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Subject: Re: questions about using fget as waiting loop

Author: Robert Hyatt

Date: 07:20:05 08/30/04

On August 30, 2004 at 05:27:46, Alessandro Scotti wrote:

>On August 29, 2004 at 19:59:40, Robert Hyatt wrote:
>
>>On August 29, 2004 at 17:44:16, Alessandro Scotti wrote:
>>
>>>On August 29, 2004 at 12:04:47, Uri Blass wrote:
>>>
>>>>2)Is it safe to use fgets()?
>>>>I remember that it is not safe to use gets() and I think that for the same
>>>>reason it is not safe to use fgets()
>>>
>>>fgets() is safe. The difference with gets() is that the latter doesn't take the
>>>buffer size as a parameter, so it can overflow your buffer. Other minor
>>>difference s are that gets() removes end of line characters from the string,
>>>while fgets() leaves them there, and also that gets() can only read from stdin.
>>
>>
>>It isn't safe from the point of view of being able to ask "has anything been
>>typed on the keyboard" because fgets() uses library buffering which hides input
>>from the operating system's "is there input" query.
>
>I assumed safe referred to security here. For the rest, it's not too bad to get
>input only after "Enter" is pressed, I've recently switched to this
>line-oriented mode and so far I'm quite happy with it as it's quite portable and
>simple to code.

What do you do about the case where you type "command"<CR>  "command"<CR> (two
commands) before your program does the "check for input"?  You do the first
fgets() and the C library sucks both commands into its internal buffer, by
reading the data from the O/S, and it gives you the first command.  Now when you
ask "is there more input" you are asking the O/S and it says "no" even though
the C library has the second command in its buffer.  This is a _common_ problem
when people first modify their engines to run with winboard/xboard.  It is such
a problem that Tim and I wrote a lot of text to explain why this is a problem
and how to get around it...

Re: questions about using fget as waiting loop Alessandro Scotti 08:25:26 08/30/04
- Re: questions about using fget as waiting loop Robert Hyatt 10:57:59 08/30/04
  - Re: questions about using fget as waiting loop Uri Blass 11:40:25 08/30/04
    - Re: questions about using fget as waiting loop Alessandro Scotti 16:10:38 08/30/04
      - Re: questions about using fget as waiting loop Alessandro Scotti 16:31:02 08/30/04
    - Re: questions about using fget as waiting loop Robert Hyatt 12:39:45 08/30/04
      - Re: questions about using fget as waiting loop Dieter Buerssner 15:39:58 08/30/04
        
        Re: questions about using fget as waiting loop Robert Hyatt 16:51:17 08/30/04
        
        Re: questions about using fget as waiting loop Dieter Buerssner 13:16:58 09/01/04
        
        Re: questions about using fget as waiting loop Robert Hyatt 13:38:20 09/01/04
        
        Re: questions about using fget as waiting loop Uri Blass 05:15:13 08/31/04
        
        Re: questions about using fget as waiting loop Uri Blass 16:18:33 08/30/04
        
        Re: questions about using fget as waiting loop Robert Hyatt 16:52:56 08/30/04
        
        Re: questions about using fget as waiting loop Dieter Buerssner 16:31:30 08/30/04
        
        Re: questions about using fget as waiting loop Anthony Cozzie 10:16:04 08/31/04
      - Re: questions about using fget as waiting loop Uri Blass 13:09:59 08/30/04
        
        Re: questions about using fget as waiting loop Robert Hyatt 13:26:16 08/30/04

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