vfscanf.c

绝对正真的stdio.h的实现

/* Copyright (C) 1991-2002, 2003, 2004 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <assert.h>
#include <errno.h>
#include <limits.h>
#include <ctype.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#include <wctype.h>
#include <bits/libc-lock.h>
#include <locale/localeinfo.h>

#ifdef	__GNUC__
# define HAVE_LONGLONG
# define LONGLONG	long long
#else
# define LONGLONG	long
#endif

/* Determine whether we have to handle `long long' at all.  */
#if LONG_MAX == LONG_LONG_MAX
# define need_longlong	0
#else
# define need_longlong	1
#endif

/* Determine whether we have to handle `long'.  */
#if INT_MAX == LONG_MAX
# define need_long	0
#else
# define need_long 	1
#endif

/* Those are flags in the conversion format. */
#define LONG		0x001	/* l: long or double */
#define LONGDBL		0x002	/* L: long long or long double */
#define SHORT		0x004	/* h: short */
#define SUPPRESS	0x008	/* *: suppress assignment */
#define POINTER		0x010	/* weird %p pointer (`fake hex') */
#define NOSKIP		0x020	/* do not skip blanks */
#define WIDTH		0x040	/* width was given */
#define GROUP		0x080	/* ': group numbers */
#define MALLOC		0x100	/* a: malloc strings */
#define CHAR		0x200	/* hh: char */
#define I18N		0x400	/* I: use locale's digits */


#include <locale/localeinfo.h>
#include <libioP.h>
#include <libio.h>

#undef va_list
#define va_list	_IO_va_list

#ifdef COMPILE_WSCANF
# define ungetc(c, s)	((void) (c == WEOF				      \
				 || (--read_in,				      \
				     INTUSE(_IO_sputbackwc) (s, c))))
# define ungetc_not_eof(c, s)	((void) (--read_in,			      \
					 INTUSE(_IO_sputbackwc) (s, c)))
# define inchar()	(c == WEOF ? ((errno = inchar_errno), WEOF)	      \
			 : ((c = _IO_getwc_unlocked (s)),		      \
			    (void) (c != WEOF				      \
				    ? ++read_in				      \
				    : (size_t) (inchar_errno = errno)), c))

# define MEMCPY(d, s, n) __wmemcpy (d, s, n)
# define ISSPACE(Ch)	  iswspace (Ch)
# define ISDIGIT(Ch)	  iswdigit (Ch)
# define ISXDIGIT(Ch)	  iswxdigit (Ch)
# define TOLOWER(Ch)	  towlower (Ch)
# define ORIENT	  if (_IO_fwide (s, 1) != 1) return WEOF
# define __strtoll_internal	__wcstoll_internal
# define __strtoull_internal	__wcstoull_internal
# define __strtol_internal	__wcstol_internal
# define __strtoul_internal	__wcstoul_internal
# define __strtold_internal	__wcstold_internal
# define __strtod_internal	__wcstod_internal
# define __strtof_internal	__wcstof_internal

# define L_(Str)	L##Str
# define CHAR_T	  	wchar_t
# define UCHAR_T	unsigned int
# define WINT_T	  	wint_t
# undef EOF
# define EOF		WEOF
#else
# define ungetc(c, s)	((void) ((int) c == EOF				      \
				 || (--read_in,				      \
				     INTUSE(_IO_sputbackc) (s, (unsigned char) c))))
# define ungetc_not_eof(c, s)	((void) (--read_in,			      \
					 INTUSE(_IO_sputbackc) (s, (unsigned char) c)))
# define inchar()	(c == EOF ? ((errno = inchar_errno), EOF)	      \
			 : ((c = _IO_getc_unlocked (s)),		      \
			    (void) (c != EOF				      \
				    ? ++read_in				      \
				    : (size_t) (inchar_errno = errno)), c))
# define MEMCPY(d, s, n) memcpy (d, s, n)
# define ISSPACE(Ch)	  __isspace_l (Ch, loc)
# define ISDIGIT(Ch)	  __isdigit_l (Ch, loc)
# define ISXDIGIT(Ch)	  __isxdigit_l (Ch, loc)
# define TOLOWER(Ch)	  __tolower_l ((unsigned char) (Ch), loc)
# define ORIENT	  if (_IO_vtable_offset (s) == 0			      \
			      && _IO_fwide (s, -1) != -1)		      \
			    return EOF

# define L_(Str)	Str
# define CHAR_T	  	char
# define UCHAR_T	unsigned char
# define WINT_T		int
#endif

#define encode_error() do {						      \
			  errval = 4;					      \
			  __set_errno (EILSEQ);				      \
			  goto errout;					      \
			} while (0)
#define conv_error()	do {						      \
			  errval = 2;					      \
			  goto errout;					      \
			} while (0)
#define input_error()	do {						      \
			  errval = 1;					      \
			  if (done == 0) done = EOF;			      \
			  goto errout;					      \
			} while (0)
#define memory_error() do {						      \
			  __set_errno (ENOMEM);				      \
			  done = EOF;					      \
			  goto errout;					      \
			} while (0)
#define ARGCHECK(s, format)						      \
  do									      \
    {									      \
      /* Check file argument for consistence.  */			      \
      CHECK_FILE (s, EOF);						      \
      if (s->_flags & _IO_NO_READS)					      \
	{								      \
	  __set_errno (EBADF);						      \
	  return EOF;							      \
	}								      \
      else if (format == NULL)						      \
	{								      \
	  MAYBE_SET_EINVAL;						      \
	  return EOF;							      \
	}								      \
    } while (0)
#define LOCK_STREAM(S)							      \
  __libc_cleanup_region_start (1, (void (*) (void *)) &_IO_funlockfile, (S)); \
  _IO_flockfile (S)
#define UNLOCK_STREAM(S)						      \
  _IO_funlockfile (S);							      \
  __libc_cleanup_region_end (0)


/* Read formatted input from S according to the format string
   FORMAT, using the argument list in ARG.
   Return the number of assignments made, or -1 for an input error.  */
#ifdef COMPILE_WSCANF
int
_IO_vfwscanf (s, format, argptr, errp)
     _IO_FILE *s;
     const wchar_t *format;
     _IO_va_list argptr;
     int *errp;
#else
int
_IO_vfscanf (s, format, argptr, errp)
     _IO_FILE *s;
     const char *format;
     _IO_va_list argptr;
     int *errp;
#endif
{
  va_list arg;
  register const CHAR_T *f = format;
  register UCHAR_T fc;	/* Current character of the format.  */
  register WINT_T done = 0;	/* Assignments done.  */
  register size_t read_in = 0;	/* Chars read in.  */
  register WINT_T c = 0;	/* Last char read.  */
  register int width;		/* Maximum field width.  */
  register int flags;		/* Modifiers for current format element.  */
  int errval = 0;
#ifndef COMPILE_WSCANF
  __locale_t loc = _NL_CURRENT_LOCALE;
  struct locale_data *const curctype = loc->__locales[LC_CTYPE];
#endif

  /* Errno of last failed inchar call.  */
  int inchar_errno = 0;
  /* Status for reading F-P nums.  */
  char got_dot, got_e, negative;
  /* If a [...] is a [^...].  */
  CHAR_T not_in;
#define exp_char not_in
  /* Base for integral numbers.  */
  int base;
  /* Signedness for integral numbers.  */
  int number_signed;
#define is_hexa number_signed
  /* Decimal point character.  */
#ifdef COMPILE_WSCANF
  wint_t decimal;
#else
  const char *decimal;
#endif
  /* The thousands character of the current locale.  */
#ifdef COMPILE_WSCANF
  wint_t thousands;
#else
  const char *thousands;
#endif
  /* State for the conversions.  */
  mbstate_t state;
  /* Integral holding variables.  */
  union
    {
      long long int q;
      unsigned long long int uq;
      long int l;
      unsigned long int ul;
    } num;
  /* Character-buffer pointer.  */
  char *str = NULL;
  wchar_t *wstr = NULL;
  char **strptr = NULL;
  ssize_t strsize = 0;
  /* We must not react on white spaces immediately because they can
     possibly be matched even if in the input stream no character is
     available anymore.  */
  int skip_space = 0;
  /* Nonzero if we are reading a pointer.  */
  int read_pointer;
  /* Workspace.  */
  CHAR_T *tw;			/* Temporary pointer.  */
  CHAR_T *wp = NULL;		/* Workspace.  */
  size_t wpmax = 0;		/* Maximal size of workspace.  */
  size_t wpsize;		/* Currently used bytes in workspace.  */
#define ADDW(Ch)							    \
  do									    \
    {									    \
      if (wpsize == wpmax)						    \
	{								    \
	  CHAR_T *old = wp;						    \
	  wpmax = (UCHAR_MAX + 1 > 2 * wpmax ? UCHAR_MAX + 1 : 2 * wpmax);  \
	  wp = (CHAR_T *) alloca (wpmax * sizeof (wchar_t));		    \
	  if (old != NULL)						    \
	    MEMCPY (wp, old, wpsize);					    \
	}								    \
      wp[wpsize++] = (Ch);						    \
    }									    \
  while (0)

#ifdef __va_copy
  __va_copy (arg, argptr);
#else
  arg = (va_list) argptr;
#endif

#ifdef ORIENT
  ORIENT;
#endif

  ARGCHECK (s, format);

 {
#ifndef COMPILE_WSCANF
   struct locale_data *const curnumeric = loc->__locales[LC_NUMERIC];
#endif

   /* Figure out the decimal point character.  */
#ifdef COMPILE_WSCANF
   decimal = _NL_CURRENT_WORD (LC_NUMERIC, _NL_NUMERIC_DECIMAL_POINT_WC);
#else
   decimal = curnumeric->values[_NL_ITEM_INDEX (DECIMAL_POINT)].string;
#endif
   /* Figure out the thousands separator character.  */
#ifdef COMPILE_WSCANF
   thousands = _NL_CURRENT_WORD (LC_NUMERIC, _NL_NUMERIC_THOUSANDS_SEP_WC);
#else
   thousands = curnumeric->values[_NL_ITEM_INDEX (THOUSANDS_SEP)].string;
   if (*thousands == '\0')
     thousands = NULL;
#endif
 }

  /* Lock the stream.  */
  LOCK_STREAM (s);


#ifndef COMPILE_WSCANF
  /* From now on we use `state' to convert the format string.  */
  memset (&state, '\0', sizeof (state));
#endif

  /* Run through the format string.  */
  while (*f != '\0')
    {
      unsigned int argpos;
      /* Extract the next argument, which is of type TYPE.
	 For a %N$... spec, this is the Nth argument from the beginning;
	 otherwise it is the next argument after the state now in ARG.  */
#ifdef __va_copy
# define ARG(type)	(argpos == 0 ? va_arg (arg, type) :		      \
			 ({ unsigned int pos = argpos;			      \
			    va_list arg;				      \
			    __va_copy (arg, argptr);			      \
			    while (--pos > 0)				      \
			      (void) va_arg (arg, void *);		      \
			    va_arg (arg, type);				      \
			  }))
#else
# if 0
      /* XXX Possible optimization.  */
#  define ARG(type)	(argpos == 0 ? va_arg (arg, type) :		      \
			 ({ va_list arg = (va_list) argptr;		      \
			    arg = (va_list) ((char *) arg		      \
					     + (argpos - 1)		      \
					     * __va_rounded_size (void *));   \
			    va_arg (arg, type);				      \
			 }))
# else
#  define ARG(type)	(argpos == 0 ? va_arg (arg, type) :		      \
			 ({ unsigned int pos = argpos;			      \
			    va_list arg = (va_list) argptr;		      \
			    while (--pos > 0)				      \
			      (void) va_arg (arg, void *);		      \
			    va_arg (arg, type);				      \
			  }))
# endif
#endif

#ifndef COMPILE_WSCANF
      if (!isascii ((unsigned char) *f))
	{
	  /* Non-ASCII, may be a multibyte.  */
	  int len = __mbrlen (f, strlen (f), &state);
	  if (len > 0)
	    {
	      do
		{
		  c = inchar ();
		  if (c == EOF)
		    input_error ();
		  else if (c != (unsigned char) *f++)
		    {
		      ungetc_not_eof (c, s);
		      conv_error ();
		    }
		}
	      while (--len > 0);
	      continue;
	    }
	}
#endif

      fc = *f++;
      if (fc != '%')
	{
	  /* Remember to skip spaces.  */
	  if (ISSPACE (fc))
	    {
	      skip_space = 1;
	      continue;
	    }

	  /* Read a character.  */
	  c = inchar ();

	  /* Characters other than format specs must just match.  */
	  if (c == EOF)
	    input_error ();

	  /* We saw white space char as the last character in the format
	     string.  Now it's time to skip all leading white space.  */
	  if (skip_space)
	    {
	      while (ISSPACE (c))
		if (inchar () == EOF)
		  input_error ();
	      skip_space = 0;
	    }

	  if (c != fc)
	    {
	      ungetc (c, s);
	      conv_error ();
	    }

	  continue;
	}

      /* This is the start of the conversion string. */
      flags = 0;

      /* Not yet decided whether we read a pointer or not.  */
      read_pointer = 0;

      /* Initialize state of modifiers.  */
      argpos = 0;

      /* Prepare temporary buffer.  */
      wpsize = 0;

      /* Check for a positional parameter specification.  */
      if (ISDIGIT ((UCHAR_T) *f))
	{
	  argpos = (UCHAR_T) *f++ - L_('0');
	  while (ISDIGIT ((UCHAR_T) *f))
	    argpos = argpos * 10 + ((UCHAR_T) *f++ - L_('0'));
	  if (*f == L_('$'))
	    ++f;
	  else
	    {
	      /* Oops; that was actually the field width.  */
	      width = argpos;
	      flags |= WIDTH;
	      argpos = 0;
	      goto got_width;
	    }
	}

      /* Check for the assignment-suppressing, the number grouping flag,
	 and the signal to use the locale's digit representation.  */
      while (*f == L_('*') || *f == L_('\'') || *f == L_('I'))
	switch (*f++)
	  {
	  case L_('*'):
	    flags |= SUPPRESS;
	    break;
	  case L_('\''):
	    flags |= GROUP;
	    break;
	  case L_('I'):
	    flags |= I18N;
	    break;
	  }

      /* We have seen width. */
      if (ISDIGIT ((UCHAR_T) *f))
	flags |= WIDTH;

      /* Find the maximum field width.  */
      width = 0;
      while (ISDIGIT ((UCHAR_T) *f))
	{
	  width *= 10;
	  width += (UCHAR_T) *f++ - L_('0');
	}
    got_width:
      if (width == 0)
	width = -1;

      /* Check for type modifiers.  */
      switch (*f++)
	{
	case L_('h'):
	  /* ints are short ints or chars.  */
	  if (*f == L_('h'))
	    {
	      ++f;
	      flags |= CHAR;
	    }
	  else
	    flags |= SHORT;
	  break;
	case L_('l'):
	  if (*f == L_('l'))
	    {
	      /* A double `l' is equivalent to an `L'.  */
	      ++f;
	      flags |= LONGDBL | LONG;
	    }
	  else
	    /* ints are long ints.  */
	    flags |= LONG;
	  break;
	case L_('q'):
	case L_('L'):
	  /* doubles are long doubles, and ints are long long ints.  */
	  flags |= LONGDBL | LONG;
	  break;
	case L_('a'):
	  /* The `a' is used as a flag only if followed by `s', `S' or
	     `['.  */
	  if (*f != L_('s') && *f != L_('S') && *f != L_('['))
	    {
	      --f;
	      break;
	    }
	  /* String conversions (%s, %[) take a `char **'
	     arg and fill it in with a malloc'd pointer.  */
	  flags |= MALLOC;
	  break;
	case L_('z'):
	  if (need_longlong && sizeof (size_t) > sizeof (unsigned long int))
	    flags |= LONGDBL;
	  else if (sizeof (size_t) > sizeof (unsigned int))
	    flags |= LONG;
	  break;
	case L_('j'):
	  if (need_longlong && sizeof (uintmax_t) > sizeof (unsigned long int))
	    flags |= LONGDBL;
	  else if (sizeof (uintmax_t) > sizeof (unsigned int))
	    flags |= LONG;
	  break;
	case L_('t'):
	  if (need_longlong && sizeof (ptrdiff_t) > sizeof (long int))
	    flags |= LONGDBL;
	  else if (sizeof (ptrdiff_t) > sizeof (int))
	    flags |= LONG;
	  break;
	default:
	  /* Not a recognized modifier.  Backup.  */
	  --f;
	  break;
	}

      /* End of the format string?  */
      if (*f == L_('\0'))
	conv_error ();

      /* Find the conversion specifier.  */
      fc = *f++;
      if (skip_space || (fc != L_('[') && fc != L_('c')
			 && fc != L_('C') && fc != L_('n')))
	{
	  /* Eat whitespace.  */
	  int save_errno = errno;
	  errno = 0;
	  do
	    if (inchar () == EOF && errno == EINTR)
	      input_error ();
	  while (ISSPACE (c));
	  errno = save_errno;
	  ungetc (c, s);
	  skip_space = 0;
	}

      switch (fc)
	{
	case L_('%'):	/* Must match a literal '%'.  */
	  c = inchar ();
	  if (c == EOF)
	    input_error ();
	  if (c != fc)
	    {
	      ungetc_not_eof (c, s);
	      conv_error ();
	    }
	  break;

	case L_('n'):	/* Answer number of assignments done.  */
	  /* Corrigendum 1 to ISO C 1990 describes the allowed flags
	     with the 'n' conversion specifier.  */
	  if (!(flags & SUPPRESS))
	    {
	      /* Don't count the read-ahead.  */
	      if (need_longlong && (flags & LONGDBL))
		*ARG (long long int *) = read_in;
	      else if (need_long && (flags & LONG))
		*ARG (long int *) = read_in;
	      else if (flags & SHORT)
		*ARG (short int *) = read_in;
	      else if (!(flags & CHAR))
		*ARG (int *) = read_in;
	      else
		*ARG (char *) = read_in;

#ifdef NO_BUG_IN_ISO_C_CORRIGENDUM_1
	      /* We have a severe problem here.  The ISO C standard
		 contradicts itself in explaining the effect of the %n
		 format in `scanf'.  While in ISO C:1990 and the ISO C
		 Amendement 1:1995 the result is described as

		   Execution of a %n directive does not effect the
		   assignment count returned at the completion of
		   execution of the f(w)scanf function.

		 in ISO C Corrigendum 1:1994 the following was added:

		   Subclause 7.9.6.2
		   Add the following fourth example:
		     In:
		       #include <stdio.h>
		       int d1, d2, n1, n2, i;
		       i = sscanf("123", "%d%n%n%d", &d1, &n1, &n2, &d2);
		     the value 123 is assigned to d1 and the value3 to n1.
		     Because %n can never get an input failure the value
		     of 3 is also assigned to n2.  The value of d2 is not
		     affected.  The value 3 is assigned to i.

		 We go for now with the historically correct code from ISO C,
		 i.e., we don't count the %n assignments.  When it ever
		 should proof to be wrong just remove the #ifdef above.  */
	      ++done;
#endif