source: trunk/third/perl/mg.c @ 10724

/*    mg.c
 *
 *    Copyright (c) 1991-1997, Larry Wall
 *
 *    You may distribute under the terms of either the GNU General Public
 *    License or the Artistic License, as specified in the README file.
 *
 */

/*
 * "Sam sat on the ground and put his head in his hands.  'I wish I had never
 * come here, and I don't want to see no more magic,' he said, and fell silent."
 */

#include "EXTERN.h"
#include "perl.h"

/* XXX If this causes problems, set i_unistd=undef in the hint file.  */
#ifdef I_UNISTD
# include <unistd.h>
#endif

#if defined(HAS_GETGROUPS) || defined(HAS_SETGROUPS)
#  ifndef NGROUPS
#    define NGROUPS 32
#  endif
#endif

/*
 * Use the "DESTRUCTOR" scope cleanup to reinstate magic.
 */

struct magic_state {
    SV* mgs_sv;
    U32 mgs_flags;
};
typedef struct magic_state MGS;

static void restore_magic _((void *p));

static void
save_magic(mgs, sv)
MGS* mgs;
SV* sv;
{
    assert(SvMAGICAL(sv));

    mgs->mgs_sv = sv;
    mgs->mgs_flags = SvMAGICAL(sv) | SvREADONLY(sv);
    SAVEDESTRUCTOR(restore_magic, mgs);

    SvMAGICAL_off(sv);
    SvREADONLY_off(sv);
    SvFLAGS(sv) |= (SvFLAGS(sv) & (SVp_IOK|SVp_NOK|SVp_POK)) >> PRIVSHIFT;
}

static void
restore_magic(p)
void* p;
{
    MGS* mgs = (MGS*)p;
    SV* sv = mgs->mgs_sv;

    if (SvTYPE(sv) >= SVt_PVMG && SvMAGIC(sv))
    {
        if (mgs->mgs_flags)
            SvFLAGS(sv) |= mgs->mgs_flags;
        else
            mg_magical(sv);
        if (SvGMAGICAL(sv))
            SvFLAGS(sv) &= ~(SVf_IOK|SVf_NOK|SVf_POK);
    }
}


void
mg_magical(sv)
SV* sv;
{
    MAGIC* mg;
    for (mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic) {
        MGVTBL* vtbl = mg->mg_virtual;
        if (vtbl) {
            if (vtbl->svt_get && !(mg->mg_flags & MGf_GSKIP))
                SvGMAGICAL_on(sv);
            if (vtbl->svt_set)
                SvSMAGICAL_on(sv);
            if (!(SvFLAGS(sv) & (SVs_GMG|SVs_SMG)) || vtbl->svt_clear)
                SvRMAGICAL_on(sv);
        }
    }
}

int
mg_get(sv)
SV* sv;
{
    MGS mgs;
    MAGIC* mg;
    MAGIC** mgp;
    int mgp_valid = 0;

    ENTER;
    save_magic(&mgs, sv);

    mgp = &SvMAGIC(sv);
    while ((mg = *mgp) != 0) {
        MGVTBL* vtbl = mg->mg_virtual;
        if (!(mg->mg_flags & MGf_GSKIP) && vtbl && vtbl->svt_get) {
            (*vtbl->svt_get)(sv, mg);
            /* Ignore this magic if it's been deleted */
            if ((mg == (mgp_valid ? *mgp : SvMAGIC(sv))) &&
                  (mg->mg_flags & MGf_GSKIP))
                mgs.mgs_flags = 0;
        }
        /* Advance to next magic (complicated by possible deletion) */
        if (mg == (mgp_valid ? *mgp : SvMAGIC(sv))) {
            mgp = &mg->mg_moremagic;
            mgp_valid = 1;
        }
        else
            mgp = &SvMAGIC(sv); /* Re-establish pointer after sv_upgrade */
    }

    LEAVE;
    return 0;
}

int
mg_set(sv)
SV* sv;
{
    MGS mgs;
    MAGIC* mg;
    MAGIC* nextmg;

    ENTER;
    save_magic(&mgs, sv);

    for (mg = SvMAGIC(sv); mg; mg = nextmg) {
        MGVTBL* vtbl = mg->mg_virtual;
        nextmg = mg->mg_moremagic;      /* it may delete itself */
        if (mg->mg_flags & MGf_GSKIP) {
            mg->mg_flags &= ~MGf_GSKIP; /* setting requires another read */
            mgs.mgs_flags = 0;
        }
        if (vtbl && vtbl->svt_set)
            (*vtbl->svt_set)(sv, mg);
    }

    LEAVE;
    return 0;
}

U32
mg_len(sv)
SV* sv;
{
    MAGIC* mg;
    char *junk;
    STRLEN len;

    for (mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic) {
        MGVTBL* vtbl = mg->mg_virtual;
        if (vtbl && vtbl->svt_len) {
            MGS mgs;

            ENTER;
            save_magic(&mgs, sv);
            /* omit MGf_GSKIP -- not changed here */
            len = (*vtbl->svt_len)(sv, mg);
            LEAVE;
            return len;
        }
    }

    junk = SvPV(sv, len);
    return len;
}

int
mg_clear(sv)
SV* sv;
{
    MGS mgs;
    MAGIC* mg;

    ENTER;
    save_magic(&mgs, sv);

    for (mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic) {
        MGVTBL* vtbl = mg->mg_virtual;
        /* omit GSKIP -- never set here */
        
        if (vtbl && vtbl->svt_clear)
            (*vtbl->svt_clear)(sv, mg);
    }

    LEAVE;
    return 0;
}

MAGIC*
mg_find(sv, type)
SV* sv;
int type;
{
    MAGIC* mg;
    for (mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic) {
        if (mg->mg_type == type)
            return mg;
    }
    return 0;
}

int
mg_copy(sv, nsv, key, klen)
SV* sv;
SV* nsv;
char *key;
I32 klen;
{
    int count = 0;
    MAGIC* mg;
    for (mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic) {
        if (isUPPER(mg->mg_type)) {
            sv_magic(nsv, mg->mg_obj, toLOWER(mg->mg_type), key, klen);
            count++;
        }
    }
    return count;
}

int
mg_free(sv)
SV* sv;
{
    MAGIC* mg;
    MAGIC* moremagic;
    for (mg = SvMAGIC(sv); mg; mg = moremagic) {
        MGVTBL* vtbl = mg->mg_virtual;
        moremagic = mg->mg_moremagic;
        if (vtbl && vtbl->svt_free)
            (*vtbl->svt_free)(sv, mg);
        if (mg->mg_ptr && mg->mg_type != 'g')
            if (mg->mg_len >= 0)
                Safefree(mg->mg_ptr);
            else if (mg->mg_len == HEf_SVKEY)
                SvREFCNT_dec((SV*)mg->mg_ptr);
        if (mg->mg_flags & MGf_REFCOUNTED)
            SvREFCNT_dec(mg->mg_obj);
        Safefree(mg);
    }
    SvMAGIC(sv) = 0;
    return 0;
}

#if !defined(NSIG) || defined(M_UNIX) || defined(M_XENIX)
#include <signal.h>
#endif

U32
magic_len(sv, mg)
SV *sv;
MAGIC *mg;
{
    register I32 paren;
    register char *s;
    register I32 i;
    register REGEXP *rx;
    char *t;

    switch (*mg->mg_ptr) {
    case '1': case '2': case '3': case '4':
    case '5': case '6': case '7': case '8': case '9': case '&':
        if (curpm && (rx = curpm->op_pmregexp)) {
            paren = atoi(mg->mg_ptr);
          getparen:
            if (paren <= rx->nparens &&
                (s = rx->startp[paren]) &&
                (t = rx->endp[paren]))
            {
                i = t - s;
                if (i >= 0)
                    return i;
            }
        }
        return 0;
    case '+':
        if (curpm && (rx = curpm->op_pmregexp)) {
            paren = rx->lastparen;
            if (paren)
                goto getparen;
        }
        return 0;
    case '`':
        if (curpm && (rx = curpm->op_pmregexp)) {
            if ((s = rx->subbeg) && rx->startp[0]) {
                i = rx->startp[0] - s;
                if (i >= 0)
                    return i;
            }
        }
        return 0;
    case '\'':
        if (curpm && (rx = curpm->op_pmregexp)) {
            if (rx->subend && (s = rx->endp[0])) {
                i = rx->subend - s;
                if (i >= 0)
                    return i;
            }
        }
        return 0;
    case ',':
        return (STRLEN)ofslen;
    case '\\':
        return (STRLEN)orslen;
    }
    magic_get(sv,mg);
    if (!SvPOK(sv) && SvNIOK(sv))
        sv_2pv(sv, &na);
    if (SvPOK(sv))
        return SvCUR(sv);
    return 0;
}

int
magic_get(sv, mg)
SV *sv;
MAGIC *mg;
{
    register I32 paren;
    register char *s;
    register I32 i;
    register REGEXP *rx;
    char *t;

    switch (*mg->mg_ptr) {
    case '\001':                /* ^A */
        sv_setsv(sv, bodytarget);
        break;
    case '\004':                /* ^D */
        sv_setiv(sv, (IV)(debug & 32767));
        break;
    case '\005':  /* ^E */
#ifdef VMS
        {
#           include <descrip.h>
#           include <starlet.h>
            char msg[255];
            $DESCRIPTOR(msgdsc,msg);
            sv_setnv(sv,(double) vaxc$errno);
            if (sys$getmsg(vaxc$errno,&msgdsc.dsc$w_length,&msgdsc,0,0) & 1)
                sv_setpvn(sv,msgdsc.dsc$a_pointer,msgdsc.dsc$w_length);
            else
                sv_setpv(sv,"");
        }
#else
#ifdef OS2
        if (!(_emx_env & 0x200)) {      /* Under DOS */
            sv_setnv(sv, (double)errno);
            sv_setpv(sv, errno ? Strerror(errno) : "");
        } else {
            if (errno != errno_isOS2)
                Perl_rc = _syserrno();
            sv_setnv(sv, (double)Perl_rc);
            sv_setpv(sv, os2error(Perl_rc));
        }
#else
        sv_setnv(sv, (double)errno);
        sv_setpv(sv, errno ? Strerror(errno) : "");
#endif
#endif
        SvNOK_on(sv);   /* what a wonderful hack! */
        break;
    case '\006':                /* ^F */
        sv_setiv(sv, (IV)maxsysfd);
        break;
    case '\010':                /* ^H */
        sv_setiv(sv, (IV)hints);
        break;
    case '\t':                  /* ^I */
        if (inplace)
            sv_setpv(sv, inplace);
        else
            sv_setsv(sv, &sv_undef);
        break;
    case '\017':                /* ^O */
        sv_setpv(sv, osname);
        break;
    case '\020':                /* ^P */
        sv_setiv(sv, (IV)perldb);
        break;
    case '\023':                /* ^S */
        if (lex_state != LEX_NOTPARSING)
            SvOK_off(sv);
        else if (in_eval)
            sv_setiv(sv, 1);
        else
            sv_setiv(sv, 0);
        break;
    case '\024':                /* ^T */
#ifdef BIG_TIME
        sv_setnv(sv, basetime);
#else
        sv_setiv(sv, (IV)basetime);
#endif
        break;
    case '\027':                /* ^W */
        sv_setiv(sv, (IV)dowarn);
        break;
    case '1': case '2': case '3': case '4':
    case '5': case '6': case '7': case '8': case '9': case '&':
        if (curpm && (rx = curpm->op_pmregexp)) {
            paren = atoi(GvENAME((GV*)mg->mg_obj));
          getparen:
            if (paren <= rx->nparens &&
                (s = rx->startp[paren]) &&
                (t = rx->endp[paren]))
            {
                i = t - s;
              getrx:
                if (i >= 0) {
                    bool was_tainted;
                    if (tainting) {
                        was_tainted = tainted;
                        tainted = FALSE;
                    }
                    sv_setpvn(sv,s,i);
                    if (tainting)
                        tainted = was_tainted || rx->exec_tainted;
                    break;
                }
            }
        }
        sv_setsv(sv,&sv_undef);
        break;
    case '+':
        if (curpm && (rx = curpm->op_pmregexp)) {
            paren = rx->lastparen;
            if (paren)
                goto getparen;
        }
        sv_setsv(sv,&sv_undef);
        break;
    case '`':
        if (curpm && (rx = curpm->op_pmregexp)) {
            if ((s = rx->subbeg) && rx->startp[0]) {
                i = rx->startp[0] - s;
                goto getrx;
            }
        }
        sv_setsv(sv,&sv_undef);
        break;
    case '\'':
        if (curpm && (rx = curpm->op_pmregexp)) {
            if (rx->subend && (s = rx->endp[0])) {
                i = rx->subend - s;
                goto getrx;
            }
        }
        sv_setsv(sv,&sv_undef);
        break;
    case '.':
#ifndef lint
        if (GvIO(last_in_gv)) {
            sv_setiv(sv, (IV)IoLINES(GvIO(last_in_gv)));
        }
#endif
        break;
    case '?':
        sv_setiv(sv, (IV)STATUS_CURRENT);
#ifdef COMPLEX_STATUS
        LvTARGOFF(sv) = statusvalue;
        LvTARGLEN(sv) = statusvalue_vms;
#endif
        break;
    case '^':
        s = IoTOP_NAME(GvIOp(defoutgv));
        if (s)
            sv_setpv(sv,s);
        else {
            sv_setpv(sv,GvENAME(defoutgv));
            sv_catpv(sv,"_TOP");
        }
        break;
    case '~':
        s = IoFMT_NAME(GvIOp(defoutgv));
        if (!s)
            s = GvENAME(defoutgv);
        sv_setpv(sv,s);
        break;
#ifndef lint
    case '=':
        sv_setiv(sv, (IV)IoPAGE_LEN(GvIOp(defoutgv)));
        break;
    case '-':
        sv_setiv(sv, (IV)IoLINES_LEFT(GvIOp(defoutgv)));
        break;
    case '%':
        sv_setiv(sv, (IV)IoPAGE(GvIOp(defoutgv)));
        break;
#endif
    case ':':
        break;
    case '/':
        break;
    case '[':
        sv_setiv(sv, (IV)curcop->cop_arybase);
        break;
    case '|':
        sv_setiv(sv, (IV)(IoFLAGS(GvIOp(defoutgv)) & IOf_FLUSH) != 0 );
        break;
    case ',':
        sv_setpvn(sv,ofs,ofslen);
        break;
    case '\\':
        sv_setpvn(sv,ors,orslen);
        break;
    case '#':
        sv_setpv(sv,ofmt);
        break;
    case '!':
#ifdef VMS
        sv_setnv(sv, (double)((errno == EVMSERR) ? vaxc$errno : errno));
        sv_setpv(sv, errno ? Strerror(errno) : "");
#else
        {
        int saveerrno = errno;
        sv_setnv(sv, (double)errno);
#ifdef OS2
        if (errno == errno_isOS2) sv_setpv(sv, os2error(Perl_rc));
        else
#endif
        sv_setpv(sv, errno ? Strerror(errno) : "");
        errno = saveerrno;
        }
#endif
        SvNOK_on(sv);   /* what a wonderful hack! */
        break;
    case '<':
        sv_setiv(sv, (IV)uid);
        break;
    case '>':
        sv_setiv(sv, (IV)euid);
        break;
    case '(':
        sv_setiv(sv, (IV)gid);
        sv_setpvf(sv, "%Vd", (IV)gid);
        goto add_groups;
    case ')':
        sv_setiv(sv, (IV)egid);
        sv_setpvf(sv, "%Vd", (IV)egid);
      add_groups:
#ifdef HAS_GETGROUPS
        {
            Groups_t gary[NGROUPS];
            i = getgroups(NGROUPS,gary);
            while (--i >= 0)
                sv_catpvf(sv, " %Vd", (IV)gary[i]);
        }
#endif
        SvIOK_on(sv);   /* what a wonderful hack! */
        break;
    case '*':
        break;
    case '0':
        break;
    }
    return 0;
}

int
magic_getuvar(sv, mg)
SV *sv;
MAGIC *mg;
{
    struct ufuncs *uf = (struct ufuncs *)mg->mg_ptr;

    if (uf && uf->uf_val)
        (*uf->uf_val)(uf->uf_index, sv);
    return 0;
}

int
magic_setenv(sv,mg)
SV* sv;
MAGIC* mg;
{
    register char *s;
    char *ptr;
    STRLEN len, klen;
    I32 i;

    s = SvPV(sv,len);
    ptr = MgPV(mg,klen);
    my_setenv(ptr, s);

#ifdef DYNAMIC_ENV_FETCH
     /* We just undefd an environment var.  Is a replacement */
     /* waiting in the wings? */
    if (!len) {
        SV **valp;
        if ((valp = hv_fetch(GvHVn(envgv), ptr, klen, FALSE)))
            s = SvPV(*valp, len);
    }
#endif

#if !defined(OS2) && !defined(AMIGAOS) && !defined(WIN32)
                            /* And you'll never guess what the dog had */
                            /*   in its mouth... */
    if (tainting) {
        MgTAINTEDDIR_off(mg);
#ifdef VMS
        if (s && klen == 8 && strEQ(ptr, "DCL$PATH")) {
            char pathbuf[256], eltbuf[256], *cp, *elt = s;
            struct stat sbuf;
            int i = 0, j = 0;

            do {          /* DCL$PATH may be a search list */
                while (1) {   /* as may dev portion of any element */
                    if ( ((cp = strchr(elt,'[')) || (cp = strchr(elt,'<'))) ) {
                        if ( *(cp+1) == '.' || *(cp+1) == '-' ||
                             cando_by_name(S_IWUSR,0,elt) ) {
                            MgTAINTEDDIR_on(mg);
                            return 0;
                        }
                    }
                    if ((cp = strchr(elt, ':')) != Nullch)
                        *cp = '\0';
                    if (my_trnlnm(elt, eltbuf, j++))
                        elt = eltbuf;
                    else
                        break;
                }
                j = 0;
            } while (my_trnlnm(s, pathbuf, i++) && (elt = pathbuf));
        }
#endif /* VMS */
        if (s && klen == 4 && strEQ(ptr,"PATH")) {
            char *strend = s + len;

            while (s < strend) {
                struct stat st;
                s = delimcpy(tokenbuf, tokenbuf + sizeof tokenbuf,
                             s, strend, ':', &i);
                s++;
                if (i >= sizeof tokenbuf   /* too long -- assume the worst */
                      || *tokenbuf != '/'
                      || (Stat(tokenbuf, &st) == 0 && (st.st_mode & 2)) ) {
                    MgTAINTEDDIR_on(mg);
                    return 0;
                }
            }
        }
    }
#endif /* neither OS2 nor AMIGAOS nor WIN32 */

    return 0;
}

int
magic_clearenv(sv,mg)
SV* sv;
MAGIC* mg;
{
    my_setenv(MgPV(mg,na),Nullch);
    return 0;
}

int
magic_set_all_env(sv,mg)
SV* sv;
MAGIC* mg;
{
#if defined(VMS)
    die("Can't make list assignment to %%ENV on this system");
#else
    if (localizing) {
        HE* entry;
        magic_clear_all_env(sv,mg);
        hv_iterinit((HV*)sv);
        while (entry = hv_iternext((HV*)sv)) {
            I32 keylen;
            my_setenv(hv_iterkey(entry, &keylen),
                      SvPV(hv_iterval((HV*)sv, entry), na));
        }
    }
#endif
    return 0;
}

int
magic_clear_all_env(sv,mg)
SV* sv;
MAGIC* mg;
{
#if defined(VMS)
    die("Can't make list assignment to %%ENV on this system");
#else
#ifdef WIN32
    char *envv = GetEnvironmentStrings();
    char *cur = envv;
    STRLEN len;
    while (*cur) {
        char *end = strchr(cur,'=');
        if (end && end != cur) {
            *end = '\0';
            my_setenv(cur,Nullch);
            *end = '=';
            cur += strlen(end+1)+1;
        }
        else if ((len = strlen(cur)))
            cur += len+1;
    }
    FreeEnvironmentStrings(envv);
#else
    I32 i;

    if (environ == origenviron)
        New(901, environ, 1, char*);
    else
        for (i = 0; environ[i]; i++)
            Safefree(environ[i]);
    environ[0] = Nullch;

#endif
#endif
    return 0;
}

int
magic_getsig(sv,mg)
SV* sv;
MAGIC* mg;
{
    I32 i;
    /* Are we fetching a signal entry? */
    i = whichsig(MgPV(mg,na));
    if (i) {
        if(psig_ptr[i])
            sv_setsv(sv,psig_ptr[i]);
        else {
            Sighandler_t sigstate = rsignal_state(i);

            /* cache state so we don't fetch it again */
            if(sigstate == SIG_IGN)
                sv_setpv(sv,"IGNORE");
            else
                sv_setsv(sv,&sv_undef);
            psig_ptr[i] = SvREFCNT_inc(sv);
            SvTEMP_off(sv);
        }
    }
    return 0;
}
int
magic_clearsig(sv,mg)
SV* sv;
MAGIC* mg;
{
    I32 i;
    /* Are we clearing a signal entry? */
    i = whichsig(MgPV(mg,na));
    if (i) {
        if(psig_ptr[i]) {
            SvREFCNT_dec(psig_ptr[i]);
            psig_ptr[i]=0;
        }
        if(psig_name[i]) {
            SvREFCNT_dec(psig_name[i]);
            psig_name[i]=0;
        }
    }
    return 0;
}

int
magic_setsig(sv,mg)
SV* sv;
MAGIC* mg;
{
    register char *s;
    I32 i;
    SV** svp;

    s = MgPV(mg,na);
    if (*s == '_') {
        if (strEQ(s,"__DIE__"))
            svp = &diehook;
        else if (strEQ(s,"__WARN__"))
            svp = &warnhook;
        else if (strEQ(s,"__PARSE__"))
            svp = &parsehook;
        else
            croak("No such hook: %s", s);
        i = 0;
        if (*svp) {
            SvREFCNT_dec(*svp);
            *svp = 0;
        }
    }
    else {
        i = whichsig(s);        /* ...no, a brick */
        if (!i) {
            if (dowarn || strEQ(s,"ALARM"))
                warn("No such signal: SIG%s", s);
            return 0;
        }
        SvREFCNT_dec(psig_name[i]);
        SvREFCNT_dec(psig_ptr[i]);
        psig_ptr[i] = SvREFCNT_inc(sv);
        SvTEMP_off(sv); /* Make sure it doesn't go away on us */
        psig_name[i] = newSVpv(s, strlen(s));
        SvREADONLY_on(psig_name[i]);
    }
    if (SvTYPE(sv) == SVt_PVGV || SvROK(sv)) {
        if (i)
            (void)rsignal(i, sighandler);
        else
            *svp = SvREFCNT_inc(sv);
        return 0;
    }
    s = SvPV_force(sv,na);
    if (strEQ(s,"IGNORE")) {
        if (i)
            (void)rsignal(i, SIG_IGN);
        else
            *svp = 0;
    }
    else if (strEQ(s,"DEFAULT") || !*s) {
        if (i)
            (void)rsignal(i, SIG_DFL);
        else
            *svp = 0;
    }
    else {
        /*
         * We should warn if HINT_STRICT_REFS, but without
         * access to a known hint bit in a known OP, we can't
         * tell whether HINT_STRICT_REFS is in force or not.
         */
        if (!strchr(s,':') && !strchr(s,'\''))
            sv_setpv(sv, form("main::%s", s));
        if (i)
            (void)rsignal(i, sighandler);
        else
            *svp = SvREFCNT_inc(sv);
    }
    return 0;
}

int
magic_setisa(sv,mg)
SV* sv;
MAGIC* mg;
{
    sub_generation++;
    return 0;
}

#ifdef OVERLOAD

int
magic_setamagic(sv,mg)
SV* sv;
MAGIC* mg;
{
    /* HV_badAMAGIC_on(Sv_STASH(sv)); */
    amagic_generation++;

    return 0;
}
#endif /* OVERLOAD */

int
magic_setnkeys(sv,mg)
SV* sv;
MAGIC* mg;
{
    if (LvTARG(sv)) {
        hv_ksplit((HV*)LvTARG(sv), SvIV(sv));
        LvTARG(sv) = Nullsv;    /* Don't allow a ref to reassign this. */
    }
    return 0;
}

static int
magic_methpack(sv,mg,meth)
SV* sv;
MAGIC* mg;
char *meth;
{
    dSP;

    ENTER;
    SAVETMPS;
    PUSHMARK(sp);
    EXTEND(sp, 2);
    PUSHs(mg->mg_obj);
    if (mg->mg_ptr) {
        if (mg->mg_len >= 0)
            PUSHs(sv_2mortal(newSVpv(mg->mg_ptr, mg->mg_len)));
        else if (mg->mg_len == HEf_SVKEY)
            PUSHs((SV*)mg->mg_ptr);
    }
    else if (mg->mg_type == 'p')
        PUSHs(sv_2mortal(newSViv(mg->mg_len)));
    PUTBACK;

    if (perl_call_method(meth, G_SCALAR))
        sv_setsv(sv, *stack_sp--);

    FREETMPS;
    LEAVE;
    return 0;
}

int
magic_getpack(sv,mg)
SV* sv;
MAGIC* mg;
{
    magic_methpack(sv,mg,"FETCH");
    if (mg->mg_ptr)
        mg->mg_flags |= MGf_GSKIP;
    return 0;
}

int
magic_setpack(sv,mg)
SV* sv;
MAGIC* mg;
{
    dSP;

    PUSHMARK(sp);
    EXTEND(sp, 3);
    PUSHs(mg->mg_obj);
    if (mg->mg_ptr) {
        if (mg->mg_len >= 0)
            PUSHs(sv_2mortal(newSVpv(mg->mg_ptr, mg->mg_len)));
        else if (mg->mg_len == HEf_SVKEY)
            PUSHs((SV*)mg->mg_ptr);
    }
    else if (mg->mg_type == 'p')
        PUSHs(sv_2mortal(newSViv(mg->mg_len)));
    PUSHs(sv);
    PUTBACK;

    perl_call_method("STORE", G_SCALAR|G_DISCARD);

    return 0;
}

int
magic_clearpack(sv,mg)
SV* sv;
MAGIC* mg;
{
    return magic_methpack(sv,mg,"DELETE");
}

int magic_wipepack(sv,mg)
SV* sv;
MAGIC* mg;
{
    dSP;

    PUSHMARK(sp);
    XPUSHs(mg->mg_obj);
    PUTBACK;

    perl_call_method("CLEAR", G_SCALAR|G_DISCARD);

    return 0;
}

int
magic_nextpack(sv,mg,key)
SV* sv;
MAGIC* mg;
SV* key;
{
    dSP;
    char *meth = SvOK(key) ? "NEXTKEY" : "FIRSTKEY";

    ENTER;
    SAVETMPS;
    PUSHMARK(sp);
    EXTEND(sp, 2);
    PUSHs(mg->mg_obj);
    if (SvOK(key))
        PUSHs(key);
    PUTBACK;

    if (perl_call_method(meth, G_SCALAR))
        sv_setsv(key, *stack_sp--);

    FREETMPS;
    LEAVE;
    return 0;
}

int
magic_existspack(sv,mg)
SV* sv;
MAGIC* mg;
{
    return magic_methpack(sv,mg,"EXISTS");
} 

int
magic_setdbline(sv,mg)
SV* sv;
MAGIC* mg;
{
    OP *o;
    I32 i;
    GV* gv;
    SV** svp;

    gv = DBline;
    i = SvTRUE(sv);
    svp = av_fetch(GvAV(gv),
                     atoi(MgPV(mg,na)), FALSE);
    if (svp && SvIOKp(*svp) && (o = (OP*)SvSTASH(*svp)))
        o->op_private = i;
    else
        warn("Can't break at that line\n");
    return 0;
}

int
magic_getarylen(sv,mg)
SV* sv;
MAGIC* mg;
{
    sv_setiv(sv, AvFILL((AV*)mg->mg_obj) + curcop->cop_arybase);
    return 0;
}

int
magic_setarylen(sv,mg)
SV* sv;
MAGIC* mg;
{
    av_fill((AV*)mg->mg_obj, SvIV(sv) - curcop->cop_arybase);
    return 0;
}

int
magic_getpos(sv,mg)
SV* sv;
MAGIC* mg;
{
    SV* lsv = LvTARG(sv);
    
    if (SvTYPE(lsv) >= SVt_PVMG && SvMAGIC(lsv)) {
        mg = mg_find(lsv, 'g');
        if (mg && mg->mg_len >= 0) {
            sv_setiv(sv, mg->mg_len + curcop->cop_arybase);
            return 0;
        }
    }
    (void)SvOK_off(sv);
    return 0;
}

int
magic_setpos(sv,mg)
SV* sv;
MAGIC* mg;
{
    SV* lsv = LvTARG(sv);
    SSize_t pos;
    STRLEN len;

    mg = 0;
    
    if (SvTYPE(lsv) >= SVt_PVMG && SvMAGIC(lsv))
        mg = mg_find(lsv, 'g');
    if (!mg) {
        if (!SvOK(sv))
            return 0;
        sv_magic(lsv, (SV*)0, 'g', Nullch, 0);
        mg = mg_find(lsv, 'g');
    }
    else if (!SvOK(sv)) {
        mg->mg_len = -1;
        return 0;
    }
    len = SvPOK(lsv) ? SvCUR(lsv) : sv_len(lsv);

    pos = SvIV(sv) - curcop->cop_arybase;
    if (pos < 0) {
        pos += len;
        if (pos < 0)
            pos = 0;
    }
    else if (pos > len)
        pos = len;
    mg->mg_len = pos;
    mg->mg_flags &= ~MGf_MINMATCH;

    return 0;
}

int
magic_getglob(sv,mg)
SV* sv;
MAGIC* mg;
{
    if (SvFAKE(sv)) {                   /* FAKE globs can get coerced */
        SvFAKE_off(sv);
        gv_efullname3(sv,((GV*)sv), "*");
        SvFAKE_on(sv);
    }
    else
        gv_efullname3(sv,((GV*)sv), "*");       /* a gv value, be nice */
    return 0;
}

int
magic_setglob(sv,mg)
SV* sv;
MAGIC* mg;
{
    register char *s;
    GV* gv;

    if (!SvOK(sv))
        return 0;
    s = SvPV(sv, na);
    if (*s == '*' && s[1])
        s++;
    gv = gv_fetchpv(s,TRUE, SVt_PVGV);
    if (sv == (SV*)gv)
        return 0;
    if (GvGP(sv))
        gp_free((GV*)sv);
    GvGP(sv) = gp_ref(GvGP(gv));
    return 0;
}

int
magic_setsubstr(sv,mg)
SV* sv;
MAGIC* mg;
{
    STRLEN len;
    char *tmps = SvPV(sv,len);
    sv_insert(LvTARG(sv),LvTARGOFF(sv),LvTARGLEN(sv), tmps, len);
    return 0;
}

int
magic_gettaint(sv,mg)
SV* sv;
MAGIC* mg;
{
    TAINT_IF((mg->mg_len & 1) ||
             (mg->mg_len & 2) && mg->mg_obj == sv);     /* kludge */
    return 0;
}

int
magic_settaint(sv,mg)
SV* sv;
MAGIC* mg;
{
    if (localizing) {
        if (localizing == 1)
            mg->mg_len <<= 1;
        else
            mg->mg_len >>= 1;
    }
    else if (tainted)
        mg->mg_len |= 1;
    else
        mg->mg_len &= ~1;
    return 0;
}

int
magic_setvec(sv,mg)
SV* sv;
MAGIC* mg;
{
    do_vecset(sv);      /* XXX slurp this routine */
    return 0;
}

int
magic_getdefelem(sv,mg)
SV* sv;
MAGIC* mg;
{
    SV *targ = Nullsv;
    if (LvTARGLEN(sv)) {
        if (mg->mg_obj) {
            HV* hv = (HV*)LvTARG(sv);
            HE* he = hv_fetch_ent(hv, mg->mg_obj, FALSE, 0);
            if (he)
                targ = HeVAL(he);
        }
        else {
            AV* av = (AV*)LvTARG(sv);
            if ((I32)LvTARGOFF(sv) <= AvFILL(av))
                targ = AvARRAY(av)[LvTARGOFF(sv)];
        }
        if (targ && targ != &sv_undef) {
            /* somebody else defined it for us */
            SvREFCNT_dec(LvTARG(sv));
            LvTARG(sv) = SvREFCNT_inc(targ);
            LvTARGLEN(sv) = 0;
            SvREFCNT_dec(mg->mg_obj);
            mg->mg_obj = Nullsv;
            mg->mg_flags &= ~MGf_REFCOUNTED;
        }
    }
    else
        targ = LvTARG(sv);
    sv_setsv(sv, targ ? targ : &sv_undef);
    return 0;
}

int
magic_setdefelem(sv,mg)
SV* sv;
MAGIC* mg;
{
    if (LvTARGLEN(sv))
        vivify_defelem(sv);
    if (LvTARG(sv)) {
        sv_setsv(LvTARG(sv), sv);
        SvSETMAGIC(LvTARG(sv));
    }
    return 0;
}

int
magic_freedefelem(sv,mg)
SV* sv;
MAGIC* mg;
{
    SvREFCNT_dec(LvTARG(sv));
    return 0;
}

void
vivify_defelem(sv)
SV* sv;
{
    MAGIC* mg;
    SV* value;

    if (!LvTARGLEN(sv) || !(mg = mg_find(sv, 'y')))
        return;
    if (mg->mg_obj) {
        HV* hv = (HV*)LvTARG(sv);
        HE* he = hv_fetch_ent(hv, mg->mg_obj, TRUE, 0);
        if (!he || (value = HeVAL(he)) == &sv_undef)
            croak(no_helem, SvPV(mg->mg_obj, na));
    }
    else {
        AV* av = (AV*)LvTARG(sv);
        if ((I32)LvTARGLEN(sv) < 0 && (I32)LvTARGOFF(sv) > AvFILL(av))
            LvTARG(sv) = Nullsv;        /* array can't be extended */
        else {
            SV** svp = av_fetch(av, LvTARGOFF(sv), TRUE);
            if (!svp || (value = *svp) == &sv_undef)
                croak(no_aelem, (I32)LvTARGOFF(sv));
        }
    }
    (void)SvREFCNT_inc(value);
    SvREFCNT_dec(LvTARG(sv));
    LvTARG(sv) = value;
    LvTARGLEN(sv) = 0;
    SvREFCNT_dec(mg->mg_obj);
    mg->mg_obj = Nullsv;
    mg->mg_flags &= ~MGf_REFCOUNTED;
}

int
magic_setmglob(sv,mg)
SV* sv;
MAGIC* mg;
{
    mg->mg_len = -1;
    SvSCREAM_off(sv);
    return 0;
}

int
magic_setbm(sv,mg)
SV* sv;
MAGIC* mg;
{
    sv_unmagic(sv, 'B');
    SvVALID_off(sv);
    return 0;
}

int
magic_setfm(sv,mg)
SV* sv;
MAGIC* mg;
{
    sv_unmagic(sv, 'f');
    SvCOMPILED_off(sv);
    return 0;
}

int
magic_setuvar(sv,mg)
SV* sv;
MAGIC* mg;
{
    struct ufuncs *uf = (struct ufuncs *)mg->mg_ptr;

    if (uf && uf->uf_set)
        (*uf->uf_set)(uf->uf_index, sv);
    return 0;
}

#ifdef USE_LOCALE_COLLATE
int
magic_setcollxfrm(sv,mg)
SV* sv;
MAGIC* mg;
{
    /*
     * René Descartes said "I think not."
     * and vanished with a faint plop.
     */
    if (mg->mg_ptr) {
        Safefree(mg->mg_ptr);
        mg->mg_ptr = NULL;
        mg->mg_len = -1;
    }
    return 0;
}
#endif /* USE_LOCALE_COLLATE */

int
magic_set(sv,mg)
SV* sv;
MAGIC* mg;
{
    register char *s;
    I32 i;
    STRLEN len;
    switch (*mg->mg_ptr) {
    case '\001':        /* ^A */
        sv_setsv(bodytarget, sv);
        break;
    case '\004':        /* ^D */
        debug = (SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv)) | 0x80000000;
        DEBUG_x(dump_all());
        break;
    case '\005':  /* ^E */
#ifdef VMS
        set_vaxc_errno(SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv));
#else
        /* will anyone ever use this? */
        SETERRNO(SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv), 4);
#endif
        break;
    case '\006':        /* ^F */
        maxsysfd = SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv);
        break;
    case '\010':        /* ^H */
        hints = SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv);
        break;
    case '\t':  /* ^I */
        if (inplace)
            Safefree(inplace);
        if (SvOK(sv))
            inplace = savepv(SvPV(sv,na));
        else
            inplace = Nullch;
        break;
    case '\017':        /* ^O */
        if (osname)
            Safefree(osname);
        if (SvOK(sv))
            osname = savepv(SvPV(sv,na));
        else
            osname = Nullch;
        break;
    case '\020':        /* ^P */
        perldb = SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv);
        break;
    case '\024':        /* ^T */
#ifdef BIG_TIME
        basetime = (Time_t)(SvNOK(sv) ? SvNVX(sv) : sv_2nv(sv));
#else
        basetime = (Time_t)(SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv));
#endif
        break;
    case '\027':        /* ^W */
        dowarn = (bool)(SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv));
        break;
    case '.':
        if (localizing) {
            if (localizing == 1)
                save_sptr((SV**)&last_in_gv);
        }
        else if (SvOK(sv) && GvIO(last_in_gv))
            IoLINES(GvIOp(last_in_gv)) = (long)SvIV(sv);
        break;
    case '^':
        Safefree(IoTOP_NAME(GvIOp(defoutgv)));
        IoTOP_NAME(GvIOp(defoutgv)) = s = savepv(SvPV(sv,na));
        IoTOP_GV(GvIOp(defoutgv)) = gv_fetchpv(s,TRUE, SVt_PVIO);
        break;
    case '~':
        Safefree(IoFMT_NAME(GvIOp(defoutgv)));
        IoFMT_NAME(GvIOp(defoutgv)) = s = savepv(SvPV(sv,na));
        IoFMT_GV(GvIOp(defoutgv)) = gv_fetchpv(s,TRUE, SVt_PVIO);
        break;
    case '=':
        IoPAGE_LEN(GvIOp(defoutgv)) = (long)(SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv));
        break;
    case '-':
        IoLINES_LEFT(GvIOp(defoutgv)) = (long)(SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv));
        if (IoLINES_LEFT(GvIOp(defoutgv)) < 0L)
            IoLINES_LEFT(GvIOp(defoutgv)) = 0L;
        break;
    case '%':
        IoPAGE(GvIOp(defoutgv)) = (long)(SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv));
        break;
    case '|':
        {
            IO *io = GvIOp(defoutgv);
            if ((SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv)) == 0)
                IoFLAGS(io) &= ~IOf_FLUSH;
            else {
                if (!(IoFLAGS(io) & IOf_FLUSH)) {
                    PerlIO *ofp = IoOFP(io);
                    if (ofp)
                        (void)PerlIO_flush(ofp);
                    IoFLAGS(io) |= IOf_FLUSH;
                }
            }
        }
        break;
    case '*':
        i = SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv);
        multiline = (i != 0);
        break;
    case '/':
        SvREFCNT_dec(nrs);
        nrs = newSVsv(sv);
        SvREFCNT_dec(rs);
        rs = SvREFCNT_inc(nrs);
        break;
    case '\\':
        if (ors)
            Safefree(ors);
        if (SvOK(sv) || SvGMAGICAL(sv))
            ors = savepv(SvPV(sv,orslen));
        else {
            ors = Nullch;
            orslen = 0;
        }
        break;
    case ',':
        if (ofs)
            Safefree(ofs);
        ofs = savepv(SvPV(sv, ofslen));
        break;
    case '#':
        if (ofmt)
            Safefree(ofmt);
        ofmt = savepv(SvPV(sv,na));
        break;
    case '[':
        compiling.cop_arybase = SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv);
        break;
    case '?':
#ifdef COMPLEX_STATUS
        if (localizing == 2) {
            statusvalue = LvTARGOFF(sv);
            statusvalue_vms = LvTARGLEN(sv);
        }
        else
#endif
#ifdef VMSISH_STATUS
        if (VMSISH_STATUS)
            STATUS_NATIVE_SET((U32)(SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv)));
        else
#endif
            STATUS_POSIX_SET(SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv));
        break;
    case '!':
        SETERRNO(SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv),
                 (SvIV(sv) == EVMSERR) ? 4 : vaxc$errno);
        break;
    case '<':
        uid = SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv);
        if (delaymagic) {
            delaymagic |= DM_RUID;
            break;                              /* don't do magic till later */
        }
#ifdef HAS_SETRUID
        (void)setruid((Uid_t)uid);
#else
#ifdef HAS_SETREUID
        (void)setreuid((Uid_t)uid, (Uid_t)-1);
#else
#ifdef HAS_SETRESUID
      (void)setresuid((Uid_t)uid, (Uid_t)-1, (Uid_t)-1);
#else
        if (uid == euid)                /* special case $< = $> */
            (void)setuid(uid);
        else {
            uid = (I32)getuid();
            croak("setruid() not implemented");
        }
#endif
#endif
#endif
        uid = (I32)getuid();
        tainting |= (uid && (euid != uid || egid != gid));
        break;
    case '>':
        euid = SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv);
        if (delaymagic) {
            delaymagic |= DM_EUID;
            break;                              /* don't do magic till later */
        }
#ifdef HAS_SETEUID
        (void)seteuid((Uid_t)euid);
#else
#ifdef HAS_SETREUID
        (void)setreuid((Uid_t)-1, (Uid_t)euid);
#else
#ifdef HAS_SETRESUID
        (void)setresuid((Uid_t)-1, (Uid_t)euid, (Uid_t)-1);
#else
        if (euid == uid)                /* special case $> = $< */
            setuid(euid);
        else {
            euid = (I32)geteuid();
            croak("seteuid() not implemented");
        }
#endif
#endif
#endif
        euid = (I32)geteuid();
        tainting |= (uid && (euid != uid || egid != gid));
        break;
    case '(':
        gid = SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv);
        if (delaymagic) {
            delaymagic |= DM_RGID;
            break;                              /* don't do magic till later */
        }
#ifdef HAS_SETRGID
        (void)setrgid((Gid_t)gid);
#else
#ifdef HAS_SETREGID
        (void)setregid((Gid_t)gid, (Gid_t)-1);
#else
#ifdef HAS_SETRESGID
      (void)setresgid((Gid_t)gid, (Gid_t)-1, (Gid_t) 1);
#else
        if (gid == egid)                        /* special case $( = $) */
            (void)setgid(gid);
        else {
            gid = (I32)getgid();
            croak("setrgid() not implemented");
        }
#endif
#endif
#endif
        gid = (I32)getgid();
        tainting |= (uid && (euid != uid || egid != gid));
        break;
    case ')':
#ifdef HAS_SETGROUPS
        {
            char *p = SvPV(sv, na);
            Groups_t gary[NGROUPS];

            SET_NUMERIC_STANDARD();
            while (isSPACE(*p))
                ++p;
            egid = I_V(atof(p));
            for (i = 0; i < NGROUPS; ++i) {
                while (*p && !isSPACE(*p))
                    ++p;
                while (isSPACE(*p))
                    ++p;
                if (!*p)
                    break;
                gary[i] = I_V(atof(p));
            }
            if (i)
                (void)setgroups(i, gary);
        }
#else  /* HAS_SETGROUPS */
        egid = SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv);
#endif /* HAS_SETGROUPS */
        if (delaymagic) {
            delaymagic |= DM_EGID;
            break;                              /* don't do magic till later */
        }
#ifdef HAS_SETEGID
        (void)setegid((Gid_t)egid);
#else
#ifdef HAS_SETREGID
        (void)setregid((Gid_t)-1, (Gid_t)egid);
#else
#ifdef HAS_SETRESGID
        (void)setresgid((Gid_t)-1, (Gid_t)egid, (Gid_t)-1);
#else
        if (egid == gid)                        /* special case $) = $( */
            (void)setgid(egid);
        else {
            egid = (I32)getegid();
            croak("setegid() not implemented");
        }
#endif
#endif
#endif
        egid = (I32)getegid();
        tainting |= (uid && (euid != uid || egid != gid));
        break;
    case ':':
        chopset = SvPV_force(sv,na);
        break;
    case '0':
        if (!origalen) {
            s = origargv[0];
            s += strlen(s);
            /* See if all the arguments are contiguous in memory */
            for (i = 1; i < origargc; i++) {
                if (origargv[i] == s + 1
#ifdef OS2
                    || origargv[i] == s + 2
#endif 
                   )
                    s += strlen(++s);   /* this one is ok too */
                else
                    break;
            }
            /* can grab env area too? */
            if (origenviron && (origenviron[0] == s + 1
#ifdef OS2
                                || (origenviron[0] == s + 9 && (s += 8))
#endif 
               )) {
                my_setenv("NoNe  SuCh", Nullch);
                                            /* force copy of environment */
                for (i = 0; origenviron[i]; i++)
                    if (origenviron[i] == s + 1)
                        s += strlen(++s);
                    else
                        break;
            }
            origalen = s - origargv[0];
        }
        s = SvPV_force(sv,len);
        i = len;
        if (i >= origalen) {
            i = origalen;
            /* don't allow system to limit $0 seen by script */
            /* SvCUR_set(sv, i); *SvEND(sv) = '\0'; */
            Copy(s, origargv[0], i, char);
            s = origargv[0]+i;
            *s = '\0';
        }
        else {
            Copy(s, origargv[0], i, char);
            s = origargv[0]+i;
            *s++ = '\0';
            while (++i < origalen)
                *s++ = ' ';
            s = origargv[0]+i;
            for (i = 1; i < origargc; i++)
                origargv[i] = Nullch;
        }
        break;
    }
    return 0;
}

I32
whichsig(sig)
char *sig;
{
    register char **sigv;

    for (sigv = sig_name+1; *sigv; sigv++)
        if (strEQ(sig,*sigv))
            return sig_num[sigv - sig_name];
#ifdef SIGCLD
    if (strEQ(sig,"CHLD"))
        return SIGCLD;
#endif
#ifdef SIGCHLD
    if (strEQ(sig,"CLD"))
        return SIGCHLD;
#endif
    return 0;
}

static SV* sig_sv;

static void
unwind_handler_stack(p)
    void *p;
{
    U32 flags = *(U32*)p;

    if (flags & 1)
        savestack_ix -= 5; /* Unprotect save in progress. */
    /* cxstack_ix-- Not needed, die already unwound it. */
    if (flags & 64)
        SvREFCNT_dec(sig_sv);
}

Signal_t
sighandler(sig)
int sig;
{
    dSP;
    GV *gv;
    HV *st;
    SV *sv, *tSv = Sv;
    CV *cv;
    AV *oldstack;
    OP *myop = op;
    U32 flags = 0;
    I32 o_save_i = savestack_ix, type;
    CONTEXT *cx;
    XPV *tXpv = Xpv;
    
    if (savestack_ix + 15 <= savestack_max)
        flags |= 1;
    if (cxstack_ix < cxstack_max - 2)
        flags |= 2;
    if (markstack_ptr < markstack_max - 2)
        flags |= 4;
    if (retstack_ix < retstack_max - 2)
        flags |= 8;
    if (scopestack_ix < scopestack_max - 3)
        flags |= 16;

    if (flags & 2) {            /* POPBLOCK may decrease cxstack too early. */
        cxstack_ix++;           /* Protect from overwrite. */
        cx = &cxstack[cxstack_ix];
        type = cx->cx_type;             /* Can be during partial write. */
        cx->cx_type = CXt_NULL;         /* Make it safe for unwind. */
    }
    if (!psig_ptr[sig])
        die("Signal SIG%s received, but no signal handler set.\n",
            sig_name[sig]);

    /* Max number of items pushed there is 3*n or 4. We cannot fix
       infinity, so we fix 4 (in fact 5): */
    if (flags & 1) {
        savestack_ix += 5;              /* Protect save in progress. */
        o_save_i = savestack_ix;
        SAVEDESTRUCTOR(unwind_handler_stack, (void*)&flags);
    }
    if (flags & 4) 
        markstack_ptr++;                /* Protect mark. */
    if (flags & 8) {
        retstack_ix++;
        retstack[retstack_ix] = NULL;
    }
    if (flags & 16)
        scopestack_ix += 1;
    /* sv_2cv is too complicated, try a simpler variant first: */
    if (!SvROK(psig_ptr[sig]) || !(cv = (CV*)SvRV(psig_ptr[sig])) 
        || SvTYPE(cv) != SVt_PVCV)
        cv = sv_2cv(psig_ptr[sig],&st,&gv,TRUE);

    if (!cv || !CvROOT(cv)) {
        if (dowarn)
            warn("SIG%s handler \"%s\" not defined.\n",
                sig_name[sig], GvENAME(gv) );
        return;
    }

    oldstack = curstack;
    if (curstack != signalstack)
        AvFILL(signalstack) = 0;
    SWITCHSTACK(curstack, signalstack);

    if(psig_name[sig]) {
        sv = SvREFCNT_inc(psig_name[sig]);
        flags |= 64;
        sig_sv = sv;
    } else {
        sv = sv_newmortal();
        sv_setpv(sv,sig_name[sig]);
    }
    PUSHMARK(sp);
    PUSHs(sv);
    PUTBACK;

    perl_call_sv((SV*)cv, G_DISCARD);

    SWITCHSTACK(signalstack, oldstack);
    if (flags & 1)
        savestack_ix -= 8; /* Unprotect save in progress. */
    if (flags & 2) {
        cxstack[cxstack_ix].cx_type = type;
        cxstack_ix -= 1;
    }
    if (flags & 4) 
        markstack_ptr--;
    if (flags & 8) 
        retstack_ix--;
    if (flags & 16)
        scopestack_ix -= 1;
    if (flags & 64)
        SvREFCNT_dec(sv);
    op = myop;                  /* Apparently not needed... */
    
    Sv = tSv;                   /* Restore global temporaries. */
    Xpv = tXpv;
    return;
}