Re: [Qemu-devel] bug writing pidfile under unix (and fix)

[Anthony Liguori]

Jim Bailey wrote:
> Hello,
>
> In qemu_create_pidfile (osdep.c:229) the current pid and a newline is
> written to the pidfile. However, the pidfile isn't truncated, so if it
> is longer than the length of the pid and the newline character you get
> trailing junk that can really mess up scripts.
>
> I noticed this when going from a 5 digit pid to a 3 digit pid, so it
> can happen in regular operation, especially if the OS randomizes pids.
>
> Truncating the file fixes the bug.
>   

Needs a Signed-off-by.

Regards,

Anthony Liguori

> dgym
>
>
> *** osdep.c.orig        Fri Nov  7 16:56:12 2008
> --- osdep.c     Fri Nov  7 16:58:49 2008
> ***************
> *** 236,241 ****
> --- 236,243 ----
>       len = snprintf(buffer, sizeof(buffer), "%ld\n", (long)getpid());
>       if (write(fd, buffer, len) != len)
>           return -1;
> + 
> +     ftruncate(fd, len);
>   #else
>       HANDLE file;
>       DWORD flags;
>
>
>