Re: [Xen-devel] [PATCH] Fix bug #709 by daemonizing blktapctrl and closing stdin, stdout and stderr

[Muli Ben-Yehuda <muli@xxxxxxxxxx>]

On Mon, Jul 31, 2006 at 04:15:42PM +0100, Harry Butterworth wrote:

> +static void daemonize(void)
> +{
> +     pid_t pid;
> +
> +     /* Separate from our parent via fork, so init inherits us. */
> +     if ((pid = fork()) < 0)
> +             DPRINTF("Failed to fork daemon\n");

It will be useful to know why fork() failed (i.e., print errno
directly or use sterror_r() and friends).

> +     if (pid != 0)
> +             exit(0);

If fork() failed, this will cause us to exit(0) which doesn't seem
particularly appropriate.

> +     /* Session leader so ^C doesn't whack us. */
> +     setsid();

In theory setsid() can fail.

> +     /* Let session leader exit so child cannot regain CTTY */
> +     if ((pid = fork()) < 0)
> +             DPRINTF("Failed to fork daemon\n");
> +     if (pid != 0)
> +             exit(0);

Same comment as above.
> +
> +#ifndef TESTING      /* Relative paths for socket names */
> +     /* Move off any mount points we might be in. */
> +     if (chdir("/") == -1)
> +             DPRINTF("Failed to chdir\n");
> +#endif
> +     /* Discard our parent's old-fashioned umask prejudices. */
> +     umask(0);
> +
> +        close(STDIN_FILENO);

Mixed tabs and spaces, ugh. Also, fileno(stdin) is nicer.

Cheers,
Muli

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