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getinput.c

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/*
  getinput.c

  Non-blocking input on stdin


Modifications:

21-Sep-1999 WPS ifdef'd out CE stuff.

  */

#ifdef WIN32

#ifdef UNDER_CE

// This is currently  impossible to implement in CE.
int getinput(char *buffer, int maxchars)
{
 return -1;
}

#else
// WIN32 but not CE, ( ie. Windows 95,98,2000, or NT)

#include <stdio.h>
#include <string.h>

/*
  getinput() blocks on stdin, returning number of chars read, -1
  if EOF.
  */
int getinput(char *buffer, int maxchars)
{
  if (NULL == fgets(buffer, maxchars, stdin))
    {
      if (feof(stdin))
        {
          return 0;
        }

      return -1;
    }

  return strlen(buffer);
}

#endif

#else

#include <unistd.h>             /* STDIN_FILENO */
#include <fcntl.h>              /* F_GETFL, O_NONBLOCK */

/*
  getinput() returns the number of chars read, -1 if no chars were available,
  or 0 if EOF. It doesn't block, so you can call this repeatedly and when
  it returns non-zero you have that many chars, not including the added NULL.
  */
int getinput(char *buffer, int maxchars)
{
  int flags;
  int nchars;
  int index = 0;

  /* save the flags */
  flags = fcntl(STDIN_FILENO, F_GETFL);

  /* make terminal non-blocking */
  fcntl(STDIN_FILENO, F_SETFL, O_NONBLOCK);

  /* read the outstanding chars, one by one, until newline or no more */
  while (1 == (nchars = read(STDIN_FILENO, &buffer[index], 1)))
    {
      if (buffer[index++] == '\n')
        {
          buffer[index] = 0;    /* null terminate */
          break;
        }
    }

  /* restore the terminal */
  fcntl(STDIN_FILENO, F_SETFL, flags);

  if (nchars == -1)
    {
      return -1;                /* nothing new */
    }

  if (nchars == 0)
    {
      return 0;                 /* end of file */
    }

  return index;
}

#endif /* not WIN32 */

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