_fmtinpt.c

上一个上传的有问题,这个是好的。visopsys包括系统内核和GUI的全部SOURCE code ,还包括一些基本的docs文档。里面src子目录对应所有SOURCE code.对于想研究操作系统的朋

// 
//  Visopsys
//  Copyright (C) 1998-2007 J. Andrew McLaughlin
//  
//  This 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.
//
//  This 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 this library; if not, write to the Free Software Foundation,
//  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
//  _fmtinpt.c
//

// This function does all the work of filling data values from input
// based on the format strings used by the scanf family of functions
// (and others, if desired)

#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <sys/cdefs.h>


int _fmtinpt(const char *input, const char *format, va_list list)
{
  int matchItems = 0;
  int inputLen = 0;
  int formatLen = 0;
  int inputCount = 0;
  int formatCount = 0;
  unsigned long long *argument = NULL;
  int zeroPad = 0;
  int leftJust = 0;
  int fieldWidth = 0; 
  int isLong = 0;
  int count;

  // How long are the input and format strings?
  inputLen = strlen(input);
  if (inputLen < 0)
    {
      errno = inputLen;
      return (matchItems = 0);
    }
  inputLen = min(inputLen, MAXSTRINGLENGTH);
  formatLen = strlen(format);
  if (formatLen < 0)
    {
      errno = formatLen;
      return (matchItems = 0);
    }
  formatLen = min(formatLen, MAXSTRINGLENGTH);

  // The argument list must already have been initialized using va_start

  // Loop through all of the characters in the format string
  for (formatCount = 0; formatCount < formatLen; )
    {
      // If we encounter any whitespace in the format string, ignore it and
      // ignore any whitespace in the input
      if ((formatCount < formatLen) && isspace(format[formatCount]))
	{
	  // Skip format string whitespace
	  while ((formatCount < formatLen) && isspace(format[formatCount]))
	    formatCount += 1;
	  // Skip input whitespace
	  while ((inputCount < inputLen) && isspace(input[inputCount]))
	    inputCount += 1;
	  continue;
	}

      // If "%%" appears in the format, we expect to match one '%' in the
      // input
      if ((format[formatCount] == '%') && (format[formatCount + 1] == '%'))
	{
	  if (input[inputCount] != '%')
	    {
	      errno = ERR_BADDATA;
	      return (matchItems);
	    }

	  formatCount += 2;
	  inputCount += 1;
	  continue;
	}

      // For other non-conversion specifiers, we simply verify that they match
      // and then skip them
      if (format[formatCount] != '%')
	{
	  if (format[formatCount] != input[inputCount])
	    {
	      errno = ERR_BADDATA;
	      return (matchItems);
	    }

	  formatCount += 1;
	  inputCount += 1;
	  continue;
	}

      // Move to the next character
      formatCount += 1;

      // We have some format characters.  Get the corresponding argument.

      // Look for a zero digit, which indicates that any field width argument
      // is to be zero-padded
      if (format[formatCount] == '0')
	{
	  zeroPad = 1;
	  formatCount  += 1;
	}
      else
	zeroPad = 0;

      // Look for left-justification (applicable if there's a field-width
      // specifier to follow
      if (format[formatCount] == '-')
	{
	  leftJust = 1;
	  formatCount += 1;
	}
      else
	leftJust = 0;

      // Look for field length indicator
      if ((format[formatCount] >= '1') && (format[formatCount] <= '9'))
	{
	  fieldWidth = atoi(format + formatCount);
	  while ((format[formatCount] >= '0') &&
		 (format[formatCount] <= '9'))   
	    formatCount++;
        }
      else
	fieldWidth = 0;

      // If there's a 'll' qualifier for long values, make note of it
      if (format[formatCount] == 'l')
	{
	  formatCount += 1;
	  if (format[formatCount] == 'l')
	    {
	      isLong = 1;
	      formatCount += 1;
	    }
	}
      else
	isLong = 0;

       // We have some format characters.  Get the corresponding argument.
      argument = (unsigned long long *) va_arg(list, unsigned);

      // What is it?
      switch(format[formatCount])
	{
	case 'd':
	case 'i':
	  // This is an integer.  Read the characters for the integer
	  // from the input string
	  if (isLong)
	    {
	      *argument = atoll(input + inputCount);
	      inputCount += _ldigits(*argument, 10, 1);
	    }
	  else
	    {
	      *((int *) argument) = atoi(input + inputCount);
	      inputCount += _digits(*argument, 10, 1);
	    }
	  break;

	case 'u':
	  // This is an unsigned integer.  Put the characters for
	  // the integer into the destination string
	  if (isLong)
	    {
	      *argument = atoull(input + inputCount);
	      inputCount += _ldigits(*argument, 10, 0);
	    }
	  else
	    {
	      *((unsigned *) argument) = atou(input + inputCount);
	      inputCount += _digits(*argument, 10, 0);
	    }
	  break;

	case 'c':
	  // A character.
	  *((char *) argument) = input[inputCount++];
	  break;

	case 's':
	  // This is a string.  Copy until we meet a whitespace character.
	  for (count = 0; ((inputCount < inputLen) &&
			   !isspace(input[inputCount])); count ++)
	    ((char *) argument)[count] = input[inputCount++];
	  ((char *) argument)[count] = '\0';
	  break;

	case 'p':
	case 'x':
	case 'X':
	  if (format[formatCount] == 'p')
	    {
	      // Bit of special stuff for pointer args
	      if (!strncmp((input + inputCount), "0x", 2))
		inputCount += 2;
	    }
	  if (isLong)
	    {
	      *argument = xtoll(input + inputCount);
	      inputCount += _ldigits(*argument, 16, 1);
	    }
	  else
	    {
	      *((int *) argument) = xtoi(input + inputCount);
	      inputCount += _digits(*argument, 16, 1);
	    }
	  break;

	default:
	  // Umm, we don't know what this is.  Fail.
	  errno = ERR_INVALID;
	  return (matchItems);
	  break;
	}

      matchItems += 1;
      formatCount += 1;
    }

  // Return the number of items we matched
  return (matchItems);
}