vfscanf.c

标准c库代码,可以应用于各个系统提供了大量的基本函数

	      n = p - p0;
	      if (n == 0)
		goto match_failure;
	      *p = 0;
	      nassigned++;
	    }
	  nread += n;
	  break;

	case CT_STRING:
	  /* like CCL, but zero-length string OK, & no NOSKIP */
	  if (width == 0)
	    width = ~0;
	  if (flags & SUPPRESS)
	    {
	      n = 0;
	      while (!isspace (*fp->_p))
		{
		  n++, fp->_r--, fp->_p++;
		  if (--width == 0)
		    break;
		  if (BufferEmpty)
		    break;
		}
	      nread += n;
	    }
	  else
	    {
	      p0 = p = va_arg (ap, char *);
	      while (!isspace (*fp->_p))
		{
		  fp->_r--;
		  *p++ = *fp->_p++;
		  if (--width == 0)
		    break;
		  if (BufferEmpty)
		    break;
		}
	      *p = 0;
	      nread += p - p0;
	      nassigned++;
	    }
	  continue;

	case CT_INT:
	  /* scan an integer as if by strtol/strtoul */
#ifdef hardway
	  if (width == 0 || width > sizeof (buf) - 1)
	    width = sizeof (buf) - 1;
#else
	  /* size_t is unsigned, hence this optimisation */
	  if (--width > sizeof (buf) - 2)
	    width = sizeof (buf) - 2;
	  width++;
#endif
	  flags |= SIGNOK | NDIGITS | NZDIGITS;
	  for (p = buf; width; width--)
	    {
	      c = *fp->_p;
	      /*
	       * Switch on the character; `goto ok' if we
	       * accept it as a part of number.
	       */
	      switch (c)
		{
		  /*
		   * The digit 0 is always legal, but is special.
		   * For %i conversions, if no digits (zero or nonzero)
		   * have been scanned (only signs), we will have base==0.
		   * In that case, we should set it to 8 and enable 0x
		   * prefixing. Also, if we have not scanned zero digits
		   * before this, do not turn off prefixing (someone else
		   * will turn it off if we have scanned any nonzero digits).
		   */
		case '0':
		  if (base == 0)
		    {
		      base = 8;
		      flags |= PFXOK;
		    }
		  if (flags & NZDIGITS)
		    flags &= ~(SIGNOK | NZDIGITS | NDIGITS);
		  else
		    flags &= ~(SIGNOK | PFXOK | NDIGITS);
		  goto ok;

		  /* 1 through 7 always legal */
		case '1':
		case '2':
		case '3':
		case '4':
		case '5':
		case '6':
		case '7':
		  base = basefix[base];
		  flags &= ~(SIGNOK | PFXOK | NDIGITS);
		  goto ok;

		  /* digits 8 and 9 ok iff decimal or hex */
		case '8':
		case '9':
		  base = basefix[base];
		  if (base <= 8)
		    break;	/* not legal here */
		  flags &= ~(SIGNOK | PFXOK | NDIGITS);
		  goto ok;

		  /* letters ok iff hex */
		case 'A':
		case 'B':
		case 'C':
		case 'D':
		case 'E':
		case 'F':
		case 'a':
		case 'b':
		case 'c':
		case 'd':
		case 'e':
		case 'f':
		  /* no need to fix base here */
		  if (base <= 10)
		    break;	/* not legal here */
		  flags &= ~(SIGNOK | PFXOK | NDIGITS);
		  goto ok;

		  /* sign ok only as first character */
		case '+':
		case '-':
		  if (flags & SIGNOK)
		    {
		      flags &= ~SIGNOK;
		      goto ok;
		    }
		  break;

		  /* x ok iff flag still set & 2nd char */
		case 'x':
		case 'X':
		  if (flags & PFXOK && p == buf + 1)
		    {
		      base = 16;/* if %i */
		      flags &= ~PFXOK;
		      goto ok;
		    }
		  break;
		}

	      /*
	       * If we got here, c is not a legal character
	       * for a number.  Stop accumulating digits.
	       */
	      break;
	    ok:
	      /*
	       * c is legal: store it and look at the next.
	       */
	      *p++ = c;
	      if (--fp->_r > 0)
		fp->_p++;
	      else
#ifndef CYGNUS_NEC
	      if (__srefill (fp))
#endif
		break;		/* EOF */
	    }
	  /*
	   * If we had only a sign, it is no good; push back the sign.
	   * If the number ends in `x', it was [sign] '0' 'x', so push back
	   * the x and treat it as [sign] '0'.
	   */
	  if (flags & NDIGITS)
	    {
	      if (p > buf)
		_CAST_VOID ungetc (*(u_char *)-- p, fp);
	      goto match_failure;
	    }
	  c = ((u_char *) p)[-1];
	  if (c == 'x' || c == 'X')
	    {
	      --p;
	      /*(void)*/ ungetc (c, fp);
	    }
	  if ((flags & SUPPRESS) == 0)
	    {
	      u_long res;

	      *p = 0;
	      res = (*ccfn) (buf, (char **) NULL, base);
	      if (flags & POINTER)
		*(va_arg (ap, _PTR *)) = (_PTR) res;
	      else if (flags & SHORT)
		{
		  sp = va_arg (ap, short *);
		  *sp = res;
		}
	      else if (flags & LONG)
		{
		  lp = va_arg (ap, long *);
		  *lp = res;
		}
	      else
		{
		  ip = va_arg (ap, int *);
		  *ip = res;
		}
	      nassigned++;
	    }
	  nread += p - buf;
	  break;

#ifdef FLOATING_POINT
	case CT_FLOAT:
	  /* scan a floating point number as if by strtod */
#ifdef hardway
	  if (width == 0 || width > sizeof (buf) - 1)
	    width = sizeof (buf) - 1;
#else
	  /* size_t is unsigned, hence this optimisation */
	  if (--width > sizeof (buf) - 2)
	    width = sizeof (buf) - 2;
	  width++;
#endif
	  flags |= SIGNOK | NDIGITS | DPTOK | EXPOK;
	  for (p = buf; width; width--)
	    {
	      c = *fp->_p;
	      /*
	       * This code mimicks the integer conversion
	       * code, but is much simpler.
	       */
	      switch (c)
		{

		case '0':
		case '1':
		case '2':
		case '3':
		case '4':
		case '5':
		case '6':
		case '7':
		case '8':
		case '9':
		  flags &= ~(SIGNOK | NDIGITS);
		  goto fok;

		case '+':
		case '-':
		  if (flags & SIGNOK)
		    {
		      flags &= ~SIGNOK;
		      goto fok;
		    }
		  break;
		case '.':
		  if (flags & DPTOK)
		    {
		      flags &= ~(SIGNOK | DPTOK);
		      goto fok;
		    }
		  break;
		case 'e':
		case 'E':
		  /* no exponent without some digits */
		  if ((flags & (NDIGITS | EXPOK)) == EXPOK)
		    {
		      flags =
			(flags & ~(EXPOK | DPTOK)) |
			SIGNOK | NDIGITS;
		      goto fok;
		    }
		  break;
		}
	      break;
	    fok:
	      *p++ = c;
	      if (--fp->_r > 0)
		fp->_p++;
	      else
#ifndef CYGNUS_NEC
	      if (__srefill (fp))
#endif
		break;		/* EOF */
	    }
	  /*
	   * If no digits, might be missing exponent digits
	   * (just give back the exponent) or might be missing
	   * regular digits, but had sign and/or decimal point.
	   */
	  if (flags & NDIGITS)
	    {
	      if (flags & EXPOK)
		{
		  /* no digits at all */
		  while (p > buf)
		    ungetc (*(u_char *)-- p, fp);
		  goto match_failure;
		}
	      /* just a bad exponent (e and maybe sign) */
	      c = *(u_char *)-- p;
	      if (c != 'e' && c != 'E')
		{
		  _CAST_VOID ungetc (c, fp);	/* sign */
		  c = *(u_char *)-- p;
		}
	      _CAST_VOID ungetc (c, fp);
	    }
	  if ((flags & SUPPRESS) == 0)
	    {
	      double res;

	      *p = 0;
	      res = atof (buf);
	      if (flags & LONG)
		{
		  dp = va_arg (ap, double *);
		  *dp = res;
		}
	      else if (flags & LONGDBL)
		{
		  ldp = va_arg (ap, _LONG_DOUBLE *);
		  *ldp = res;
		}
	      else
		{
		  flp = va_arg (ap, float *);
		  *flp = res;
		}
	      nassigned++;
	    }
	  nread += p - buf;
	  break;
#endif /* FLOATING_POINT */
	}
    }
input_failure:
  return nassigned ? nassigned : -1;
match_failure:
  return nassigned;
}

/*
 * Fill in the given table from the scanset at the given format
 * (just after `[').  Return a pointer to the character past the
 * closing `]'.  The table has a 1 wherever characters should be
 * considered part of the scanset.
 */

/*static*/
u_char *
__sccl (tab, fmt)
     register char *tab;
     register u_char *fmt;
{
  register int c, n, v;

  /* first `clear' the whole table */
  c = *fmt++;			/* first char hat => negated scanset */
  if (c == '^')
    {
      v = 1;			/* default => accept */
      c = *fmt++;		/* get new first char */
    }
  else
    v = 0;			/* default => reject */
  /* should probably use memset here */
  for (n = 0; n < 256; n++)
    tab[n] = v;
  if (c == 0)
    return fmt - 1;		/* format ended before closing ] */

  /*
   * Now set the entries corresponding to the actual scanset to the
   * opposite of the above.
   *
   * The first character may be ']' (or '-') without being special; the
   * last character may be '-'.
   */

  v = 1 - v;
  for (;;)
    {
      tab[c] = v;		/* take character c */
    doswitch:
      n = *fmt++;		/* and examine the next */
      switch (n)
	{

	case 0:		/* format ended too soon */
	  return fmt - 1;

	case '-':
	  /*
	   * A scanset of the form [01+-] is defined as `the digit 0, the
	   * digit 1, the character +, the character -', but the effect of a
	   * scanset such as [a-zA-Z0-9] is implementation defined.  The V7
	   * Unix scanf treats `a-z' as `the letters a through z', but treats
	   * `a-a' as `the letter a, the character -, and the letter a'.
	   *
	   * For compatibility, the `-' is not considerd to define a range if
	   * the character following it is either a close bracket (required by
	   * ANSI) or is not numerically greater than the character we just
	   * stored in the table (c).
	   */
	  n = *fmt;
	  if (n == ']' || n < c)
	    {
	      c = '-';
	      break;		/* resume the for(;;) */
	    }
	  fmt++;
	  do
	    {			/* fill in the range */
	      tab[++c] = v;
	    }
	  while (c < n);
#if 1			/* XXX another disgusting compatibility hack */
	  /*
	   * Alas, the V7 Unix scanf also treats formats such
	   * as [a-c-e] as `the letters a through e'. This too
	   * is permitted by the standard....
	   */
	  goto doswitch;
#else
	  c = *fmt++;
	  if (c == 0)
	    return fmt - 1;
	  if (c == ']')
	    return fmt;
#endif

	  break;


	case ']':		/* end of scanset */
	  return fmt;

	default:		/* just another character */
	  c = n;
	  break;
	}
    }
  /* NOTREACHED */
}