Date: Tue, 28 Aug 2001 13:19:33 +1000 From: Edwin Groothuis <edwin@mavetju.org> To: FreeBSD <freebsd@XtremeDev.com> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: open() in FreeBSD? Message-ID: <20010828131933.G29422@k7.mavetju.org> In-Reply-To: <20010827210707.G43076-100000@Amber.XtremeDev.com>; from freebsd@XtremeDev.com on Mon, Aug 27, 2001 at 09:13:28PM -0600 References: <20010827210707.G43076-100000@Amber.XtremeDev.com>
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On Mon, Aug 27, 2001 at 09:13:28PM -0600, FreeBSD wrote:
> Hello, I have the following test program:
>
> #include <stdio.h>
> #include <stdlib.h>
> #include <fcntl.h>
>
> int main()
> {
> int fd = open("blah", O_WRONLY|O_CREAT);
> close(fd);
> return EXIT_SUCCESS;
> }
>
> When I compiled this and run it, ls -l blah gives me:
>
> ---------x 1 freebsd freebsd - 0 Aug 27 20:46 blah*
>
> Looking through man 2 umask, the default umask is 022. Yet the file
> created by open() gives me a mask of 001? In the shell I checked the
> umask, and it indeed is at 022. If the default umask is 022, why does
> leaving out the third argument to open() not follow chmod/umask as implied
> by the man 2 open?
>
> "open requires a third argument mode_t mode, and the file is created
> with mode mode as described in chmod(2) and modified by the process'
> umask value (see umask(2))." - man 2 open
You didn't quote everything:
The file name specified by path is opened for reading and/or writing as
specified by the argument flags and the file descriptor returned to the
| calling process. The flags argument may indicate the file is to be cre-
| ated if it does not exist (by specifying the O_CREAT flag). In this case
| open requires a third argument mode_t mode, and the file is created with
mode mode as described in chmod(2) and modified by the process' umask
value (see umask(2)).
So, if you use O_CREAT, you *have to* supply the third argument!
Otherwise you're not playing according to the rules and you will
be punished for it. Like a 001 :-)
Edwin
--
Edwin Groothuis | Personal website: http://www.MavEtJu.org
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