fgets.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.
//
//  fgets.c
//

// This is the standard "fgets" function, as found in standard C libraries

#include <stdio.h>
#include <stdlib.h>
#include <readline.h>
#include <errno.h>
#include <sys/api.h>


char *fgets(char *string, int size, FILE *theStream)
{
  // fgets() reads a line from the file stream into the buffer pointed to by
  // string until either a terminating newline or EOF, which it replaces with
  // '\0'.  No check for buffer overrun is performed.

  int status = 0;
  char *tmpString = NULL;

  if (visopsys_in_kernel)
    {
      errno = ERR_BUG;
      return (string = NULL);
    }

  if (theStream == stdin)
    {
      tmpString = readline(NULL);
      
      if (tmpString == NULL)
	{
	  errno = ERR_IO;
	  return (string = NULL);
	}

      strncpy(string, tmpString, size);
      free(tmpString);
    }
  else
    {
      status = fileStreamReadLine(theStream, (size - 1), string);
      if (status < 0)
	{
	  errno = status;
	  return (string = NULL);
	}
    }

  string[size - 1] = '\0';

  return (string);
}