universal.c

   1 /*    universal.c
   2  *
   3  *    Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
   4  *    2005, 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     const char *type = Nullch;
 141     HV *stash = Nullhv;
 142     HV *name_stash;
 143
 144     if (SvGMAGICAL(sv))
 145         mg_get(sv) ;
 146
 147     if (SvROK(sv)) {
 148         sv = SvRV(sv);
 149         type = sv_reftype(sv,0);
 150         if (SvOBJECT(sv))
 151             stash = SvSTASH(sv);
 152     }
 153     else {
 154         stash = gv_stashsv(sv, FALSE);
 155     }
 156
 157     name_stash = gv_stashpv(name, FALSE);
 158
 159     return (type && strEQ(type,name)) ||
 160             (stash && isa_lookup(stash, name, name_stash, strlen(name), 0)
 161              == &PL_sv_yes)
 162         ? TRUE
 163         : FALSE ;
 164 }
 165
 166 #include "XSUB.h"
 167
 168 PERL_XS_EXPORT_C void XS_UNIVERSAL_isa(pTHX_ CV *cv);
 169 PERL_XS_EXPORT_C void XS_UNIVERSAL_can(pTHX_ CV *cv);
 170 PERL_XS_EXPORT_C void XS_UNIVERSAL_VERSION(pTHX_ CV *cv);
 171 XS(XS_version_new);
 172 XS(XS_version_stringify);
 173 XS(XS_version_numify);
 174 XS(XS_version_vcmp);
 175 XS(XS_version_boolean);
 176 XS(XS_version_noop);
 177 XS(XS_version_is_alpha);
 178 XS(XS_version_qv);
 179 XS(XS_utf8_is_utf8);
 180 XS(XS_utf8_valid);
 181 XS(XS_utf8_encode);
 182 XS(XS_utf8_decode);
 183 XS(XS_utf8_upgrade);
 184 XS(XS_utf8_downgrade);
 185 XS(XS_utf8_unicode_to_native);
 186 XS(XS_utf8_native_to_unicode);
 187 XS(XS_Internals_SvREADONLY);
 188 XS(XS_Internals_SvREFCNT);
 189 XS(XS_Internals_hv_clear_placehold);
 190 XS(XS_PerlIO_get_layers);
 191 XS(XS_Regexp_DESTROY);
 192 XS(XS_Internals_hash_seed);
 193 XS(XS_Internals_rehash_seed);
 194 XS(XS_Internals_HvREHASH);
 195
 196 void
 197 Perl_boot_core_UNIVERSAL(pTHX)
 198 {
 199     const char file[] = __FILE__;
 200
 201     newXS("UNIVERSAL::isa",             XS_UNIVERSAL_isa,         file);
 202     newXS("UNIVERSAL::can",             XS_UNIVERSAL_can,         file);
 203     newXS("UNIVERSAL::VERSION",         XS_UNIVERSAL_VERSION,     file);
 204     {
 205         /* register the overloading (type 'A') magic */
 206         PL_amagic_generation++;
 207         /* Make it findable via fetchmethod */
 208         newXS("version::()", XS_version_noop, file);
 209         newXS("version::new", XS_version_new, file);
 210         newXS("version::(\"\"", XS_version_stringify, file);
 211         newXS("version::stringify", XS_version_stringify, file);
 212         newXS("version::(0+", XS_version_numify, file);
 213         newXS("version::numify", XS_version_numify, file);
 214         newXS("version::(cmp", XS_version_vcmp, file);
 215         newXS("version::(<=>", XS_version_vcmp, file);
 216         newXS("version::vcmp", XS_version_vcmp, file);
 217         newXS("version::(bool", XS_version_boolean, file);
 218         newXS("version::boolean", XS_version_boolean, file);
 219         newXS("version::(nomethod", XS_version_noop, file);
 220         newXS("version::noop", XS_version_noop, file);
 221         newXS("version::is_alpha", XS_version_is_alpha, file);
 222         newXS("version::qv", XS_version_qv, file);
 223     }
 224     newXS("utf8::is_utf8", XS_utf8_is_utf8, file);
 225     newXS("utf8::valid", XS_utf8_valid, file);
 226     newXS("utf8::encode", XS_utf8_encode, file);
 227     newXS("utf8::decode", XS_utf8_decode, file);
 228     newXS("utf8::upgrade", XS_utf8_upgrade, file);
 229     newXS("utf8::downgrade", XS_utf8_downgrade, file);
 230     newXS("utf8::native_to_unicode", XS_utf8_native_to_unicode, file);
 231     newXS("utf8::unicode_to_native", XS_utf8_unicode_to_native, file);
 232     newXSproto("Internals::SvREADONLY",XS_Internals_SvREADONLY, file, "\\[$%@];$");
 233     newXSproto("Internals::SvREFCNT",XS_Internals_SvREFCNT, file, "\\[$%@];$");
 234     newXSproto("Internals::hv_clear_placeholders",
 235                XS_Internals_hv_clear_placehold, file, "\\%");
 236     newXSproto("PerlIO::get_layers",
 237                XS_PerlIO_get_layers, file, "*;@");
 238     newXS("Regexp::DESTROY", XS_Regexp_DESTROY, file);
 239     newXSproto("Internals::hash_seed",XS_Internals_hash_seed, file, "");
 240     newXSproto("Internals::rehash_seed",XS_Internals_rehash_seed, file, "");
 241     newXSproto("Internals::HvREHASH", XS_Internals_HvREHASH, file, "\\%");
 242 }
 243
 244
 245 XS(XS_UNIVERSAL_isa)
 246 {
 247     dXSARGS;
 248     SV *sv;
 249     const char *name;
 250     STRLEN n_a;
 251
 252     if (items != 2)
 253         Perl_croak(aTHX_ "Usage: UNIVERSAL::isa(reference, kind)");
 254
 255     sv = ST(0);
 256
 257     if (SvGMAGICAL(sv))
 258         mg_get(sv);
 259
 260     if (!SvOK(sv) || !(SvROK(sv) || (SvPOK(sv) && SvCUR(sv))
 261                 || (SvGMAGICAL(sv) && SvPOKp(sv) && SvCUR(sv))))
 262         XSRETURN_UNDEF;
 263
 264     name = (const char *)SvPV(ST(1),n_a);
 265
 266     ST(0) = boolSV(sv_derived_from(sv, name));
 267     XSRETURN(1);
 268 }
 269
 270 XS(XS_UNIVERSAL_can)
 271 {
 272     dXSARGS;
 273     SV   *sv;
 274     const char *name;
 275     SV   *rv;
 276     HV   *pkg = NULL;
 277     STRLEN n_a;
 278
 279     if (items != 2)
 280         Perl_croak(aTHX_ "Usage: UNIVERSAL::can(object-ref, method)");
 281
 282     sv = ST(0);
 283
 284     if (SvGMAGICAL(sv))
 285         mg_get(sv);
 286
 287     if (!SvOK(sv) || !(SvROK(sv) || (SvPOK(sv) && SvCUR(sv))
 288                 || (SvGMAGICAL(sv) && SvPOKp(sv) && SvCUR(sv))))
 289         XSRETURN_UNDEF;
 290
 291     name = (const char *)SvPV(ST(1),n_a);
 292     rv = &PL_sv_undef;
 293
 294     if (SvROK(sv)) {
 295         sv = (SV*)SvRV(sv);
 296         if (SvOBJECT(sv))
 297             pkg = SvSTASH(sv);
 298     }
 299     else {
 300         pkg = gv_stashsv(sv, FALSE);
 301     }
 302
 303     if (pkg) {
 304         GV *gv = gv_fetchmethod_autoload(pkg, name, FALSE);
 305         if (gv && isGV(gv))
 306             rv = sv_2mortal(newRV((SV*)GvCV(gv)));
 307     }
 308
 309     ST(0) = rv;
 310     XSRETURN(1);
 311 }
 312
 313 XS(XS_UNIVERSAL_VERSION)
 314 {
 315     dXSARGS;
 316     HV *pkg;
 317     GV **gvp;
 318     GV *gv;
 319     SV *sv;
 320     const char *undef;
 321
 322     if (SvROK(ST(0))) {
 323         sv = (SV*)SvRV(ST(0));
 324         if (!SvOBJECT(sv))
 325             Perl_croak(aTHX_ "Cannot find version of an unblessed reference");
 326         pkg = SvSTASH(sv);
 327     }
 328     else {
 329         pkg = gv_stashsv(ST(0), FALSE);
 330     }
 331
 332     gvp = pkg ? (GV**)hv_fetch(pkg,"VERSION",7,FALSE) : Null(GV**);
 333
 334     if (gvp && isGV(gv = *gvp) && SvOK(sv = GvSV(gv))) {
 335         SV *nsv = sv_newmortal();
 336         sv_setsv(nsv, sv);
 337         sv = nsv;
 338         if ( !sv_derived_from(sv, "version"))
 339             upg_version(sv);
 340         undef = Nullch;
 341     }
 342     else {
 343         sv = (SV*)&PL_sv_undef;
 344         undef = "(undef)";
 345     }
 346
 347     if (items > 1) {
 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                 STRLEN n_a;
 357                 Perl_croak(aTHX_
 358                              "%s defines neither package nor VERSION--version check failed",
 359                              SvPVx(ST(0),n_a) );
 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 ( SvOK(sv) && 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         const char *classname = 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(classname,"version") != 0 ) /* inherited new() */
 404             sv_bless(rv, gv_stashpv(classname,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 = Nullsv;
 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 = Nullsv;
 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 = Nullsv;
 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 = Nullsv;
 511
 512           if (sv_derived_from(ST(0), "version")) {
 513                /* XXX If tmp serves a purpose, explain it. */
 514                SV *tmp = SvRV(ST(0));
 515                lobj = tmp;
 516           }
 517           else
 518                Perl_croak(aTHX_ "lobj is not of type version");
 519
 520           {
 521                SV       *rs;
 522                rs = newSViv( vcmp(lobj,new_version(newSVpvn("0",1))) );
 523                PUSHs(sv_2mortal(rs));
 524           }
 525
 526           PUTBACK;
 527           return;
 528      }
 529 }
 530
 531 XS(XS_version_noop)
 532 {
 533      dXSARGS;
 534      if (items < 1)
 535           Perl_croak(aTHX_ "Usage: version::noop(lobj, ...)");
 536      {
 537           SV *  lobj = Nullsv;
 538
 539           if (sv_derived_from(ST(0), "version")) {
 540                SV *tmp = SvRV(ST(0));
 541                lobj = tmp;
 542           }
 543           else
 544                Perl_croak(aTHX_ "lobj is not of type version");
 545
 546           {
 547                Perl_croak(aTHX_ "operation not supported with version object");
 548           }
 549
 550      }
 551      XSRETURN_EMPTY;
 552 }
 553
 554 XS(XS_version_is_alpha)
 555 {
 556     dXSARGS;
 557     if (items != 1)
 558         Perl_croak(aTHX_ "Usage: version::is_alpha(lobj)");
 559     SP -= items;
 560     {
 561         SV * lobj = Nullsv;
 562
 563         if (sv_derived_from(ST(0), "version")) {
 564                 /* XXX If tmp serves a purpose, explain it. */
 565                 SV *tmp = SvRV(ST(0));
 566                 lobj = tmp;
 567         }
 568         else
 569                 Perl_croak(aTHX_ "lobj is not of type version");
 570 {
 571     const I32 len = av_len((AV *)lobj);
 572     const I32 digit = SvIVX(*av_fetch((AV *)lobj, len, 0));
 573     if ( digit < 0 )
 574         XSRETURN_YES;
 575     else
 576         XSRETURN_NO;
 577 }
 578         PUTBACK;
 579         return;
 580     }
 581 }
 582
 583 XS(XS_version_qv)
 584 {
 585     dXSARGS;
 586     if (items != 1)
 587         Perl_croak(aTHX_ "Usage: version::qv(ver)");
 588     SP -= items;
 589     {
 590         SV *    ver = ST(0);
 591         if ( !SvVOK(ver) ) /* only need to do with if not already v-string */
 592         {
 593             SV *vs = sv_newmortal();
 594             char *version;
 595             if ( SvNOK(ver) ) /* may get too much accuracy */
 596             {
 597                 char tbuf[64];
 598                 sprintf(tbuf,"%.9"NVgf, SvNVX(ver));
 599                 version = savepv(tbuf);
 600             }
 601             else
 602             {
 603                 version = savesvpv(ver);
 604             }
 605             (void)scan_version(version,vs,TRUE);
 606             Safefree(version);
 607
 608             PUSHs(vs);
 609         }
 610         else
 611         {
 612             PUSHs(sv_2mortal(new_version(ver)));
 613         }
 614
 615         PUTBACK;
 616         return;
 617     }
 618 }
 619
 620 XS(XS_utf8_is_utf8)
 621 {
 622      dXSARGS;
 623      if (items != 1)
 624           Perl_croak(aTHX_ "Usage: utf8::is_utf8(sv)");
 625      {
 626           const SV *sv = ST(0);
 627           {
 628                if (SvUTF8(sv))
 629                     XSRETURN_YES;
 630                else
 631                     XSRETURN_NO;
 632           }
 633      }
 634      XSRETURN_EMPTY;
 635 }
 636
 637 XS(XS_utf8_valid)
 638 {
 639      dXSARGS;
 640      if (items != 1)
 641           Perl_croak(aTHX_ "Usage: utf8::valid(sv)");
 642      {
 643           SV *  sv = ST(0);
 644           {
 645                STRLEN len;
 646                const char *s = SvPV(sv,len);
 647                if (!SvUTF8(sv) || is_utf8_string((const U8*)s,len))
 648                     XSRETURN_YES;
 649                else
 650                     XSRETURN_NO;
 651           }
 652      }
 653      XSRETURN_EMPTY;
 654 }
 655
 656 XS(XS_utf8_encode)
 657 {
 658     dXSARGS;
 659     if (items != 1)
 660         Perl_croak(aTHX_ "Usage: utf8::encode(sv)");
 661     {
 662         SV *    sv = ST(0);
 663
 664         sv_utf8_encode(sv);
 665     }
 666     XSRETURN_EMPTY;
 667 }
 668
 669 XS(XS_utf8_decode)
 670 {
 671     dXSARGS;
 672     if (items != 1)
 673         Perl_croak(aTHX_ "Usage: utf8::decode(sv)");
 674     {
 675         SV *    sv = ST(0);
 676         const bool 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         const bool failok = (items < 2) ? 0 : (int)SvIV(ST(1));
 707         const bool RETVAL = sv_utf8_downgrade(sv, failok);
 708
 709         ST(0) = boolSV(RETVAL);
 710         sv_2mortal(ST(0));
 711     }
 712     XSRETURN(1);
 713 }
 714
 715 XS(XS_utf8_native_to_unicode)
 716 {
 717  dXSARGS;
 718  const UV uv = SvUV(ST(0));
 719
 720  if (items > 1)
 721      Perl_croak(aTHX_ "Usage: utf8::native_to_unicode(sv)");
 722
 723  ST(0) = sv_2mortal(newSViv(NATIVE_TO_UNI(uv)));
 724  XSRETURN(1);
 725 }
 726
 727 XS(XS_utf8_unicode_to_native)
 728 {
 729  dXSARGS;
 730  const UV uv = SvUV(ST(0));
 731
 732  if (items > 1)
 733      Perl_croak(aTHX_ "Usage: utf8::unicode_to_native(sv)");
 734
 735  ST(0) = sv_2mortal(newSViv(UNI_TO_NATIVE(uv)));
 736  XSRETURN(1);
 737 }
 738
 739 XS(XS_Internals_SvREADONLY)     /* This is dangerous stuff. */
 740 {
 741     dXSARGS;
 742     SV *sv = SvRV(ST(0));
 743
 744     if (items == 1) {
 745          if (SvREADONLY(sv))
 746              XSRETURN_YES;
 747          else
 748              XSRETURN_NO;
 749     }
 750     else if (items == 2) {
 751         if (SvTRUE(ST(1))) {
 752             SvREADONLY_on(sv);
 753             XSRETURN_YES;
 754         }
 755         else {
 756             /* I hope you really know what you are doing. */
 757             SvREADONLY_off(sv);
 758             XSRETURN_NO;
 759         }
 760     }
 761     XSRETURN_UNDEF; /* Can't happen. */
 762 }
 763
 764 XS(XS_Internals_SvREFCNT)       /* This is dangerous stuff. */
 765 {
 766     dXSARGS;
 767     SV *sv = SvRV(ST(0));
 768
 769     if (items == 1)
 770          XSRETURN_IV(SvREFCNT(sv) - 1); /* Minus the ref created for us. */
 771     else if (items == 2) {
 772          /* I hope you really know what you are doing. */
 773          SvREFCNT(sv) = SvIV(ST(1));
 774          XSRETURN_IV(SvREFCNT(sv));
 775     }
 776     XSRETURN_UNDEF; /* Can't happen. */
 777 }
 778
 779 XS(XS_Internals_hv_clear_placehold)
 780 {
 781     dXSARGS;
 782     HV *hv = (HV *) SvRV(ST(0));
 783
 784     if (items != 1)
 785         Perl_croak(aTHX_ "Usage: UNIVERSAL::hv_clear_placeholders(hv)");
 786     hv_clear_placeholders(hv);
 787     XSRETURN(0);
 788 }
 789
 790 XS(XS_Regexp_DESTROY)
 791 {
 792 }
 793
 794 XS(XS_PerlIO_get_layers)
 795 {
 796     dXSARGS;
 797     if (items < 1 || items % 2 == 0)
 798         Perl_croak(aTHX_ "Usage: PerlIO_get_layers(filehandle[,args])");
 799 #ifdef USE_PERLIO
 800     {
 801         SV *    sv;
 802         GV *    gv;
 803         IO *    io;
 804         bool    input = TRUE;
 805         bool    details = FALSE;
 806
 807         if (items > 1) {
 808              SV **svp;
 809
 810              for (svp = MARK + 2; svp <= SP; svp += 2) {
 811                   SV **varp = svp;
 812                   SV **valp = svp + 1;
 813                   STRLEN klen;
 814                   const char *key = SvPV(*varp, klen);
 815
 816                   switch (*key) {
 817                   case 'i':
 818                        if (klen == 5 && memEQ(key, "input", 5)) {
 819                             input = SvTRUE(*valp);
 820                             break;
 821                        }
 822                        goto fail;
 823                   case 'o':
 824                        if (klen == 6 && memEQ(key, "output", 6)) {
 825                             input = !SvTRUE(*valp);
 826                             break;
 827                        }
 828                        goto fail;
 829                   case 'd':
 830                        if (klen == 7 && memEQ(key, "details", 7)) {
 831                             details = SvTRUE(*valp);
 832                             break;
 833                        }
 834                        goto fail;
 835                   default:
 836                   fail:
 837                        Perl_croak(aTHX_
 838                                   "get_layers: unknown argument '%s'",
 839                                   key);
 840                   }
 841              }
 842
 843              SP -= (items - 1);
 844         }
 845
 846         sv = POPs;
 847         gv = (GV*)sv;
 848
 849         if (!isGV(sv)) {
 850              if (SvROK(sv) && isGV(SvRV(sv)))
 851                   gv = (GV*)SvRV(sv);
 852              else
 853                   gv = gv_fetchsv(sv, FALSE, SVt_PVIO);
 854         }
 855
 856         if (gv && (io = GvIO(gv))) {
 857              dTARGET;
 858              AV* av = PerlIO_get_layers(aTHX_ input ?
 859                                         IoIFP(io) : IoOFP(io));
 860              I32 i;
 861              I32 last = av_len(av);
 862              I32 nitem = 0;
 863
 864              for (i = last; i >= 0; i -= 3) {
 865                   SV **namsvp;
 866                   SV **argsvp;
 867                   SV **flgsvp;
 868                   bool namok, argok, flgok;
 869
 870                   namsvp = av_fetch(av, i - 2, FALSE);
 871                   argsvp = av_fetch(av, i - 1, FALSE);
 872                   flgsvp = av_fetch(av, i,     FALSE);
 873
 874                   namok = namsvp && *namsvp && SvPOK(*namsvp);
 875                   argok = argsvp && *argsvp && SvPOK(*argsvp);
 876                   flgok = flgsvp && *flgsvp && SvIOK(*flgsvp);
 877
 878                   if (details) {
 879                        XPUSHs(namok ?
 880                              newSVpv(SvPVX_const(*namsvp), 0) : &PL_sv_undef);
 881                        XPUSHs(argok ?
 882                              newSVpv(SvPVX_const(*argsvp), 0) : &PL_sv_undef);
 883                        if (flgok)
 884                             XPUSHi(SvIVX(*flgsvp));
 885                        else
 886                             XPUSHs(&PL_sv_undef);
 887                        nitem += 3;
 888                   }
 889                   else {
 890                        if (namok && argok)
 891                             XPUSHs(Perl_newSVpvf(aTHX_ "%"SVf"(%"SVf")",
 892                                                *namsvp, *argsvp));
 893                        else if (namok)
 894                             XPUSHs(Perl_newSVpvf(aTHX_ "%"SVf, *namsvp));
 895                        else
 896                             XPUSHs(&PL_sv_undef);
 897                        nitem++;
 898                        if (flgok) {
 899                             IV flags = SvIVX(*flgsvp);
 900
 901                             if (flags & PERLIO_F_UTF8) {
 902                                  XPUSHs(newSVpvn("utf8", 4));
 903                                  nitem++;
 904                             }
 905                        }
 906                   }
 907              }
 908
 909              SvREFCNT_dec(av);
 910
 911              XSRETURN(nitem);
 912         }
 913     }
 914 #endif
 915
 916     XSRETURN(0);
 917 }
 918
 919 XS(XS_Internals_hash_seed)
 920 {
 921     /* Using dXSARGS would also have dITEM and dSP,
 922      * which define 2 unused local variables.  */
 923     dAXMARK;
 924     XSRETURN_UV(PERL_HASH_SEED);
 925 }
 926
 927 XS(XS_Internals_rehash_seed)
 928 {
 929     /* Using dXSARGS would also have dITEM and dSP,
 930      * which define 2 unused local variables.  */
 931     dAXMARK;
 932     XSRETURN_UV(PL_rehash_seed);
 933 }
 934
 935 XS(XS_Internals_HvREHASH)       /* Subject to change  */
 936 {
 937     dXSARGS;
 938     if (SvROK(ST(0))) {
 939         const HV *hv = (HV *) SvRV(ST(0));
 940         if (items == 1 && SvTYPE(hv) == SVt_PVHV) {
 941             if (HvREHASH(hv))
 942                 XSRETURN_YES;
 943             else
 944                 XSRETURN_NO;
 945         }
 946     }
 947     Perl_croak(aTHX_ "Internals::HvREHASH $hashref");
 948 }
 949
 950 /*
 951  * Local variables:
 952  * c-indentation-style: bsd
 953  * c-basic-offset: 4
 954  * indent-tabs-mode: t
 955  * End:
 956  *
 957  * ex: set ts=8 sts=4 sw=4 noet:
 958  */