Date: Thu, 10 Oct 2002 18:37:14 -0700 (PDT) From: Lamont Granquist <lamont@scriptkiddie.org> To: freebsd-gnats-submit@FreeBSD.org Subject: misc/43905: kqueues: EV_SET(kevp++, ...) is non-intuitive Message-ID: <200210110137.g9B1bENM017363@www.freebsd.org>
next in thread | raw e-mail | index | archive | help
>Number: 43905
>Category: misc
>Synopsis: kqueues: EV_SET(kevp++, ...) is non-intuitive
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Thu Oct 10 18:40:02 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: Lamont Granquist
>Release: 5.0-current Sept 29, 2002
>Organization:
>Environment:
> uname -a
FreeBSD coredump.scriptkiddie.org 5.0-CURRENT FreeBSD 5.0-CURRENT #14: Sun Sep 29 21:38:54 PDT 2002 lamont@coredump.scriptkiddie.org:/usr/obj/usr/src/sys/COREDUMP i386
>Description:
EV_SET() macro call references the first argument 6 times making calls like EV_SET(kevp++, [...]); not work as-expected and violates principle of least-surprise.
>How-To-Repeat:
#include <sys/types.h>
#include <sys/event.h>
#include <stdio.h>
#include <stdlib.h>
int main(void) {
int i;
struct kevent *kevp = (struct kevent *) malloc(sizeof(struct kevent) * 100);
for(i = 0; i < 7; i++) {
printf("%d %p\n", i, kevp + i);
}
printf("%p\n", kevp);
EV_SET(kevp++, 0, EVFILT_READ, EV_ADD, 0, 0, 0);
printf("%p\n", kevp);
exit(0);
}
>Fix:
best i can suggest is to convert to an inline function:
static __inline void EV_SET(struct kevent *kevp, const uintptr_t ident, const short filter, const u_short flags, const u_int fflags, const intptr_t data, void * const udata)
{
(kevp)->ident = ident;
(kevp)->filter = filter;
(kevp)->flags = flags;
(kevp)->fflags = fflags;
(kevp)->data = data;
(kevp)->udata = udata;
}
You could introduce a temporary variable in the EV_SET macro, but things get interesting if there's a namespace collision between that temporary variable and the first argument to EV_SET().
>Release-Note:
>Audit-Trail:
>Unformatted:
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-bugs" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200210110137.g9B1bENM017363>