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