common/bltins/print.c

	print.c revision 7c2fbfb345896881c631598ee3852ce9ce33fb07
/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1982-2008 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*            http://www.opensource.org/licenses/cpl1.0.txt             *
*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                  David Korn <dgk@research.att.com>                   *
*                                                                      *
***********************************************************************/
#pragma prototyped
/*
 * echo [arg...]
 * print [-nrps] [-f format] [-u filenum] [arg...]
 * printf  format [arg...]
 *
 *   David Korn
 *   AT&T Labs
 */

#include    "defs.h"
#include    <error.h>
#include    <stak.h>
#include    "io.h"
#include    "name.h"
#include    "history.h"
#include    "builtins.h"
#include    "streval.h"
#include    <tmx.h>
#include    <ctype.h>
#include    <ccode.h>

union types_t
{
    unsigned char   c;
    short       h;
    int     i;
    long        l;
    Sflong_t    ll;
    Sfdouble_t  ld;
    double      d;
    float       f;
    char        *s;
    int     *ip;
    char        **p;
};

struct printf
{
    Sffmt_t     hdr;
    int     argsize;
    int     intvar;
    char        **nextarg;
    char        *lastarg;
    char        cescape;
    char        err;
    Shell_t     *sh;
};

static int      extend(Sfio_t*,void*, Sffmt_t*);
static const char       preformat[] = "";
static char     *genformat(char*);
static int      fmtvecho(const char*, struct printf*);
static ssize_t      fmtbase64(Sfio_t*, char*, int);

struct print
{
    Shell_t         *sh;
    const char  *options;
    char        raw;
    char        echon;
};

static char*    nullarg[] = { 0, 0 };

#if !SHOPT_ECHOPRINT
   int    B_echo(int argc, char *argv[],void *extra)
   {
    static char bsd_univ;
    struct print prdata;
    prdata.options = sh_optecho+5;
    prdata.raw = prdata.echon = 0;
    prdata.sh = ((Shbltin_t*)extra)->shp;
    NOT_USED(argc);
    /* This mess is because /bin/echo on BSD is different */
    if(!prdata.sh->universe)
    {
        register char *universe;
        if(universe=astconf("UNIVERSE",0,0))
            bsd_univ = (strcmp(universe,"ucb")==0);
        prdata.sh->universe = 1;
    }
    if(!bsd_univ)
        return(b_print(0,argv,&prdata));
    prdata.options = sh_optecho;
    prdata.raw = 1;
    while(argv[1] && *argv[1]=='-')
    {
        if(strcmp(argv[1],"-n")==0)
            prdata.echon = 1;
#if !SHOPT_ECHOE
        else if(strcmp(argv[1],"-e")==0)
            prdata.raw = 0;
        else if(strcmp(argv[1],"-ne")==0 || strcmp(argv[1],"-en")==0)
        {
            prdata.raw = 0;
            prdata.echon = 1;
        }
#endif /* SHOPT_ECHOE */
        else
            break;
        argv++;
    }
    return(b_print(0,argv,&prdata));
   }
#endif /* SHOPT_ECHOPRINT */

int    b_printf(int argc, char *argv[],void *extra)
{
    struct print prdata;
    NOT_USED(argc);
    memset(&prdata,0,sizeof(prdata));
    prdata.sh = ((Shbltin_t*)extra)->shp;
    prdata.options = sh_optprintf;
    return(b_print(-1,argv,&prdata));
}

/*
 * argc==0 when called from echo
 * argc==-1 when called from printf
 */

int    b_print(int argc, char *argv[], void *extra)
{
    register Sfio_t *outfile;
    register int exitval=0,n, fd = 1;
    register Shell_t *shp = ((Shbltin_t*)extra)->shp;
    const char *options, *msg = e_file+4;
    char *format = 0;
    int sflag = 0, nflag=0, rflag=0, vflag=0;
    if(argc>0)
    {
        options = sh_optprint;
        nflag = rflag = 0;
        format = 0;
    }
    else
    {
        struct print *pp = (struct print*)extra;
        shp = pp->sh;
        options = pp->options;
        if(argc==0)
        {
            nflag = pp->echon;
            rflag = pp->raw;
            argv++;
            goto skip;
        }
    }
    while((n = optget(argv,options))) switch(n)
    {
        case 'n':
            nflag++;
            break;
        case 'p':
            fd = shp->coutpipe;
            msg = e_query;
            break;
        case 'f':
            format = opt_info.arg;
            break;
        case 's':
            /* print to history file */
            if(!sh_histinit((void*)shp))
                errormsg(SH_DICT,ERROR_system(1),e_history);
            fd = sffileno(shp->hist_ptr->histfp);
            sh_onstate(SH_HISTORY);
            sflag++;
            break;
        case 'e':
            rflag = 0;
            break;
        case 'r':
            rflag = 1;
            break;
        case 'u':
            fd = (int)strtol(opt_info.arg,&opt_info.arg,10);
            if(*opt_info.arg)
                fd = -1;
            else if(fd<0 || fd >= shp->lim.open_max)
                fd = -1;
            else if(!(sh.inuse_bits&(1<<fd)) && (sh_inuse(fd) || (shp->hist_ptr && fd==sffileno(shp->hist_ptr->histfp))))

                fd = -1;
            break;
        case 'v':
            vflag=1;
            break;
        case ':':
            /* The following is for backward compatibility */
#if OPT_VERSION >= 19990123
            if(strcmp(opt_info.name,"-R")==0)
#else
            if(strcmp(opt_info.option,"-R")==0)
#endif
            {
                rflag = 1;
                if(error_info.errors==0)
                {
                    argv += opt_info.index+1;
                    /* special case test for -Rn */
                    if(strchr(argv[-1],'n'))
                        nflag++;
                    if(*argv && strcmp(*argv,"-n")==0)
                    {

                        nflag++;
                        argv++;
                    }
                    goto skip2;
                }
            }
            else
                errormsg(SH_DICT,2, "%s", opt_info.arg);
            break;
        case '?':
            errormsg(SH_DICT,ERROR_usage(2), "%s", opt_info.arg);
            break;
    }
    argv += opt_info.index;
    if(error_info.errors || (argc<0 && !(format = *argv++)))
        errormsg(SH_DICT,ERROR_usage(2),"%s",optusage((char*)0));
    if(vflag && format)
        errormsg(SH_DICT,ERROR_usage(2),"-v and -f are mutually exclusive");
skip:
    if(format)
        format = genformat(format);
    /* handle special case of '-' operand for print */
    if(argc>0 && *argv && strcmp(*argv,"-")==0 && strcmp(argv[-1],"--"))
        argv++;
skip2:
    if(fd < 0)
    {
        errno = EBADF;
        n = 0;
    }
    else if(!(n=shp->fdstatus[fd]))
        n = sh_iocheckfd(shp,fd);
    if(!(n&IOWRITE))
    {
        /* don't print error message for stdout for compatibility */
        if(fd==1)
            return(1);
        errormsg(SH_DICT,ERROR_system(1),msg);
    }
    if(!(outfile=shp->sftable[fd]))
    {
        sh_onstate(SH_NOTRACK);
        n = SF_WRITE|((n&IOREAD)?SF_READ:0);
        shp->sftable[fd] = outfile = sfnew(NIL(Sfio_t*),shp->outbuff,IOBSIZE,fd,n);
        sh_offstate(SH_NOTRACK);
        sfpool(outfile,shp->outpool,SF_WRITE);
    }
    /* turn off share to guarantee atomic writes for printf */
    n = sfset(outfile,SF_SHARE|SF_PUBLIC,0);
    if(format)
    {
        /* printf style print */
        Sfio_t *pool;
        struct printf pdata;
        memset(&pdata, 0, sizeof(pdata));
        pdata.sh = shp;
        pdata.hdr.version = SFIO_VERSION;
        pdata.hdr.extf = extend;
        pdata.nextarg = argv;
        sh_offstate(SH_STOPOK);
        pool=sfpool(sfstderr,NIL(Sfio_t*),SF_WRITE);
        do
        {
            if(shp->trapnote&SH_SIGSET)
                break;
            pdata.hdr.form = format;
            sfprintf(outfile,"%!",&pdata);
        } while(*pdata.nextarg && pdata.nextarg!=argv);
        if(pdata.nextarg == nullarg && pdata.argsize>0)
            sfwrite(outfile,stakptr(staktell()),pdata.argsize);
        sfpool(sfstderr,pool,SF_WRITE);
        exitval = pdata.err;
    }
    else if(vflag)
    {
        while(*argv)
            fmtbase64(outfile,*argv++,0);
    }
    else
    {
        /* echo style print */
        if(nflag && !argv[0])
            sfsync((Sfio_t*)0);
        else if(sh_echolist(outfile,rflag,argv) && !nflag)
            sfputc(outfile,'\n');
    }
    if(sflag)
    {
        hist_flush(shp->hist_ptr);
        sh_offstate(SH_HISTORY);
    }
    else if(n&SF_SHARE)
    {
        sfset(outfile,SF_SHARE|SF_PUBLIC,1);
        sfsync(outfile);
    }
    return(exitval);
}

/*
 * echo the argument list onto <outfile>
 * if <raw> is non-zero then \ is not a special character.
 * returns 0 for \c otherwise 1.
 */

int sh_echolist(Sfio_t *outfile, int raw, char *argv[])
{
    register char   *cp;
    register int    n;
    struct printf pdata;
    pdata.cescape = 0;
    pdata.err = 0;
    while(!pdata.cescape && (cp= *argv++))
    {
        if(!raw  && (n=fmtvecho(cp,&pdata))>=0)
        {
            if(n)
                sfwrite(outfile,stakptr(staktell()),n);
        }
        else
            sfputr(outfile,cp,-1);
        if(*argv)
            sfputc(outfile,' ');
        sh_sigcheck();
    }
    return(!pdata.cescape);
}

/*
 * modified version of stresc for generating formats
 */
static char strformat(char *s)
{
        register char*  t;
        register int    c;
        char*           b;
        char*           p;

        b = t = s;
        for (;;)
        {
                switch (c = *s++)
                {
                    case '\\':
            if(*s==0)
                break;
                        c = chresc(s - 1, &p);
                        s = p;
#if SHOPT_MULTIBYTE
            if(c>UCHAR_MAX && mbwide())
            {
                t += wctomb(t, c);
                continue;
            }
#endif /* SHOPT_MULTIBYTE */
            if(c=='%')
                *t++ = '%';
            else if(c==0)
            {
                *t++ = '%';
                c = 'Z';
            }
                        break;
                    case 0:
                        *t = 0;
                        return(t - b);
                }
                *t++ = c;
        }
}


static char *genformat(char *format)
{
    register char *fp;
    stakseek(0);
    stakputs(preformat);
    stakputs(format);
    fp = (char*)stakfreeze(1);
    strformat(fp+sizeof(preformat)-1);
    return(fp);
}

static char *fmthtml(const char *string)
{
    register const char *cp = string;
    register int c, offset = staktell();
    while(c= *(unsigned char*)cp++)
    {
#if SHOPT_MULTIBYTE
        register int s;
        if((s=mbsize(cp-1)) > 1)
        {
            cp += (s-1);
            continue;
        }
#endif /* SHOPT_MULTIBYTE */
        if(c=='<')
            stakputs("&lt;");
        else if(c=='>')
            stakputs("&gt;");
        else if(c=='&')
            stakputs("&amp;");
        else if(c=='"')
            stakputs("&quot;");
        else if(c=='\'')
            stakputs("&apos;");
        else if(c==' ')
            stakputs("&nbsp;");
        else if(!isprint(c) && c!='\n' && c!='\r')
            sfprintf(stkstd,"&#%X;",CCMAPC(c,CC_NATIVE,CC_ASCII));
        else
            stakputc(c);
    }
    stakputc(0);
    return(stakptr(offset));
}

#if 1
static ssize_t fmtbase64(Sfio_t *iop, char *string, int alt)
#else
static void *fmtbase64(char *string, ssize_t *sz, int alt)
#endif
{
    char            *cp;
    Sfdouble_t      d;
    ssize_t         size;
    Namval_t        *np = nv_open(string, NiL, NV_VARNAME|NV_NOASSIGN|NV_NOADD);
    static union types_t    number;
    if(!np || nv_isnull(np))
    {
        if(sh_isoption(SH_NOUNSET))
            errormsg(SH_DICT,ERROR_exit(1),e_notset,string);
        return(0);
    }
    if(nv_isattr(np,NV_INTEGER))
    {
        d = nv_getnum(np);
        if(nv_isattr(np,NV_DOUBLE))
        {
            if(nv_isattr(np,NV_LONG))
            {
                size = sizeof(Sfdouble_t);
                number.ld = d;
            }
            else if(nv_isattr(np,NV_SHORT))
            {
                size = sizeof(float);
                number.f = (float)d;
            }
            else
            {
                size = sizeof(double);
                number.d = (double)d;
            }
        }
        else
        {
            if(nv_isattr(np,NV_LONG))
            {
                size =  sizeof(Sflong_t);
                number.ll = (Sflong_t)d;
            }
            else if(nv_isattr(np,NV_SHORT))
            {
                size =  sizeof(short);
                number.h = (short)d;
            }
            else
            {
                size =  sizeof(short);
                number.i = (int)d;
            }
        }
#if 1
        return(sfwrite(iop, (void*)&number, size));
#else
        if(sz)
            *sz = size;
        return((void*)&number);
#endif
    }
    if(nv_isattr(np,NV_BINARY))
#if 1
    {
        Namfun_t *fp;
        for(fp=np->nvfun; fp;fp=fp->next)
        {
            if(fp->disc && fp->disc->writef)
                break;
        }
        if(fp)
            return (*fp->disc->writef)(np, iop, 0, fp);
        else
        {
            int n = nv_size(np);
            cp = (char*)np->nvalue.cp;
            if((size = n)==0)
                size = strlen(cp);
            size = sfwrite(iop, cp, size);
            return(n?n:size);
        }
    }
    else if(nv_isarray(np) && nv_arrayptr(np))
    {
        nv_outnode(np,iop,(alt?-1:0),0);
        sfputc(iop,')');
        return(sftell(iop));
    }
    else
    {
        if(alt && nv_isvtree(np))
            nv_onattr(np,NV_EXPORT);
        if(!(cp = nv_getval(np)))
            return(0);
        size = strlen(cp);
        return(sfwrite(iop,cp,size));
    }
#else
        nv_onattr(np,NV_RAW);
    cp = nv_getval(np);
    if(nv_isattr(np,NV_BINARY))
        nv_offattr(np,NV_RAW);
    if((size = nv_size(np))==0)
        size = strlen(cp);
    if(sz)
        *sz = size;
    return((void*)cp);
#endif
}

static int varname(const char *str, int n)
{
    register int c,dot=1,len=1;
    if(n < 0)
    {
        if(*str=='.')
            str++;
        n = strlen(str);
    }
    for(;n > 0; n-=len)
    {
#ifdef SHOPT_MULTIBYTE
        len = mbsize(str);
        c = mbchar(str);
#else
        c = *(unsigned char*)str++;
#endif
        if(dot && !(isalpha(c)||c=='_'))
            break;
        else if(dot==0 && !(isalnum(c) || c=='_' || c == '.'))
            break;
        dot = (c=='.');
    }
    return(n==0);
}

static int extend(Sfio_t* sp, void* v, Sffmt_t* fe)
{
    char*       lastchar = "";
    register int    neg = 0;
    Sfdouble_t  d;
    Sfdouble_t  longmin = LDBL_LLONG_MIN;
    Sfdouble_t  longmax = LDBL_LLONG_MAX;
    int     format = fe->fmt;
    int     n;
    int     fold = fe->base;
    union types_t*  value = (union types_t*)v;
    struct printf*  pp = (struct printf*)fe;
    register char*  argp = *pp->nextarg;

    if(fe->n_str>0 && varname(fe->t_str,fe->n_str) && (!argp || varname(argp,-1)))
    {
        if(argp)
            pp->lastarg = argp;
        else
            argp = pp->lastarg;
        if(argp)
        {
            sfprintf(pp->sh->strbuf,"%s.%.*s%c",argp,fe->n_str,fe->t_str,0);
            argp = sfstruse(pp->sh->strbuf);
        }
    }
    else
        pp->lastarg = 0;
    fe->flags |= SFFMT_VALUE;
    if(!argp || format=='Z')
    {
        switch(format)
        {
        case 'c':
            value->c = 0;
            fe->flags &= ~SFFMT_LONG;
            break;
        case 'q':
            format = 's';
            /* FALL THROUGH */
        case 's':
        case 'H':
        case 'B':
        case 'P':
        case 'R':
        case 'Z':
        case 'b':
            fe->fmt = 's';
            fe->size = -1;
            fe->base = -1;
            value->s = "";
            fe->flags &= ~SFFMT_LONG;
            break;
        case 'a':
        case 'e':
        case 'f':
        case 'g':
        case 'A':
        case 'E':
        case 'F':
        case 'G':
                        if(SFFMT_LDOUBLE)
                value->ld = 0.;
            else
                value->d = 0.;
            break;
        case 'n':
            value->ip = &pp->intvar;
            break;
        case 'Q':
            value->ll = 0;
            break;
        case 'T':
            fe->fmt = 'd';
            value->ll = tmxgettime();
            break;
        default:
            if(!strchr("DdXxoUu",format))
                errormsg(SH_DICT,ERROR_exit(1),e_formspec,format);
            fe->fmt = 'd';
            value->ll = 0;
            break;
        }
    }
    else
    {
        switch(format)
        {
        case 'p':
            value->p = (char**)strtol(argp,&lastchar,10);
            break;
        case 'n':
        {
            Namval_t *np;
            np = nv_open(argp,sh.var_tree,NV_VARNAME|NV_NOASSIGN|NV_NOARRAY);
            nv_unset(np);
            nv_onattr(np,NV_INTEGER);
            if (np->nvalue.lp = new_of(int32_t,0))
                *np->nvalue.lp = 0;
            nv_setsize(np,10);
            if(sizeof(int)==sizeof(int32_t))
                value->ip = (int*)np->nvalue.lp;
            else
            {
                int32_t sl = 1;
                value->ip = (int*)(((char*)np->nvalue.lp) + (*((char*)&sl) ? 0 : sizeof(int)));
            }
            nv_close(np);
            break;
        }
        case 'q':
        case 'b':
        case 's':
        case 'B':
        case 'H':
        case 'P':
        case 'R':
            fe->fmt = 's';
            fe->size = -1;
            if(format=='s' && fe->base>=0)
            {
                value->p = pp->nextarg;
                pp->nextarg = nullarg;
            }
            else
            {
                fe->base = -1;
                value->s = argp;
            }
            fe->flags &= ~SFFMT_LONG;
            break;
        case 'c':
            if(fe->base >=0)
                value->s = argp;
            else
                value->c = *argp;
            fe->flags &= ~SFFMT_LONG;
            break;
        case 'o':
        case 'x':
        case 'X':
        case 'u':
        case 'U':
            longmax = LDBL_ULLONG_MAX;
        case '.':
            if(fe->size==2 && strchr("bcsqHPRQTZ",*fe->form))
            {
                value->ll = ((unsigned char*)argp)[0];
                break;
            }
        case 'd':
        case 'D':
        case 'i':
            switch(*argp)
            {
            case '\'':
            case '"':
                value->ll = ((unsigned char*)argp)[1];
                if(argp[2] && (argp[2] != argp[0] || argp[3]))
                {
                    errormsg(SH_DICT,ERROR_warn(0),e_charconst,argp);
                    pp->err = 1;
                }
                break;
            default:
                d = sh_strnum(argp,&lastchar,0);
                if(d<longmin)
                {
                    errormsg(SH_DICT,ERROR_warn(0),e_overflow,argp);
                    pp->err = 1;
                    d = longmin;
                }
                else if(d>longmax)
                {
                    errormsg(SH_DICT,ERROR_warn(0),e_overflow,argp);
                    pp->err = 1;
                    d = longmax;
                }
                value->ll = (Sflong_t)d;
                if(lastchar == *pp->nextarg)
                {
                    value->ll = *argp;
                    lastchar = "";
                }
                break;
            }
            if(neg)
                value->ll = -value->ll;
            fe->size = sizeof(value->ll);
            break;
        case 'a':
        case 'e':
        case 'f':
        case 'g':
        case 'A':
        case 'E':
        case 'F':
        case 'G':
            d = sh_strnum(*pp->nextarg,&lastchar,0);
            switch(*argp)
            {
                case '\'':
                case '"':
                d = ((unsigned char*)argp)[1];
                if(argp[2] && (argp[2] != argp[0] || argp[3]))
                {
                    errormsg(SH_DICT,ERROR_warn(0),e_charconst,argp);
                    pp->err = 1;
                }
                break;
                default:
                d = sh_strnum(*pp->nextarg,&lastchar,0);
                break;
            }
                        if(SFFMT_LDOUBLE)
            {
                value->ld = d;
                fe->size = sizeof(value->ld);
            }
            else
            {
                value->d = d;
                fe->size = sizeof(value->d);
            }
            break;
        case 'Q':
            value->ll = (Sflong_t)strelapsed(*pp->nextarg,&lastchar,1);
            break;
        case 'T':
            value->ll = (Sflong_t)tmxdate(*pp->nextarg,&lastchar,TMX_NOW);
            break;
        default:
            value->ll = 0;
            fe->fmt = 'd';
            fe->size = sizeof(value->ll);
            errormsg(SH_DICT,ERROR_exit(1),e_formspec,format);
            break;
        }
        if (format == '.')
            value->i = value->ll;
        if(*lastchar)
        {
            errormsg(SH_DICT,ERROR_warn(0),e_argtype,format);
            pp->err = 1;
        }
        pp->nextarg++;
    }
    switch(format)
    {
    case 'Z':
        fe->fmt = 'c';
        fe->base = -1;
        value->c = 0;
        break;
    case 'b':
        if((n=fmtvecho(value->s,pp))>=0)
        {
            if(pp->nextarg == nullarg)
            {
                pp->argsize = n;
                return -1;
            }
            value->s = stakptr(staktell());
        }
        break;
    case 'B':
        if(!sh.strbuf2)
            sh.strbuf2 = sfstropen();
        fe->size = fmtbase64(sh.strbuf2,value->s, fe->flags&SFFMT_ALTER);
        value->s = sfstruse(sh.strbuf2);
        fe->flags |= SFFMT_SHORT;
        break;
    case 'H':
        value->s = fmthtml(value->s);
        break;
    case 'q':
        value->s = sh_fmtqf(value->s, !!(fe->flags & SFFMT_ALTER), fold);
        break;
    case 'P':
    {
        char *s = fmtmatch(value->s);
        if(!s || *s==0)
            errormsg(SH_DICT,ERROR_exit(1),e_badregexp,value->s);
        value->s = s;
        break;
    }
    case 'R':
        value->s = fmtre(value->s);
        if(*value->s==0)
            errormsg(SH_DICT,ERROR_exit(1),e_badregexp,value->s);
        break;
    case 'Q':
        if (fe->n_str>0)
        {
            fe->fmt = 'd';
            fe->size = sizeof(value->ll);
        }
        else
        {
            value->s = fmtelapsed(value->ll, 1);
            fe->fmt = 's';
            fe->size = -1;
        }
        break;
    case 'T':
        if(fe->n_str>0)
        {
            n = fe->t_str[fe->n_str];
            fe->t_str[fe->n_str] = 0;
            value->s = fmttmx(fe->t_str, value->ll);
            fe->t_str[fe->n_str] = n;
        }
        else value->s = fmttmx(NIL(char*), value->ll);
        fe->fmt = 's';
        fe->size = -1;
        break;
    }
    return 0;
}

/*
 * construct System V echo string out of <cp>
 * If there are not escape sequences, returns -1
 * Otherwise, puts null terminated result on stack, but doesn't freeze it
 * returns length of output.
 */

static int fmtvecho(const char *string, struct printf *pp)
{
    register const char *cp = string, *cpmax;
    register int c;
    register int offset = staktell();
#if SHOPT_MULTIBYTE
    int chlen;
    if(mbwide())
    {
        while(1)
        {
            if ((chlen = mbsize(cp)) > 1)
                /* Skip over multibyte characters */
                cp += chlen;
            else if((c= *cp++)==0 || c == '\\')
                break;
        }
    }
    else
#endif /* SHOPT_MULTIBYTE */
    while((c= *cp++) && (c!='\\'));
    if(c==0)
        return(-1);
    c = --cp - string;
    if(c>0)
        stakwrite((void*)string,c);
    for(; c= *cp; cp++)
    {
#if SHOPT_MULTIBYTE
        if (mbwide() && ((chlen = mbsize(cp)) > 1))
        {
            stakwrite(cp,chlen);
            cp +=  (chlen-1);
            continue;
        }
#endif /* SHOPT_MULTIBYTE */
        if( c=='\\') switch(*++cp)
        {
            case 'E':
                c = ('a'==97?'\033':39); /* ASCII/EBCDIC */
                break;
            case 'a':
                c = '\a';
                break;
            case 'b':
                c = '\b';
                break;
            case 'c':
                pp->cescape++;
                pp->nextarg = nullarg;
                goto done;
            case 'f':
                c = '\f';
                break;
            case 'n':
                c = '\n';
                break;
            case 'r':
                c = '\r';
                break;
            case 'v':
                c = '\v';
                break;
            case 't':
                c = '\t';
                break;
            case '\\':
                c = '\\';
                break;
            case '0':
                c = 0;
                cpmax = cp + 4;
                while(++cp<cpmax && *cp>='0' && *cp<='7')
                {
                    c <<= 3;
                    c |= (*cp-'0');
                }
            default:
                cp--;
        }
        stakputc(c);
    }
done:
    c = staktell()-offset;
    stakputc(0);
    stakseek(offset);
    return(c);
}