From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Ku1U2-0006DS-Ju for qemu-devel@nongnu.org; Sun, 26 Oct 2008 05:00:26 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Ku1U1-0006Ce-2e for qemu-devel@nongnu.org; Sun, 26 Oct 2008 05:00:26 -0400 Received: from [199.232.76.173] (port=60050 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Ku1U0-0006CZ-SJ for qemu-devel@nongnu.org; Sun, 26 Oct 2008 05:00:24 -0400 Received: from wf-out-1314.google.com ([209.85.200.168]:46627) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1Ku1U0-0000qm-7K for qemu-devel@nongnu.org; Sun, 26 Oct 2008 05:00:24 -0400 Received: by wf-out-1314.google.com with SMTP id 27so1556435wfd.4 for ; Sun, 26 Oct 2008 02:00:22 -0700 (PDT) Message-ID: Date: Sun, 26 Oct 2008 11:00:22 +0200 From: "Blue Swirl" Subject: Re: [Qemu-devel] [5532] Replace uses of strndup (a GNU extension) with Qemu pstrdup In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org On 10/25/08, andrzej zaborowski wrote: > 2008/10/25 Blue Swirl : > > On 10/25/08, andrzej zaborowski wrote: > >> 2008/10/25 Blue Swirl : > >> > On 10/25/08, andrzej zaborowski wrote: > >> >> 2008/10/25 Blue Swirl : > >> >> > On 10/25/08, andrzej zaborowski wrote: > >> >> >> 2008/10/25 Blue Swirl : > >> >> >> > >> >> >> > Revision: 5532 > >> >> >> > http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5532 > >> >> >> > Author: blueswir1 > >> >> >> > Date: 2008-10-25 11:23:27 +0000 (Sat, 25 Oct 2008) > >> >> >> > > >> >> >> > Log Message: > >> >> >> > ----------- > >> >> >> > Replace uses of strndup (a GNU extension) with Qemu pstrdup > >> >> >> > > >> >> >> > Modified Paths: > >> >> >> > -------------- > >> >> >> > trunk/cutils.c > >> >> >> > trunk/hw/bt-hci.c > >> >> >> > trunk/qemu-common.h > >> >> >> > > >> >> >> > Modified: trunk/cutils.c > >> >> >> > =================================================================== > >> >> >> > --- trunk/cutils.c 2008-10-25 11:21:28 UTC (rev 5531) > >> >> >> > +++ trunk/cutils.c 2008-10-25 11:23:27 UTC (rev 5532) > >> >> >> > @@ -50,6 +50,18 @@ > >> >> >> > return buf; > >> >> >> > } > >> >> >> > > >> >> >> > +/* strdup with a limit */ > >> >> >> > +char *pstrdup(const char *str, size_t buf_size) > >> >> >> > +{ > >> >> >> > + size_t len; > >> >> >> > + char *buf; > >> >> >> > + > >> >> >> > + len = MIN(buf_size, strlen(str)); > >> >> >> > + buf = qemu_malloc(len); > >> >> >> > + pstrcpy(buf, len, str); > >> >> >> > + return buf; > >> >> >> > +} > >> >> >> > >> >> >> > >> >> >> I think here also pstrcpy will only copy up to buf_size - 1 characters > >> >> >> while strndup would copy buf_size chars. > >> >> > > >> >> > That is actually safer if we always want the strings to be NUL terminated. > >> >> > >> >> > >> >> strndup also always NUL terminates the string so it's just as safe, > >> >> the length is just different. > >> >> > >> >> > >> >> > > >> >> > But the allocation length is wrong, it should be MIN(buf_size, strlen(str) + 1). > >> >> > >> >> > >> >> By my reading of the manual, it should rather be MIN(buf_size, strlen(str)) + 1. > >> > > >> > But then the length could be incorrect: buf_size + 1. > >> > >> > >> That's what it should be in case lmp_name is 248 chars long. I think > >> the confusion is because you called the parameter buf_size while > >> strndup calls it n (the number of characters.. not buffer size). > > > > If strlen(lmp_name) >= 248, only first 247 should be copied and the > > final character should be NUL, because sizeof(read_local_name_rp.name) > > == buf_size == 248. > > > Nope, actually now I notice that I assumed that strndup never executes > strlen() on the parameter... I think it's a sane assumption (?). Yes, glibc uses strnlen: http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/string/strndup.c?rev=1.11&content-type=text/x-cvsweb-markup&cvsroot=glibc > read_local_name_rp.name format is specified by the bluetooth "Volume 2 > Core system package, part E - Host Controller Interface Functional > Specification" on pg. 394: > > 6.24 LOCAL NAME > <...> > If the name contained in the parameter is shorter than 248 octets, the > end of the name is indicated by a NULL octet (0x00), and the following > octets (to fill up 248 octets, which is the length of the parameter) do not > have valid values. So, in this case neither strndup nor pstrdup are correct, because you do not want the string to be NUL terminated in the strlen(lmp_name) >= 248 case?