universal.c

   1 /*    universal.c
   2  *
   3  *    Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
   4  *    by Larry Wall and others
   5  *
   6  *    You may distribute under the terms of either the GNU General Public
   7  *    License or the Artistic License, as specified in the README file.
   8  *
   9  */
  10
  11 /*
  12  * "The roots of those mountains must be roots indeed; there must be
  13  * great secrets buried there which have not been discovered since the
  14  * beginning." --Gandalf, relating Gollum's story
  15  */
  16
  17 /* This file contains the code that implements the functions in Perl's
  18  * UNIVERSAL package, such as UNIVERSAL->can().
  19  */
  20
  21 #include "EXTERN.h"
  22 #define PERL_IN_UNIVERSAL_C
  23 #include "perl.h"
  24
  25 #ifdef USE_PERLIO
  26 #include "perliol.h" /* For the PERLIO_F_XXX */
  27 #endif
  28
  29 /*
  30  * Contributed by Graham Barr  <Graham.Barr@tiuk.ti.com>
  31  * The main guts of traverse_isa was actually copied from gv_fetchmeth
  32  */
  33
  34 STATIC SV *
  35 S_isa_lookup(pTHX_ HV *stash, const char *name, HV* name_stash,
  36              int len, int level)
  37 {
  38     AV* av;
  39     GV* gv;
  40     GV** gvp;
  41     HV* hv = Nullhv;
  42     SV* subgen = Nullsv;
  43
  44     /* A stash/class can go by many names (ie. User == main::User), so
  45        we compare the stash itself just in case */
  46     if (name_stash && (stash == name_stash))
  47         return &PL_sv_yes;
  48
  49     if (strEQ(HvNAME(stash), name))
  50         return &PL_sv_yes;
  51
  52     if (strEQ(name, "UNIVERSAL"))
  53         return &PL_sv_yes;
  54
  55     if (level > 100)
  56         Perl_croak(aTHX_ "Recursive inheritance detected in package '%s'",
  57                    HvNAME(stash));
  58
  59     gvp = (GV**)hv_fetch(stash, "::ISA::CACHE::", 14, FALSE);
  60
  61     if (gvp && (gv = *gvp) != (GV*)&PL_sv_undef && (subgen = GvSV(gv))
  62         && (hv = GvHV(gv)))
  63     {
  64         if (SvIV(subgen) == (IV)PL_sub_generation) {
  65             SV* sv;
  66             SV** svp = (SV**)hv_fetch(hv, name, len, FALSE);
  67             if (svp && (sv = *svp) != (SV*)&PL_sv_undef) {
  68                 DEBUG_o( Perl_deb(aTHX_ "Using cached ISA %s for package %s\n",
  69                                   name, HvNAME(stash)) );
  70                 return sv;
  71             }
  72         }
  73         else {
  74             DEBUG_o( Perl_deb(aTHX_ "ISA Cache in package %s is stale\n",
  75                               HvNAME(stash)) );
  76             hv_clear(hv);
  77             sv_setiv(subgen, PL_sub_generation);
  78         }
  79     }
  80
  81     gvp = (GV**)hv_fetch(stash,"ISA",3,FALSE);
  82
  83     if (gvp && (gv = *gvp) != (GV*)&PL_sv_undef && (av = GvAV(gv))) {
  84         if (!hv || !subgen) {
  85             gvp = (GV**)hv_fetch(stash, "::ISA::CACHE::", 14, TRUE);
  86
  87             gv = *gvp;
  88
  89             if (SvTYPE(gv) != SVt_PVGV)
  90                 gv_init(gv, stash, "::ISA::CACHE::", 14, TRUE);
  91
  92             if (!hv)
  93                 hv = GvHVn(gv);
  94             if (!subgen) {
  95                 subgen = newSViv(PL_sub_generation);
  96                 GvSV(gv) = subgen;
  97             }
  98         }
  99         if (hv) {
 100             SV** svp = AvARRAY(av);
 101             /* NOTE: No support for tied ISA */
 102             I32 items = AvFILLp(av) + 1;
 103             while (items--) {
 104                 SV* sv = *svp++;
 105                 HV* basestash = gv_stashsv(sv, FALSE);
 106                 if (!basestash) {
 107                     if (ckWARN(WARN_MISC))
 108                         Perl_warner(aTHX_ packWARN(WARN_SYNTAX),
 109                              "Can't locate package %"SVf" for @%s::ISA",
 110                             sv, HvNAME(stash));
 111                     continue;
 112                 }
 113                 if (&PL_sv_yes == isa_lookup(basestash, name, name_stash,
 114                                              len, level + 1)) {
 115                     (void)hv_store(hv,name,len,&PL_sv_yes,0);
 116                     return &PL_sv_yes;
 117                 }
 118             }
 119             (void)hv_store(hv,name,len,&PL_sv_no,0);
 120         }
 121     }
 122     return &PL_sv_no;
 123 }
 124
 125 /*
 126 =head1 SV Manipulation Functions
 127
 128 =for apidoc sv_derived_from
 129
 130 Returns a boolean indicating whether the SV is derived from the specified
 131 class.  This is the function that implements C<UNIVERSAL::isa>.  It works
 132 for class names as well as for objects.
 133
 134 =cut
 135 */
 136
 137 bool
 138 Perl_sv_derived_from(pTHX_ SV *sv, const char *name)
 139 {
 140     char *type;
 141     HV *stash;
 142     HV *name_stash;
 143
 144     stash = Nullhv;
 145     type = Nullch;
 146
 147     if (SvGMAGICAL(sv))
 148         mg_get(sv) ;
 149
 150     if (SvROK(sv)) {
 151         sv = SvRV(sv);
 152         type = sv_reftype(sv,0);
 153         if (SvOBJECT(sv))
 154             stash = SvSTASH(sv);
 155     }
 156     else {
 157         stash = gv_stashsv(sv, FALSE);
 158     }
 159
 160     name_stash = gv_stashpv(name, FALSE);
 161
 162     return (type && strEQ(type,name)) ||
 163             (stash && isa_lookup(stash, name, name_stash, strlen(name), 0)
 164              == &PL_sv_yes)
 165         ? TRUE
 166         : FALSE ;
 167 }
 168
 169 #include "XSUB.h"
 170
 171 void XS_UNIVERSAL_isa(pTHX_ CV *cv);
 172 void XS_UNIVERSAL_can(pTHX_ CV *cv);
 173 void XS_UNIVERSAL_VERSION(pTHX_ CV *cv);
 174 XS(XS_version_new);
 175 XS(XS_version_stringify);
 176 XS(XS_version_numify);
 177 XS(XS_version_vcmp);
 178 XS(XS_version_boolean);
 179 XS(XS_version_noop);
 180 XS(XS_version_is_alpha);
 181 XS(XS_version_qv);
 182 XS(XS_utf8_is_utf8);
 183 XS(XS_utf8_valid);
 184 XS(XS_utf8_encode);
 185 XS(XS_utf8_decode);
 186 XS(XS_utf8_upgrade);
 187 XS(XS_utf8_downgrade);
 188 XS(XS_utf8_unicode_to_native);
 189 XS(XS_utf8_native_to_unicode);
 190 XS(XS_Internals_SvREADONLY);
 191 XS(XS_Internals_SvREFCNT);
 192 XS(XS_Internals_hv_clear_placehold);
 193 XS(XS_PerlIO_get_layers);
 194 XS(XS_Regexp_DESTROY);
 195 XS(XS_Internals_hash_seed);
 196 XS(XS_Internals_rehash_seed);
 197 XS(XS_Internals_HvREHASH);
 198
 199 void
 200 Perl_boot_core_UNIVERSAL(pTHX)
 201 {
 202     char *file = __FILE__;
 203
 204     newXS("UNIVERSAL::isa",             XS_UNIVERSAL_isa,         file);
 205     newXS("UNIVERSAL::can",             XS_UNIVERSAL_can,         file);
 206     newXS("UNIVERSAL::VERSION",         XS_UNIVERSAL_VERSION,     file);
 207     {
 208         /* register the overloading (type 'A') magic */
 209         PL_amagic_generation++;
 210         /* Make it findable via fetchmethod */
 211         newXS("version::()", XS_version_noop, file);
 212         newXS("version::new", XS_version_new, file);
 213         newXS("version::(\"\"", XS_version_stringify, file);
 214         newXS("version::stringify", XS_version_stringify, file);
 215         newXS("version::(0+", XS_version_numify, file);
 216         newXS("version::numify", XS_version_numify, file);
 217         newXS("version::(cmp", XS_version_vcmp, file);
 218         newXS("version::(<=>", XS_version_vcmp, file);
 219         newXS("version::vcmp", XS_version_vcmp, file);
 220         newXS("version::(bool", XS_version_boolean, file);
 221         newXS("version::boolean", XS_version_boolean, file);
 222         newXS("version::(nomethod", XS_version_noop, file);
 223         newXS("version::noop", XS_version_noop, file);
 224         newXS("version::is_alpha", XS_version_is_alpha, file);
 225         newXS("version::qv", XS_version_qv, file);
 226     }
 227     newXS("utf8::is_utf8", XS_utf8_is_utf8, file);
 228     newXS("utf8::valid", XS_utf8_valid, file);
 229     newXS("utf8::encode", XS_utf8_encode, file);
 230     newXS("utf8::decode", XS_utf8_decode, file);
 231     newXS("utf8::upgrade", XS_utf8_upgrade, file);
 232     newXS("utf8::downgrade", XS_utf8_downgrade, file);
 233     newXS("utf8::native_to_unicode", XS_utf8_native_to_unicode, file);
 234     newXS("utf8::unicode_to_native", XS_utf8_unicode_to_native, file);
 235     newXSproto("Internals::SvREADONLY",XS_Internals_SvREADONLY, file, "\\[$%@];$");
 236     newXSproto("Internals::SvREFCNT",XS_Internals_SvREFCNT, file, "\\[$%@];$");
 237     newXSproto("Internals::hv_clear_placeholders",
 238                XS_Internals_hv_clear_placehold, file, "\\%");
 239     newXSproto("PerlIO::get_layers",
 240                XS_PerlIO_get_layers, file, "*;@");
 241     newXS("Regexp::DESTROY", XS_Regexp_DESTROY, file);
 242     newXSproto("Internals::hash_seed",XS_Internals_hash_seed, file, "");
 243     newXSproto("Internals::rehash_seed",XS_Internals_rehash_seed, file, "");
 244     newXSproto("Internals::HvREHASH", XS_Internals_HvREHASH, file, "\\%");
 245 }
 246
 247
 248 XS(XS_UNIVERSAL_isa)
 249 {
 250     dXSARGS;
 251     SV *sv;
 252     char *name;
 253     STRLEN n_a;
 254
 255     if (items != 2)
 256         Perl_croak(aTHX_ "Usage: UNIVERSAL::isa(reference, kind)");
 257
 258     sv = ST(0);
 259
 260     if (SvGMAGICAL(sv))
 261         mg_get(sv);
 262
 263     if (!SvOK(sv) || !(SvROK(sv) || (SvPOK(sv) && SvCUR(sv))
 264                 || (SvGMAGICAL(sv) && SvPOKp(sv) && SvCUR(sv))))
 265         XSRETURN_UNDEF;
 266
 267     name = (char *)SvPV(ST(1),n_a);
 268
 269     ST(0) = boolSV(sv_derived_from(sv, name));
 270     XSRETURN(1);
 271 }
 272
 273 XS(XS_UNIVERSAL_can)
 274 {
 275     dXSARGS;
 276     SV   *sv;
 277     char *name;
 278     SV   *rv;
 279     HV   *pkg = NULL;
 280     STRLEN n_a;
 281
 282     if (items != 2)
 283         Perl_croak(aTHX_ "Usage: UNIVERSAL::can(object-ref, method)");
 284
 285     sv = ST(0);
 286
 287     if (SvGMAGICAL(sv))
 288         mg_get(sv);
 289
 290     if (!SvOK(sv) || !(SvROK(sv) || (SvPOK(sv) && SvCUR(sv))
 291                 || (SvGMAGICAL(sv) && SvPOKp(sv) && SvCUR(sv))))
 292         XSRETURN_UNDEF;
 293
 294     name = (char *)SvPV(ST(1),n_a);
 295     rv = &PL_sv_undef;
 296
 297     if (SvROK(sv)) {
 298         sv = (SV*)SvRV(sv);
 299         if (SvOBJECT(sv))
 300             pkg = SvSTASH(sv);
 301     }
 302     else {
 303         pkg = gv_stashsv(sv, FALSE);
 304     }
 305
 306     if (pkg) {
 307         GV *gv = gv_fetchmethod_autoload(pkg, name, FALSE);
 308         if (gv && isGV(gv))
 309             rv = sv_2mortal(newRV((SV*)GvCV(gv)));
 310     }
 311
 312     ST(0) = rv;
 313     XSRETURN(1);
 314 }
 315
 316 XS(XS_UNIVERSAL_VERSION)
 317 {
 318     dXSARGS;
 319     HV *pkg;
 320     GV **gvp;
 321     GV *gv;
 322     SV *sv;
 323     char *undef;
 324
 325     if (SvROK(ST(0))) {
 326         sv = (SV*)SvRV(ST(0));
 327         if (!SvOBJECT(sv))
 328             Perl_croak(aTHX_ "Cannot find version of an unblessed reference");
 329         pkg = SvSTASH(sv);
 330     }
 331     else {
 332         pkg = gv_stashsv(ST(0), FALSE);
 333     }
 334
 335     gvp = pkg ? (GV**)hv_fetch(pkg,"VERSION",7,FALSE) : Null(GV**);
 336
 337     if (gvp && isGV(gv = *gvp) && SvOK(sv = GvSV(gv))) {
 338         SV *nsv = sv_newmortal();
 339         sv_setsv(nsv, sv);
 340         sv = nsv;
 341         if ( !sv_derived_from(sv, "version"))
 342             upg_version(sv);
 343         undef = Nullch;
 344     }
 345     else {
 346         sv = (SV*)&PL_sv_undef;
 347         undef = "(undef)";
 348     }
 349
 350     if (items > 1) {
 351         STRLEN len;
 352         SV *req = ST(1);
 353
 354         if (undef) {
 355              if (pkg)
 356                   Perl_croak(aTHX_
 357                              "%s does not define $%s::VERSION--version check failed",
 358                              HvNAME(pkg), HvNAME(pkg));
 359              else {
 360                   char *str = SvPVx(ST(0), len);
 361
 362                   Perl_croak(aTHX_
 363                              "%s defines neither package nor VERSION--version check failed", str);
 364              }
 365         }
 366
 367         if ( !sv_derived_from(req, "version")) {
 368             /* req may very well be R/O, so create a new object */
 369             SV *nsv = sv_newmortal();
 370             sv_setsv(nsv, req);
 371             req = nsv;
 372             upg_version(req);
 373         }
 374
 375         if ( vcmp( req, sv ) > 0 )
 376             Perl_croak(aTHX_ "%s version %"SVf" (%"SVf") required--"
 377                     "this is only version %"SVf" (%"SVf")", HvNAME(pkg),
 378                     vnumify(req),vnormal(req),vnumify(sv),vnormal(sv));
 379     }
 380
 381     if ( SvOK(sv) && sv_derived_from(sv, "version") ) {
 382         ST(0) = vnumify(sv);
 383     } else {
 384         ST(0) = sv;
 385     }
 386
 387     XSRETURN(1);
 388 }
 389
 390 XS(XS_version_new)
 391 {
 392     dXSARGS;
 393     if (items > 3)
 394         Perl_croak(aTHX_ "Usage: version::new(class, version)");
 395     SP -= items;
 396     {
 397         char *  class = (char *)SvPV_nolen(ST(0));
 398         SV *vs = ST(1);
 399         SV *rv;
 400         if (items == 3 )
 401         {
 402             vs = sv_newmortal();
 403             Perl_sv_setpvf(aTHX_ vs,"v%s",SvPV_nolen(ST(2)));
 404         }
 405
 406         rv = new_version(vs);
 407         if ( strcmp(class,"version") != 0 ) /* inherited new() */
 408             sv_bless(rv, gv_stashpv(class,TRUE));
 409
 410         PUSHs(sv_2mortal(rv));
 411         PUTBACK;
 412         return;
 413     }
 414 }
 415
 416 XS(XS_version_stringify)
 417 {
 418      dXSARGS;
 419      if (items < 1)
 420           Perl_croak(aTHX_ "Usage: version::stringify(lobj, ...)");
 421      SP -= items;
 422      {
 423           SV *  lobj;
 424
 425           if (sv_derived_from(ST(0), "version")) {
 426                SV *tmp = SvRV(ST(0));
 427                lobj = tmp;
 428           }
 429           else
 430                Perl_croak(aTHX_ "lobj is not of type version");
 431
 432           PUSHs(sv_2mortal(vstringify(lobj)));
 433
 434           PUTBACK;
 435           return;
 436      }
 437 }
 438
 439 XS(XS_version_numify)
 440 {
 441      dXSARGS;
 442      if (items < 1)
 443           Perl_croak(aTHX_ "Usage: version::numify(lobj, ...)");
 444      SP -= items;
 445      {
 446           SV *  lobj;
 447
 448           if (sv_derived_from(ST(0), "version")) {
 449                SV *tmp = SvRV(ST(0));
 450                lobj = tmp;
 451           }
 452           else
 453                Perl_croak(aTHX_ "lobj is not of type version");
 454
 455           PUSHs(sv_2mortal(vnumify(lobj)));
 456
 457           PUTBACK;
 458           return;
 459      }
 460 }
 461
 462 XS(XS_version_vcmp)
 463 {
 464      dXSARGS;
 465      if (items < 1)
 466           Perl_croak(aTHX_ "Usage: version::vcmp(lobj, ...)");
 467      SP -= items;
 468      {
 469           SV *  lobj;
 470
 471           if (sv_derived_from(ST(0), "version")) {
 472                SV *tmp = SvRV(ST(0));
 473                lobj = tmp;
 474           }
 475           else
 476                Perl_croak(aTHX_ "lobj is not of type version");
 477
 478           {
 479                SV       *rs;
 480                SV       *rvs;
 481                SV * robj = ST(1);
 482                IV        swap = (IV)SvIV(ST(2));
 483
 484                if ( ! sv_derived_from(robj, "version") )
 485                {
 486                     robj = new_version(robj);
 487                }
 488                rvs = SvRV(robj);
 489
 490                if ( swap )
 491                {
 492                     rs = newSViv(vcmp(rvs,lobj));
 493                }
 494                else
 495                {
 496                     rs = newSViv(vcmp(lobj,rvs));
 497                }
 498
 499                PUSHs(sv_2mortal(rs));
 500           }
 501
 502           PUTBACK;
 503           return;
 504      }
 505 }
 506
 507 XS(XS_version_boolean)
 508 {
 509      dXSARGS;
 510      if (items < 1)
 511           Perl_croak(aTHX_ "Usage: version::boolean(lobj, ...)");
 512      SP -= items;
 513      {
 514           SV *  lobj;
 515
 516           if (sv_derived_from(ST(0), "version")) {
 517                SV *tmp = SvRV(ST(0));
 518                lobj = tmp;
 519           }
 520           else
 521                Perl_croak(aTHX_ "lobj is not of type version");
 522
 523           {
 524                SV       *rs;
 525                rs = newSViv( vcmp(lobj,new_version(newSVpvn("0",1))) );
 526                PUSHs(sv_2mortal(rs));
 527           }
 528
 529           PUTBACK;
 530           return;
 531      }
 532 }
 533
 534 XS(XS_version_noop)
 535 {
 536      dXSARGS;
 537      if (items < 1)
 538           Perl_croak(aTHX_ "Usage: version::noop(lobj, ...)");
 539      {
 540           SV *  lobj;
 541
 542           if (sv_derived_from(ST(0), "version")) {
 543                SV *tmp = SvRV(ST(0));
 544                lobj = tmp;
 545           }
 546           else
 547                Perl_croak(aTHX_ "lobj is not of type version");
 548
 549           {
 550                Perl_croak(aTHX_ "operation not supported with version object");
 551           }
 552
 553      }
 554      XSRETURN_EMPTY;
 555 }
 556
 557 XS(XS_version_is_alpha)
 558 {
 559     dXSARGS;
 560     if (items != 1)
 561         Perl_croak(aTHX_ "Usage: version::is_alpha(lobj)");
 562     SP -= items;
 563     {
 564         SV *lobj;
 565
 566         if (sv_derived_from(ST(0), "version")) {
 567                 SV *tmp = SvRV(ST(0));
 568                 lobj = tmp;
 569         }
 570         else
 571                 Perl_croak(aTHX_ "lobj is not of type version");
 572 {
 573     I32 len = av_len((AV *)lobj);
 574     I32 digit = SvIVX(*av_fetch((AV *)lobj, len, 0));
 575     if ( digit < 0 )
 576         XSRETURN_YES;
 577     else
 578         XSRETURN_NO;
 579 }
 580         PUTBACK;
 581         return;
 582     }
 583 }
 584
 585 XS(XS_version_qv)
 586 {
 587     dXSARGS;
 588     if (items != 1)
 589         Perl_croak(aTHX_ "Usage: version::qv(ver)");
 590     SP -= items;
 591     {
 592         SV *    ver = ST(0);
 593         if ( !SvVOK(ver) ) /* only need to do with if not already v-string */
 594         {
 595             SV *vs = sv_newmortal();
 596             char *version;
 597             if ( SvNOK(ver) ) /* may get too much accuracy */
 598             {
 599                 char tbuf[64];
 600                 sprintf(tbuf,"%.9"NVgf, SvNVX(ver));
 601                 version = savepv(tbuf);
 602             }
 603             else
 604             {
 605                 version = savepv(SvPV_nolen(ver));
 606             }
 607             (void)scan_version(version,vs,TRUE);
 608             Safefree(version);
 609
 610             PUSHs(vs);
 611         }
 612         else
 613         {
 614             PUSHs(sv_2mortal(new_version(ver)));
 615         }
 616
 617         PUTBACK;
 618         return;
 619     }
 620 }
 621
 622 XS(XS_utf8_is_utf8)
 623 {
 624      dXSARGS;
 625      if (items != 1)
 626           Perl_croak(aTHX_ "Usage: utf8::is_utf8(sv)");
 627      {
 628           SV *  sv = ST(0);
 629           {
 630                if (SvUTF8(sv))
 631                     XSRETURN_YES;
 632                else
 633                     XSRETURN_NO;
 634           }
 635      }
 636      XSRETURN_EMPTY;
 637 }
 638
 639 XS(XS_utf8_valid)
 640 {
 641      dXSARGS;
 642      if (items != 1)
 643           Perl_croak(aTHX_ "Usage: utf8::valid(sv)");
 644      {
 645           SV *  sv = ST(0);
 646           {
 647                STRLEN len;
 648                char *s = SvPV(sv,len);
 649                if (!SvUTF8(sv) || is_utf8_string((U8*)s,len))
 650                     XSRETURN_YES;
 651                else
 652                     XSRETURN_NO;
 653           }
 654      }
 655      XSRETURN_EMPTY;
 656 }
 657
 658 XS(XS_utf8_encode)
 659 {
 660     dXSARGS;
 661     if (items != 1)
 662         Perl_croak(aTHX_ "Usage: utf8::encode(sv)");
 663     {
 664         SV *    sv = ST(0);
 665
 666         sv_utf8_encode(sv);
 667     }
 668     XSRETURN_EMPTY;
 669 }
 670
 671 XS(XS_utf8_decode)
 672 {
 673     dXSARGS;
 674     if (items != 1)
 675         Perl_croak(aTHX_ "Usage: utf8::decode(sv)");
 676     {
 677         SV *    sv = ST(0);
 678         bool    RETVAL;
 679
 680         RETVAL = sv_utf8_decode(sv);
 681         ST(0) = boolSV(RETVAL);
 682         sv_2mortal(ST(0));
 683     }
 684     XSRETURN(1);
 685 }
 686
 687 XS(XS_utf8_upgrade)
 688 {
 689     dXSARGS;
 690     if (items != 1)
 691         Perl_croak(aTHX_ "Usage: utf8::upgrade(sv)");
 692     {
 693         SV *    sv = ST(0);
 694         STRLEN  RETVAL;
 695         dXSTARG;
 696
 697         RETVAL = sv_utf8_upgrade(sv);
 698         XSprePUSH; PUSHi((IV)RETVAL);
 699     }
 700     XSRETURN(1);
 701 }
 702
 703 XS(XS_utf8_downgrade)
 704 {
 705     dXSARGS;
 706     if (items < 1 || items > 2)
 707         Perl_croak(aTHX_ "Usage: utf8::downgrade(sv, failok=0)");
 708     {
 709         SV *    sv = ST(0);
 710         bool    failok;
 711         bool    RETVAL;
 712
 713         if (items < 2)
 714             failok = 0;
 715         else {
 716             failok = (int)SvIV(ST(1));
 717         }
 718
 719         RETVAL = sv_utf8_downgrade(sv, failok);
 720         ST(0) = boolSV(RETVAL);
 721         sv_2mortal(ST(0));
 722     }
 723     XSRETURN(1);
 724 }
 725
 726 XS(XS_utf8_native_to_unicode)
 727 {
 728  dXSARGS;
 729  UV uv = SvUV(ST(0));
 730
 731  if (items > 1)
 732      Perl_croak(aTHX_ "Usage: utf8::native_to_unicode(sv)");
 733
 734  ST(0) = sv_2mortal(newSViv(NATIVE_TO_UNI(uv)));
 735  XSRETURN(1);
 736 }
 737
 738 XS(XS_utf8_unicode_to_native)
 739 {
 740  dXSARGS;
 741  UV uv = SvUV(ST(0));
 742
 743  if (items > 1)
 744      Perl_croak(aTHX_ "Usage: utf8::unicode_to_native(sv)");
 745
 746  ST(0) = sv_2mortal(newSViv(UNI_TO_NATIVE(uv)));
 747  XSRETURN(1);
 748 }
 749
 750 XS(XS_Internals_SvREADONLY)     /* This is dangerous stuff. */
 751 {
 752     dXSARGS;
 753     SV *sv = SvRV(ST(0));
 754     if (items == 1) {
 755          if (SvREADONLY(sv))
 756              XSRETURN_YES;
 757          else
 758              XSRETURN_NO;
 759     }
 760     else if (items == 2) {
 761         if (SvTRUE(ST(1))) {
 762             SvREADONLY_on(sv);
 763             XSRETURN_YES;
 764         }
 765         else {
 766             /* I hope you really know what you are doing. */
 767             SvREADONLY_off(sv);
 768             XSRETURN_NO;
 769         }
 770     }
 771     XSRETURN_UNDEF; /* Can't happen. */
 772 }
 773
 774 XS(XS_Internals_SvREFCNT)       /* This is dangerous stuff. */
 775 {
 776     dXSARGS;
 777     SV *sv = SvRV(ST(0));
 778     if (items == 1)
 779          XSRETURN_IV(SvREFCNT(sv) - 1); /* Minus the ref created for us. */
 780     else if (items == 2) {
 781          /* I hope you really know what you are doing. */
 782          SvREFCNT(sv) = SvIV(ST(1));
 783          XSRETURN_IV(SvREFCNT(sv));
 784     }
 785     XSRETURN_UNDEF; /* Can't happen. */
 786 }
 787
 788 XS(XS_Internals_hv_clear_placehold)
 789 {
 790     dXSARGS;
 791     HV *hv = (HV *) SvRV(ST(0));
 792     if (items != 1)
 793         Perl_croak(aTHX_ "Usage: UNIVERSAL::hv_clear_placeholders(hv)");
 794     hv_clear_placeholders(hv);
 795     XSRETURN(0);
 796 }
 797
 798 XS(XS_Regexp_DESTROY)
 799 {
 800
 801 }
 802
 803 XS(XS_PerlIO_get_layers)
 804 {
 805     dXSARGS;
 806     if (items < 1 || items % 2 == 0)
 807         Perl_croak(aTHX_ "Usage: PerlIO_get_layers(filehandle[,args])");
 808 #ifdef USE_PERLIO
 809     {
 810         SV *    sv;
 811         GV *    gv;
 812         IO *    io;
 813         bool    input = TRUE;
 814         bool    details = FALSE;
 815
 816         if (items > 1) {
 817              SV **svp;
 818
 819              for (svp = MARK + 2; svp <= SP; svp += 2) {
 820                   SV **varp = svp;
 821                   SV **valp = svp + 1;
 822                   STRLEN klen;
 823                   char *key = SvPV(*varp, klen);
 824
 825                   switch (*key) {
 826                   case 'i':
 827                        if (klen == 5 && memEQ(key, "input", 5)) {
 828                             input = SvTRUE(*valp);
 829                             break;
 830                        }
 831                        goto fail;
 832                   case 'o':
 833                        if (klen == 6 && memEQ(key, "output", 6)) {
 834                             input = !SvTRUE(*valp);
 835                             break;
 836                        }
 837                        goto fail;
 838                   case 'd':
 839                        if (klen == 7 && memEQ(key, "details", 7)) {
 840                             details = SvTRUE(*valp);
 841                             break;
 842                        }
 843                        goto fail;
 844                   default:
 845                   fail:
 846                        Perl_croak(aTHX_
 847                                   "get_layers: unknown argument '%s'",
 848                                   key);
 849                   }
 850              }
 851
 852              SP -= (items - 1);
 853         }
 854
 855         sv = POPs;
 856         gv = (GV*)sv;
 857
 858         if (!isGV(sv)) {
 859              if (SvROK(sv) && isGV(SvRV(sv)))
 860                   gv = (GV*)SvRV(sv);
 861              else
 862                   gv = gv_fetchsv(sv, FALSE, SVt_PVIO);
 863         }
 864
 865         if (gv && (io = GvIO(gv))) {
 866              dTARGET;
 867              AV* av = PerlIO_get_layers(aTHX_ input ?
 868                                         IoIFP(io) : IoOFP(io));
 869              I32 i;
 870              I32 last = av_len(av);
 871              I32 nitem = 0;
 872
 873              for (i = last; i >= 0; i -= 3) {
 874                   SV **namsvp;
 875                   SV **argsvp;
 876                   SV **flgsvp;
 877                   bool namok, argok, flgok;
 878
 879                   namsvp = av_fetch(av, i - 2, FALSE);
 880                   argsvp = av_fetch(av, i - 1, FALSE);
 881                   flgsvp = av_fetch(av, i,     FALSE);
 882
 883                   namok = namsvp && *namsvp && SvPOK(*namsvp);
 884                   argok = argsvp && *argsvp && SvPOK(*argsvp);
 885                   flgok = flgsvp && *flgsvp && SvIOK(*flgsvp);
 886
 887                   if (details) {
 888                        XPUSHs(namok ?
 889                              newSVpv(SvPVX(*namsvp), 0) : &PL_sv_undef);
 890                        XPUSHs(argok ?
 891                              newSVpv(SvPVX(*argsvp), 0) : &PL_sv_undef);
 892                        if (flgok)
 893                             XPUSHi(SvIVX(*flgsvp));
 894                        else
 895                             XPUSHs(&PL_sv_undef);
 896                        nitem += 3;
 897                   }
 898                   else {
 899                        if (namok && argok)
 900                             XPUSHs(Perl_newSVpvf(aTHX_ "%"SVf"(%"SVf")",
 901                                                *namsvp, *argsvp));
 902                        else if (namok)
 903                             XPUSHs(Perl_newSVpvf(aTHX_ "%"SVf, *namsvp));
 904                        else
 905                             XPUSHs(&PL_sv_undef);
 906                        nitem++;
 907                        if (flgok) {
 908                             IV flags = SvIVX(*flgsvp);
 909
 910                             if (flags & PERLIO_F_UTF8) {
 911                                  XPUSHs(newSVpvn("utf8", 4));
 912                                  nitem++;
 913                             }
 914                        }
 915                   }
 916              }
 917
 918              SvREFCNT_dec(av);
 919
 920              XSRETURN(nitem);
 921         }
 922     }
 923 #endif
 924
 925     XSRETURN(0);
 926 }
 927
 928 XS(XS_Internals_hash_seed)
 929 {
 930     /* Using dXSARGS would also have dITEM and dSP,
 931      * which define 2 unused local variables.  */
 932     dMARK; dAX;
 933     XSRETURN_UV(PERL_HASH_SEED);
 934 }
 935
 936 XS(XS_Internals_rehash_seed)
 937 {
 938     /* Using dXSARGS would also have dITEM and dSP,
 939      * which define 2 unused local variables.  */
 940     dMARK; dAX;
 941     XSRETURN_UV(PL_rehash_seed);
 942 }
 943
 944 XS(XS_Internals_HvREHASH)       /* Subject to change  */
 945 {
 946     dXSARGS;
 947     if (SvROK(ST(0))) {
 948         HV *hv = (HV *) SvRV(ST(0));
 949         if (items == 1 && SvTYPE(hv) == SVt_PVHV) {
 950             if (HvREHASH(hv))
 951                 XSRETURN_YES;
 952             else
 953                 XSRETURN_NO;
 954         }
 955     }
 956     Perl_croak(aTHX_ "Internals::HvREHASH $hashref");
 957 }