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fmtquote.c

/*
 * The authors of this software are Rob Pike and Ken Thompson.
 *              Copyright (c) 2002 by Lucent Technologies.
 * Permission to use, copy, modify, and distribute this software for any
 * purpose without fee is hereby granted, provided that this entire notice
 * is included in all copies of any software which is or includes a copy
 * or modification of this software and in all copies of the supporting
 * documentation for such software.
 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTY.  IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
 * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
 */
#include <u.h>
#include <libc.h>
#include "fmt.h"
#include "fmtdef.h"

extern int (*doquote)(int);

/*
 * How many bytes of output UTF will be produced by quoting (if necessary) this string?
 * How many runes? How much of the input will be consumed?
 * The parameter q is filled in by _quotesetup.
 * The string may be UTF or Runes (s or r).
 * Return count does not include NUL.
 * Terminate the scan at the first of:
 *    NUL in input
 *    count exceeded in input
 *    count exceeded on output
 * *ninp is set to number of input bytes accepted.
 * nin may be <0 initially, to avoid checking input by count.
 */
void
__quotesetup(char *s, int nin, int nout, Quoteinfo *q, int sharp)
{
      int c;

      q->quoted = 0;
      q->nbytesout = 0;
      q->nrunesout = 0;
      q->nbytesin = 0;
      q->nrunesin = 0;
      if(sharp || nin==0 || *s=='\0'){
            if(nout < 2)
                  return;
            q->quoted = 1;
            q->nbytesout = 2;
            q->nrunesout = 2;
      }
      for(; nin!=0; nin-=1){
            c = *s;

            if(c == '\0')
                  break;
            if(q->nrunesout+1 > nout)
                  break;

            if((c <= L' ') || (c == L'\'') || (doquote!=nil && doquote(c))){
                  if(!q->quoted){
                        if(1+q->nrunesout+1+1 > nout) /* no room for quotes */
                              break;
                        q->nrunesout += 2;      /* include quotes */
                        q->nbytesout += 2;      /* include quotes */
                        q->quoted = 1;
                  }
                  if(c == '\'')     {
                        q->nbytesout++;
                        q->nrunesout++;   /* quotes reproduce as two characters */
                  }
            }

            /* advance input */
            s++;
            q->nbytesin++;
            q->nrunesin++;

            /* advance output */
            q->nbytesout++;
            q->nrunesout++;
      }
}

static int
qstrfmt(char *sin, Quoteinfo *q, Fmt *f)
{
      int r;
      char *t, *s, *m, *me;
      ulong fl;
      int nc, w;

      m = sin;
      me = m + q->nbytesin;

      w = f->width;
      fl = f->flags;
      if(!(fl & FmtLeft) && __fmtpad(f, w - q->nbytesout) < 0)
            return -1;
      t = f->to;
      s = f->stop;
      FMTCHAR(f, t, s, '\'');
      for(nc = q->nrunesin; nc > 0; nc--){
            r = *(uchar*)m++;
            FMTCHAR(f, t, s, r);
            if(r == '\'')
                  FMTCHAR(f, t, s, r);
      }

      FMTCHAR(f, t, s, '\'');
      f->nfmt += t - (char *)f->to;
      f->to = t;
      if(fl & FmtLeft && __fmtpad(f, w - q->nbytesout) < 0)
            return -1;
      return 0;
}

int
__quotestrfmt(int runesin, Fmt *f)
{
      int outlen;
      char *s;
      Quoteinfo q;

      f->flags &= ~FmtPrec;   /* ignored for %q %Q, so disable for %s %S in easy case */
      s = va_arg(f->args, char *);
      if(!s)
            return __fmtcpy(f, "<nil>", 5, 5);

      if(f->flush)
            outlen = 0x7FFFFFFF;    /* if we can flush, no output limit */
      else
            outlen = (char*)f->stop - (char*)f->to;

      __quotesetup(s, -1, outlen, &q, f->flags&FmtSharp);

      if(!q.quoted)
            return __fmtcpy(f, s, q.nrunesin, q.nbytesin);
      return qstrfmt(s, &q, f);
}

int
quotestrfmt(Fmt *f)
{
      return __quotestrfmt(0, f);
}

void
quotefmtinstall(void)
{
      fmtinstall('q', quotestrfmt);
}

int
__needsquotes(char *s, int *quotelenp)
{
      Quoteinfo q;

      __quotesetup(s, -1, 0x7FFFFFFF, &q, 0);
      *quotelenp = q.nbytesout;

      return q.quoted;
}

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