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

/* No user fns here. Pesch 15apr92. */

/*
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include <_ansi.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#ifdef _HAVE_STDC
#include <stdarg.h>
#else
#include <varargs.h>
#endif
#include "local.h"

#ifndef	NO_FLOATING_POINT
#define FLOATING_POINT
#endif

#ifdef FLOATING_POINT
#include "floatio.h"
#define	BUF	(MAXEXP+MAXFRACT+3)	/* 3 = sign + decimal point + NUL */
#else
#define	BUF	40
#endif

/*
 * Flags used during conversion.
 */

#define	LONG		0x01	/* l: long or double */
#define	LONGDBL		0x02	/* L: long double; unimplemented */
#define	SHORT		0x04	/* h: short */
#define	SUPPRESS	0x08	/* suppress assignment */
#define	POINTER		0x10	/* weird %p pointer (`fake hex') */
#define	NOSKIP		0x20	/* do not skip blanks */

/*
 * The following are used in numeric conversions only:
 * SIGNOK, NDIGITS, DPTOK, and EXPOK are for floating point;
 * SIGNOK, NDIGITS, PFXOK, and NZDIGITS are for integral.
 */

#define	SIGNOK		0x40	/* +/- is (still) legal */
#define	NDIGITS		0x80	/* no digits detected */

#define	DPTOK		0x100	/* (float) decimal point is still legal */
#define	EXPOK		0x200	/* (float) exponent (e+3, etc) still legal */

#define	PFXOK		0x100	/* 0x prefix is (still) legal */
#define	NZDIGITS	0x200	/* no zero digits detected */

/*
 * Conversion types.
 */

#define	CT_CHAR		0	/* %c conversion */
#define	CT_CCL		1	/* %[...] conversion */
#define	CT_STRING	2	/* %s conversion */
#define	CT_INT		3	/* integer, i.e., strtol or strtoul */
#define	CT_FLOAT	4	/* floating, i.e., strtod */

#if 0
#define u_char unsigned char
#endif
#define u_char char
#define u_long unsigned long

/*static*/ u_char *__sccl ();

/*
 * vfscanf
 */

#define BufferEmpty (fp->_r <= 0 && __srefill(fp))

int
__svfscanf (fp, fmt0, ap)
     register FILE *fp;
     char _CONST *fmt0;
     va_list ap;
{
  register u_char *fmt = (u_char *) fmt0;
  register int c;		/* character from format, or conversion */
  register size_t width;	/* field width, or 0 */
  register char *p;		/* points into all kinds of strings */
  register int n;		/* handy integer */
  register int flags;		/* flags as defined above */
  register char *p0;		/* saves original value of p when necessary */
  int nassigned;		/* number of fields assigned */
  int nread;			/* number of characters consumed from fp */
  int base = 0;			/* base argument to strtol/strtoul */

  u_long (*ccfn) () = 0;	/* conversion function (strtol/strtoul) */
  char ccltab[256];		/* character class table for %[...] */
  char buf[BUF];		/* buffer for numeric conversions */

  short *sp;
  int *ip;
  float *flp;
  _LONG_DOUBLE *ldp;
  double *dp;
  long *lp;

  /* `basefix' is used to avoid `if' tests in the integer scanner */
  static _CONST short basefix[17] =
    {10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16};

  nassigned = 0;
  nread = 0;
  for (;;)
    {
      c = *fmt++;
      if (c == 0)
	return nassigned;
      if (isspace (c))
	{
	  for (;;)
	    {
	      if (BufferEmpty)
		return nassigned;
	      if (!isspace (*fp->_p))
		break;
	      nread++, fp->_r--, fp->_p++;
	    }
	  continue;
	}
      if (c != '%')
	goto literal;
      width = 0;
      flags = 0;

      /*
       * switch on the format.  continue if done; break once format
       * type is derived.
       */

    again:
      c = *fmt++;

      switch (c)
	{
	case '%':
	literal:
	  if (BufferEmpty)
	    goto input_failure;
	  if (*fp->_p != c)
	    goto match_failure;
	  fp->_r--, fp->_p++;
	  nread++;
	  continue;

	case '*':
	  flags |= SUPPRESS;
	  goto again;
	case 'l':
	  flags |= LONG;
	  goto again;
	case 'L':
	  flags |= LONGDBL;
	  goto again;
	case 'h':
	  flags |= SHORT;
	  goto again;

	case '0':
	case '1':
	case '2':
	case '3':
	case '4':
	case '5':
	case '6':
	case '7':
	case '8':
	case '9':
	  width = width * 10 + c - '0';
	  goto again;

	  /*
	   * Conversions. Those marked `compat' are for
	   * 4.[123]BSD compatibility.
	   *
	   * (According to ANSI, E and X formats are supposed to
	   * the same as e and x.  Sorry about that.)
	   */

	case 'D':		/* compat */
	  flags |= LONG;
	  /* FALLTHROUGH */
	case 'd':
	  c = CT_INT;
	  ccfn = (u_long (*)())strtol;
	  base = 10;
	  break;

	case 'i':
	  c = CT_INT;
	  ccfn = (u_long (*)())strtol;
	  base = 0;
	  break;

	case 'O':		/* compat */
	  flags |= LONG;
	  /* FALLTHROUGH */
	case 'o':
	  c = CT_INT;
	  ccfn = strtoul;
	  base = 8;
	  break;

	case 'u':
	  c = CT_INT;
	  ccfn = strtoul;
	  base = 10;
	  break;

	case 'X':		/* compat   XXX */
	case 'x':
	  flags |= PFXOK;	/* enable 0x prefixing */
	  c = CT_INT;
	  ccfn = strtoul;
	  base = 16;
	  break;

#ifdef FLOATING_POINT
	case 'E':		/* compat   XXX */
	case 'G':		/* compat   XXX */
/* ANSI says that E,G and X behave the same way as e,g,x */
	  /* FALLTHROUGH */
	case 'e':
	case 'f':
	case 'g':
	  c = CT_FLOAT;
	  break;
#endif

	case 's':
	  c = CT_STRING;
	  break;

	case '[':
	  fmt = __sccl (ccltab, fmt);
	  flags |= NOSKIP;
	  c = CT_CCL;
	  break;

	case 'c':
	  flags |= NOSKIP;
	  c = CT_CHAR;
	  break;

	case 'p':		/* pointer format is like hex */
	  flags |= POINTER | PFXOK;
	  c = CT_INT;
	  ccfn = strtoul;
	  base = 16;
	  break;

	case 'n':
	  if (flags & SUPPRESS)	/* ??? */
	    continue;
	  if (flags & SHORT)
	    {
	      sp = va_arg (ap, short *);
	      *sp = nread;
	    }
	  else if (flags & LONG)
	    {
	      lp = va_arg (ap, long *);
	      *lp = nread;
	    }
	  else
	    {
	      ip = va_arg (ap, int *);
	      *ip = nread;
	    }
	  continue;

	  /*
	   * Disgusting backwards compatibility hacks.	XXX
	   */
	case '\0':		/* compat */
	  return EOF;

	default:		/* compat */
	  if (isupper (c))
	    flags |= LONG;
	  c = CT_INT;
	  ccfn = (u_long (*)())strtol;
	  base = 10;
	  break;
	}

      /*
       * We have a conversion that requires input.
       */
      if (BufferEmpty)
	goto input_failure;

      /*
       * Consume leading white space, except for formats that
       * suppress this.
       */
      if ((flags & NOSKIP) == 0)
	{
	  while (isspace (*fp->_p))
	    {
	      nread++;
	      if (--fp->_r > 0)
		fp->_p++;
	      else
#ifndef CYGNUS_NEC
	      if (__srefill (fp))
#endif
		goto input_failure;
	    }
	  /*
	   * Note that there is at least one character in the
	   * buffer, so conversions that do not set NOSKIP ca
	   * no longer result in an input failure.
	   */
	}

      /*
       * Do the conversion.
       */
      switch (c)
	{

	case CT_CHAR:
	  /* scan arbitrary characters (sets NOSKIP) */
	  if (width == 0)
	    width = 1;
	  if (flags & SUPPRESS)
	    {
	      size_t sum = 0;

	      for (;;)
		{
		  if ((n = fp->_r) < width)
		    {
		      sum += n;
		      width -= n;
		      fp->_p += n;
#ifndef CYGNUS_NEC
		      if (__srefill (fp))
			{
#endif
			  if (sum == 0)
			    goto input_failure;
			  break;
#ifndef CYGNUS_NEC
			}
#endif
		    }
		  else
		    {
		      sum += width;
		      fp->_r -= width;
		      fp->_p += width;
		      break;
		    }
		}
	      nread += sum;
	    }
	  else
	    {
#ifdef CYGNUS_NEC
	      /* Kludge city for the moment */
	      char *dest = va_arg (ap, char *);
	      int n = width;
	      if (fp->_r == 0)
		goto input_failure;

	      while (n && fp->_r)
		{
		  *dest++ = *(fp->_p++);
		  n--;
		  fp->_r--;
		  nread++;
		}
#else
	      size_t r = fread ((_PTR) va_arg (ap, char *), 1, width, fp);

	      if (r == 0)
		goto input_failure;
	      nread += r;
#endif
	      nassigned++;
	    }
	  break;

	case CT_CCL:
	  /* scan a (nonempty) character class (sets NOSKIP) */
	  if (width == 0)
	    width = ~0;		/* `infinity' */
	  /* take only those things in the class */
	  if (flags & SUPPRESS)
	    {
	      n = 0;
	      while (ccltab[*fp->_p])
		{
		  n++, fp->_r--, fp->_p++;
		  if (--width == 0)
		    break;
		  if (BufferEmpty)
		    {
		      if (n == 0)
			goto input_failure;
		      break;
		    }
		}
	      if (n == 0)
		goto match_failure;
	    }
	  else
	    {
	      p0 = p = va_arg (ap, char *);
	      while (ccltab[*fp->_p])
		{
		  fp->_r--;
		  *p++ = *fp->_p++;
		  if (--width == 0)
		    break;
		  if (BufferEmpty)
		    {
		      if (p == p0)
			goto input_failure;
		      break;
		    }
		}