 extern IV PerlIOBase_popped(pTHX_ PerlIO *f);
 extern IV PerlIOBase_binmode(pTHX_ PerlIO *f);
 extern SSize_t PerlIOBase_read(pTHX_ PerlIO *f, void *vbuf, Size_t count);
@@ -168,7 +169,7 @@ extern PerlIO *PerlIOBuf_open(pTHX_ PerlIO_funcs *self,
 			      PerlIO_list_t *layers, IV n,
 			      const char *mode, int fd, int imode,
 			      int perm, PerlIO *old, int narg, SV **args);
-extern IV PerlIOBuf_pushed(pTHX_ PerlIO *f, const char *mode, SV *arg);
+extern IV PerlIOBuf_pushed(pTHX_ PerlIO *f, const char *mode, SV *arg, PerlIO_funcs *tab);
 extern IV PerlIOBuf_popped(pTHX_ PerlIO *f);
 extern PerlIO *PerlIOBuf_dup(pTHX_ PerlIO *f, PerlIO *o, CLONE_PARAMS *param, int flags);
 extern SSize_t PerlIOBuf_read(pTHX_ PerlIO *f, void *vbuf, Size_t count);