readline.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.
//
//  readline.c
//

// This is a simplified version of the readline function from GNU.  The
// description from the man page is exceprted as follows:
//
// readline will read a line from the terminal and return it,
// using prompt as a prompt.  If prompt is null, no prompt is
// issued.  The line returned is allocated with malloc(3), so
// the  caller must free it when finished.  The line returned
// has the final newline removed, so only  the  text  of  the
// line remains.
//
// readline returns the text of the line read.  A blank  line
// returns  the  empty  string.   If EOF is encountered while
// reading a line, and the line is empty, NULL  is  returned.
// If  an EOF is read with a non-empty line, it is treated as
// a newline.

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


char *readline(const char *prompt)
{
  char *returnString = NULL;
  int inputCount = 0;
  char oneChar;

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

  // Allocate an array to hold the data
  returnString = malloc(MAXSTRINGLENGTH);
  if (returnString == NULL)
    return (returnString);

  // Output the prompt, if there is any
  if (prompt != NULL)
    textPrint(prompt);

  while(1)
    {
      // Get one char
      while (!textInputCount())
	multitaskerYield();
      textInputGetc(&oneChar);

      // Is it a newline?  If so, quit
      if (oneChar == '\n')
	break;

      // Put it into the array
      returnString[inputCount++] = oneChar;
    }

  // Put a NULL at the end
  returnString[inputCount] = '\0';

  return (returnString);
}