Date: Wed, 16 Jan 2002 20:48:46 +1000 From: Greg Black <gjb@gbch.net> To: Foldi Tamas <crow@localhost.hu> Cc: freebsd-hackers@freebsd.org Subject: Re: interesting open() issue Message-ID: <nospam-1011178126.76622@bambi.gbch.net> In-Reply-To: <20020116105923.A29210@hax0r.hu> of Wed, 16 Jan 2002 10:59:23 %2B0100 References: <20020116105923.A29210@hax0r.hu>
next in thread | previous in thread | raw e-mail | index | archive | help
Foldi Tamas wrote:
| Hello hackers,
Don't send this sort of newbie programmer question to the
hackers list (or to any of the FreeBSD lists).
| I tried the following program on Tru64, FreeBSD and linux:
|
| #include <stdio.h>
| #include <fcntl.h>
| #include <sys/stat.h>
| #include <sys/types.h>
| main() {
| int fd;
| fd = open ( "/tmp/foobar", (O_RDWR | O_CREAT), 0020);
| perror("open");
| close(fd);
| }
|
| The program ran successfully, but the created file was different.
| On Linux:
| -----w---- 1 crow crow 0 Jan 16 10:32 /tmp/foobar
|
| On Tru64/FreeBSD:
| ---------- 1 crow users 0 Jan 16 10:30 /tmp/foobar
|
| I'm not sure what the result supposed to be. Any ideas ?
If you want the exact same results on each system and if you
want the file to have the mode you set, you need to put two
additional system calls *before* the open(2) call:
unlink("/tmp/foobar");
umask(0);
If the file exists, the mode in the open() won't affect it and
it will retain whatever it already had, so you need to ensure
that it's not there first. If your umask setting masks the
group write bit, it won't be set unless you first clear the
umask setting.
Now go and read about Unix programming.
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?nospam-1011178126.76622>