PerlIO layer table as PL_perlio (per-interpreter)

[perl5.git] / perlio.c

/*
 * perlio.c Copyright (c) 1996-2001, Nick Ing-Simmons You may distribute
 * under the terms of either the GNU General Public License or the
 * Artistic License, as specified in the README file.
 */

/*
 * If we have ActivePerl-like PERL_IMPLICIT_SYS then we need a dTHX to get
 * at the dispatch tables, even when we do not need it for other reasons.
 * Invent a dSYS macro to abstract this out
 */
#ifdef PERL_IMPLICIT_SYS
#define dSYS dTHX
#else
#define dSYS dNOOP
#endif

#define VOIDUSED 1
#ifdef PERL_MICRO
#   include "uconfig.h"
#else
#   include "config.h"
#endif

#define PERLIO_NOT_STDIO 0
#if !defined(PERLIO_IS_STDIO) && !defined(USE_SFIO)
/*
 * #define PerlIO FILE
 */
#endif
/*
 * This file provides those parts of PerlIO abstraction
 * which are not #defined in perlio.h.
 * Which these are depends on various Configure #ifdef's
 */

#include "EXTERN.h"
#define PERL_IN_PERLIO_C
#include "perl.h"

#include "XSUB.h"

int
perlsio_binmode(FILE *fp, int iotype, int mode)
{
    /*
     * This used to be contents of do_binmode in doio.c
     */
#ifdef DOSISH
#  if defined(atarist) || defined(__MINT__)
    if (!fflush(fp)) {
	if (mode & O_BINARY)
	    ((FILE *) fp)->_flag |= _IOBIN;
	else
	    ((FILE *) fp)->_flag &= ~_IOBIN;
	return 1;
    }
    return 0;
#  else
    dTHX;
#ifdef NETWARE
    if (PerlLIO_setmode(fp, mode) != -1) {
#else
    if (PerlLIO_setmode(fileno(fp), mode) != -1) {
#endif
#    if defined(WIN32) && defined(__BORLANDC__)
	/*
	 * The translation mode of the stream is maintained independent of
	 * the translation mode of the fd in the Borland RTL (heavy
	 * digging through their runtime sources reveal).  User has to set
	 * the mode explicitly for the stream (though they don't document
	 * this anywhere). GSAR 97-5-24
	 */
	fseek(fp, 0L, 0);
	if (mode & O_BINARY)
	    fp->flags |= _F_BIN;
	else
	    fp->flags &= ~_F_BIN;
#    endif
	return 1;
    }
    else
	return 0;
#  endif
#else
#  if defined(USEMYBINMODE)
    if (my_binmode(fp, iotype, mode) != FALSE)
	return 1;
    else
	return 0;
#  else
    return 1;
#  endif
#endif
}

#ifndef O_ACCMODE
#define O_ACCMODE 3		/* Assume traditional implementation */
#endif

int
PerlIO_intmode2str(int rawmode, char *mode, int *writing)
{
    int result = rawmode & O_ACCMODE;
    int ix = 0;
    int ptype;
    switch (result) {
    case O_RDONLY:
	ptype = IoTYPE_RDONLY;
	break;
    case O_WRONLY:
	ptype = IoTYPE_WRONLY;
	break;
    case O_RDWR:
    default:
	ptype = IoTYPE_RDWR;
	break;
    }
    if (writing)
	*writing = (result != O_RDONLY);

    if (result == O_RDONLY) {
	mode[ix++] = 'r';
    }
#ifdef O_APPEND
    else if (rawmode & O_APPEND) {
	mode[ix++] = 'a';
	if (result != O_WRONLY)
	    mode[ix++] = '+';
    }
#endif
    else {
	if (result == O_WRONLY)
	    mode[ix++] = 'w';
	else {
	    mode[ix++] = 'r';
	    mode[ix++] = '+';
	}
    }
    if (rawmode & O_BINARY)
	mode[ix++] = 'b';
    mode[ix] = '\0';
    return ptype;
}

#ifndef PERLIO_LAYERS
int
PerlIO_apply_layers(pTHX_ PerlIO *f, const char *mode, const char *names)
{
    if (!names || !*names || strEQ(names, ":crlf") || strEQ(names, ":raw")) {
	return 0;
    }
    Perl_croak(aTHX_ "Cannot apply \"%s\" in non-PerlIO perl", names);
    /*
     * NOTREACHED
     */
    return -1;
}

void
PerlIO_destruct(pTHX)
{
}

int
PerlIO_binmode(pTHX_ PerlIO *fp, int iotype, int mode, const char *names)
{
#ifdef USE_SFIO
    return 1;
#else
    return perlsio_binmode(fp, iotype, mode);
#endif
}

PerlIO *
PerlIO_fdupopen(pTHX_ PerlIO *f, CLONE_PARAMS *param)
{
    if (f) {
	int fd = PerlLIO_dup(PerlIO_fileno(f));
	if (fd >= 0) {
	    char mode[8];
	    int omode = fcntl(fd, F_GETFL);
	    PerlIO_intmode2str(omode,mode,NULL);
	    /* the r+ is a hack */
	    return PerlIO_fdopen(fd, mode);
	}
	return NULL;
    }
    else {
	SETERRNO(EBADF, SS$_IVCHAN);
    }
    return NULL;
}


/*
 * De-mux PerlIO_openn() into fdopen, freopen and fopen type entries
 */

PerlIO *
PerlIO_openn(pTHX_ const char *layers, const char *mode, int fd,
	     int imode, int perm, PerlIO *old, int narg, SV **args)
{
    if (narg == 1) {
	if (*args == &PL_sv_undef)
	    return PerlIO_tmpfile();
	else {
	    char *name = SvPV_nolen(*args);
	    if (*mode == '#') {
		fd = PerlLIO_open3(name, imode, perm);
		if (fd >= 0)
		    return PerlIO_fdopen(fd, (char *) mode + 1);
	    }
	    else if (old) {
		return PerlIO_reopen(name, mode, old);
	    }
	    else {
		return PerlIO_open(name, mode);
	    }
	}
    }
    else {
	return PerlIO_fdopen(fd, (char *) mode);
    }
    return NULL;
}

XS(XS_PerlIO__Layer__find)
{
    dXSARGS;
    if (items < 2)
	Perl_croak(aTHX_ "Usage class->find(name[,load])");
    else {
	char *name = SvPV_nolen(ST(1));
	ST(0) = (strEQ(name, "crlf")
		 || strEQ(name, "raw")) ? &PL_sv_yes : &PL_sv_undef;
	XSRETURN(1);
    }
}


void
Perl_boot_core_PerlIO(pTHX)
{
    newXS("PerlIO::Layer::find", XS_PerlIO__Layer__find, __FILE__);
}

#endif


#ifdef PERLIO_IS_STDIO

void
PerlIO_init(void)
{
    /*
     * Does nothing (yet) except force this file to be included in perl
     * binary. That allows this file to force inclusion of other functions
     * that may be required by loadable extensions e.g. for
     * FileHandle::tmpfile
     */
}

#undef PerlIO_tmpfile
PerlIO *
PerlIO_tmpfile(void)
{
    return tmpfile();
}

#else				/* PERLIO_IS_STDIO */

#ifdef USE_SFIO

#undef HAS_FSETPOS
#undef HAS_FGETPOS

/*
 * This section is just to make sure these functions get pulled in from
 * libsfio.a
 */

#undef PerlIO_tmpfile
PerlIO *
PerlIO_tmpfile(void)
{
    return sftmp(0);
}

void
PerlIO_init(void)
{
    /*
     * Force this file to be included in perl binary. Which allows this
     * file to force inclusion of other functions that may be required by
     * loadable extensions e.g. for FileHandle::tmpfile
     */

    /*
     * Hack sfio does its own 'autoflush' on stdout in common cases. Flush
     * results in a lot of lseek()s to regular files and lot of small
     * writes to pipes.
     */
    sfset(sfstdout, SF_SHARE, 0);
}

PerlIO *
PerlIO_importFILE(FILE *stdio, int fl)
{
    int fd = fileno(stdio);
    PerlIO *r = PerlIO_fdopen(fd, "r+");
    return r;
}

FILE *
PerlIO_findFILE(PerlIO *pio)
{
    int fd = PerlIO_fileno(pio);
    FILE *f = fdopen(fd, "r+");
    PerlIO_flush(pio);
    if (!f && errno == EINVAL)
	f = fdopen(fd, "w");
    if (!f && errno == EINVAL)
	f = fdopen(fd, "r");
    return f;
}


#else				/* USE_SFIO */
/*======================================================================================*/
/*
 * Implement all the PerlIO interface ourselves.
 */

#include "perliol.h"

/*
 * We _MUST_ have <unistd.h> if we are using lseek() and may have large
 * files
 */
#ifdef I_UNISTD
#include <unistd.h>
#endif
#ifdef HAS_MMAP
#include <sys/mman.h>
#endif


void PerlIO_debug(const char *fmt, ...)
    __attribute__ ((format(__printf__, 1, 2)));

void
PerlIO_debug(const char *fmt, ...)
{
    static int dbg = 0;
    va_list ap;
    dSYS;
    va_start(ap, fmt);
    if (!dbg) {
	char *s = PerlEnv_getenv("PERLIO_DEBUG");
	if (s && *s)
	    dbg = PerlLIO_open3(s, O_WRONLY | O_CREAT | O_APPEND, 0666);
	else
	    dbg = -1;
    }
    if (dbg > 0) {
	dTHX;
#ifdef USE_ITHREADS
	/* Use fixed buffer as sv_catpvf etc. needs SVs */
	char buffer[1024];
	char *s;
	STRLEN len;
	s = CopFILE(PL_curcop);
	if (!s)
	    s = "(none)";
	sprintf(buffer, "%s:%" IVdf " ", s, (IV) CopLINE(PL_curcop));
        len = strlen(buffer);
	vsprintf(buffer+len, fmt, ap);
	PerlLIO_write(dbg, buffer, strlen(buffer));
#else
	SV *sv = newSVpvn("", 0);
	char *s;
	STRLEN len;
	s = CopFILE(PL_curcop);
	if (!s)
	    s = "(none)";
	Perl_sv_catpvf(aTHX_ sv, "%s:%" IVdf " ", s,
		       (IV) CopLINE(PL_curcop));
	Perl_sv_vcatpvf(aTHX_ sv, fmt, &ap);

	s = SvPV(sv, len);
	PerlLIO_write(dbg, s, len);
	SvREFCNT_dec(sv);
#endif
    }
    va_end(ap);
}

/*--------------------------------------------------------------------------------------*/

/*
 * Inner level routines
 */

/*
 * Table of pointers to the PerlIO structs (malloc'ed)
 */
#define PERLIO_TABLE_SIZE 64

PerlIO *
PerlIO_allocate(pTHX)
{
    /*
     * Find a free slot in the table, allocating new table as necessary
     */
    PerlIO **last;
    PerlIO *f;
    last = &PL_perlio;
    while ((f = *last)) {
	int i;
	last = (PerlIO **) (f);
	for (i = 1; i < PERLIO_TABLE_SIZE; i++) {
	    if (!*++f) {
		return f;
	    }
	}
    }
    f = PerlMemShared_calloc(PERLIO_TABLE_SIZE, sizeof(PerlIO));
    if (!f) {
	return NULL;
    }
    *last = f;
    return f + 1;
}

#undef PerlIO_fdupopen
PerlIO *
PerlIO_fdupopen(pTHX_ PerlIO *f, CLONE_PARAMS *param)
{
    if (f && *f) {
	PerlIO_funcs *tab = PerlIOBase(f)->tab;
	PerlIO *new;
	PerlIO_debug("fdupopen f=%p param=%p\n",f,param);
        new = (*tab->Dup)(aTHX_ PerlIO_allocate(aTHX),f,param);
	return new;
    }
    else {
	SETERRNO(EBADF, SS$_IVCHAN);
	return NULL;
    }
}

void
PerlIO_clone(pTHX_ PerlIO *proto, CLONE_PARAMS *param)
{
    PerlIO **table = &proto;
    PerlIO *f;
    PL_perlio = NULL;
    PerlIO_allocate(aTHX); /* root slot is never used */
    while ((f = *table)) {
	    int i;
	    table = (PerlIO **) (f++);
	    for (i = 1; i < PERLIO_TABLE_SIZE; i++) {
		if (*f) {
		    PerlIO_fdupopen(aTHX_ f, param);
		}
		f++;
	    }
	}
}

void
PerlIO_cleantable(pTHX_ PerlIO **tablep)
{
    PerlIO *table = *tablep;
    if (table) {
	int i;
	PerlIO_cleantable(aTHX_(PerlIO **) & (table[0]));
	for (i = PERLIO_TABLE_SIZE - 1; i > 0; i--) {
	    PerlIO *f = table + i;
	    if (*f) {
		PerlIO_close(f);
	    }
	}
	PerlMemShared_free(table);
	*tablep = NULL;
    }
}

PerlIO_list_t *PerlIO_known_layers;
PerlIO_list_t *PerlIO_def_layerlist;

PerlIO_list_t *
PerlIO_list_alloc(void)
{
    PerlIO_list_t *list;
    Newz('L', list, 1, PerlIO_list_t);
    list->refcnt = 1;
    return list;
}

void
PerlIO_list_free(PerlIO_list_t *list)
{
    if (list) {
	if (--list->refcnt == 0) {
	    if (list->array) {
		dTHX;
		IV i;
		for (i = 0; i < list->cur; i++) {
		    if (list->array[i].arg)
			SvREFCNT_dec(list->array[i].arg);
		}
		Safefree(list->array);
	    }
	    Safefree(list);
	}
    }
}

void
PerlIO_list_push(PerlIO_list_t *list, PerlIO_funcs *funcs, SV *arg)
{
    dTHX;
    PerlIO_pair_t *p;
    if (list->cur >= list->len) {
	list->len += 8;
	if (list->array)
	    Renew(list->array, list->len, PerlIO_pair_t);
	else
	    New('l', list->array, list->len, PerlIO_pair_t);
    }
    p = &(list->array[list->cur++]);
    p->funcs = funcs;
    if ((p->arg = arg)) {
	SvREFCNT_inc(arg);
    }
}


void
PerlIO_cleanup_layers(pTHX_ void *data)
{
#if 0
    PerlIO_known_layers = Nullhv;
    PerlIO_def_layerlist = Nullav;
#endif
}

void
PerlIO_cleanup()
{
    dTHX;
    PerlIO_cleantable(aTHX_ &PL_perlio);
}

void
PerlIO_destruct(pTHX)
{
    PerlIO **table = &PL_perlio;
    PerlIO *f;
    while ((f = *table)) {
	int i;
	table = (PerlIO **) (f++);
	for (i = 1; i < PERLIO_TABLE_SIZE; i++) {
	    PerlIO *x = f;
	    PerlIOl *l;
	    while ((l = *x)) {
		if (l->tab->kind & PERLIO_K_DESTRUCT) {
		    PerlIO_debug("Destruct popping %s\n", l->tab->name);
		    PerlIO_flush(x);
		    PerlIO_pop(aTHX_ x);
		}
		else {
		    x = PerlIONext(x);
		}
	    }
	    f++;
	}
    }
}

void
PerlIO_pop(pTHX_ PerlIO *f)
{
    PerlIOl *l = *f;
    if (l) {
	PerlIO_debug("PerlIO_pop f=%p %s\n", f, l->tab->name);
	if (l->tab->Popped) {
	    /*
	     * If popped returns non-zero do not free its layer structure
	     * it has either done so itself, or it is shared and still in
	     * use
	     */
	    if ((*l->tab->Popped) (f) != 0)
		return;
	}
	*f = l->next;;
	PerlMemShared_free(l);
    }
}

/*--------------------------------------------------------------------------------------*/
/*
 * XS Interface for perl code
 */

PerlIO_funcs *
PerlIO_find_layer(pTHX_ const char *name, STRLEN len, int load)
{
    IV i;
    if ((SSize_t) len <= 0)
	len = strlen(name);
    for (i = 0; i < PerlIO_known_layers->cur; i++) {
	PerlIO_funcs *f = PerlIO_known_layers->array[i].funcs;
	if (memEQ(f->name, name, len)) {
	    PerlIO_debug("%.*s => %p\n", (int) len, name, f);
	    return f;
	}
    }
    if (load && PL_subname && PerlIO_def_layerlist
	&& PerlIO_def_layerlist->cur >= 2) {
	SV *pkgsv = newSVpvn("PerlIO", 6);
	SV *layer = newSVpvn(name, len);
	ENTER;
	/*
	 * The two SVs are magically freed by load_module
	 */
	Perl_load_module(aTHX_ 0, pkgsv, Nullsv, layer, Nullsv);
	LEAVE;
	return PerlIO_find_layer(aTHX_ name, len, 0);
    }
    PerlIO_debug("Cannot find %.*s\n", (int) len, name);
    return NULL;
}

#ifdef USE_ATTRIBUTES_FOR_PERLIO

static int
perlio_mg_set(pTHX_ SV *sv, MAGIC *mg)
{
    if (SvROK(sv)) {
	IO *io = GvIOn((GV *) SvRV(sv));
	PerlIO *ifp = IoIFP(io);
	PerlIO *ofp = IoOFP(io);
	Perl_warn(aTHX_ "set %" SVf " %p %p %p", sv, io, ifp, ofp);
    }
    return 0;
}

static int
perlio_mg_get(pTHX_ SV *sv, MAGIC *mg)
{
    if (SvROK(sv)) {
	IO *io = GvIOn((GV *) SvRV(sv));
	PerlIO *ifp = IoIFP(io);
	PerlIO *ofp = IoOFP(io);
	Perl_warn(aTHX_ "get %" SVf " %p %p %p", sv, io, ifp, ofp);
    }
    return 0;
}

static int
perlio_mg_clear(pTHX_ SV *sv, MAGIC *mg)
{
    Perl_warn(aTHX_ "clear %" SVf, sv);
    return 0;
}

static int
perlio_mg_free(pTHX_ SV *sv, MAGIC *mg)
{
    Perl_warn(aTHX_ "free %" SVf, sv);
    return 0;
}

MGVTBL perlio_vtab = {
    perlio_mg_get,
    perlio_mg_set,
    NULL,			/* len */
    perlio_mg_clear,
    perlio_mg_free
};

XS(XS_io_MODIFY_SCALAR_ATTRIBUTES)
{
    dXSARGS;
    SV *sv = SvRV(ST(1));
    AV *av = newAV();
    MAGIC *mg;
    int count = 0;
    int i;
    sv_magic(sv, (SV *) av, PERL_MAGIC_ext, NULL, 0);
    SvRMAGICAL_off(sv);
    mg = mg_find(sv, PERL_MAGIC_ext);
    mg->mg_virtual = &perlio_vtab;
    mg_magical(sv);
    Perl_warn(aTHX_ "attrib %" SVf, sv);
    for (i = 2; i < items; i++) {
	STRLEN len;
	const char *name = SvPV(ST(i), len);
	SV *layer = PerlIO_find_layer(aTHX_ name, len, 1);
	if (layer) {
	    av_push(av, SvREFCNT_inc(layer));
	}
	else {
	    ST(count) = ST(i);
	    count++;
	}
    }
    SvREFCNT_dec(av);
    XSRETURN(count);
}

#endif				/* USE_ATTIBUTES_FOR_PERLIO */

SV *
PerlIO_tab_sv(pTHX_ PerlIO_funcs *tab)
{
    HV *stash = gv_stashpv("PerlIO::Layer", TRUE);
    SV *sv = sv_bless(newRV_noinc(newSViv(PTR2IV(tab))), stash);
    return sv;
}

XS(XS_PerlIO__Layer__find)
{
    dXSARGS;
    if (items < 2)
	Perl_croak(aTHX_ "Usage class->find(name[,load])");
    else {
	STRLEN len = 0;
	char *name = SvPV(ST(1), len);
	bool load = (items > 2) ? SvTRUE(ST(2)) : 0;
	PerlIO_funcs *layer = PerlIO_find_layer(aTHX_ name, len, load);
	ST(0) =
	    (layer) ? sv_2mortal(PerlIO_tab_sv(aTHX_ layer)) :
	    &PL_sv_undef;
	XSRETURN(1);
    }
}

void
PerlIO_define_layer(pTHX_ PerlIO_funcs *tab)
{
    if (!PerlIO_known_layers)
	PerlIO_known_layers = PerlIO_list_alloc();
    PerlIO_list_push(PerlIO_known_layers, tab, Nullsv);
    PerlIO_debug("define %s %p\n", tab->name, tab);
}

int
PerlIO_parse_layers(pTHX_ PerlIO_list_t *av, const char *names)
{
    if (names) {
	const char *s = names;
	while (*s) {
	    while (isSPACE(*s) || *s == ':')
		s++;
	    if (*s) {
		STRLEN llen = 0;
		const char *e = s;
		const char *as = Nullch;
		STRLEN alen = 0;
		if (!isIDFIRST(*s)) {
		    /*
		     * Message is consistent with how attribute lists are
		     * passed. Even though this means "foo : : bar" is
		     * seen as an invalid separator character.
		     */
		    char q = ((*s == '\'') ? '"' : '\'');
		    Perl_warn(aTHX_
			      "perlio: invalid separator character %c%c%c in layer specification list",
			      q, *s, q);
		    return -1;
		}
		do {
		    e++;
		} while (isALNUM(*e));
		llen = e - s;
		if (*e == '(') {
		    int nesting = 1;
		    as = ++e;
		    while (nesting) {
			switch (*e++) {
			case ')':
			    if (--nesting == 0)
				alen = (e - 1) - as;
			    break;
			case '(':
			    ++nesting;
			    break;
			case '\\':
			    /*
			     * It's a nul terminated string, not allowed
			     * to \ the terminating null. Anything other
			     * character is passed over.
			     */
			    if (*e++) {
				break;
			    }
			    /*
			     * Drop through
			     */
			case '\0':
			    e--;
			    Perl_warn(aTHX_
				      "perlio: argument list not closed for layer \"%.*s\"",
				      (int) (e - s), s);
			    return -1;
			default:
			    /*
			     * boring.
			     */
			    break;
			}
		    }
		}
		if (e > s) {
		    PerlIO_funcs *layer =
			PerlIO_find_layer(aTHX_ s, llen, 1);
		    if (layer) {
			PerlIO_list_push(av, layer,
					 (as) ? newSVpvn(as,
							 alen) :
					 &PL_sv_undef);
		    }
		    else {
			Perl_warn(aTHX_ "perlio: unknown layer \"%.*s\"",
				  (int) llen, s);
			return -1;
		    }
		}
		s = e;
	    }
	}
    }
    return 0;
}

void
PerlIO_default_buffer(pTHX_ PerlIO_list_t *av)
{
    PerlIO_funcs *tab = &PerlIO_perlio;
    if (O_BINARY != O_TEXT) {
	tab = &PerlIO_crlf;
    }
    else {
	if (PerlIO_stdio.Set_ptrcnt) {
	    tab = &PerlIO_stdio;
	}
    }
    PerlIO_debug("Pushing %s\n", tab->name);
    PerlIO_list_push(av, PerlIO_find_layer(aTHX_ tab->name, 0, 0),
		     &PL_sv_undef);
}

SV *
PerlIO_arg_fetch(PerlIO_list_t *av, IV n)
{
    return av->array[n].arg;
}

PerlIO_funcs *
PerlIO_layer_fetch(pTHX_ PerlIO_list_t *av, IV n, PerlIO_funcs *def)
{
    if (n >= 0 && n < av->cur) {
	PerlIO_debug("Layer %" IVdf " is %s\n", n,
		     av->array[n].funcs->name);
	return av->array[n].funcs;
    }
    if (!def)
	Perl_croak(aTHX_ "panic: PerlIO layer array corrupt");
    return def;
}

PerlIO_list_t *
PerlIO_default_layers(pTHX)
{
    if (!PerlIO_def_layerlist) {
	const char *s = (PL_tainting) ? Nullch : PerlEnv_getenv("PERLIO");
	PerlIO_funcs *osLayer = &PerlIO_unix;
	PerlIO_def_layerlist = PerlIO_list_alloc();
	PerlIO_define_layer(aTHX_ & PerlIO_unix);
#if defined(WIN32) && !defined(UNDER_CE)
	PerlIO_define_layer(aTHX_ & PerlIO_win32);
#if 0
	osLayer = &PerlIO_win32;
#endif
#endif
	PerlIO_define_layer(aTHX_ & PerlIO_raw);
	PerlIO_define_layer(aTHX_ & PerlIO_perlio);
	PerlIO_define_layer(aTHX_ & PerlIO_stdio);
	PerlIO_define_layer(aTHX_ & PerlIO_crlf);
#ifdef HAS_MMAP
	PerlIO_define_layer(aTHX_ & PerlIO_mmap);
#endif
	PerlIO_define_layer(aTHX_ & PerlIO_utf8);
	PerlIO_define_layer(aTHX_ & PerlIO_byte);
	PerlIO_list_push(PerlIO_def_layerlist,
			 PerlIO_find_layer(aTHX_ osLayer->name, 0, 0),
			 &PL_sv_undef);
	if (s) {
	    PerlIO_parse_layers(aTHX_ PerlIO_def_layerlist, s);
	}
	else {
	    PerlIO_default_buffer(aTHX_ PerlIO_def_layerlist);
	}
    }
    if (PerlIO_def_layerlist->cur < 2) {
	PerlIO_default_buffer(aTHX_ PerlIO_def_layerlist);
    }
    return PerlIO_def_layerlist;
}

void
Perl_boot_core_PerlIO(pTHX)
{
#ifdef USE_ATTRIBUTES_FOR_PERLIO
    newXS("io::MODIFY_SCALAR_ATTRIBUTES", XS_io_MODIFY_SCALAR_ATTRIBUTES,
	  __FILE__);
#endif
    newXS("PerlIO::Layer::find", XS_PerlIO__Layer__find, __FILE__);
}

PerlIO_funcs *
PerlIO_default_layer(pTHX_ I32 n)
{
    PerlIO_list_t *av = PerlIO_default_layers(aTHX);
    if (n < 0)
	n += av->cur;
    return PerlIO_layer_fetch(aTHX_ av, n, &PerlIO_stdio);
}

#define PerlIO_default_top() PerlIO_default_layer(aTHX_ -1)
#define PerlIO_default_btm() PerlIO_default_layer(aTHX_ 0)

void
PerlIO_stdstreams(pTHX)
{
    if (!PL_perlio) {
	PerlIO_allocate(aTHX);
	PerlIO_fdopen(0, "Ir" PERLIO_STDTEXT);
	PerlIO_fdopen(1, "Iw" PERLIO_STDTEXT);
	PerlIO_fdopen(2, "Iw" PERLIO_STDTEXT);
    }
}

PerlIO *
PerlIO_push(pTHX_ PerlIO *f, PerlIO_funcs *tab, const char *mode, SV *arg)
{
    PerlIOl *l = NULL;
    l = PerlMemShared_calloc(tab->size, sizeof(char));
    if (l) {
	Zero(l, tab->size, char);
	l->next = *f;
	l->tab = tab;
	*f = l;
	PerlIO_debug("PerlIO_push f=%p %s %s %p\n", f, tab->name,
		     (mode) ? mode : "(Null)", arg);
	if ((*l->tab->Pushed) (f, mode, arg) != 0) {
	    PerlIO_pop(aTHX_ f);
	    return NULL;
	}
    }
    return f;
}

IV
PerlIOPop_pushed(PerlIO *f, const char *mode, SV *arg)
{
    dTHX;
    PerlIO_pop(aTHX_ f);
    if (*f) {
	PerlIO_flush(f);
	PerlIO_pop(aTHX_ f);
	return 0;
    }
    return -1;
}

IV
PerlIORaw_pushed(PerlIO *f, const char *mode, SV *arg)
{
    /*
     * Remove the dummy layer
     */
    dTHX;
    PerlIO_pop(aTHX_ f);
    /*
     * Pop back to bottom layer
     */
    if (f && *f) {
	PerlIO_flush(f);
	while (!(PerlIOBase(f)->tab->kind & PERLIO_K_RAW)) {
	    if (*PerlIONext(f)) {
		PerlIO_pop(aTHX_ f);
	    }
	    else {
		/*
		 * Nothing bellow - push unix on top then remove it
		 */
		if (PerlIO_push(aTHX_ f, PerlIO_default_btm(), mode, arg)) {
		    PerlIO_pop(aTHX_ PerlIONext(f));
		}
		break;
	    }
	}
	PerlIO_debug(":raw f=%p :%s\n", f, PerlIOBase(f)->tab->name);
	return 0;
    }
    return -1;
}

int
PerlIO_apply_layera(pTHX_ PerlIO *f, const char *mode,
		    PerlIO_list_t *layers, IV n)
{
    IV max = layers->cur;
    int code = 0;
    while (n < max) {
	PerlIO_funcs *tab = PerlIO_layer_fetch(aTHX_ layers, n, NULL);
	if (tab) {
	    if (!PerlIO_push(aTHX_ f, tab, mode, PerlIOArg)) {
		code = -1;
		break;
	    }
	}
	n++;
    }
    return code;
}

int
PerlIO_apply_layers(pTHX_ PerlIO *f, const char *mode, const char *names)
{
    int code = 0;
    if (names) {
	PerlIO_list_t *layers = PerlIO_list_alloc();
	code = PerlIO_parse_layers(aTHX_ layers, names);
	if (code == 0) {
	    code = PerlIO_apply_layera(aTHX_ f, mode, layers, 0);
	}
	PerlIO_list_free(layers);
    }
    return code;
}


/*--------------------------------------------------------------------------------------*/
/*
 * Given the abstraction above the public API functions
 */

int
PerlIO_binmode(pTHX_ PerlIO *f, int iotype, int mode, const char *names)
{
    PerlIO_debug("PerlIO_binmode f=%p %s %c %x %s\n",
		 f, PerlIOBase(f)->tab->name, iotype, mode,
		 (names) ? names : "(Null)");
    PerlIO_flush(f);
    if (!names && (O_TEXT != O_BINARY && (mode & O_BINARY))) {
	PerlIO *top = f;
	while (*top) {
	    if (PerlIOBase(top)->tab == &PerlIO_crlf) {
		PerlIOBase(top)->flags &= ~PERLIO_F_CRLF;
		break;
	    }
	    top = PerlIONext(top);
	    PerlIO_flush(top);
	}
    }
    return PerlIO_apply_layers(aTHX_ f, NULL, names) == 0 ? TRUE : FALSE;
}

#undef PerlIO__close
int
PerlIO__close(PerlIO *f)
{
    if (f && *f)
	return (*PerlIOBase(f)->tab->Close) (f);
    else {
	SETERRNO(EBADF, SS$_IVCHAN);
	return -1;
    }
}

#undef PerlIO_close
int
PerlIO_close(PerlIO *f)
{
    dTHX;
    int code = -1;
    if (f && *f) {
	code = (*PerlIOBase(f)->tab->Close) (f);
	while (*f) {
	    PerlIO_pop(aTHX_ f);
	}
    }
    return code;
}

#undef PerlIO_fileno
int
PerlIO_fileno(PerlIO *f)
{
    if (f && *f)
	return (*PerlIOBase(f)->tab->Fileno) (f);
    else {
	SETERRNO(EBADF, SS$_IVCHAN);
	return -1;
    }
}

static const char *
PerlIO_context_layers(pTHX_ const char *mode)
{
    const char *type = NULL;
    /*
     * Need to supply default layer info from open.pm
     */
    if (PL_curcop) {
	SV *layers = PL_curcop->cop_io;
	if (layers) {
	    STRLEN len;
	    type = SvPV(layers, len);
	    if (type && mode[0] != 'r') {
		/*
		 * Skip to write part
		 */
		const char *s = strchr(type, 0);
		if (s && (s - type) < len) {
		    type = s + 1;
		}
	    }
	}
    }
    return type;
}

static PerlIO_funcs *
PerlIO_layer_from_ref(pTHX_ SV *sv)
{
    /*
     * For any scalar type load the handler which is bundled with perl
     */
    if (SvTYPE(sv) < SVt_PVAV)
	return PerlIO_find_layer(aTHX_ "Scalar", 6, 1);

    /*
     * For other types allow if layer is known but don't try and load it
     */
    switch (SvTYPE(sv)) {
    case SVt_PVAV:
	return PerlIO_find_layer(aTHX_ "Array", 5, 0);
    case SVt_PVHV:
	return PerlIO_find_layer(aTHX_ "Hash", 4, 0);
    case SVt_PVCV:
	return PerlIO_find_layer(aTHX_ "Code", 4, 0);
    case SVt_PVGV:
	return PerlIO_find_layer(aTHX_ "Glob", 4, 0);
    }
    return NULL;
}

PerlIO_list_t *
PerlIO_resolve_layers(pTHX_ const char *layers,
		      const char *mode, int narg, SV **args)
{
    PerlIO_list_t *def = PerlIO_default_layers(aTHX);
    int incdef = 1;
    if (!PL_perlio)
	PerlIO_stdstreams(aTHX);
    if (narg) {
	SV *arg = *args;
	/*
	 * If it is a reference but not an object see if we have a handler
	 * for it
	 */
	if (SvROK(arg) && !sv_isobject(arg)) {
	    PerlIO_funcs *handler = PerlIO_layer_from_ref(aTHX_ SvRV(arg));
	    if (handler) {
		def = PerlIO_list_alloc();
		PerlIO_list_push(def, handler, &PL_sv_undef);
		incdef = 0;
	    }
	    /*
	     * Don't fail if handler cannot be found :Via(...) etc. may do
	     * something sensible else we will just stringfy and open
	     * resulting string.
	     */
	}
    }
    if (!layers)
	layers = PerlIO_context_layers(aTHX_ mode);
    if (layers && *layers) {
	PerlIO_list_t *av;
	if (incdef) {
	    IV i = def->cur;
	    av = PerlIO_list_alloc();
	    for (i = 0; i < def->cur; i++) {
		PerlIO_list_push(av, def->array[i].funcs,
				 def->array[i].arg);
	    }
	}
	else {
	    av = def;
	}
	PerlIO_parse_layers(aTHX_ av, layers);
	return av;
    }
    else {
	if (incdef)
	    def->refcnt++;
	return def;
    }
}

PerlIO *
PerlIO_openn(pTHX_ const char *layers, const char *mode, int fd,
	     int imode, int perm, PerlIO *f, int narg, SV **args)
{
    if (!f && narg == 1 && *args == &PL_sv_undef) {
	if ((f = PerlIO_tmpfile())) {
	    if (!layers)
		layers = PerlIO_context_layers(aTHX_ mode);
	    if (layers && *layers)
		PerlIO_apply_layers(aTHX_ f, mode, layers);
	}
    }
    else {
	PerlIO_list_t *layera = NULL;
	IV n;
	PerlIO_funcs *tab = NULL;
	if (f && *f) {
	    /*
	     * This is "reopen" - it is not tested as perl does not use it
	     * yet
	     */
	    PerlIOl *l = *f;
	    layera = PerlIO_list_alloc();
	    while (l) {
		SV *arg =
		    (l->tab->Getarg) ? (*l->tab->
					Getarg) (&l) : &PL_sv_undef;
		PerlIO_list_push(layera, l->tab, arg);
		l = *PerlIONext(&l);
	    }
	}
	else {
	    layera = PerlIO_resolve_layers(aTHX_ layers, mode, narg, args);
	}
	/*
	 * Start at "top" of layer stack
	 */
	n = layera->cur - 1;
	while (n >= 0) {
	    PerlIO_funcs *t = PerlIO_layer_fetch(aTHX_ layera, n, NULL);
	    if (t && t->Open) {
		tab = t;
		break;
	    }
	    n--;
	}
	if (tab) {
	    /*
	     * Found that layer 'n' can do opens - call it
	     */
	    PerlIO_debug("openn(%s,'%s','%s',%d,%x,%o,%p,%d,%p)\n",
			 tab->name, layers, mode, fd, imode, perm, f, narg,
			 args);
	    f = (*tab->Open) (aTHX_ tab, layera, n, mode, fd, imode, perm,
			      f, narg, args);
	    if (f) {
		if (n + 1 < layera->cur) {
		    /*
		     * More layers above the one that we used to open -
		     * apply them now
		     */
		    if (PerlIO_apply_layera(aTHX_ f, mode, layera, n + 1)
			!= 0) {
			f = NULL;
		    }
		}
	    }
	}
	PerlIO_list_free(layera);
    }
    return f;
}


#undef PerlIO_fdopen
PerlIO *
PerlIO_fdopen(int fd, const char *mode)
{
    dTHX;
    return PerlIO_openn(aTHX_ Nullch, mode, fd, 0, 0, NULL, 0, NULL);
}

#undef PerlIO_open
PerlIO *
PerlIO_open(const char *path, const char *mode)
{
    dTHX;
    SV *name = sv_2mortal(newSVpvn(path, strlen(path)));
    return PerlIO_openn(aTHX_ Nullch, mode, -1, 0, 0, NULL, 1, &name);
}

#undef PerlIO_reopen
PerlIO *
PerlIO_reopen(const char *path, const char *mode, PerlIO *f)
{
    dTHX;
    SV *name = sv_2mortal(newSVpvn(path, strlen(path)));
    return PerlIO_openn(aTHX_ Nullch, mode, -1, 0, 0, f, 1, &name);
}

#undef PerlIO_read
SSize_t
PerlIO_read(PerlIO *f, void *vbuf, Size_t count)
{
    if (f && *f)
	return (*PerlIOBase(f)->tab->Read) (f, vbuf, count);
    else {
	SETERRNO(EBADF, SS$_IVCHAN);
	return -1;
    }
}

#undef PerlIO_unread
SSize_t
PerlIO_unread(PerlIO *f, const void *vbuf, Size_t count)
{
    if (f && *f)
	return (*PerlIOBase(f)->tab->Unread) (f, vbuf, count);
    else {
	SETERRNO(EBADF, SS$_IVCHAN);
	return -1;
    }
}

#undef PerlIO_write
SSize_t
PerlIO_write(PerlIO *f, const void *vbuf, Size_t count)
{
    if (f && *f)
	return (*PerlIOBase(f)->tab->Write) (f, vbuf, count);
    else {
	SETERRNO(EBADF, SS$_IVCHAN);
	return -1;
    }
}

#undef PerlIO_seek
int
PerlIO_seek(PerlIO *f, Off_t offset, int whence)
{
    if (f && *f)
	return (*PerlIOBase(f)->tab->Seek) (f, offset, whence);
    else {
	SETERRNO(EBADF, SS$_IVCHAN);
	return -1;
    }
}

#undef PerlIO_tell
Off_t
PerlIO_tell(PerlIO *f)
{
    if (f && *f)
	return (*PerlIOBase(f)->tab->Tell) (f);
    else {
	SETERRNO(EBADF, SS$_IVCHAN);
	return -1;
    }
}

#undef PerlIO_flush
int
PerlIO_flush(PerlIO *f)
{
    if (f) {
	if (*f) {
	    PerlIO_funcs *tab = PerlIOBase(f)->tab;
	    if (tab && tab->Flush) {
		return (*tab->Flush) (f);
	    }
	    else {
		PerlIO_debug("Cannot flush f=%p :%s\n", f, tab->name);
		SETERRNO(EBADF, SS$_IVCHAN);
		return -1;
	    }
	}
	else {
	    PerlIO_debug("Cannot flush f=%p\n", f);
	    SETERRNO(EBADF, SS$_IVCHAN);
	    return -1;
	}
    }
    else {
	/*
	 * Is it good API design to do flush-all on NULL, a potentially
	 * errorneous input? Maybe some magical value (PerlIO*
	 * PERLIO_FLUSH_ALL = (PerlIO*)-1;)? Yes, stdio does similar
	 * things on fflush(NULL), but should we be bound by their design
	 * decisions? --jhi
	 */
	dTHX;
	PerlIO **table = &PL_perlio;
	int code = 0;
	while ((f = *table)) {
	    int i;
	    table = (PerlIO **) (f++);
	    for (i = 1; i < PERLIO_TABLE_SIZE; i++) {
		if (*f && PerlIO_flush(f) != 0)
		    code = -1;
		f++;
	    }
	}
	return code;
    }
}

void
PerlIOBase_flush_linebuf()
{
    dTHX;
    PerlIO **table = &PL_perlio;
    PerlIO *f;
    while ((f = *table)) {
	int i;
	table = (PerlIO **) (f++);
	for (i = 1; i < PERLIO_TABLE_SIZE; i++) {
	    if (*f
		&& (PerlIOBase(f)->
		    flags & (PERLIO_F_LINEBUF | PERLIO_F_CANWRITE))
		== (PERLIO_F_LINEBUF | PERLIO_F_CANWRITE))
		PerlIO_flush(f);
	    f++;
	}
    }
}

#undef PerlIO_fill
int
PerlIO_fill(PerlIO *f)
{
    if (f && *f)
	return (*PerlIOBase(f)->tab->Fill) (f);
    else {
	SETERRNO(EBADF, SS$_IVCHAN);
	return -1;
    }
}

#undef PerlIO_isutf8
int
PerlIO_isutf8(PerlIO *f)
{
    if (f && *f)
	return (PerlIOBase(f)->flags & PERLIO_F_UTF8) != 0;
    else {
	SETERRNO(EBADF, SS$_IVCHAN);
	return -1;
    }
}

#undef PerlIO_eof
int
PerlIO_eof(PerlIO *f)
{
    if (f && *f)
	return (*PerlIOBase(f)->tab->Eof) (f);
    else {
	SETERRNO(EBADF, SS$_IVCHAN);
	return -1;
    }
}

#undef PerlIO_error
int
PerlIO_error(PerlIO *f)
{
    if (f && *f)
	return (*PerlIOBase(f)->tab->Error) (f);
    else {
	SETERRNO(EBADF, SS$_IVCHAN);
	return -1;
    }
}

#undef PerlIO_clearerr
void
PerlIO_clearerr(PerlIO *f)
{
    if (f && *f)
	(*PerlIOBase(f)->tab->Clearerr) (f);
    else
	SETERRNO(EBADF, SS$_IVCHAN);
}

#undef PerlIO_setlinebuf
void
PerlIO_setlinebuf(PerlIO *f)
{
    if (f && *f)
	(*PerlIOBase(f)->tab->Setlinebuf) (f);
    else
	SETERRNO(EBADF, SS$_IVCHAN);
}

#undef PerlIO_has_base
int
PerlIO_has_base(PerlIO *f)
{
    if (f && *f) {
	return (PerlIOBase(f)->tab->Get_base != NULL);
    }
    return 0;
}

#undef PerlIO_fast_gets
int
PerlIO_fast_gets(PerlIO *f)
{
    if (f && *f && (PerlIOBase(f)->flags & PERLIO_F_FASTGETS)) {
	PerlIO_funcs *tab = PerlIOBase(f)->tab;
	return (tab->Set_ptrcnt != NULL);
    }
    return 0;
}

#undef PerlIO_has_cntptr
int
PerlIO_has_cntptr(PerlIO *f)
{
    if (f && *f) {
	PerlIO_funcs *tab = PerlIOBase(f)->tab;
	return (tab->Get_ptr != NULL && tab->Get_cnt != NULL);
    }
    return 0;
}

#undef PerlIO_canset_cnt
int
PerlIO_canset_cnt(PerlIO *f)
{
    if (f && *f) {
	PerlIOl *l = PerlIOBase(f);
	return (l->tab->Set_ptrcnt != NULL);
    }
    return 0;
}

#undef PerlIO_get_base
STDCHAR *
PerlIO_get_base(PerlIO *f)
{
    if (f && *f)
	return (*PerlIOBase(f)->tab->Get_base) (f);
    return NULL;
}

#undef PerlIO_get_bufsiz
int
PerlIO_get_bufsiz(PerlIO *f)
{
    if (f && *f)
	return (*PerlIOBase(f)->tab->Get_bufsiz) (f);
    return 0;
}

#undef PerlIO_get_ptr
STDCHAR *
PerlIO_get_ptr(PerlIO *f)
{
    PerlIO_funcs *tab = PerlIOBase(f)->tab;
    if (tab->Get_ptr == NULL)
	return NULL;
    return (*tab->Get_ptr) (f);
}

#undef PerlIO_get_cnt
int
PerlIO_get_cnt(PerlIO *f)
{
    PerlIO_funcs *tab = PerlIOBase(f)->tab;
    if (tab->Get_cnt == NULL)
	return 0;
    return (*tab->Get_cnt) (f);
}

#undef PerlIO_set_cnt
void
PerlIO_set_cnt(PerlIO *f, int cnt)
{
    (*PerlIOBase(f)->tab->Set_ptrcnt) (f, NULL, cnt);
}

#undef PerlIO_set_ptrcnt
void
PerlIO_set_ptrcnt(PerlIO *f, STDCHAR * ptr, int cnt)
{
    PerlIO_funcs *tab = PerlIOBase(f)->tab;
    if (tab->Set_ptrcnt == NULL) {
	dTHX;
	Perl_croak(aTHX_ "PerlIO buffer snooping abuse");
    }
    (*PerlIOBase(f)->tab->Set_ptrcnt) (f, ptr, cnt);
}

/*--------------------------------------------------------------------------------------*/
/*
 * utf8 and raw dummy layers
 */

IV
PerlIOUtf8_pushed(PerlIO *f, const char *mode, SV *arg)
{
    if (PerlIONext(f)) {
	dTHX;
	PerlIO_funcs *tab = PerlIOBase(f)->tab;
	PerlIO_pop(aTHX_ f);
	if (tab->kind & PERLIO_K_UTF8)
	    PerlIOBase(f)->flags |= PERLIO_F_UTF8;
	else
	    PerlIOBase(f)->flags &= ~PERLIO_F_UTF8;
	return 0;
    }
    return -1;
}

PerlIO_funcs PerlIO_utf8 = {
    "utf8",
    sizeof(PerlIOl),
    PERLIO_K_DUMMY | PERLIO_F_UTF8,
    PerlIOUtf8_pushed,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,			/* flush */
    NULL,			/* fill */
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,			/* get_base */
    NULL,			/* get_bufsiz */
    NULL,			/* get_ptr */
    NULL,			/* get_cnt */
    NULL,			/* set_ptrcnt */
};

PerlIO_funcs PerlIO_byte = {
    "bytes",
    sizeof(PerlIOl),
    PERLIO_K_DUMMY,
    PerlIOUtf8_pushed,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,			/* flush */
    NULL,			/* fill */
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,			/* get_base */
    NULL,			/* get_bufsiz */
    NULL,			/* get_ptr */
    NULL,			/* get_cnt */
    NULL,			/* set_ptrcnt */
};

PerlIO *
PerlIORaw_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)
{
    PerlIO_funcs *tab = PerlIO_default_btm();
    return (*tab->Open) (aTHX_ tab, layers, n - 1, mode, fd, imode, perm,
			 old, narg, args);
}

PerlIO_funcs PerlIO_raw = {
    "raw",
    sizeof(PerlIOl),
    PERLIO_K_DUMMY,
    PerlIORaw_pushed,
    PerlIOBase_popped,
    PerlIORaw_open,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,			/* flush */
    NULL,			/* fill */
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,			/* get_base */
    NULL,			/* get_bufsiz */
    NULL,			/* get_ptr */
    NULL,			/* get_cnt */
    NULL,			/* set_ptrcnt */
};
/*--------------------------------------------------------------------------------------*/
/*--------------------------------------------------------------------------------------*/
/*
 * "Methods" of the "base class"
 */

IV
PerlIOBase_fileno(PerlIO *f)
{
    return PerlIO_fileno(PerlIONext(f));
}

char *
PerlIO_modestr(PerlIO *f, char *buf)
{
    char *s = buf;
    IV flags = PerlIOBase(f)->flags;
    if (flags & PERLIO_F_APPEND) {
	*s++ = 'a';
	if (flags & PERLIO_F_CANREAD) {
	    *s++ = '+';
	}
    }
    else if (flags & PERLIO_F_CANREAD) {
	*s++ = 'r';
	if (flags & PERLIO_F_CANWRITE)
	    *s++ = '+';
    }
    else if (flags & PERLIO_F_CANWRITE) {
	*s++ = 'w';
	if (flags & PERLIO_F_CANREAD) {
	    *s++ = '+';
	}
    }
#if O_TEXT != O_BINARY
    if (!(flags & PERLIO_F_CRLF))
	*s++ = 'b';
#endif
    *s = '\0';
    return buf;
}

IV
PerlIOBase_pushed(PerlIO *f, const char *mode, SV *arg)
{
    PerlIOl *l = PerlIOBase(f);
#if 0
    const char *omode = mode;
    char temp[8];
#endif
    PerlIO_funcs *tab = PerlIOBase(f)->tab;
    l->flags &= ~(PERLIO_F_CANREAD | PERLIO_F_CANWRITE |
		  PERLIO_F_TRUNCATE | PERLIO_F_APPEND);
    if (tab->Set_ptrcnt != NULL)
	l->flags |= PERLIO_F_FASTGETS;
    if (mode) {
	if (*mode == '#' || *mode == 'I')
	    mode++;
	switch (*mode++) {
	case 'r':
	    l->flags |= PERLIO_F_CANREAD;
	    break;
	case 'a':
	    l->flags |= PERLIO_F_APPEND | PERLIO_F_CANWRITE;
	    break;
	case 'w':
	    l->flags |= PERLIO_F_TRUNCATE | PERLIO_F_CANWRITE;
	    break;
	default:
	    SETERRNO(EINVAL, LIB$_INVARG);
	    return -1;
	}
	while (*mode) {
	    switch (*mode++) {
	    case '+':
		l->flags |= PERLIO_F_CANREAD | PERLIO_F_CANWRITE;
		break;
	    case 'b':
		l->flags &= ~PERLIO_F_CRLF;
		break;
	    case 't':
		l->flags |= PERLIO_F_CRLF;
		break;
	    default:
		SETERRNO(EINVAL, LIB$_INVARG);
		return -1;
	    }
	}
    }
    else {
	if (l->next) {
	    l->flags |= l->next->flags &
		(PERLIO_F_CANREAD | PERLIO_F_CANWRITE | PERLIO_F_TRUNCATE |
		 PERLIO_F_APPEND);
	}
    }
#if 0
    PerlIO_debug("PerlIOBase_pushed f=%p %s %s fl=%08" UVxf " (%s)\n",
		 f, PerlIOBase(f)->tab->name, (omode) ? omode : "(Null)",
		 l->flags, PerlIO_modestr(f, temp));
#endif
    return 0;
}

IV
PerlIOBase_popped(PerlIO *f)
{
    return 0;
}

SSize_t
PerlIOBase_unread(PerlIO *f, const void *vbuf, Size_t count)
{
    dTHX;
    /*
     * Save the position as current head considers it
     */
    Off_t old = PerlIO_tell(f);
    SSize_t done;
    PerlIO_push(aTHX_ f, &PerlIO_pending, "r", Nullsv);
    PerlIOSelf(f, PerlIOBuf)->posn = old;
    done = PerlIOBuf_unread(f, vbuf, count);
    return done;
}

SSize_t
PerlIOBase_read(PerlIO *f, void *vbuf, Size_t count)
{
    STDCHAR *buf = (STDCHAR *) vbuf;
    if (f) {
	if (!(PerlIOBase(f)->flags & PERLIO_F_CANREAD))
	    return 0;
	while (count > 0) {
	    SSize_t avail = PerlIO_get_cnt(f);
	    SSize_t take = 0;
	    if (avail > 0)
		take = (count < avail) ? count : avail;
	    if (take > 0) {
		STDCHAR *ptr = PerlIO_get_ptr(f);
		Copy(ptr, buf, take, STDCHAR);
		PerlIO_set_ptrcnt(f, ptr + take, (avail -= take));
		count -= take;
		buf += take;
	    }
	    if (count > 0 && avail <= 0) {
		if (PerlIO_fill(f) != 0)
		    break;
	    }
	}
	return (buf - (STDCHAR *) vbuf);
    }
    return 0;
}

IV
PerlIOBase_noop_ok(PerlIO *f)
{
    return 0;
}

IV
PerlIOBase_noop_fail(PerlIO *f)
{
    return -1;
}

IV
PerlIOBase_close(PerlIO *f)
{
    IV code = 0;
    PerlIO *n = PerlIONext(f);
    if (PerlIO_flush(f) != 0)
	code = -1;
    if (n && *n && (*PerlIOBase(n)->tab->Close) (n) != 0)
	code = -1;
    PerlIOBase(f)->flags &=
	~(PERLIO_F_CANREAD | PERLIO_F_CANWRITE | PERLIO_F_OPEN);
    return code;
}

IV
PerlIOBase_eof(PerlIO *f)
{
    if (f && *f) {
	return (PerlIOBase(f)->flags & PERLIO_F_EOF) != 0;
    }
    return 1;
}

IV
PerlIOBase_error(PerlIO *f)
{
    if (f && *f) {
	return (PerlIOBase(f)->flags & PERLIO_F_ERROR) != 0;
    }
    return 1;
}

void
PerlIOBase_clearerr(PerlIO *f)
{
    if (f && *f) {
	PerlIO *n = PerlIONext(f);
	PerlIOBase(f)->flags &= ~(PERLIO_F_ERROR | PERLIO_F_EOF);
	if (n)
	    PerlIO_clearerr(n);
    }
}

void
PerlIOBase_setlinebuf(PerlIO *f)
{
    if (f) {
	PerlIOBase(f)->flags |= PERLIO_F_LINEBUF;
    }
}

/*--------------------------------------------------------------------------------------*/
/*
 * Bottom-most level for UNIX-like case
 */

typedef struct {
    struct _PerlIO base;	/* The generic part */
    int fd;			/* UNIX like file descriptor */
    int oflags;			/* open/fcntl flags */
} PerlIOUnix;

int
PerlIOUnix_oflags(const char *mode)
{
    int oflags = -1;
    if (*mode == 'I' || *mode == '#')
	mode++;
    switch (*mode) {
    case 'r':
	oflags = O_RDONLY;
	if (*++mode == '+') {
	    oflags = O_RDWR;
	    mode++;
	}
	break;

    case 'w':
	oflags = O_CREAT | O_TRUNC;
	if (*++mode == '+') {
	    oflags |= O_RDWR;
	    mode++;
	}
	else
	    oflags |= O_WRONLY;
	break;

    case 'a':
	oflags = O_CREAT | O_APPEND;
	if (*++mode == '+') {
	    oflags |= O_RDWR;
	    mode++;
	}
	else
	    oflags |= O_WRONLY;
	break;
    }
    if (*mode == 'b') {
	oflags |= O_BINARY;
	oflags &= ~O_TEXT;
	mode++;
    }
    else if (*mode == 't') {
	oflags |= O_TEXT;
	oflags &= ~O_BINARY;
	mode++;
    }
    /*
     * Always open in binary mode
     */
    oflags |= O_BINARY;
    if (*mode || oflags == -1) {
	SETERRNO(EINVAL, LIB$_INVARG);
	oflags = -1;
    }
    return oflags;
}

IV
PerlIOUnix_fileno(PerlIO *f)
{
    return PerlIOSelf(f, PerlIOUnix)->fd;
}

IV
PerlIOUnix_pushed(PerlIO *f, const char *mode, SV *arg)
{
    IV code = PerlIOBase_pushed(f, mode, arg);
    if (*PerlIONext(f)) {
	PerlIOUnix *s = PerlIOSelf(f, PerlIOUnix);
	s->fd = PerlIO_fileno(PerlIONext(f));
	/*
	 * XXX could (or should) we retrieve the oflags from the open file
	 * handle rather than believing the "mode" we are passed in? XXX
	 * Should the value on NULL mode be 0 or -1?
	 */
	s->oflags = mode ? PerlIOUnix_oflags(mode) : -1;
    }
    PerlIOBase(f)->flags |= PERLIO_F_OPEN;
    return code;
}

PerlIO *
PerlIOUnix_open(pTHX_ PerlIO_funcs *self, PerlIO_list_t *layers,
		IV n, const char *mode, int fd, int imode,
		int perm, PerlIO *f, int narg, SV **args)
{
    if (f) {
	if (PerlIOBase(f)->flags & PERLIO_F_OPEN)
	    (*PerlIOBase(f)->tab->Close) (f);
    }
    if (narg > 0) {
	char *path = SvPV_nolen(*args);
	if (*mode == '#')
	    mode++;
	else {
	    imode = PerlIOUnix_oflags(mode);
	    perm = 0666;
	}
	if (imode != -1) {
	    fd = PerlLIO_open3(path, imode, perm);
	}
    }
    if (fd >= 0) {
	PerlIOUnix *s;
	if (*mode == 'I')
	    mode++;
	if (!f) {
	    f = PerlIO_allocate(aTHX);
	    s = PerlIOSelf(PerlIO_push(aTHX_ f, self, mode, PerlIOArg),
			   PerlIOUnix);
	}
	else
	    s = PerlIOSelf(f, PerlIOUnix);
	s->fd = fd;
	s->oflags = imode;
	PerlIOBase(f)->flags |= PERLIO_F_OPEN;
	return f;
    }
    else {
	if (f) {
	    /*
	     * FIXME: pop layers ???
	     */
	}
	return NULL;
    }
}

SV *
PerlIO_sv_dup(pTHX_ SV *arg, CLONE_PARAMS *param)
{
    if (!arg)
	return Nullsv;
#ifdef sv_dup
    if (param) {
	return sv_dup(arg, param);
    }
    else {
	return newSVsv(arg);
    }
#else
    return newSVsv(arg);
#endif
}

PerlIO *
PerlIOBase_dup(pTHX_ PerlIO *f, PerlIO *o, CLONE_PARAMS *param)
{
    PerlIO *nexto = PerlIONext(o);
    if (*nexto) {
	PerlIO_funcs *tab = PerlIOBase(nexto)->tab;
	f = (*tab->Dup)(aTHX_ f, nexto, param);
    }
    if (f) {
	PerlIO_funcs *self = PerlIOBase(o)->tab;
	SV *arg = Nullsv;
	char buf[8];
	PerlIO_debug("PerlIOBase_dup %s f=%p o=%p param=%p\n",self->name,f,o,param);
	if (self->Getarg) {
	    arg = (*self->Getarg)(o);
	    if (arg) {
		arg = PerlIO_sv_dup(aTHX_ arg, param);
	    }
	}
	f = PerlIO_push(aTHX_ f, self, PerlIO_modestr(o,buf), arg);
	if (!f && arg) {
	    SvREFCNT_dec(arg);
	}
    }
    return f;
}

PerlIO *
PerlIOUnix_dup(pTHX_ PerlIO *f, PerlIO *o, CLONE_PARAMS *param)
{
    PerlIOUnix *os = PerlIOSelf(o, PerlIOUnix);
    int fd = PerlLIO_dup(os->fd);
    if (fd >= 0) {
	f = PerlIOBase_dup(aTHX_ f, o, param);
	if (f) {
	    /* If all went well overwrite fd in dup'ed lay with the dup()'ed fd */
	    PerlIOUnix *s = PerlIOSelf(f, PerlIOUnix);
	    s->fd = fd;
	    return f;
	}
	else {
	    PerlLIO_close(fd);
	}
    }
    return NULL;
}


SSize_t
PerlIOUnix_read(PerlIO *f, void *vbuf, Size_t count)
{
    dTHX;
    int fd = PerlIOSelf(f, PerlIOUnix)->fd;
    if (!(PerlIOBase(f)->flags & PERLIO_F_CANREAD))
	return 0;
    while (1) {
	SSize_t len = PerlLIO_read(fd, vbuf, count);
	if (len >= 0 || errno != EINTR) {
	    if (len < 0)
		PerlIOBase(f)->flags |= PERLIO_F_ERROR;
	    else if (len == 0 && count != 0)
		PerlIOBase(f)->flags |= PERLIO_F_EOF;
	    return len;
	}
	PERL_ASYNC_CHECK();
    }
}

SSize_t
PerlIOUnix_write(PerlIO *f, const void *vbuf, Size_t count)
{
    dTHX;
    int fd = PerlIOSelf(f, PerlIOUnix)->fd;
    while (1) {
	SSize_t len = PerlLIO_write(fd, vbuf, count);
	if (len >= 0 || errno != EINTR) {
	    if (len < 0)
		PerlIOBase(f)->flags |= PERLIO_F_ERROR;
	    return len;
	}
	PERL_ASYNC_CHECK();
    }
}

IV
PerlIOUnix_seek(PerlIO *f, Off_t offset, int whence)
{
    dSYS;
    Off_t new =
	PerlLIO_lseek(PerlIOSelf(f, PerlIOUnix)->fd, offset, whence);
    PerlIOBase(f)->flags &= ~PERLIO_F_EOF;
    return (new == (Off_t) - 1) ? -1 : 0;
}

Off_t
PerlIOUnix_tell(PerlIO *f)
{
    dSYS;
    return PerlLIO_lseek(PerlIOSelf(f, PerlIOUnix)->fd, 0, SEEK_CUR);
}


IV
PerlIOUnix_close(PerlIO *f)
{
    dTHX;
    int fd = PerlIOSelf(f, PerlIOUnix)->fd;
    int code = 0;
    while (PerlLIO_close(fd) != 0) {
	if (errno != EINTR) {
	    code = -1;
	    break;
	}
	PERL_ASYNC_CHECK();
    }
    if (code == 0) {
	PerlIOBase(f)->flags &= ~PERLIO_F_OPEN;
    }
    return code;
}

PerlIO_funcs PerlIO_unix = {
    "unix",
    sizeof(PerlIOUnix),
    PERLIO_K_RAW,
    PerlIOUnix_pushed,
    PerlIOBase_noop_ok,
    PerlIOUnix_open,
    NULL,
    PerlIOUnix_fileno,
    PerlIOUnix_dup,
    PerlIOUnix_read,
    PerlIOBase_unread,
    PerlIOUnix_write,
    PerlIOUnix_seek,
    PerlIOUnix_tell,
    PerlIOUnix_close,
    PerlIOBase_noop_ok,		/* flush */
    PerlIOBase_noop_fail,	/* fill */
    PerlIOBase_eof,
    PerlIOBase_error,
    PerlIOBase_clearerr,
    PerlIOBase_setlinebuf,
    NULL,			/* get_base */
    NULL,			/* get_bufsiz */
    NULL,			/* get_ptr */
    NULL,			/* get_cnt */
    NULL,			/* set_ptrcnt */
};

/*--------------------------------------------------------------------------------------*/
/*
 * stdio as a layer
 */

typedef struct {
    struct _PerlIO base;
    FILE *stdio;		/* The stream */
} PerlIOStdio;

IV
PerlIOStdio_fileno(PerlIO *f)
{
    dSYS;
    return PerlSIO_fileno(PerlIOSelf(f, PerlIOStdio)->stdio);
}

char *
PerlIOStdio_mode(const char *mode, char *tmode)
{
    char *ret = tmode;
    while (*mode) {
	*tmode++ = *mode++;
    }
    if (O_BINARY != O_TEXT) {
	*tmode++ = 'b';
    }
    *tmode = '\0';
    return ret;
}

/*
 * This isn't used yet ...
 */
IV
PerlIOStdio_pushed(PerlIO *f, const char *mode, SV *arg)
{
    if (*PerlIONext(f)) {
	dSYS;
	PerlIOStdio *s = PerlIOSelf(f, PerlIOStdio);
	char tmode[8];
	FILE *stdio =
	    PerlSIO_fdopen(PerlIO_fileno(PerlIONext(f)), mode =
			   PerlIOStdio_mode(mode, tmode));
	if (stdio)
	    s->stdio = stdio;
	else
	    return -1;
    }
    return PerlIOBase_pushed(f, mode, arg);
}

#undef PerlIO_importFILE
PerlIO *
PerlIO_importFILE(FILE *stdio, int fl)
{
    dTHX;
    PerlIO *f = NULL;
    if (stdio) {
	PerlIOStdio *s =
	    PerlIOSelf(PerlIO_push
		       (aTHX_(f = PerlIO_allocate(aTHX)), &PerlIO_stdio,
			"r+", Nullsv), PerlIOStdio);
	s->stdio = stdio;
    }
    return f;
}

PerlIO *
PerlIOStdio_open(pTHX_ PerlIO_funcs *self, PerlIO_list_t *layers,
		 IV n, const char *mode, int fd, int imode,
		 int perm, PerlIO *f, int narg, SV **args)
{
    char tmode[8];
    if (f) {
	char *path = SvPV_nolen(*args);
	PerlIOStdio *s = PerlIOSelf(f, PerlIOStdio);
	FILE *stdio =
	    PerlSIO_freopen(path, (mode = PerlIOStdio_mode(mode, tmode)),
			    s->stdio);
	if (!s->stdio)
	    return NULL;
	s->stdio = stdio;
	return f;
    }
    else {
	if (narg > 0) {
	    char *path = SvPV_nolen(*args);
	    if (*mode == '#') {
		mode++;
		fd = PerlLIO_open3(path, imode, perm);
	    }
	    else {
		FILE *stdio = PerlSIO_fopen(path, mode);
		if (stdio) {
		    PerlIOStdio *s =
			PerlIOSelf(PerlIO_push
				   (aTHX_(f = PerlIO_allocate(aTHX)), self,
				    (mode = PerlIOStdio_mode(mode, tmode)),
				    PerlIOArg),
				   PerlIOStdio);
		    s->stdio = stdio;
		}
		return f;
	    }
	}
	if (fd >= 0) {
	    FILE *stdio = NULL;
	    int init = 0;
	    if (*mode == 'I') {
		init = 1;
		mode++;
	    }
	    if (init) {
		switch (fd) {
		case 0:
		    stdio = PerlSIO_stdin;
		    break;
		case 1:
		    stdio = PerlSIO_stdout;
		    break;
		case 2:
		    stdio = PerlSIO_stderr;
		    break;
		}
	    }
	    else {
		stdio = PerlSIO_fdopen(fd, mode =
				       PerlIOStdio_mode(mode, tmode));
	    }
	    if (stdio) {
		PerlIOStdio *s =
		    PerlIOSelf(PerlIO_push
			       (aTHX_(f = PerlIO_allocate(aTHX)), self,
				mode, PerlIOArg), PerlIOStdio);
		s->stdio = stdio;
		return f;
	    }
	}
    }
    return NULL;
}

SSize_t
PerlIOStdio_read(PerlIO *f, void *vbuf, Size_t count)
{
    dSYS;
    FILE *s = PerlIOSelf(f, PerlIOStdio)->stdio;
    SSize_t got = 0;
    if (count == 1) {
	STDCHAR *buf = (STDCHAR *) vbuf;
	/*
	 * Perl is expecting PerlIO_getc() to fill the buffer Linux's
	 * stdio does not do that for fread()
	 */
	int ch = PerlSIO_fgetc(s);
	if (ch != EOF) {
	    *buf = ch;
	    got = 1;
	}
    }
    else
	got = PerlSIO_fread(vbuf, 1, count, s);
    return got;
}

SSize_t
PerlIOStdio_unread(PerlIO *f, const void *vbuf, Size_t count)
{
    dSYS;
    FILE *s = PerlIOSelf(f, PerlIOStdio)->stdio;
    STDCHAR *buf = ((STDCHAR *) vbuf) + count - 1;
    SSize_t unread = 0;
    while (count > 0) {
	int ch = *buf-- & 0xff;
	if (PerlSIO_ungetc(ch, s) != ch)
	    break;
	unread++;
	count--;
    }
    return unread;
}

SSize_t
PerlIOStdio_write(PerlIO *f, const void *vbuf, Size_t count)
{
    dSYS;
    return PerlSIO_fwrite(vbuf, 1, count,
			  PerlIOSelf(f, PerlIOStdio)->stdio);
}

IV
PerlIOStdio_seek(PerlIO *f, Off_t offset, int whence)
{
    dSYS;
    FILE *stdio = PerlIOSelf(f, PerlIOStdio)->stdio;
    return PerlSIO_fseek(stdio, offset, whence);
}

Off_t
PerlIOStdio_tell(PerlIO *f)
{
    dSYS;
    FILE *stdio = PerlIOSelf(f, PerlIOStdio)->stdio;
    return PerlSIO_ftell(stdio);
}

IV
PerlIOStdio_close(PerlIO *f)
{
    dSYS;
#ifdef SOCKS5_VERSION_NAME
    int optval;
    Sock_size_t optlen = sizeof(int);
#endif
    FILE *stdio = PerlIOSelf(f, PerlIOStdio)->stdio;
    return (
#ifdef SOCKS5_VERSION_NAME
	       (getsockopt
		(PerlIO_fileno(f), SOL_SOCKET, SO_TYPE, (void *) &optval,
		 &optlen) <
		0) ? PerlSIO_fclose(stdio) : close(PerlIO_fileno(f))
#else
	       PerlSIO_fclose(stdio)
#endif
	);

}

IV
PerlIOStdio_flush(PerlIO *f)
{
    dSYS;
    FILE *stdio = PerlIOSelf(f, PerlIOStdio)->stdio;
    if (PerlIOBase(f)->flags & PERLIO_F_CANWRITE) {
	return PerlSIO_fflush(stdio);
    }
    else {
#if 0
	/*
	 * FIXME: This discards ungetc() and pre-read stuff which is not
	 * right if this is just a "sync" from a layer above Suspect right
	 * design is to do _this_ but not have layer above flush this
	 * layer read-to-read
	 */
	/*
	 * Not writeable - sync by attempting a seek
	 */
	int err = errno;
	if (PerlSIO_fseek(stdio, (Off_t) 0, SEEK_CUR) != 0)
	    errno = err;
#endif
    }
    return 0;
}

IV
PerlIOStdio_fill(PerlIO *f)
{
    dSYS;
    FILE *stdio = PerlIOSelf(f, PerlIOStdio)->stdio;
    int c;
    /*
     * fflush()ing read-only streams can cause trouble on some stdio-s
     */
    if ((PerlIOBase(f)->flags & PERLIO_F_CANWRITE)) {
	if (PerlSIO_fflush(stdio) != 0)
	    return EOF;
    }
    c = PerlSIO_fgetc(stdio);
    if (c == EOF || PerlSIO_ungetc(c, stdio) != c)
	return EOF;
    return 0;
}

IV
PerlIOStdio_eof(PerlIO *f)
{
    dSYS;
    return PerlSIO_feof(PerlIOSelf(f, PerlIOStdio)->stdio);
}

IV
PerlIOStdio_error(PerlIO *f)
{
    dSYS;
    return PerlSIO_ferror(PerlIOSelf(f, PerlIOStdio)->stdio);
}

void
PerlIOStdio_clearerr(PerlIO *f)
{
    dSYS;
    PerlSIO_clearerr(PerlIOSelf(f, PerlIOStdio)->stdio);
}

void
PerlIOStdio_setlinebuf(PerlIO *f)
{
    dSYS;
#ifdef HAS_SETLINEBUF
    PerlSIO_setlinebuf(PerlIOSelf(f, PerlIOStdio)->stdio);
#else
    PerlSIO_setvbuf(PerlIOSelf(f, PerlIOStdio)->stdio, Nullch, _IOLBF, 0);
#endif
}

#ifdef FILE_base
STDCHAR *
PerlIOStdio_get_base(PerlIO *f)
{
    dSYS;
    FILE *stdio = PerlIOSelf(f, PerlIOStdio)->stdio;
    return PerlSIO_get_base(stdio);
}

Size_t
PerlIOStdio_get_bufsiz(PerlIO *f)
{
    dSYS;
    FILE *stdio = PerlIOSelf(f, PerlIOStdio)->stdio;
    return PerlSIO_get_bufsiz(stdio);
}
#endif

#ifdef USE_STDIO_PTR
STDCHAR *
PerlIOStdio_get_ptr(PerlIO *f)
{
    dSYS;
    FILE *stdio = PerlIOSelf(f, PerlIOStdio)->stdio;
    return PerlSIO_get_ptr(stdio);
}

SSize_t
PerlIOStdio_get_cnt(PerlIO *f)
{
    dSYS;
    FILE *stdio = PerlIOSelf(f, PerlIOStdio)->stdio;
    return PerlSIO_get_cnt(stdio);
}

void
PerlIOStdio_set_ptrcnt(PerlIO *f, STDCHAR * ptr, SSize_t cnt)
{
    FILE *stdio = PerlIOSelf(f, PerlIOStdio)->stdio;
    dSYS;
    if (ptr != NULL) {
#ifdef STDIO_PTR_LVALUE
	PerlSIO_set_ptr(stdio, ptr);
#ifdef STDIO_PTR_LVAL_SETS_CNT
	if (PerlSIO_get_cnt(stdio) != (cnt)) {
	    dTHX;
	    assert(PerlSIO_get_cnt(stdio) == (cnt));
	}
#endif
#if (!defined(STDIO_PTR_LVAL_NOCHANGE_CNT))
	/*
	 * Setting ptr _does_ change cnt - we are done
	 */
	return;
#endif
#else				/* STDIO_PTR_LVALUE */
	PerlProc_abort();
#endif				/* STDIO_PTR_LVALUE */
    }
    /*
     * Now (or only) set cnt
     */
#ifdef STDIO_CNT_LVALUE
    PerlSIO_set_cnt(stdio, cnt);
#else				/* STDIO_CNT_LVALUE */
#if (defined(STDIO_PTR_LVALUE) && defined(STDIO_PTR_LVAL_SETS_CNT))
    PerlSIO_set_ptr(stdio,
		    PerlSIO_get_ptr(stdio) + (PerlSIO_get_cnt(stdio) -
					      cnt));
#else				/* STDIO_PTR_LVAL_SETS_CNT */
    PerlProc_abort();
#endif				/* STDIO_PTR_LVAL_SETS_CNT */
#endif				/* STDIO_CNT_LVALUE */
}

#endif

PerlIO *
PerlIOStdio_dup(pTHX_ PerlIO *f, PerlIO *o, CLONE_PARAMS *param)
{
    /* This assumes no layers underneath - which is what
       happens, but is not how I remember it. NI-S 2001/10/16
     */
    int fd = PerlLIO_dup(PerlIO_fileno(o));
    if (fd >= 0) {
	char buf[8];
	FILE *stdio = PerlSIO_fdopen(fd, PerlIO_modestr(o, buf));
	if (stdio) {
	    if ((f = PerlIOBase_dup(aTHX_ f, o, param))) {
		PerlIOSelf(f, PerlIOStdio)->stdio = stdio;
	    }
	    else {
		PerlSIO_fclose(stdio);
	    }
	}
	else {
	    PerlLIO_close(fd);
	    f = NULL;
	}
    }
    return f;
}

PerlIO_funcs PerlIO_stdio = {
    "stdio",
    sizeof(PerlIOStdio),
    PERLIO_K_BUFFERED,
    PerlIOBase_pushed,
    PerlIOBase_noop_ok,
    PerlIOStdio_open,
    NULL,
    PerlIOStdio_fileno,
    PerlIOStdio_dup,
    PerlIOStdio_read,
    PerlIOStdio_unread,
    PerlIOStdio_write,
    PerlIOStdio_seek,
    PerlIOStdio_tell,
    PerlIOStdio_close,
    PerlIOStdio_flush,
    PerlIOStdio_fill,
    PerlIOStdio_eof,
    PerlIOStdio_error,
    PerlIOStdio_clearerr,
    PerlIOStdio_setlinebuf,
#ifdef FILE_base
    PerlIOStdio_get_base,
    PerlIOStdio_get_bufsiz,
#else
    NULL,
    NULL,
#endif
#ifdef USE_STDIO_PTR
    PerlIOStdio_get_ptr,
    PerlIOStdio_get_cnt,
#if (defined(STDIO_PTR_LVALUE) && (defined(STDIO_CNT_LVALUE) || defined(STDIO_PTR_LVAL_SETS_CNT)))
    PerlIOStdio_set_ptrcnt
#else				/* STDIO_PTR_LVALUE */
    NULL
#endif				/* STDIO_PTR_LVALUE */
#else				/* USE_STDIO_PTR */
    NULL,
    NULL,
    NULL
#endif				/* USE_STDIO_PTR */
};

#undef PerlIO_exportFILE
FILE *
PerlIO_exportFILE(PerlIO *f, int fl)
{
    FILE *stdio;
    PerlIO_flush(f);
    stdio = fdopen(PerlIO_fileno(f), "r+");
    if (stdio) {
	dTHX;
	PerlIOStdio *s =
	    PerlIOSelf(PerlIO_push(aTHX_ f, &PerlIO_stdio, "r+", Nullsv),
		       PerlIOStdio);
	s->stdio = stdio;
    }
    return stdio;
}

#undef PerlIO_findFILE
FILE *
PerlIO_findFILE(PerlIO *f)
{
    PerlIOl *l = *f;
    while (l) {
	if (l->tab == &PerlIO_stdio) {
	    PerlIOStdio *s = PerlIOSelf(&l, PerlIOStdio);
	    return s->stdio;
	}
	l = *PerlIONext(&l);
    }
    return PerlIO_exportFILE(f, 0);
}

#undef PerlIO_releaseFILE
void
PerlIO_releaseFILE(PerlIO *p, FILE *f)
{
}

/*--------------------------------------------------------------------------------------*/
/*
 * perlio buffer layer
 */

IV
PerlIOBuf_pushed(PerlIO *f, const char *mode, SV *arg)
{
    dSYS;
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    int fd = PerlIO_fileno(f);
    Off_t posn;
    if (fd >= 0 && PerlLIO_isatty(fd)) {
	PerlIOBase(f)->flags |= PERLIO_F_LINEBUF | PERLIO_F_TTY;
    }
    posn = PerlIO_tell(PerlIONext(f));
    if (posn != (Off_t) - 1) {
	b->posn = posn;
    }
    return PerlIOBase_pushed(f, mode, arg);
}

PerlIO *
PerlIOBuf_open(pTHX_ PerlIO_funcs *self, PerlIO_list_t *layers,
	       IV n, const char *mode, int fd, int imode, int perm,
	       PerlIO *f, int narg, SV **args)
{
    if (f) {
	PerlIO *next = PerlIONext(f);
	PerlIO_funcs *tab =
	    PerlIO_layer_fetch(aTHX_ layers, n - 1, PerlIOBase(next)->tab);
	next =
	    (*tab->Open) (aTHX_ tab, layers, n - 1, mode, fd, imode, perm,
			  next, narg, args);
	if (!next
	    || (*PerlIOBase(f)->tab->Pushed) (f, mode, PerlIOArg) != 0) {
	    return NULL;
	}
    }
    else {
	PerlIO_funcs *tab =
	    PerlIO_layer_fetch(aTHX_ layers, n - 1, PerlIO_default_btm());
	int init = 0;
	if (*mode == 'I') {
	    init = 1;
	    /*
	     * mode++;
	     */
	}
	f = (*tab->Open) (aTHX_ tab, layers, n - 1, mode, fd, imode, perm,
			  NULL, narg, args);
	if (f) {
	    PerlIO_push(aTHX_ f, self, mode, PerlIOArg);
	    fd = PerlIO_fileno(f);
#if O_BINARY != O_TEXT
	    /*
	     * do something about failing setmode()? --jhi
	     */
	    PerlLIO_setmode(fd, O_BINARY);
#endif
	    if (init && fd == 2) {
		/*
		 * Initial stderr is unbuffered
		 */
		PerlIOBase(f)->flags |= PERLIO_F_UNBUF;
	    }
	}
    }
    return f;
}

/*
 * This "flush" is akin to sfio's sync in that it handles files in either
 * read or write state
 */
IV
PerlIOBuf_flush(PerlIO *f)
{
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    int code = 0;
    if (PerlIOBase(f)->flags & PERLIO_F_WRBUF) {
	/*
	 * write() the buffer
	 */
	STDCHAR *buf = b->buf;
	STDCHAR *p = buf;
	PerlIO *n = PerlIONext(f);
	while (p < b->ptr) {
	    SSize_t count = PerlIO_write(n, p, b->ptr - p);
	    if (count > 0) {
		p += count;
	    }
	    else if (count < 0 || PerlIO_error(n)) {
		PerlIOBase(f)->flags |= PERLIO_F_ERROR;
		code = -1;
		break;
	    }
	}
	b->posn += (p - buf);
    }
    else if (PerlIOBase(f)->flags & PERLIO_F_RDBUF) {
	STDCHAR *buf = PerlIO_get_base(f);
	/*
	 * Note position change
	 */
	b->posn += (b->ptr - buf);
	if (b->ptr < b->end) {
	    /*
	     * We did not consume all of it
	     */
	    if (PerlIO_seek(PerlIONext(f), b->posn, SEEK_SET) == 0) {
		b->posn = PerlIO_tell(PerlIONext(f));
	    }
	}
    }
    b->ptr = b->end = b->buf;
    PerlIOBase(f)->flags &= ~(PERLIO_F_RDBUF | PERLIO_F_WRBUF);
    /*
     * FIXME: Is this right for read case ?
     */
    if (PerlIO_flush(PerlIONext(f)) != 0)
	code = -1;
    return code;
}

IV
PerlIOBuf_fill(PerlIO *f)
{
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    PerlIO *n = PerlIONext(f);
    SSize_t avail;
    /*
     * FIXME: doing the down-stream flush is a bad idea if it causes
     * pre-read data in stdio buffer to be discarded but this is too
     * simplistic - as it skips _our_ hosekeeping and breaks tell tests.
     * if (!(PerlIOBase(f)->flags & PERLIO_F_RDBUF)) { }
     */
    if (PerlIO_flush(f) != 0)
	return -1;
    if (PerlIOBase(f)->flags & PERLIO_F_TTY)
	PerlIOBase_flush_linebuf();

    if (!b->buf)
	PerlIO_get_base(f);	/* allocate via vtable */

    b->ptr = b->end = b->buf;
    if (PerlIO_fast_gets(n)) {
	/*
	 * Layer below is also buffered We do _NOT_ want to call its
	 * ->Read() because that will loop till it gets what we asked for
	 * which may hang on a pipe etc. Instead take anything it has to
	 * hand, or ask it to fill _once_.
	 */
	avail = PerlIO_get_cnt(n);
	if (avail <= 0) {
	    avail = PerlIO_fill(n);
	    if (avail == 0)
		avail = PerlIO_get_cnt(n);
	    else {
		if (!PerlIO_error(n) && PerlIO_eof(n))
		    avail = 0;
	    }
	}
	if (avail > 0) {
	    STDCHAR *ptr = PerlIO_get_ptr(n);
	    SSize_t cnt = avail;
	    if (avail > b->bufsiz)
		avail = b->bufsiz;
	    Copy(ptr, b->buf, avail, STDCHAR);
	    PerlIO_set_ptrcnt(n, ptr + avail, cnt - avail);
	}
    }
    else {
	avail = PerlIO_read(n, b->ptr, b->bufsiz);
    }
    if (avail <= 0) {
	if (avail == 0)
	    PerlIOBase(f)->flags |= PERLIO_F_EOF;
	else
	    PerlIOBase(f)->flags |= PERLIO_F_ERROR;
	return -1;
    }
    b->end = b->buf + avail;
    PerlIOBase(f)->flags |= PERLIO_F_RDBUF;
    return 0;
}

SSize_t
PerlIOBuf_read(PerlIO *f, void *vbuf, Size_t count)
{
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    if (f) {
	if (!b->ptr)
	    PerlIO_get_base(f);
	return PerlIOBase_read(f, vbuf, count);
    }
    return 0;
}

SSize_t
PerlIOBuf_unread(PerlIO *f, const void *vbuf, Size_t count)
{
    const STDCHAR *buf = (const STDCHAR *) vbuf + count;
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    SSize_t unread = 0;
    SSize_t avail;
    if (PerlIOBase(f)->flags & PERLIO_F_WRBUF)
	PerlIO_flush(f);
    if (!b->buf)
	PerlIO_get_base(f);
    if (b->buf) {
	if (PerlIOBase(f)->flags & PERLIO_F_RDBUF) {
	    /*
	     * Buffer is already a read buffer, we can overwrite any chars
	     * which have been read back to buffer start
	     */
	    avail = (b->ptr - b->buf);
	}
	else {
	    /*
	     * Buffer is idle, set it up so whole buffer is available for
	     * unread
	     */
	    avail = b->bufsiz;
	    b->end = b->buf + avail;
	    b->ptr = b->end;
	    PerlIOBase(f)->flags |= PERLIO_F_RDBUF;
	    /*
	     * Buffer extends _back_ from where we are now
	     */
	    b->posn -= b->bufsiz;
	}
	if (avail > (SSize_t) count) {
	    /*
	     * If we have space for more than count, just move count
	     */
	    avail = count;
	}
	if (avail > 0) {
	    b->ptr -= avail;
	    buf -= avail;
	    /*
	     * In simple stdio-like ungetc() case chars will be already
	     * there
	     */
	    if (buf != b->ptr) {
		Copy(buf, b->ptr, avail, STDCHAR);
	    }
	    count -= avail;
	    unread += avail;
	    PerlIOBase(f)->flags &= ~PERLIO_F_EOF;
	}
    }
    return unread;
}

SSize_t
PerlIOBuf_write(PerlIO *f, const void *vbuf, Size_t count)
{
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    const STDCHAR *buf = (const STDCHAR *) vbuf;
    Size_t written = 0;
    if (!b->buf)
	PerlIO_get_base(f);
    if (!(PerlIOBase(f)->flags & PERLIO_F_CANWRITE))
	return 0;
    while (count > 0) {
	SSize_t avail = b->bufsiz - (b->ptr - b->buf);
	if ((SSize_t) count < avail)
	    avail = count;
	PerlIOBase(f)->flags |= PERLIO_F_WRBUF;
	if (PerlIOBase(f)->flags & PERLIO_F_LINEBUF) {
	    while (avail > 0) {
		int ch = *buf++;
		*(b->ptr)++ = ch;
		count--;
		avail--;
		written++;
		if (ch == '\n') {
		    PerlIO_flush(f);
		    break;
		}
	    }
	}
	else {
	    if (avail) {
		Copy(buf, b->ptr, avail, STDCHAR);
		count -= avail;
		buf += avail;
		written += avail;
		b->ptr += avail;
	    }
	}
	if (b->ptr >= (b->buf + b->bufsiz))
	    PerlIO_flush(f);
    }
    if (PerlIOBase(f)->flags & PERLIO_F_UNBUF)
	PerlIO_flush(f);
    return written;
}

IV
PerlIOBuf_seek(PerlIO *f, Off_t offset, int whence)
{
    IV code;
    if ((code = PerlIO_flush(f)) == 0) {
	PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
	PerlIOBase(f)->flags &= ~PERLIO_F_EOF;
	code = PerlIO_seek(PerlIONext(f), offset, whence);
	if (code == 0) {
	    b->posn = PerlIO_tell(PerlIONext(f));
	}
    }
    return code;
}

Off_t
PerlIOBuf_tell(PerlIO *f)
{
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    /*
     * b->posn is file position where b->buf was read, or will be written
     */
    Off_t posn = b->posn;
    if (b->buf) {
	/*
	 * If buffer is valid adjust position by amount in buffer
	 */
	posn += (b->ptr - b->buf);
    }
    return posn;
}

IV
PerlIOBuf_close(PerlIO *f)
{
    IV code = PerlIOBase_close(f);
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    if (b->buf && b->buf != (STDCHAR *) & b->oneword) {
	safefree(b->buf);
    }
    b->buf = NULL;
    b->ptr = b->end = b->buf;
    PerlIOBase(f)->flags &= ~(PERLIO_F_RDBUF | PERLIO_F_WRBUF);
    return code;
}

STDCHAR *
PerlIOBuf_get_ptr(PerlIO *f)
{
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    if (!b->buf)
	PerlIO_get_base(f);
    return b->ptr;
}

SSize_t
PerlIOBuf_get_cnt(PerlIO *f)
{
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    if (!b->buf)
	PerlIO_get_base(f);
    if (PerlIOBase(f)->flags & PERLIO_F_RDBUF)
	return (b->end - b->ptr);
    return 0;
}

STDCHAR *
PerlIOBuf_get_base(PerlIO *f)
{
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    if (!b->buf) {
	if (!b->bufsiz)
	    b->bufsiz = 4096;
	b->buf =
	Newz('B',b->buf,b->bufsiz, STDCHAR);
	if (!b->buf) {
	    b->buf = (STDCHAR *) & b->oneword;
	    b->bufsiz = sizeof(b->oneword);
	}
	b->ptr = b->buf;
	b->end = b->ptr;
    }
    return b->buf;
}

Size_t
PerlIOBuf_bufsiz(PerlIO *f)
{
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    if (!b->buf)
	PerlIO_get_base(f);
    return (b->end - b->buf);
}

void
PerlIOBuf_set_ptrcnt(PerlIO *f, STDCHAR * ptr, SSize_t cnt)
{
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    if (!b->buf)
	PerlIO_get_base(f);
    b->ptr = ptr;
    if (PerlIO_get_cnt(f) != cnt || b->ptr < b->buf) {
	dTHX;
	assert(PerlIO_get_cnt(f) == cnt);
	assert(b->ptr >= b->buf);
    }
    PerlIOBase(f)->flags |= PERLIO_F_RDBUF;
}

PerlIO *
PerlIOBuf_dup(pTHX_ PerlIO *f, PerlIO *o, CLONE_PARAMS *param)
{
 return PerlIOBase_dup(aTHX_ f, o, param);
}



PerlIO_funcs PerlIO_perlio = {
    "perlio",
    sizeof(PerlIOBuf),
    PERLIO_K_BUFFERED,
    PerlIOBuf_pushed,
    PerlIOBase_noop_ok,
    PerlIOBuf_open,
    NULL,
    PerlIOBase_fileno,
    PerlIOBuf_dup,
    PerlIOBuf_read,
    PerlIOBuf_unread,
    PerlIOBuf_write,
    PerlIOBuf_seek,
    PerlIOBuf_tell,
    PerlIOBuf_close,
    PerlIOBuf_flush,
    PerlIOBuf_fill,
    PerlIOBase_eof,
    PerlIOBase_error,
    PerlIOBase_clearerr,
    PerlIOBase_setlinebuf,
    PerlIOBuf_get_base,
    PerlIOBuf_bufsiz,
    PerlIOBuf_get_ptr,
    PerlIOBuf_get_cnt,
    PerlIOBuf_set_ptrcnt,
};

/*--------------------------------------------------------------------------------------*/
/*
 * Temp layer to hold unread chars when cannot do it any other way
 */

IV
PerlIOPending_fill(PerlIO *f)
{
    /*
     * Should never happen
     */
    PerlIO_flush(f);
    return 0;
}

IV
PerlIOPending_close(PerlIO *f)
{
    /*
     * A tad tricky - flush pops us, then we close new top
     */
    PerlIO_flush(f);
    return PerlIO_close(f);
}

IV
PerlIOPending_seek(PerlIO *f, Off_t offset, int whence)
{
    /*
     * A tad tricky - flush pops us, then we seek new top
     */
    PerlIO_flush(f);
    return PerlIO_seek(f, offset, whence);
}


IV
PerlIOPending_flush(PerlIO *f)
{
    dTHX;
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    if (b->buf && b->buf != (STDCHAR *) & b->oneword) {
	PerlMemShared_free(b->buf);
	b->buf = NULL;
    }
    PerlIO_pop(aTHX_ f);
    return 0;
}

void
PerlIOPending_set_ptrcnt(PerlIO *f, STDCHAR * ptr, SSize_t cnt)
{
    if (cnt <= 0) {
	PerlIO_flush(f);
    }
    else {
	PerlIOBuf_set_ptrcnt(f, ptr, cnt);
    }
}

IV
PerlIOPending_pushed(PerlIO *f, const char *mode, SV *arg)
{
    IV code = PerlIOBase_pushed(f, mode, arg);
    PerlIOl *l = PerlIOBase(f);
    /*
     * Our PerlIO_fast_gets must match what we are pushed on, or sv_gets()
     * etc. get muddled when it changes mid-string when we auto-pop.
     */
    l->flags = (l->flags & ~(PERLIO_F_FASTGETS | PERLIO_F_UTF8)) |
	(PerlIOBase(PerlIONext(f))->
	 flags & (PERLIO_F_FASTGETS | PERLIO_F_UTF8));
    return code;
}

SSize_t
PerlIOPending_read(PerlIO *f, void *vbuf, Size_t count)
{
    SSize_t avail = PerlIO_get_cnt(f);
    SSize_t got = 0;
    if (count < avail)
	avail = count;
    if (avail > 0)
	got = PerlIOBuf_read(f, vbuf, avail);
    if (got >= 0 && got < count) {
	SSize_t more =
	    PerlIO_read(f, ((STDCHAR *) vbuf) + got, count - got);
	if (more >= 0 || got == 0)
	    got += more;
    }
    return got;
}

PerlIO_funcs PerlIO_pending = {
    "pending",
    sizeof(PerlIOBuf),
    PERLIO_K_BUFFERED,
    PerlIOPending_pushed,
    PerlIOBase_noop_ok,
    NULL,
    NULL,
    PerlIOBase_fileno,
    PerlIOBuf_dup,
    PerlIOPending_read,
    PerlIOBuf_unread,
    PerlIOBuf_write,
    PerlIOPending_seek,
    PerlIOBuf_tell,
    PerlIOPending_close,
    PerlIOPending_flush,
    PerlIOPending_fill,
    PerlIOBase_eof,
    PerlIOBase_error,
    PerlIOBase_clearerr,
    PerlIOBase_setlinebuf,
    PerlIOBuf_get_base,
    PerlIOBuf_bufsiz,
    PerlIOBuf_get_ptr,
    PerlIOBuf_get_cnt,
    PerlIOPending_set_ptrcnt,
};



/*--------------------------------------------------------------------------------------*/
/*
 * crlf - translation On read translate CR,LF to "\n" we do this by
 * overriding ptr/cnt entries to hand back a line at a time and keeping a
 * record of which nl we "lied" about. On write translate "\n" to CR,LF
 */

typedef struct {
    PerlIOBuf base;		/* PerlIOBuf stuff */
    STDCHAR *nl;		/* Position of crlf we "lied" about in the
				 * buffer */
} PerlIOCrlf;

IV
PerlIOCrlf_pushed(PerlIO *f, const char *mode, SV *arg)
{
    IV code;
    PerlIOBase(f)->flags |= PERLIO_F_CRLF;
    code = PerlIOBuf_pushed(f, mode, arg);
#if 0
    PerlIO_debug("PerlIOCrlf_pushed f=%p %s %s fl=%08" UVxf "\n",
		 f, PerlIOBase(f)->tab->name, (mode) ? mode : "(Null)",
		 PerlIOBase(f)->flags);
#endif
    return code;
}


SSize_t
PerlIOCrlf_unread(PerlIO *f, const void *vbuf, Size_t count)
{
    PerlIOCrlf *c = PerlIOSelf(f, PerlIOCrlf);
    if (c->nl) {
	*(c->nl) = 0xd;
	c->nl = NULL;
    }
    if (!(PerlIOBase(f)->flags & PERLIO_F_CRLF))
	return PerlIOBuf_unread(f, vbuf, count);
    else {
	const STDCHAR *buf = (const STDCHAR *) vbuf + count;
	PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
	SSize_t unread = 0;
	if (PerlIOBase(f)->flags & PERLIO_F_WRBUF)
	    PerlIO_flush(f);
	if (!b->buf)
	    PerlIO_get_base(f);
	if (b->buf) {
	    if (!(PerlIOBase(f)->flags & PERLIO_F_RDBUF)) {
		b->end = b->ptr = b->buf + b->bufsiz;
		PerlIOBase(f)->flags |= PERLIO_F_RDBUF;
		b->posn -= b->bufsiz;
	    }
	    while (count > 0 && b->ptr > b->buf) {
		int ch = *--buf;
		if (ch == '\n') {
		    if (b->ptr - 2 >= b->buf) {
			*--(b->ptr) = 0xa;
			*--(b->ptr) = 0xd;
			unread++;
			count--;
		    }
		    else {
			buf++;
			break;
		    }
		}
		else {
		    *--(b->ptr) = ch;
		    unread++;
		    count--;
		}
	    }
	}
	return unread;
    }
}

SSize_t
PerlIOCrlf_get_cnt(PerlIO *f)
{
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    if (!b->buf)
	PerlIO_get_base(f);
    if (PerlIOBase(f)->flags & PERLIO_F_RDBUF) {
	PerlIOCrlf *c = PerlIOSelf(f, PerlIOCrlf);
	if ((PerlIOBase(f)->flags & PERLIO_F_CRLF) && !c->nl) {
	    STDCHAR *nl = b->ptr;
	  scan:
	    while (nl < b->end && *nl != 0xd)
		nl++;
	    if (nl < b->end && *nl == 0xd) {
	      test:
		if (nl + 1 < b->end) {
		    if (nl[1] == 0xa) {
			*nl = '\n';
			c->nl = nl;
		    }
		    else {
			/*
			 * Not CR,LF but just CR
			 */
			nl++;
			goto scan;
		    }
		}
		else {
		    /*
		     * Blast - found CR as last char in buffer
		     */
		    if (b->ptr < nl) {
			/*
			 * They may not care, defer work as long as
			 * possible
			 */
			return (nl - b->ptr);
		    }
		    else {
			int code;
			b->ptr++;	/* say we have read it as far as
					 * flush() is concerned */
			b->buf++;	/* Leave space an front of buffer */
			b->bufsiz--;	/* Buffer is thus smaller */
			code = PerlIO_fill(f);	/* Fetch some more */
			b->bufsiz++;	/* Restore size for next time */
			b->buf--;	/* Point at space */
			b->ptr = nl = b->buf;	/* Which is what we hand
						 * off */
			b->posn--;	/* Buffer starts here */
			*nl = 0xd;	/* Fill in the CR */
			if (code == 0)
			    goto test;	/* fill() call worked */
			/*
			 * CR at EOF - just fall through
			 */
		    }
		}
	    }
	}
	return (((c->nl) ? (c->nl + 1) : b->end) - b->ptr);
    }
    return 0;
}

void
PerlIOCrlf_set_ptrcnt(PerlIO *f, STDCHAR * ptr, SSize_t cnt)
{
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    PerlIOCrlf *c = PerlIOSelf(f, PerlIOCrlf);
    IV flags = PerlIOBase(f)->flags;
    if (!b->buf)
	PerlIO_get_base(f);
    if (!ptr) {
	if (c->nl)
	    ptr = c->nl + 1;
	else {
	    ptr = b->end;
	    if ((flags & PERLIO_F_CRLF) && ptr > b->buf && ptr[-1] == 0xd)
		ptr--;
	}
	ptr -= cnt;
    }
    else {
	/*
	 * Test code - delete when it works ...
	 */
	STDCHAR *chk;
	if (c->nl)
	    chk = c->nl + 1;
	else {
	    chk = b->end;
	    if ((flags & PERLIO_F_CRLF) && chk > b->buf && chk[-1] == 0xd)
		chk--;
	}
	chk -= cnt;

	if (ptr != chk) {
	    dTHX;
	    Perl_croak(aTHX_ "ptr wrong %p != %p fl=%08" UVxf
		       " nl=%p e=%p for %d", ptr, chk, flags, c->nl,
		       b->end, cnt);
	}
    }
    if (c->nl) {
	if (ptr > c->nl) {
	    /*
	     * They have taken what we lied about
	     */
	    *(c->nl) = 0xd;
	    c->nl = NULL;
	    ptr++;
	}
    }
    b->ptr = ptr;
    PerlIOBase(f)->flags |= PERLIO_F_RDBUF;
}

SSize_t
PerlIOCrlf_write(PerlIO *f, const void *vbuf, Size_t count)
{
    if (!(PerlIOBase(f)->flags & PERLIO_F_CRLF))
	return PerlIOBuf_write(f, vbuf, count);
    else {
	PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
	const STDCHAR *buf = (const STDCHAR *) vbuf;
	const STDCHAR *ebuf = buf + count;
	if (!b->buf)
	    PerlIO_get_base(f);
	if (!(PerlIOBase(f)->flags & PERLIO_F_CANWRITE))
	    return 0;
	while (buf < ebuf) {
	    STDCHAR *eptr = b->buf + b->bufsiz;
	    PerlIOBase(f)->flags |= PERLIO_F_WRBUF;
	    while (buf < ebuf && b->ptr < eptr) {
		if (*buf == '\n') {
		    if ((b->ptr + 2) > eptr) {
			/*
			 * Not room for both
			 */
			PerlIO_flush(f);
			break;
		    }
		    else {
			*(b->ptr)++ = 0xd;	/* CR */
			*(b->ptr)++ = 0xa;	/* LF */
			buf++;
			if (PerlIOBase(f)->flags & PERLIO_F_LINEBUF) {
			    PerlIO_flush(f);
			    break;
			}
		    }
		}
		else {
		    int ch = *buf++;
		    *(b->ptr)++ = ch;
		}
		if (b->ptr >= eptr) {
		    PerlIO_flush(f);
		    break;
		}
	    }
	}
	if (PerlIOBase(f)->flags & PERLIO_F_UNBUF)
	    PerlIO_flush(f);
	return (buf - (STDCHAR *) vbuf);
    }
}

IV
PerlIOCrlf_flush(PerlIO *f)
{
    PerlIOCrlf *c = PerlIOSelf(f, PerlIOCrlf);
    if (c->nl) {
	*(c->nl) = 0xd;
	c->nl = NULL;
    }
    return PerlIOBuf_flush(f);
}

PerlIO_funcs PerlIO_crlf = {
    "crlf",
    sizeof(PerlIOCrlf),
    PERLIO_K_BUFFERED | PERLIO_K_CANCRLF,
    PerlIOCrlf_pushed,
    PerlIOBase_noop_ok,		/* popped */
    PerlIOBuf_open,
    NULL,
    PerlIOBase_fileno,
    PerlIOBuf_dup,
    PerlIOBuf_read,		/* generic read works with ptr/cnt lies
				 * ... */
    PerlIOCrlf_unread,		/* Put CR,LF in buffer for each '\n' */
    PerlIOCrlf_write,		/* Put CR,LF in buffer for each '\n' */
    PerlIOBuf_seek,
    PerlIOBuf_tell,
    PerlIOBuf_close,
    PerlIOCrlf_flush,
    PerlIOBuf_fill,
    PerlIOBase_eof,
    PerlIOBase_error,
    PerlIOBase_clearerr,
    PerlIOBase_setlinebuf,
    PerlIOBuf_get_base,
    PerlIOBuf_bufsiz,
    PerlIOBuf_get_ptr,
    PerlIOCrlf_get_cnt,
    PerlIOCrlf_set_ptrcnt,
};

#ifdef HAS_MMAP
/*--------------------------------------------------------------------------------------*/
/*
 * mmap as "buffer" layer
 */

typedef struct {
    PerlIOBuf base;		/* PerlIOBuf stuff */
    Mmap_t mptr;		/* Mapped address */
    Size_t len;			/* mapped length */
    STDCHAR *bbuf;		/* malloced buffer if map fails */
} PerlIOMmap;

static size_t page_size = 0;

IV
PerlIOMmap_map(PerlIO *f)
{
    dTHX;
    PerlIOMmap *m = PerlIOSelf(f, PerlIOMmap);
    IV flags = PerlIOBase(f)->flags;
    IV code = 0;
    if (m->len)
	abort();
    if (flags & PERLIO_F_CANREAD) {
	PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
	int fd = PerlIO_fileno(f);
	struct stat st;
	code = fstat(fd, &st);
	if (code == 0 && S_ISREG(st.st_mode)) {
	    SSize_t len = st.st_size - b->posn;
	    if (len > 0) {
		Off_t posn;
		if (!page_size) {
#if defined(HAS_SYSCONF) && (defined(_SC_PAGESIZE) || defined(_SC_PAGE_SIZE))
		    {
			SETERRNO(0, SS$_NORMAL);
#   ifdef _SC_PAGESIZE
			page_size = sysconf(_SC_PAGESIZE);
#   else
			page_size = sysconf(_SC_PAGE_SIZE);
#   endif
			if ((long) page_size < 0) {
			    if (errno) {
				SV *error = ERRSV;
				char *msg;
				STRLEN n_a;
				(void) SvUPGRADE(error, SVt_PV);
				msg = SvPVx(error, n_a);
				Perl_croak(aTHX_ "panic: sysconf: %s",
					   msg);
			    }
			    else
				Perl_croak(aTHX_
					   "panic: sysconf: pagesize unknown");
			}
		    }
#else
#   ifdef HAS_GETPAGESIZE
		    page_size = getpagesize();
#   else
#       if defined(I_SYS_PARAM) && defined(PAGESIZE)
		    page_size = PAGESIZE;	/* compiletime, bad */
#       endif
#   endif
#endif
		    if ((IV) page_size <= 0)
			Perl_croak(aTHX_ "panic: bad pagesize %" IVdf,
				   (IV) page_size);
		}
		if (b->posn < 0) {
		    /*
		     * This is a hack - should never happen - open should
		     * have set it !
		     */
		    b->posn = PerlIO_tell(PerlIONext(f));
		}
		posn = (b->posn / page_size) * page_size;
		len = st.st_size - posn;
		m->mptr = mmap(NULL, len, PROT_READ, MAP_SHARED, fd, posn);
		if (m->mptr && m->mptr != (Mmap_t) - 1) {
#if 0 && defined(HAS_MADVISE) && defined(MADV_SEQUENTIAL)
		    madvise(m->mptr, len, MADV_SEQUENTIAL);
#endif
#if 0 && defined(HAS_MADVISE) && defined(MADV_WILLNEED)
		    madvise(m->mptr, len, MADV_WILLNEED);
#endif
		    PerlIOBase(f)->flags =
			(flags & ~PERLIO_F_EOF) | PERLIO_F_RDBUF;
		    b->end = ((STDCHAR *) m->mptr) + len;
		    b->buf = ((STDCHAR *) m->mptr) + (b->posn - posn);
		    b->ptr = b->buf;
		    m->len = len;
		}
		else {
		    b->buf = NULL;
		}
	    }
	    else {
		PerlIOBase(f)->flags =
		    flags | PERLIO_F_EOF | PERLIO_F_RDBUF;
		b->buf = NULL;
		b->ptr = b->end = b->ptr;
		code = -1;
	    }
	}
    }
    return code;
}

IV
PerlIOMmap_unmap(PerlIO *f)
{
    PerlIOMmap *m = PerlIOSelf(f, PerlIOMmap);
    PerlIOBuf *b = &m->base;
    IV code = 0;
    if (m->len) {
	if (b->buf) {
	    code = munmap(m->mptr, m->len);
	    b->buf = NULL;
	    m->len = 0;
	    m->mptr = NULL;
	    if (PerlIO_seek(PerlIONext(f), b->posn, SEEK_SET) != 0)
		code = -1;
	}
	b->ptr = b->end = b->buf;
	PerlIOBase(f)->flags &= ~(PERLIO_F_RDBUF | PERLIO_F_WRBUF);
    }
    return code;
}

STDCHAR *
PerlIOMmap_get_base(PerlIO *f)
{
    PerlIOMmap *m = PerlIOSelf(f, PerlIOMmap);
    PerlIOBuf *b = &m->base;
    if (b->buf && (PerlIOBase(f)->flags & PERLIO_F_RDBUF)) {
	/*
	 * Already have a readbuffer in progress
	 */
	return b->buf;
    }
    if (b->buf) {
	/*
	 * We have a write buffer or flushed PerlIOBuf read buffer
	 */
	m->bbuf = b->buf;	/* save it in case we need it again */
	b->buf = NULL;		/* Clear to trigger below */
    }
    if (!b->buf) {
	PerlIOMmap_map(f);	/* Try and map it */
	if (!b->buf) {
	    /*
	     * Map did not work - recover PerlIOBuf buffer if we have one
	     */
	    b->buf = m->bbuf;
	}
    }
    b->ptr = b->end = b->buf;
    if (b->buf)
	return b->buf;
    return PerlIOBuf_get_base(f);
}

SSize_t
PerlIOMmap_unread(PerlIO *f, const void *vbuf, Size_t count)
{
    PerlIOMmap *m = PerlIOSelf(f, PerlIOMmap);
    PerlIOBuf *b = &m->base;
    if (PerlIOBase(f)->flags & PERLIO_F_WRBUF)
	PerlIO_flush(f);
    if (b->ptr && (b->ptr - count) >= b->buf
	&& memEQ(b->ptr - count, vbuf, count)) {
	b->ptr -= count;
	PerlIOBase(f)->flags &= ~PERLIO_F_EOF;
	return count;
    }
    if (m->len) {
	/*
	 * Loose the unwritable mapped buffer
	 */
	PerlIO_flush(f);
	/*
	 * If flush took the "buffer" see if we have one from before
	 */
	if (!b->buf && m->bbuf)
	    b->buf = m->bbuf;
	if (!b->buf) {
	    PerlIOBuf_get_base(f);
	    m->bbuf = b->buf;
	}
    }
    return PerlIOBuf_unread(f, vbuf, count);
}

SSize_t
PerlIOMmap_write(PerlIO *f, const void *vbuf, Size_t count)
{
    PerlIOMmap *m = PerlIOSelf(f, PerlIOMmap);
    PerlIOBuf *b = &m->base;
    if (!b->buf || !(PerlIOBase(f)->flags & PERLIO_F_WRBUF)) {
	/*
	 * No, or wrong sort of, buffer
	 */
	if (m->len) {
	    if (PerlIOMmap_unmap(f) != 0)
		return 0;
	}
	/*
	 * If unmap took the "buffer" see if we have one from before
	 */
	if (!b->buf && m->bbuf)
	    b->buf = m->bbuf;
	if (!b->buf) {
	    PerlIOBuf_get_base(f);
	    m->bbuf = b->buf;
	}
    }
    return PerlIOBuf_write(f, vbuf, count);
}

IV
PerlIOMmap_flush(PerlIO *f)
{
    PerlIOMmap *m = PerlIOSelf(f, PerlIOMmap);
    PerlIOBuf *b = &m->base;
    IV code = PerlIOBuf_flush(f);
    /*
     * Now we are "synced" at PerlIOBuf level
     */
    if (b->buf) {
	if (m->len) {
	    /*
	     * Unmap the buffer
	     */
	    if (PerlIOMmap_unmap(f) != 0)
		code = -1;
	}
	else {
	    /*
	     * We seem to have a PerlIOBuf buffer which was not mapped
	     * remember it in case we need one later
	     */
	    m->bbuf = b->buf;
	}
    }
    return code;
}

IV
PerlIOMmap_fill(PerlIO *f)
{
    PerlIOBuf *b = PerlIOSelf(f, PerlIOBuf);
    IV code = PerlIO_flush(f);
    if (code == 0 && !b->buf) {
	code = PerlIOMmap_map(f);
    }
    if (code == 0 && !(PerlIOBase(f)->flags & PERLIO_F_RDBUF)) {
	code = PerlIOBuf_fill(f);
    }
    return code;
}

IV
PerlIOMmap_close(PerlIO *f)
{
    PerlIOMmap *m = PerlIOSelf(f, PerlIOMmap);
    PerlIOBuf *b = &m->base;
    IV code = PerlIO_flush(f);
    if (m->bbuf) {
	b->buf = m->bbuf;
	m->bbuf = NULL;
	b->ptr = b->end = b->buf;
    }
    if (PerlIOBuf_close(f) != 0)
	code = -1;
    return code;
}

PerlIO *
PerlIOMmap_dup(pTHX_ PerlIO *f, PerlIO *o, CLONE_PARAMS *param)
{
 return PerlIOBase_dup(aTHX_ f, o, param);
}


PerlIO_funcs PerlIO_mmap = {
    "mmap",
    sizeof(PerlIOMmap),
    PERLIO_K_BUFFERED,
    PerlIOBuf_pushed,
    PerlIOBase_noop_ok,
    PerlIOBuf_open,
    NULL,
    PerlIOBase_fileno,
    PerlIOMmap_dup,
    PerlIOBuf_read,
    PerlIOMmap_unread,
    PerlIOMmap_write,
    PerlIOBuf_seek,
    PerlIOBuf_tell,
    PerlIOBuf_close,
    PerlIOMmap_flush,
    PerlIOMmap_fill,
    PerlIOBase_eof,
    PerlIOBase_error,
    PerlIOBase_clearerr,
    PerlIOBase_setlinebuf,
    PerlIOMmap_get_base,
    PerlIOBuf_bufsiz,
    PerlIOBuf_get_ptr,
    PerlIOBuf_get_cnt,
    PerlIOBuf_set_ptrcnt,
};

#endif				/* HAS_MMAP */

void
PerlIO_init(void)
{
    dTHX;
#ifndef WIN32
    call_atexit(PerlIO_cleanup_layers, NULL);
#endif
    if (!PL_perlio) {
#ifndef WIN32
	atexit(&PerlIO_cleanup);
#endif
    }
}

#undef PerlIO_stdin
PerlIO *
PerlIO_stdin(void)
{
    dTHX;
    if (!PL_perlio) {
	PerlIO_stdstreams(aTHX);
    }
    return &PL_perlio[1];
}

#undef PerlIO_stdout
PerlIO *
PerlIO_stdout(void)
{
    dTHX;
    if (!PL_perlio) {
	PerlIO_stdstreams(aTHX);
    }
    return &PL_perlio[2];
}

#undef PerlIO_stderr
PerlIO *
PerlIO_stderr(void)
{
    dTHX;
    if (!PL_perlio) {
	PerlIO_stdstreams(aTHX);
    }
    return &PL_perlio[3];
}

/*--------------------------------------------------------------------------------------*/

#undef PerlIO_getname
char *
PerlIO_getname(PerlIO *f, char *buf)
{
    dTHX;
    char *name = NULL;
#ifdef VMS
    FILE *stdio = PerlIOSelf(f, PerlIOStdio)->stdio;
    if (stdio)
	name = fgetname(stdio, buf);
#else
    Perl_croak(aTHX_ "Don't know how to get file name");
#endif
    return name;
}


/*--------------------------------------------------------------------------------------*/
/*
 * Functions which can be called on any kind of PerlIO implemented in
 * terms of above
 */

#undef PerlIO_getc
int
PerlIO_getc(PerlIO *f)
{
    STDCHAR buf[1];
    SSize_t count = PerlIO_read(f, buf, 1);
    if (count == 1) {
	return (unsigned char) buf[0];
    }
    return EOF;
}

#undef PerlIO_ungetc
int
PerlIO_ungetc(PerlIO *f, int ch)
{
    if (ch != EOF) {
	STDCHAR buf = ch;
	if (PerlIO_unread(f, &buf, 1) == 1)
	    return ch;
    }
    return EOF;
}

#undef PerlIO_putc
int
PerlIO_putc(PerlIO *f, int ch)
{
    STDCHAR buf = ch;
    return PerlIO_write(f, &buf, 1);
}

#undef PerlIO_puts
int
PerlIO_puts(PerlIO *f, const char *s)
{
    STRLEN len = strlen(s);
    return PerlIO_write(f, s, len);
}

#undef PerlIO_rewind
void
PerlIO_rewind(PerlIO *f)
{
    PerlIO_seek(f, (Off_t) 0, SEEK_SET);
    PerlIO_clearerr(f);
}

#undef PerlIO_vprintf
int
PerlIO_vprintf(PerlIO *f, const char *fmt, va_list ap)
{
    dTHX;
    SV *sv = newSVpvn("", 0);
    char *s;
    STRLEN len;
    SSize_t wrote;
#ifdef NEED_VA_COPY
    va_list apc;
    Perl_va_copy(ap, apc);
    sv_vcatpvf(sv, fmt, &apc);
#else
    sv_vcatpvf(sv, fmt, &ap);
#endif
    s = SvPV(sv, len);
    wrote = PerlIO_write(f, s, len);
    SvREFCNT_dec(sv);
    return wrote;
}

#undef PerlIO_printf
int
PerlIO_printf(PerlIO *f, const char *fmt, ...)
{
    va_list ap;
    int result;
    va_start(ap, fmt);
    result = PerlIO_vprintf(f, fmt, ap);
    va_end(ap);
    return result;
}

#undef PerlIO_stdoutf
int
PerlIO_stdoutf(const char *fmt, ...)
{
    va_list ap;
    int result;
    va_start(ap, fmt);
    result = PerlIO_vprintf(PerlIO_stdout(), fmt, ap);
    va_end(ap);
    return result;
}

#undef PerlIO_tmpfile
PerlIO *
PerlIO_tmpfile(void)
{
    /*
     * I have no idea how portable mkstemp() is ...
     */
#if defined(WIN32) || !defined(HAVE_MKSTEMP)
    dTHX;
    PerlIO *f = NULL;
    FILE *stdio = PerlSIO_tmpfile();
    if (stdio) {
	PerlIOStdio *s =
	    PerlIOSelf(PerlIO_push
		       (aTHX_(f = PerlIO_allocate(aTHX)), &PerlIO_stdio,
			"w+", Nullsv), PerlIOStdio);
	s->stdio = stdio;
    }
    return f;
#else
    dTHX;
    SV *sv = newSVpv("/tmp/PerlIO_XXXXXX", 0);
    int fd = mkstemp(SvPVX(sv));
    PerlIO *f = NULL;
    if (fd >= 0) {
	f = PerlIO_fdopen(fd, "w+");
	if (f) {
	    PerlIOBase(f)->flags |= PERLIO_F_TEMP;
	}
	PerlLIO_unlink(SvPVX(sv));
	SvREFCNT_dec(sv);
    }
    return f;
#endif
}

#undef HAS_FSETPOS
#undef HAS_FGETPOS

#endif				/* USE_SFIO */
#endif				/* PERLIO_IS_STDIO */

/*======================================================================================*/
/*
 * Now some functions in terms of above which may be needed even if we are
 * not in true PerlIO mode
 */

#ifndef HAS_FSETPOS
#undef PerlIO_setpos
int
PerlIO_setpos(PerlIO *f, SV *pos)
{
    dTHX;
    if (SvOK(pos)) {
	STRLEN len;
	Off_t *posn = (Off_t *) SvPV(pos, len);
	if (f && len == sizeof(Off_t))
	    return PerlIO_seek(f, *posn, SEEK_SET);
    }
    SETERRNO(EINVAL, SS$_IVCHAN);
    return -1;
}
#else
#undef PerlIO_setpos
int
PerlIO_setpos(PerlIO *f, SV *pos)
{
    dTHX;
    if (SvOK(pos)) {
	STRLEN len;
	Fpos_t *fpos = (Fpos_t *) SvPV(pos, len);
	if (f && len == sizeof(Fpos_t)) {
#if defined(USE_64_BIT_STDIO) && defined(USE_FSETPOS64)
	    return fsetpos64(f, fpos);
#else
	    return fsetpos(f, fpos);
#endif
	}
    }
    SETERRNO(EINVAL, SS$_IVCHAN);
    return -1;
}
#endif

#ifndef HAS_FGETPOS
#undef PerlIO_getpos
int
PerlIO_getpos(PerlIO *f, SV *pos)
{
    dTHX;
    Off_t posn = PerlIO_tell(f);
    sv_setpvn(pos, (char *) &posn, sizeof(posn));
    return (posn == (Off_t) - 1) ? -1 : 0;
}
#else
#undef PerlIO_getpos
int
PerlIO_getpos(PerlIO *f, SV *pos)
{
    dTHX;
    Fpos_t fpos;
    int code;
#if defined(USE_64_BIT_STDIO) && defined(USE_FSETPOS64)
    code = fgetpos64(f, &fpos);
#else
    code = fgetpos(f, &fpos);
#endif
    sv_setpvn(pos, (char *) &fpos, sizeof(fpos));
    return code;
}
#endif

#if (defined(PERLIO_IS_STDIO) || !defined(USE_SFIO)) && !defined(HAS_VPRINTF)

int
vprintf(char *pat, char *args)
{
    _doprnt(pat, args, stdout);
    return 0;			/* wrong, but perl doesn't use the return
				 * value */
}

int
vfprintf(FILE *fd, char *pat, char *args)
{
    _doprnt(pat, args, fd);
    return 0;			/* wrong, but perl doesn't use the return
				 * value */
}

#endif

#ifndef PerlIO_vsprintf
int
PerlIO_vsprintf(char *s, int n, const char *fmt, va_list ap)
{
    int val = vsprintf(s, fmt, ap);
    if (n >= 0) {
	if (strlen(s) >= (STRLEN) n) {
	    dTHX;
	    (void) PerlIO_puts(Perl_error_log,
			       "panic: sprintf overflow - memory corrupted!\n");
	    my_exit(1);
	}
    }
    return val;
}
#endif

#ifndef PerlIO_sprintf
int
PerlIO_sprintf(char *s, int n, const char *fmt, ...)
{
    va_list ap;
    int result;
    va_start(ap, fmt);
    result = PerlIO_vsprintf(s, n, fmt, ap);
    va_end(ap);
    return result;
}
#endif