From owner-freebsd-hackers@FreeBSD.ORG Thu Apr 29 21:19:53 2010 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 8593D106564A; Thu, 29 Apr 2010 21:19:53 +0000 (UTC) (envelope-from czerner.lukas@gmail.com) Received: from fg-out-1718.google.com (fg-out-1718.google.com [72.14.220.156]) by mx1.freebsd.org (Postfix) with ESMTP id C92B38FC13; Thu, 29 Apr 2010 21:19:52 +0000 (UTC) Received: by fg-out-1718.google.com with SMTP id 22so3419024fge.13 for ; Thu, 29 Apr 2010 14:19:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:date:from:x-x-sender:to:cc :subject:in-reply-to:message-id:references:user-agent:mime-version :content-type; bh=qqeXIzzYqEvJhVMBj67EbjBE6HF0/Z8UW1S7uV8oKvg=; b=In3zUWrC7NSxar3CCGnpnLs861i+rHJAMyHTFFJd2tHwaEr+dXrbV5ZqCQT8a9pG/D Mk+yCMgC8XFcWIAfv8r7/37EgN6lhSPEBjusQPrM1EMf2OLU7SWFZ/44Y/tiu4yeaVuM ZPeHALe8+Y0u19w92ffJ3BbCkw0+O/3XndeoY= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version:content-type; b=sGIrvzM2vcGKk3R5ZOu+9tEX40T1HmfMX6G5yzPud1nsILUSMEFbUCHhpvFAvuVZYD qhBsrkacoj2EwgqkWSidlZotjx4w+XneyM824ze4s4Eb/RsyGOrDexWM4SQFuBZtgpk1 XI32oJSmEfhlXB0LaEz6Y6nXjvaFLoWD0Fd4o= Received: by 10.87.53.28 with SMTP id f28mr2496657fgk.70.1272575991777; Thu, 29 Apr 2010 14:19:51 -0700 (PDT) Received: from a04-0215a.kn.vutbr.cz (a04-0215a.kn.vutbr.cz [147.229.216.20]) by mx.google.com with ESMTPS id e3sm2797760fga.4.2010.04.29.14.19.50 (version=TLSv1/SSLv3 cipher=RC4-MD5); Thu, 29 Apr 2010 14:19:51 -0700 (PDT) Date: Thu, 29 Apr 2010 23:19:54 +0200 (CEST) From: "=?ISO-8859-15?Q?Luk=E1=A8_Czerner?=" X-X-Sender: bratt@a04-0215a.kn.vutbr.cz To: John Baldwin In-Reply-To: <201004291656.12565.jhb@freebsd.org> Message-ID: References: <201004291606.35899.jhb@freebsd.org> <201004291656.12565.jhb@freebsd.org> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="8323329-1067549723-1272575995=:30007" Cc: freebsd-hackers@freebsd.org, =?ISO-8859-15?Q?Luk=E1=A8_Czerner?= Subject: Re: ioctl, copy string from user X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 29 Apr 2010 21:19:53 -0000 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323329-1067549723-1272575995=:30007 Content-Type: TEXT/PLAIN; charset=iso-8859-15 Content-Transfer-Encoding: 8BIT On Thu, 29 Apr 2010, John Baldwin wrote: > Date: Thu, 29 Apr 2010 16:56:12 -0400 > From: John Baldwin > To: LukᨠCzerner > Cc: freebsd-hackers@freebsd.org > Subject: Re: ioctl, copy string from user > > On Thursday 29 April 2010 4:28:31 pm LukᨠCzerner wrote: > > On Thu, 29 Apr 2010, John Baldwin wrote: > > > > > > > > > > On Thursday 29 April 2010 1:52:45 pm LukᨠCzerner wrote: > > > > > > Hi, > > > > > > > > > > > > I know that there are plenty of examples in the kernel code, but I > > > > > > just can not get it working, so maybe I am doing some stupid mistake > > > > > > I am not aware of. Please give me a hint if you can. > > > > > > > > > > > > What I want to do is simply call the ioctl from the userspace with > > > > > > (char *) argument. Then, in kernel ioctl handling function copy the > > > > > > string argument into the kernel space. I have tried it various ways, > > > > > > everything without any success. > > > > > > > > > > > > *** Userspace *** > > > > > > char name[MAXLEN]; > > > > > > > > > > > > strncpy(name, argv[1], MAXLEN); > > > > > > fprintf(stdout,"Name: %s\n",name); > > > > > > > > > > > > if (ioctl(fd, MYIOCTL, name)) { > > > > > > > > > > On BSD systems, ioctl() copies the data into the kernel for you ahead of > > > time. > > > > > What does the definition of MYIOCTL look like? > > > > > > > > #define MYIOCTL _IOW('M', 0, char *) > > > > > > Ok. In that case the argument to ioctl needs to be a pointer to a char *, > > > not the raw char * itself. Try doing 'ioctl(fd, MYIOCTL, &name)' from > > > userland to see if that fixes it. > > > > I have already tried that, but still without any success. The buffer > > remains unchanged (which is weird IMO). > > Can you print out the value of 'ap->a_data' from the kernel and the value of > '&name' in userland? fprintf(stdout,"Name: %s\n",name); Name: Dummyflt uprintf("Name: %s\n", name) Name: When I set the name variable before copyinstr() it remains unchanged. > > > > Generally yes, but it depends on the lock. If it is the vn_lock lock then it > > > is ok to do a blocking malloc(). As a general rule I do try to call malloc() > > > before acquiring locks (basically preallocating) whenever possible. > > > > So I suppose M_NOWAIT will do the trick when there is no other way > > (preallocations etc..) ? Of course I should test if it does not > > return NULL then. > > Yes, but in a VOP_IOCTL() handler it should be safe to M_WAITOK malloc() as > long as you do it before you acquire any mutexes. Good to know, thanks! -Lukas --8323329-1067549723-1272575995=:30007--