Implement new style readline and the slow fallback

embed.fnc

@@ -3342,6 +3342,8 @@ Apdh	|SSize_t|PerlIO_read		|NULLOK PerlIO *f|NN void *vbuf \
 					|Size_t count
 Apdh	|SSize_t|PerlIO_write		|NULLOK PerlIO *f|NN const void *vbuf \
 					|Size_t count
+Ap	|SSize_t|PerlIO_readdelim	|NULLOK PerlIO *f|NN STDCHAR *vbuf \
+					|Size_t count|STDCHAR delim
 Ap	|SSize_t|PerlIO_unread		|NULLOK PerlIO *f|NN const void *vbuf \
 					|Size_t count
 Apdh	|Off_t	|PerlIO_tell		|NULLOK PerlIO *f

embed.h

@@ -912,6 +912,7 @@
 #define PerlIO_get_cnt(a)	Perl_PerlIO_get_cnt(aTHX_ a)
 #define PerlIO_get_ptr(a)	Perl_PerlIO_get_ptr(aTHX_ a)
 #define PerlIO_read(a,b,c)	Perl_PerlIO_read(aTHX_ a,b,c)
+#define PerlIO_readdelim(a,b,c,d)	Perl_PerlIO_readdelim(aTHX_ a,b,c,d)
 #define PerlIO_seek(a,b,c)	Perl_PerlIO_seek(aTHX_ a,b,c)
 #define PerlIO_set_cnt(a,b)	Perl_PerlIO_set_cnt(aTHX_ a,b)
 #define PerlIO_set_ptrcnt(a,b,c)	Perl_PerlIO_set_ptrcnt(aTHX_ a,b,c)

perlio.c

@@ -1583,6 +1583,14 @@ Perl_PerlIO_read(pTHX_ PerlIO *f, void *vbuf, Size_t count)
      Perl_PerlIO_or_Base(f, Read, read, -1, (aTHX_ f, vbuf, count));
 }
 
+SSize_t
+Perl_PerlIO_readdelim(pTHX_ PerlIO*f, STDCHAR* vbuf, Size_t count, STDCHAR delim)
+{
+     PERL_ARGS_ASSERT_PERLIO_READDELIM;
+
+     Perl_PerlIO_or_Base(f, Readdelim, readdelim, -1, (aTHX_ f, vbuf, count, delim));
+}
+
 SSize_t
 Perl_PerlIO_unread(pTHX_ PerlIO *f, const void *vbuf, Size_t count)
 {
@@ -2115,6 +2123,20 @@ PerlIOBase_read(pTHX_ PerlIO *f, void *vbuf, Size_t count)
     return 0;
 }
 
+SSize_t
+PerlIOBase_readdelim(pTHX_ PerlIO* f, STDCHAR* buffer, Size_t count, STDCHAR delim)
+{
+   /*The slow and stupid way. */
+    const STDCHAR * const bpe = buffer + count;
+    STDCHAR *bp = buffer;
+    int i;
+    while ((i = PerlIO_getc(f)) != EOF && (*bp++ = (STDCHAR)i) != delim && bp < bpe)
+        ; /* keep reading */
+    if (bp - buffer == 0 && PerlIO_error(f))
+        return -1;
+    return bp - buffer;
+}
+
 IV
 PerlIOBase_noop_ok(pTHX_ PerlIO *f)
 {

perliol.h

@@ -49,6 +49,7 @@ struct _PerlIO_funcs {
     STDCHAR *(*Get_ptr) (pTHX_ PerlIO *f);
      SSize_t(*Get_cnt) (pTHX_ PerlIO *f);
     void (*Set_ptrcnt) (pTHX_ PerlIO *f, STDCHAR * ptr, SSize_t cnt);
+    IV (*Readdelim) (pTHX_ PerlIO* f, STDCHAR* buffer, Size_t count, STDCHAR delim);
 };
 
 /*--------------------------------------------------------------------------------------*/
@@ -187,6 +188,7 @@ PERL_CALLCONV IV        PerlIOBase_popped(pTHX_ PerlIO *f);
 PERL_CALLCONV IV        PerlIOBase_pushed(pTHX_ PerlIO *f, const char *mode, SV *arg, PerlIO_funcs *tab);
 PERL_CALLCONV PerlIO *  PerlIOBase_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);
 PERL_CALLCONV SSize_t   PerlIOBase_read(pTHX_ PerlIO *f, void *vbuf, Size_t count);
+PERL_CALLCONV SSize_t   PerlIOBase_readdelim(pTHX_ PerlIO *f, STDCHAR *vbuf, Size_t count, STDCHAR delim);
 PERL_CALLCONV void      PerlIOBase_setlinebuf(pTHX_ PerlIO *f);
 PERL_CALLCONV SSize_t   PerlIOBase_unread(pTHX_ PerlIO *f, const void *vbuf, Size_t count);
 

proto.h

@@ -6869,6 +6869,9 @@ PERL_CALLCONV STDCHAR *	Perl_PerlIO_get_ptr(pTHX_ PerlIO *f);
 PERL_CALLCONV SSize_t	Perl_PerlIO_read(pTHX_ PerlIO *f, void *vbuf, Size_t count);
 #define PERL_ARGS_ASSERT_PERLIO_READ	\
 	assert(vbuf)
+PERL_CALLCONV SSize_t	Perl_PerlIO_readdelim(pTHX_ PerlIO *f, STDCHAR *vbuf, Size_t count, STDCHAR delim);
+#define PERL_ARGS_ASSERT_PERLIO_READDELIM	\
+	assert(vbuf)
 PERL_CALLCONV void	Perl_PerlIO_restore_errno(pTHX_ PerlIO *f);
 #define PERL_ARGS_ASSERT_PERLIO_RESTORE_ERRNO
 PERL_CALLCONV void	Perl_PerlIO_save_errno(pTHX_ PerlIO *f);