Solved

fcntl system call

Posted on 1998-12-13
3
640 Views
Last Modified: 2013-12-26
I've been studying Stevens' "Unix Network Programming", and I decided to write a program to investigate the fcntl system call. The program below is supposed to print the status flags for the file in question. It in fact prints 0. Is this likely to be correct? Stevens is not specific as to what the third argument for fcntl should be.

Thanks,

David King.


#include <fcntl.h>
#include <errno.h>

#define      thisprog      "/home/vexil/fcntltest"

main()
{
      int value, fd;
      if ((fd = open(thisprog, 0)) < 0)
            {
            printf("Error with open\n");
            exit(errno);
            }
      if ((value = fcntl(fd, F_GETFL, 0)) <  0)
            {
            printf("Error with fcntl\n");
            exit(errno);
            }
      printf("Status flags are: %d\n", value);
}
0
Comment
Question by:sevrin
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
3 Comments
 
LVL 84

Expert Comment

by:ozo
ID: 1294801
try setting a few flags:
(fd = open(thisprog, O_APPEND|O_RDWR|O_NDELAY))
0
 
LVL 2

Accepted Solution

by:
rdelfino earned 50 total points
ID: 1294802

It's not wrong, what happened was that the file descriptor didn't have any flag set.
As ozo already said try setting some flags.

About the third argument, actualy you don't have to pass anything. You could use

flags = fcntl(fd, F_GETFL);

The third argument is used in other fcntl requests such as F_SETFL

I hope it helps

Reginaldo

0
 

Author Comment

by:sevrin
ID: 1294803
Really these point should be split with ozo... but as you *answered* the question first, they're yours. Thanks,

David King
0

Featured Post

Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction: Database storage, where is the exe actually on the disc? Playing a game selected randomly (how to generate random numbers).  Error trapping with try..catch to help the code run even if something goes wrong. Continuing from the seve…
Exception Handling is in the core of any application that is able to dignify its name. In this article, I'll guide you through the process of writing a DRY (Don't Repeat Yourself) Exception Handling mechanism, using Aspect Oriented Programming.
This video will show you how to get GIT to work in Eclipse.   It will walk you through how to install the EGit plugin in eclipse and how to checkout an existing repository.
Monitoring a network: how to monitor network services and why? Michael Kulchisky, MCSE, MCSA, MCP, VTSP, VSP, CCSP outlines the philosophy behind service monitoring and why a handshake validation is critical in network monitoring. Software utilized …

719 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question