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     const char *hvname;
  44
  45     /* A stash/class can go by many names (ie. User == main::User), so
  46        we compare the stash itself just in case */
  47     if (name_stash && (stash == name_stash))
  48         return &PL_sv_yes;
  49
  50     hvname = HvNAME_get(stash);
  51
  52     if (strEQ(hvname, name))
  53         return &PL_sv_yes;
  54
  55     if (strEQ(name, "UNIVERSAL"))
  56         return &PL_sv_yes;
  57
  58     if (level > 100)
  59         Perl_croak(aTHX_ "Recursive inheritance detected in package '%s'",
  60                    hvname);
  61
  62     gvp = (GV**)hv_fetch(stash, "::ISA::CACHE::", 14, FALSE);
  63
  64     if (gvp && (gv = *gvp) != (GV*)&PL_sv_undef && (subgen = GvSV(gv))
  65         && (hv = GvHV(gv)))
  66     {
  67         if (SvIV(subgen) == (IV)PL_sub_generation) {
  68             SV* sv;
  69             SV** svp = (SV**)hv_fetch(hv, name, len, FALSE);
  70             if (svp && (sv = *svp) != (SV*)&PL_sv_undef) {
  71                 DEBUG_o( Perl_deb(aTHX_ "Using cached ISA %s for package %s\n",
  72                                   name, hvname) );
  73                 return sv;
  74             }
  75         }
  76         else {
  77             DEBUG_o( Perl_deb(aTHX_ "ISA Cache in package %s is stale\n",
  78                               hvname) );
  79             hv_clear(hv);
  80             sv_setiv(subgen, PL_sub_generation);
  81         }
  82     }
  83
  84     gvp = (GV**)hv_fetch(stash,"ISA",3,FALSE);
  85
  86     if (gvp && (gv = *gvp) != (GV*)&PL_sv_undef && (av = GvAV(gv))) {
  87         if (!hv || !subgen) {
  88             gvp = (GV**)hv_fetch(stash, "::ISA::CACHE::", 14, TRUE);
  89
  90             gv = *gvp;
  91
  92             if (SvTYPE(gv) != SVt_PVGV)
  93                 gv_init(gv, stash, "::ISA::CACHE::", 14, TRUE);
  94
  95             if (!hv)
  96                 hv = GvHVn(gv);
  97             if (!subgen) {
  98                 subgen = newSViv(PL_sub_generation);
  99                 GvSV(gv) = subgen;
 100             }
 101         }
 102         if (hv) {
 103             SV** svp = AvARRAY(av);
 104             /* NOTE: No support for tied ISA */
 105             I32 items = AvFILLp(av) + 1;
 106             while (items--) {
 107                 SV* sv = *svp++;
 108                 HV* basestash = gv_stashsv(sv, FALSE);
 109                 if (!basestash) {
 110                     if (ckWARN(WARN_MISC))
 111                         Perl_warner(aTHX_ packWARN(WARN_SYNTAX),
 112                                     "Can't locate package %"SVf" for @%s::ISA",
 113                                     sv, hvname);
 114                     continue;
 115                 }
 116                 if (&PL_sv_yes == isa_lookup(basestash, name, name_stash,
 117                                              len, level + 1)) {
 118                     (void)hv_store(hv,name,len,&PL_sv_yes,0);
 119                     return &PL_sv_yes;
 120                 }
 121             }
 122             (void)hv_store(hv,name,len,&PL_sv_no,0);
 123         }
 124     }
 125     return &PL_sv_no;
 126 }
 127
 128 /*
 129 =head1 SV Manipulation Functions
 130
 131 =for apidoc sv_derived_from
 132
 133 Returns a boolean indicating whether the SV is derived from the specified
 134 class.  This is the function that implements C<UNIVERSAL::isa>.  It works
 135 for class names as well as for objects.
 136
 137 =cut
 138 */
 139
 140 bool
 141 Perl_sv_derived_from(pTHX_ SV *sv, const char *name)
 142 {
 143     const char *type = Nullch;
 144     HV *stash = Nullhv;
 145     HV *name_stash;
 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 PERL_XS_EXPORT_C void XS_UNIVERSAL_isa(pTHX_ CV *cv);
 172 PERL_XS_EXPORT_C void XS_UNIVERSAL_can(pTHX_ CV *cv);
 173 PERL_XS_EXPORT_C 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 #ifdef HASATTRIBUTE_NORETURN
 180 XS(XS_version_noop) __attribute__noreturn__;
 181 #else
 182 XS(XS_version_noop);
 183 #endif
 184 XS(XS_version_is_alpha);
 185 XS(XS_version_qv);
 186 XS(XS_utf8_is_utf8);
 187 XS(XS_utf8_valid);
 188 XS(XS_utf8_encode);
 189 XS(XS_utf8_decode);
 190 XS(XS_utf8_upgrade);
 191 XS(XS_utf8_downgrade);
 192 XS(XS_utf8_unicode_to_native);
 193 XS(XS_utf8_native_to_unicode);
 194 XS(XS_Internals_SvREADONLY);
 195 XS(XS_Internals_SvREFCNT);
 196 XS(XS_Internals_hv_clear_placehold);
 197 XS(XS_PerlIO_get_layers);
 198 XS(XS_Regexp_DESTROY);
 199 XS(XS_Internals_hash_seed);
 200 XS(XS_Internals_rehash_seed);
 201 XS(XS_Internals_HvREHASH);
 202
 203 void
 204 Perl_boot_core_UNIVERSAL(pTHX)
 205 {
 206     const char file[] = __FILE__;
 207
 208     newXS("UNIVERSAL::isa",             XS_UNIVERSAL_isa,         file);
 209     newXS("UNIVERSAL::can",             XS_UNIVERSAL_can,         file);
 210     newXS("UNIVERSAL::VERSION",         XS_UNIVERSAL_VERSION,     file);
 211     {
 212         /* register the overloading (type 'A') magic */
 213         PL_amagic_generation++;
 214         /* Make it findable via fetchmethod */
 215         newXS("version::()", XS_version_noop, file);
 216         newXS("version::new", XS_version_new, file);
 217         newXS("version::(\"\"", XS_version_stringify, file);
 218         newXS("version::stringify", XS_version_stringify, file);
 219         newXS("version::(0+", XS_version_numify, file);
 220         newXS("version::numify", XS_version_numify, file);
 221         newXS("version::(cmp", XS_version_vcmp, file);
 222         newXS("version::(<=>", XS_version_vcmp, file);
 223         newXS("version::vcmp", XS_version_vcmp, file);
 224         newXS("version::(bool", XS_version_boolean, file);
 225         newXS("version::boolean", XS_version_boolean, file);
 226         newXS("version::(nomethod", XS_version_noop, file);
 227         newXS("version::noop", XS_version_noop, file);
 228         newXS("version::is_alpha", XS_version_is_alpha, file);
 229         newXS("version::qv", XS_version_qv, file);
 230     }
 231     newXS("utf8::is_utf8", XS_utf8_is_utf8, file);
 232     newXS("utf8::valid", XS_utf8_valid, file);
 233     newXS("utf8::encode", XS_utf8_encode, file);
 234     newXS("utf8::decode", XS_utf8_decode, file);
 235     newXS("utf8::upgrade", XS_utf8_upgrade, file);
 236     newXS("utf8::downgrade", XS_utf8_downgrade, file);
 237     newXS("utf8::native_to_unicode", XS_utf8_native_to_unicode, file);
 238     newXS("utf8::unicode_to_native", XS_utf8_unicode_to_native, file);
 239     newXSproto("Internals::SvREADONLY",XS_Internals_SvREADONLY, file, "\\[$%@];$");
 240     newXSproto("Internals::SvREFCNT",XS_Internals_SvREFCNT, file, "\\[$%@];$");
 241     newXSproto("Internals::hv_clear_placeholders",
 242                XS_Internals_hv_clear_placehold, file, "\\%");
 243     newXSproto("PerlIO::get_layers",
 244                XS_PerlIO_get_layers, file, "*;@");
 245     newXS("Regexp::DESTROY", XS_Regexp_DESTROY, file);
 246     newXSproto("Internals::hash_seed",XS_Internals_hash_seed, file, "");
 247     newXSproto("Internals::rehash_seed",XS_Internals_rehash_seed, file, "");
 248     newXSproto("Internals::HvREHASH", XS_Internals_HvREHASH, file, "\\%");
 249 }
 250
 251
 252 XS(XS_UNIVERSAL_isa)
 253 {
 254     dXSARGS;
 255     SV *sv;
 256     const char *name;
 257     STRLEN n_a;
 258
 259     if (items != 2)
 260         Perl_croak(aTHX_ "Usage: UNIVERSAL::isa(reference, kind)");
 261
 262     sv = ST(0);
 263
 264     if (SvGMAGICAL(sv))
 265         mg_get(sv);
 266
 267     if (!SvOK(sv) || !(SvROK(sv) || (SvPOK(sv) && SvCUR(sv))
 268                 || (SvGMAGICAL(sv) && SvPOKp(sv) && SvCUR(sv))))
 269         XSRETURN_UNDEF;
 270
 271     name = (const char *)SvPV(ST(1),n_a);
 272
 273     ST(0) = boolSV(sv_derived_from(sv, name));
 274     XSRETURN(1);
 275 }
 276
 277 XS(XS_UNIVERSAL_can)
 278 {
 279     dXSARGS;
 280     SV   *sv;
 281     const char *name;
 282     SV   *rv;
 283     HV   *pkg = NULL;
 284     STRLEN n_a;
 285
 286     if (items != 2)
 287         Perl_croak(aTHX_ "Usage: UNIVERSAL::can(object-ref, method)");
 288
 289     sv = ST(0);
 290
 291     if (SvGMAGICAL(sv))
 292         mg_get(sv);
 293
 294     if (!SvOK(sv) || !(SvROK(sv) || (SvPOK(sv) && SvCUR(sv))
 295                 || (SvGMAGICAL(sv) && SvPOKp(sv) && SvCUR(sv))))
 296         XSRETURN_UNDEF;
 297
 298     name = (const char *)SvPV(ST(1),n_a);
 299     rv = &PL_sv_undef;
 300
 301     if (SvROK(sv)) {
 302         sv = (SV*)SvRV(sv);
 303         if (SvOBJECT(sv))
 304             pkg = SvSTASH(sv);
 305     }
 306     else {
 307         pkg = gv_stashsv(sv, FALSE);
 308     }
 309
 310     if (pkg) {
 311         GV *gv = gv_fetchmethod_autoload(pkg, name, FALSE);
 312         if (gv && isGV(gv))
 313             rv = sv_2mortal(newRV((SV*)GvCV(gv)));
 314     }
 315
 316     ST(0) = rv;
 317     XSRETURN(1);
 318 }
 319
 320 XS(XS_UNIVERSAL_VERSION)
 321 {
 322     dXSARGS;
 323     HV *pkg;
 324     GV **gvp;
 325     GV *gv;
 326     SV *sv;
 327     const char *undef;
 328
 329     if (SvROK(ST(0))) {
 330         sv = (SV*)SvRV(ST(0));
 331         if (!SvOBJECT(sv))
 332             Perl_croak(aTHX_ "Cannot find version of an unblessed reference");
 333         pkg = SvSTASH(sv);
 334     }
 335     else {
 336         pkg = gv_stashsv(ST(0), FALSE);
 337     }
 338
 339     gvp = pkg ? (GV**)hv_fetch(pkg,"VERSION",7,FALSE) : Null(GV**);
 340
 341     if (gvp && isGV(gv = *gvp) && SvOK(sv = GvSV(gv))) {
 342         SV *nsv = sv_newmortal();
 343         sv_setsv(nsv, sv);
 344         sv = nsv;
 345         if ( !sv_derived_from(sv, "version"))
 346             upg_version(sv);
 347         undef = Nullch;
 348     }
 349     else {
 350         sv = (SV*)&PL_sv_undef;
 351         undef = "(undef)";
 352     }
 353
 354     if (items > 1) {
 355         SV *req = ST(1);
 356
 357         if (undef) {
 358             if (pkg) {
 359                 const char *name = HvNAME_get(pkg);
 360                 Perl_croak(aTHX_
 361                            "%s does not define $%s::VERSION--version check failed",
 362                            name, name);
 363             } else {
 364                 STRLEN n_a;
 365                 Perl_croak(aTHX_
 366                              "%s defines neither package nor VERSION--version check failed",
 367                              SvPVx(ST(0),n_a) );
 368              }
 369         }
 370
 371         if ( !sv_derived_from(req, "version")) {
 372             /* req may very well be R/O, so create a new object */
 373             SV *nsv = sv_newmortal();
 374             sv_setsv(nsv, req);
 375             req = nsv;
 376             upg_version(req);
 377         }
 378
 379         if ( vcmp( req, sv ) > 0 )
 380             Perl_croak(aTHX_ "%s version %"SVf" (%"SVf") required--"
 381                     "this is only version %"SVf" (%"SVf")", HvNAME_get(pkg),
 382                     vnumify(req),vnormal(req),vnumify(sv),vnormal(sv));
 383     }
 384
 385     if ( SvOK(sv) && sv_derived_from(sv, "version") ) {
 386         ST(0) = vnumify(sv);
 387     } else {
 388         ST(0) = sv;
 389     }
 390
 391     XSRETURN(1);
 392 }
 393
 394 XS(XS_version_new)
 395 {
 396     dXSARGS;
 397     if (items > 3)
 398         Perl_croak(aTHX_ "Usage: version::new(class, version)");
 399     SP -= items;
 400     {
 401         const char *classname = SvPV_nolen(ST(0));
 402         SV *vs = ST(1);
 403         SV *rv;
 404         if (items == 3 )
 405         {
 406             vs = sv_newmortal();
 407             Perl_sv_setpvf(aTHX_ vs,"v%s",SvPV_nolen(ST(2)));
 408         }
 409
 410         rv = new_version(vs);
 411         if ( strcmp(classname,"version") != 0 ) /* inherited new() */
 412             sv_bless(rv, gv_stashpv(classname,TRUE));
 413
 414         PUSHs(sv_2mortal(rv));
 415         PUTBACK;
 416         return;
 417     }
 418 }
 419
 420 XS(XS_version_stringify)
 421 {
 422      dXSARGS;
 423      if (items < 1)
 424           Perl_croak(aTHX_ "Usage: version::stringify(lobj, ...)");
 425      SP -= items;
 426      {
 427           SV *  lobj = Nullsv;
 428
 429           if (sv_derived_from(ST(0), "version")) {
 430                SV *tmp = SvRV(ST(0));
 431                lobj = tmp;
 432           }
 433           else
 434                Perl_croak(aTHX_ "lobj is not of type version");
 435
 436           PUSHs(sv_2mortal(vstringify(lobj)));
 437
 438           PUTBACK;
 439           return;
 440      }
 441 }
 442
 443 XS(XS_version_numify)
 444 {
 445      dXSARGS;
 446      if (items < 1)
 447           Perl_croak(aTHX_ "Usage: version::numify(lobj, ...)");
 448      SP -= items;
 449      {
 450           SV *  lobj = Nullsv;
 451
 452           if (sv_derived_from(ST(0), "version")) {
 453                SV *tmp = SvRV(ST(0));
 454                lobj = tmp;
 455           }
 456           else
 457                Perl_croak(aTHX_ "lobj is not of type version");
 458
 459           PUSHs(sv_2mortal(vnumify(lobj)));
 460
 461           PUTBACK;
 462           return;
 463      }
 464 }
 465
 466 XS(XS_version_vcmp)
 467 {
 468      dXSARGS;
 469      if (items < 1)
 470           Perl_croak(aTHX_ "Usage: version::vcmp(lobj, ...)");
 471      SP -= items;
 472      {
 473           SV *  lobj = Nullsv;
 474
 475           if (sv_derived_from(ST(0), "version")) {
 476                SV *tmp = SvRV(ST(0));
 477                lobj = tmp;
 478           }
 479           else
 480                Perl_croak(aTHX_ "lobj is not of type version");
 481
 482           {
 483                SV       *rs;
 484                SV       *rvs;
 485                SV * robj = ST(1);
 486                IV        swap = (IV)SvIV(ST(2));
 487
 488                if ( ! sv_derived_from(robj, "version") )
 489                {
 490                     robj = new_version(robj);
 491                }
 492                rvs = SvRV(robj);
 493
 494                if ( swap )
 495                {
 496                     rs = newSViv(vcmp(rvs,lobj));
 497                }
 498                else
 499                {
 500                     rs = newSViv(vcmp(lobj,rvs));
 501                }
 502
 503                PUSHs(sv_2mortal(rs));
 504           }
 505
 506           PUTBACK;
 507           return;
 508      }
 509 }
 510
 511 XS(XS_version_boolean)
 512 {
 513      dXSARGS;
 514      if (items < 1)
 515           Perl_croak(aTHX_ "Usage: version::boolean(lobj, ...)");
 516      SP -= items;
 517      {
 518           SV *  lobj = Nullsv;
 519
 520           if (sv_derived_from(ST(0), "version")) {
 521                /* XXX If tmp serves a purpose, explain it. */
 522                SV *tmp = SvRV(ST(0));
 523                lobj = tmp;
 524           }
 525           else
 526                Perl_croak(aTHX_ "lobj is not of type version");
 527
 528           {
 529                SV       *rs;
 530                rs = newSViv( vcmp(lobj,new_version(newSVpvn("0",1))) );
 531                PUSHs(sv_2mortal(rs));
 532           }
 533
 534           PUTBACK;
 535           return;
 536      }
 537 }
 538
 539 XS(XS_version_noop)
 540 {
 541     dXSARGS;
 542     if (items < 1)
 543         Perl_croak(aTHX_ "Usage: version::noop(lobj, ...)");
 544     if (sv_derived_from(ST(0), "version"))
 545         Perl_croak(aTHX_ "operation not supported with version object");
 546     else
 547         Perl_croak(aTHX_ "lobj is not of type version");
 548 #ifndef HASATTRIBUTE_NORETURN
 549     XSRETURN_EMPTY;
 550 #endif
 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 = Nullsv;
 561
 562         if (sv_derived_from(ST(0), "version")) {
 563                 /* XXX If tmp serves a purpose, explain it. */
 564                 SV *tmp = SvRV(ST(0));
 565                 lobj = tmp;
 566         }
 567         else
 568                 Perl_croak(aTHX_ "lobj is not of type version");
 569 {
 570     const I32 len = av_len((AV *)lobj);
 571     const I32 digit = SvIVX(*av_fetch((AV *)lobj, len, 0));
 572     if ( digit < 0 )
 573         XSRETURN_YES;
 574     else
 575         XSRETURN_NO;
 576 }
 577         PUTBACK;
 578         return;
 579     }
 580 }
 581
 582 XS(XS_version_qv)
 583 {
 584     dXSARGS;
 585     if (items != 1)
 586         Perl_croak(aTHX_ "Usage: version::qv(ver)");
 587     SP -= items;
 588     {
 589         SV *    ver = ST(0);
 590         if ( !SvVOK(ver) ) /* only need to do with if not already v-string */
 591         {
 592             SV *vs = sv_newmortal();
 593             char *version;
 594             if ( SvNOK(ver) ) /* may get too much accuracy */
 595             {
 596                 char tbuf[64];
 597                 sprintf(tbuf,"%.9"NVgf, SvNVX(ver));
 598                 version = savepv(tbuf);
 599             }
 600             else
 601             {
 602                 version = savesvpv(ver);
 603             }
 604             (void)scan_version(version,vs,TRUE);
 605             Safefree(version);
 606
 607             PUSHs(vs);
 608         }
 609         else
 610         {
 611             PUSHs(sv_2mortal(new_version(ver)));
 612         }
 613
 614         PUTBACK;
 615         return;
 616     }
 617 }
 618
 619 XS(XS_utf8_is_utf8)
 620 {
 621      dXSARGS;
 622      if (items != 1)
 623           Perl_croak(aTHX_ "Usage: utf8::is_utf8(sv)");
 624      {
 625           const SV *sv = ST(0);
 626           {
 627                if (SvUTF8(sv))
 628                     XSRETURN_YES;
 629                else
 630                     XSRETURN_NO;
 631           }
 632      }
 633      XSRETURN_EMPTY;
 634 }
 635
 636 XS(XS_utf8_valid)
 637 {
 638      dXSARGS;
 639      if (items != 1)
 640           Perl_croak(aTHX_ "Usage: utf8::valid(sv)");
 641      {
 642           SV *  sv = ST(0);
 643           {
 644                STRLEN len;
 645                const char *s = SvPV(sv,len);
 646                if (!SvUTF8(sv) || is_utf8_string((const U8*)s,len))
 647                     XSRETURN_YES;
 648                else
 649                     XSRETURN_NO;
 650           }
 651      }
 652      XSRETURN_EMPTY;
 653 }
 654
 655 XS(XS_utf8_encode)
 656 {
 657     dXSARGS;
 658     if (items != 1)
 659         Perl_croak(aTHX_ "Usage: utf8::encode(sv)");
 660     {
 661         SV *    sv = ST(0);
 662
 663         sv_utf8_encode(sv);
 664     }
 665     XSRETURN_EMPTY;
 666 }
 667
 668 XS(XS_utf8_decode)
 669 {
 670     dXSARGS;
 671     if (items != 1)
 672         Perl_croak(aTHX_ "Usage: utf8::decode(sv)");
 673     {
 674         SV *    sv = ST(0);
 675         const bool RETVAL = sv_utf8_decode(sv);
 676         ST(0) = boolSV(RETVAL);
 677         sv_2mortal(ST(0));
 678     }
 679     XSRETURN(1);
 680 }
 681
 682 XS(XS_utf8_upgrade)
 683 {
 684     dXSARGS;
 685     if (items != 1)
 686         Perl_croak(aTHX_ "Usage: utf8::upgrade(sv)");
 687     {
 688         SV *    sv = ST(0);
 689         STRLEN  RETVAL;
 690         dXSTARG;
 691
 692         RETVAL = sv_utf8_upgrade(sv);
 693         XSprePUSH; PUSHi((IV)RETVAL);
 694     }
 695     XSRETURN(1);
 696 }
 697
 698 XS(XS_utf8_downgrade)
 699 {
 700     dXSARGS;
 701     if (items < 1 || items > 2)
 702         Perl_croak(aTHX_ "Usage: utf8::downgrade(sv, failok=0)");
 703     {
 704         SV *    sv = ST(0);
 705         const bool failok = (items < 2) ? 0 : (int)SvIV(ST(1));
 706         const bool RETVAL = sv_utf8_downgrade(sv, failok);
 707
 708         ST(0) = boolSV(RETVAL);
 709         sv_2mortal(ST(0));
 710     }
 711     XSRETURN(1);
 712 }
 713
 714 XS(XS_utf8_native_to_unicode)
 715 {
 716  dXSARGS;
 717  const UV uv = SvUV(ST(0));
 718
 719  if (items > 1)
 720      Perl_croak(aTHX_ "Usage: utf8::native_to_unicode(sv)");
 721
 722  ST(0) = sv_2mortal(newSViv(NATIVE_TO_UNI(uv)));
 723  XSRETURN(1);
 724 }
 725
 726 XS(XS_utf8_unicode_to_native)
 727 {
 728  dXSARGS;
 729  const UV uv = SvUV(ST(0));
 730
 731  if (items > 1)
 732      Perl_croak(aTHX_ "Usage: utf8::unicode_to_native(sv)");
 733
 734  ST(0) = sv_2mortal(newSViv(UNI_TO_NATIVE(uv)));
 735  XSRETURN(1);
 736 }
 737
 738 XS(XS_Internals_SvREADONLY)     /* This is dangerous stuff. */
 739 {
 740     dXSARGS;
 741     SV *sv = SvRV(ST(0));
 742
 743     if (items == 1) {
 744          if (SvREADONLY(sv))
 745              XSRETURN_YES;
 746          else
 747              XSRETURN_NO;
 748     }
 749     else if (items == 2) {
 750         if (SvTRUE(ST(1))) {
 751             SvREADONLY_on(sv);
 752             XSRETURN_YES;
 753         }
 754         else {
 755             /* I hope you really know what you are doing. */
 756             SvREADONLY_off(sv);
 757             XSRETURN_NO;
 758         }
 759     }
 760     XSRETURN_UNDEF; /* Can't happen. */
 761 }
 762
 763 XS(XS_Internals_SvREFCNT)       /* This is dangerous stuff. */
 764 {
 765     dXSARGS;
 766     SV *sv = SvRV(ST(0));
 767
 768     if (items == 1)
 769          XSRETURN_IV(SvREFCNT(sv) - 1); /* Minus the ref created for us. */
 770     else if (items == 2) {
 771          /* I hope you really know what you are doing. */
 772          SvREFCNT(sv) = SvIV(ST(1));
 773          XSRETURN_IV(SvREFCNT(sv));
 774     }
 775     XSRETURN_UNDEF; /* Can't happen. */
 776 }
 777
 778 XS(XS_Internals_hv_clear_placehold)
 779 {
 780     dXSARGS;
 781     HV *hv = (HV *) SvRV(ST(0));
 782
 783     if (items != 1)
 784         Perl_croak(aTHX_ "Usage: UNIVERSAL::hv_clear_placeholders(hv)");
 785     hv_clear_placeholders(hv);
 786     XSRETURN(0);
 787 }
 788
 789 XS(XS_Regexp_DESTROY)
 790 {
 791 }
 792
 793 XS(XS_PerlIO_get_layers)
 794 {
 795     dXSARGS;
 796     if (items < 1 || items % 2 == 0)
 797         Perl_croak(aTHX_ "Usage: PerlIO_get_layers(filehandle[,args])");
 798 #ifdef USE_PERLIO
 799     {
 800         SV *    sv;
 801         GV *    gv;
 802         IO *    io;
 803         bool    input = TRUE;
 804         bool    details = FALSE;
 805
 806         if (items > 1) {
 807              SV **svp;
 808
 809              for (svp = MARK + 2; svp <= SP; svp += 2) {
 810                   SV **varp = svp;
 811                   SV **valp = svp + 1;
 812                   STRLEN klen;
 813                   const char *key = SvPV(*varp, klen);
 814
 815                   switch (*key) {
 816                   case 'i':
 817                        if (klen == 5 && memEQ(key, "input", 5)) {
 818                             input = SvTRUE(*valp);
 819                             break;
 820                        }
 821                        goto fail;
 822                   case 'o':
 823                        if (klen == 6 && memEQ(key, "output", 6)) {
 824                             input = !SvTRUE(*valp);
 825                             break;
 826                        }
 827                        goto fail;
 828                   case 'd':
 829                        if (klen == 7 && memEQ(key, "details", 7)) {
 830                             details = SvTRUE(*valp);
 831                             break;
 832                        }
 833                        goto fail;
 834                   default:
 835                   fail:
 836                        Perl_croak(aTHX_
 837                                   "get_layers: unknown argument '%s'",
 838                                   key);
 839                   }
 840              }
 841
 842              SP -= (items - 1);
 843         }
 844
 845         sv = POPs;
 846         gv = (GV*)sv;
 847
 848         if (!isGV(sv)) {
 849              if (SvROK(sv) && isGV(SvRV(sv)))
 850                   gv = (GV*)SvRV(sv);
 851              else
 852                   gv = gv_fetchsv(sv, FALSE, SVt_PVIO);
 853         }
 854
 855         if (gv && (io = GvIO(gv))) {
 856              dTARGET;
 857              AV* av = PerlIO_get_layers(aTHX_ input ?
 858                                         IoIFP(io) : IoOFP(io));
 859              I32 i;
 860              I32 last = av_len(av);
 861              I32 nitem = 0;
 862
 863              for (i = last; i >= 0; i -= 3) {
 864                   SV **namsvp;
 865                   SV **argsvp;
 866                   SV **flgsvp;
 867                   bool namok, argok, flgok;
 868
 869                   namsvp = av_fetch(av, i - 2, FALSE);
 870                   argsvp = av_fetch(av, i - 1, FALSE);
 871                   flgsvp = av_fetch(av, i,     FALSE);
 872
 873                   namok = namsvp && *namsvp && SvPOK(*namsvp);
 874                   argok = argsvp && *argsvp && SvPOK(*argsvp);
 875                   flgok = flgsvp && *flgsvp && SvIOK(*flgsvp);
 876
 877                   if (details) {
 878                        XPUSHs(namok ?
 879                              newSVpv(SvPVX_const(*namsvp), 0) : &PL_sv_undef);
 880                        XPUSHs(argok ?
 881                              newSVpv(SvPVX_const(*argsvp), 0) : &PL_sv_undef);
 882                        if (flgok)
 883                             XPUSHi(SvIVX(*flgsvp));
 884                        else
 885                             XPUSHs(&PL_sv_undef);
 886                        nitem += 3;
 887                   }
 888                   else {
 889                        if (namok && argok)
 890                             XPUSHs(Perl_newSVpvf(aTHX_ "%"SVf"(%"SVf")",
 891                                                *namsvp, *argsvp));
 892                        else if (namok)
 893                             XPUSHs(Perl_newSVpvf(aTHX_ "%"SVf, *namsvp));
 894                        else
 895                             XPUSHs(&PL_sv_undef);
 896                        nitem++;
 897                        if (flgok) {
 898                             IV flags = SvIVX(*flgsvp);
 899
 900                             if (flags & PERLIO_F_UTF8) {
 901                                  XPUSHs(newSVpvn("utf8", 4));
 902                                  nitem++;
 903                             }
 904                        }
 905                   }
 906              }
 907
 908              SvREFCNT_dec(av);
 909
 910              XSRETURN(nitem);
 911         }
 912     }
 913 #endif
 914
 915     XSRETURN(0);
 916 }
 917
 918 XS(XS_Internals_hash_seed)
 919 {
 920     /* Using dXSARGS would also have dITEM and dSP,
 921      * which define 2 unused local variables.  */
 922     dAXMARK;
 923     (void)mark;
 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     (void)mark;
 933     XSRETURN_UV(PL_rehash_seed);
 934 }
 935
 936 XS(XS_Internals_HvREHASH)       /* Subject to change  */
 937 {
 938     dXSARGS;
 939     if (SvROK(ST(0))) {
 940         const HV *hv = (HV *) SvRV(ST(0));
 941         if (items == 1 && SvTYPE(hv) == SVt_PVHV) {
 942             if (HvREHASH(hv))
 943                 XSRETURN_YES;
 944             else
 945                 XSRETURN_NO;
 946         }
 947     }
 948     Perl_croak(aTHX_ "Internals::HvREHASH $hashref");
 949 }
 950
 951 /*
 952  * Local variables:
 953  * c-indentation-style: bsd
 954  * c-basic-offset: 4
 955  * indent-tabs-mode: t
 956  * End:
 957  *
 958  * ex: set ts=8 sts=4 sw=4 noet:
 959  */