lockf: Invalid argument on pipe
Robert Watson
rwatson at FreeBSD.org
Mon Mar 9 16:35:59 PDT 2009
On Mon, 9 Mar 2009, Timothy Redaelli wrote:
> Why can't I do a lockf on a file descriptor that does not point a real file
> (such as stderr, stdout, or a character device)?
>
> Since it works under NetBSD, Linux, Solaris. For portability between systems
> I hope I can do it under FreeBSD.
>
> The following code is simple, but It reproduce the problem. Under
> non-FreeBSD systems, It will block before the puts. Instead under FreeBSD
> the lockf calls return error and, so, the lock does not works.
Could you file a PR for this, with pretty much this e-mail and sample code
included? There's no real reason not for it to work other than that it is
likely not implemented for devfs; that should be easy to fix it but opening a
PR will help us keep track of the fact that it wants to be fixed.
thanks,
Robert N M Watson
Computer Laboratory
University of Cambridge
>
> Any suggest?
>
> <snip>
> #include <stdio.h>
> #include <unistd.h>
> #include <stdlib.h>
> #include <string.h>
>
> int main(int argc, char *argv[]) {
> char tmp[256];
>
> if (lockf(2, F_LOCK, 0) == -1)
> perror("lock");
> snprintf (tmp, 256, "%s XXX", argv[0]);
> if (!argv[1] || strcmp(argv[1], "XXX"))
> system(tmp);
> puts("You should see it only after ctrl+c");
> return EXIT_SUCCESS;
> }
> <end snip>
>
> --
> Timothy Redaelli
> IT Consultant
> Email: timothy at redaelli.eu
> Mobile: +39 (338) 1187273
> WWW: http://www.redaelli.eu/
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