vfprintf.c

绝对正真的stdio.h的实现

	LABEL (form_unknown):
	  if (spec == L_('\0'))
	    {
	      /* The format string ended before the specifier is complete.  */
	      done = -1;
	      goto all_done;
	    }

	  /* If we are in the fast loop force entering the complicated
	     one.  */
	  goto do_positional;
	}

      /* The format is correctly handled.  */
      ++nspecs_done;

      if (__builtin_expect (workstart != NULL, 0))
	free (workstart);
      workstart = NULL;

      /* Look for next format specifier.  */
#ifdef COMPILE_WPRINTF
      f = __find_specwc ((end_of_spec = ++f));
#else
      f = __find_specmb ((end_of_spec = ++f), &mbstate);
#endif

      /* Write the following constant string.  */
      outstring (end_of_spec, f - end_of_spec);
    }
  while (*f != L_('\0'));

  /* Unlock stream and return.  */
  goto all_done;

  /* Here starts the more complex loop to handle positional parameters.  */
do_positional:
  {
    /* Array with information about the needed arguments.  This has to
       be dynamically extensible.  */
    size_t nspecs = 0;
    size_t nspecs_max = 32;	/* A more or less arbitrary start value.  */
    struct printf_spec *specs
      = alloca (nspecs_max * sizeof (struct printf_spec));

    /* The number of arguments the format string requests.  This will
       determine the size of the array needed to store the argument
       attributes.  */
    size_t nargs = 0;
    int *args_type;
    union printf_arg *args_value = NULL;

    /* Positional parameters refer to arguments directly.  This could
       also determine the maximum number of arguments.  Track the
       maximum number.  */
    size_t max_ref_arg = 0;

    /* Just a counter.  */
    size_t cnt;


    if (grouping == (const char *) -1)
      {
#ifdef COMPILE_WPRINTF
	thousands_sep = _NL_CURRENT_WORD (LC_NUMERIC,
					  _NL_NUMERIC_THOUSANDS_SEP_WC);
#else
	thousands_sep = _NL_CURRENT (LC_NUMERIC, THOUSANDS_SEP);
#endif

	grouping = _NL_CURRENT (LC_NUMERIC, GROUPING);
	if (*grouping == '\0' || *grouping == CHAR_MAX)
	  grouping = NULL;
      }

    for (f = lead_str_end; *f != L_('\0'); f = specs[nspecs++].next_fmt)
      {
	if (nspecs >= nspecs_max)
	  {
	    /* Extend the array of format specifiers.  */
	    struct printf_spec *old = specs;

	    nspecs_max *= 2;
	    specs = alloca (nspecs_max * sizeof (struct printf_spec));

	    if (specs == &old[nspecs])
	      /* Stack grows up, OLD was the last thing allocated;
		 extend it.  */
	      nspecs_max += nspecs_max / 2;
	    else
	      {
		/* Copy the old array's elements to the new space.  */
		memcpy (specs, old, nspecs * sizeof (struct printf_spec));
		if (old == &specs[nspecs])
		  /* Stack grows down, OLD was just below the new
		     SPECS.  We can use that space when the new space
		     runs out.  */
		  nspecs_max += nspecs_max / 2;
	      }
	  }

	/* Parse the format specifier.  */
#ifdef COMPILE_WPRINTF
	nargs += __parse_one_specwc (f, nargs, &specs[nspecs], &max_ref_arg);
#else
	nargs += __parse_one_specmb (f, nargs, &specs[nspecs], &max_ref_arg,
				     &mbstate);
#endif
      }

    /* Determine the number of arguments the format string consumes.  */
    nargs = MAX (nargs, max_ref_arg);

    /* Allocate memory for the argument descriptions.  */
    args_type = alloca (nargs * sizeof (int));
    memset (args_type, s->_flags2 & _IO_FLAGS2_FORTIFY ? '\xff' : '\0',
	    nargs * sizeof (int));
    args_value = alloca (nargs * sizeof (union printf_arg));

    /* XXX Could do sanity check here: If any element in ARGS_TYPE is
       still zero after this loop, format is invalid.  For now we
       simply use 0 as the value.  */

    /* Fill in the types of all the arguments.  */
    for (cnt = 0; cnt < nspecs; ++cnt)
      {
	/* If the width is determined by an argument this is an int.  */
	if (specs[cnt].width_arg != -1)
	  args_type[specs[cnt].width_arg] = PA_INT;

	/* If the precision is determined by an argument this is an int.  */
	if (specs[cnt].prec_arg != -1)
	  args_type[specs[cnt].prec_arg] = PA_INT;

	switch (specs[cnt].ndata_args)
	  {
	  case 0:		/* No arguments.  */
	    break;
	  case 1:		/* One argument; we already have the type.  */
	    args_type[specs[cnt].data_arg] = specs[cnt].data_arg_type;
	    break;
	  default:
	    /* We have more than one argument for this format spec.
	       We must call the arginfo function again to determine
	       all the types.  */
	    (void) (*__printf_arginfo_table[specs[cnt].info.spec])
	      (&specs[cnt].info,
	       specs[cnt].ndata_args, &args_type[specs[cnt].data_arg]);
	    break;
	  }
      }

    /* Now we know all the types and the order.  Fill in the argument
       values.  */
    for (cnt = 0; cnt < nargs; ++cnt)
      switch (args_type[cnt])
	{
#define T(tag, mem, type)						      \
	case tag:							      \
	  args_value[cnt].mem = va_arg (ap_save, type);			      \
	  break

	T (PA_CHAR, pa_int, int); /* Promoted.  */
	T (PA_WCHAR, pa_wchar, wint_t);
	T (PA_INT|PA_FLAG_SHORT, pa_int, int); /* Promoted.  */
	T (PA_INT, pa_int, int);
	T (PA_INT|PA_FLAG_LONG, pa_long_int, long int);
	T (PA_INT|PA_FLAG_LONG_LONG, pa_long_long_int, long long int);
	T (PA_FLOAT, pa_double, double);	/* Promoted.  */
	T (PA_DOUBLE, pa_double, double);
	T (PA_DOUBLE|PA_FLAG_LONG_DOUBLE, pa_long_double, long double);
	T (PA_STRING, pa_string, const char *);
	T (PA_WSTRING, pa_wstring, const wchar_t *);
	T (PA_POINTER, pa_pointer, void *);
#undef T
	default:
	  if ((args_type[cnt] & PA_FLAG_PTR) != 0)
	    args_value[cnt].pa_pointer = va_arg (ap_save, void *);
	  else
	    args_value[cnt].pa_long_double = 0.0;
	  break;
	case -1:
	  /* Error case.  Not all parameters appear in N$ format
	     strings.  We have no way to determine their type.  */
	  assert (s->_flags2 & _IO_FLAGS2_FORTIFY);
	  __libc_fatal ("*** invalid %N$ use detected ***\n");
	}

    /* Now walk through all format specifiers and process them.  */
    for (; (size_t) nspecs_done < nspecs; ++nspecs_done)
      {
#undef REF
#if defined HAVE_SUBTRACT_LOCAL_LABELS && defined SHARED
# define REF(Name) &&do2_##Name - &&do_form_unknown
#else
# define REF(Name) &&do2_##Name
#endif
#undef LABEL
#define LABEL(Name) do2_##Name
	STEP4_TABLE;

	int is_negative;
	union
	{
	  unsigned long long int longlong;
	  unsigned long int word;
	} number;
	int base;
	union printf_arg the_arg;
	CHAR_T *string;		/* Pointer to argument string.  */

	/* Fill variables from values in struct.  */
	int alt = specs[nspecs_done].info.alt;
	int space = specs[nspecs_done].info.space;
	int left = specs[nspecs_done].info.left;
	int showsign = specs[nspecs_done].info.showsign;
	int group = specs[nspecs_done].info.group;
	int is_long_double = specs[nspecs_done].info.is_long_double;
	int is_short = specs[nspecs_done].info.is_short;
	int is_char = specs[nspecs_done].info.is_char;
	int is_long = specs[nspecs_done].info.is_long;
	int width = specs[nspecs_done].info.width;
	int prec = specs[nspecs_done].info.prec;
	int use_outdigits = specs[nspecs_done].info.i18n;
	char pad = specs[nspecs_done].info.pad;
	CHAR_T spec = specs[nspecs_done].info.spec;
	CHAR_T *workstart = NULL;

	/* Fill in last information.  */
	if (specs[nspecs_done].width_arg != -1)
	  {
	    /* Extract the field width from an argument.  */
	    specs[nspecs_done].info.width =
	      args_value[specs[nspecs_done].width_arg].pa_int;

	    if (specs[nspecs_done].info.width < 0)
	      /* If the width value is negative left justification is
		 selected and the value is taken as being positive.  */
	      {
		specs[nspecs_done].info.width *= -1;
		left = specs[nspecs_done].info.left = 1;
	      }
	    width = specs[nspecs_done].info.width;
	  }

	if (specs[nspecs_done].prec_arg != -1)
	  {
	    /* Extract the precision from an argument.  */
	    specs[nspecs_done].info.prec =
	      args_value[specs[nspecs_done].prec_arg].pa_int;

	    if (specs[nspecs_done].info.prec < 0)
	      /* If the precision is negative the precision is
		 omitted.  */
	      specs[nspecs_done].info.prec = -1;

	    prec = specs[nspecs_done].info.prec;
	  }

	/* Maybe the buffer is too small.  */
	if (MAX (prec, width) + 32 > (int) (sizeof (work_buffer)
					    / sizeof (CHAR_T)))
	  {
	    if (__libc_use_alloca ((MAX (prec, width) + 32)
				   * sizeof (CHAR_T)))
	      workend = ((CHAR_T *) alloca ((MAX (prec, width) + 32)
					    * sizeof (CHAR_T))
			 + (MAX (prec, width) + 32));
	    else
	      {
		workstart = (CHAR_T *) malloc ((MAX (prec, width) + 32)
					       * sizeof (CHAR_T));
		workend = workstart + (MAX (prec, width) + 32);
	      }
	  }

	/* Process format specifiers.  */
	while (1)
	  {
	    JUMP (spec, step4_jumps);

	    process_arg ((&specs[nspecs_done]));
	    process_string_arg ((&specs[nspecs_done]));

	  LABEL (form_unknown):
	    {
	      extern printf_function **__printf_function_table;
	      int function_done;
	      printf_function *function;
	      unsigned int i;
	      const void **ptr;

	      function =
		(__printf_function_table == NULL ? NULL :
		 __printf_function_table[specs[nspecs_done].info.spec]);

	      if (function == NULL)
		function = &printf_unknown;

	      ptr = alloca (specs[nspecs_done].ndata_args
			    * sizeof (const void *));

	      /* Fill in an array of pointers to the argument values.  */
	      for (i = 0; i < specs[nspecs_done].ndata_args; ++i)
		ptr[i] = &args_value[specs[nspecs_done].data_arg + i];

	      /* Call the function.  */
	      function_done = (*function) (s, &specs[nspecs_done].info, ptr);

	      /* If an error occurred we don't have information about #
		 of chars.  */
	      if (function_done < 0)
		{
		  done = -1;
		  goto all_done;
		}

	      done += function_done;
	    }
	    break;
	  }

	if (__builtin_expect (workstart != NULL, 0))
	  free (workstart);
	workstart = NULL;

	/* Write the following constant string.  */
	outstring (specs[nspecs_done].end_of_fmt,
		   specs[nspecs_done].next_fmt
		   - specs[nspecs_done].end_of_fmt);
      }
  }

all_done:
  if (__builtin_expect (workstart != NULL, 0))
    free (workstart);
  /* Unlock the stream.  */
  _IO_funlockfile (s);
  _IO_cleanup_region_end (0);

  return done;
}

/* Handle an unknown format specifier.  This prints out a canonicalized
   representation of the format spec itself.  */
static int
printf_unknown (FILE *s, const struct printf_info *info,
		const void *const *args)

{
  int done = 0;
  CHAR_T work_buffer[MAX (info->width, info->spec) + 32];
  CHAR_T *const workend
    = &work_buffer[sizeof (work_buffer) / sizeof (CHAR_T)];
  register CHAR_T *w;

  outchar (L_('%'));

  if (info->alt)
    outchar (L_('#'));
  if (info->group)
    outchar (L_('\''));
  if (info->showsign)
    outchar (L_('+'));
  else if (info->space)
    outchar (L_(' '));
  if (info->left)
    outchar (L_('-'));
  if (info->pad == L_('0'))
    outchar (L_('0'));
  if (info->i18n)
    outchar (L_('I'));

  if (info->width != 0)
    {
      w = _itoa_word (info->width, workend, 10, 0);
      while (w < workend)
	outchar (*w++);
    }

  if (info->prec != -1)