# Re: SEGV when lookup_* returns NULL 5 messages from 2006-11-27 to 2006-11-28. Participants: Junio C Hamano, Morten Welinder, Johannes Schindelin, Martin Waitz. Thread: https://gitlist.dev/t/43555 ## Martin Waitz, 2006-11-27 21:13 Subject: SEGV when lookup_* returns NULL Message-ID: <20061127211315.GC18810@admingilde.org> URL: https://gitlist.dev/e/20061127211315.GC18810%40admingilde.org ``` hoi :) When trying to an unmodified GIT on a repository with submodules it segfaults a lot. All the lookup_{blob,tree,commit} functions check that the object really is of the requested type and return NULL otherwise. However this NULL pointer is not checked in the calling functions. Should we make lookup_* to just die when invoked on another object-type? Or modify all the callers? Is there a sane error-handling strategy besides dying in this case? Really checking all the return values in the whole chain would be a lot of work. -- Martin Waitz ``` ## Junio C Hamano, 2006-11-27 21:55 Subject: Re: SEGV when lookup_* returns NULL Message-ID: <7vu00kftbq.fsf@assigned-by-dhcp.cox.net> URL: https://gitlist.dev/e/7vu00kftbq.fsf%40assigned-by-dhcp.cox.net In-Reply-To: <20061127211315.GC18810@admingilde.org> ``` Martin Waitz writes: > All the lookup_{blob,tree,commit} functions check that the object > really is of the requested type and return NULL otherwise. > However this NULL pointer is not checked in the calling functions. > > Should we make lookup_* to just die when invoked on another object-type? Making lookup_{specific type} die when they see unexpected type would not hurt that much, I think, aside from the possibility that some callers may check NULL to see if object already exists, but they should be using has_sha1_file() instead. ``` ## Johannes Schindelin, 2006-11-27 23:33 Subject: Re: SEGV when lookup_* returns NULL Message-ID: URL: https://gitlist.dev/e/Pine.LNX.4.63.0611280032300.30004%40wbgn013.biozentrum.uni-wuerzburg.de In-Reply-To: <7vu00kftbq.fsf@assigned-by-dhcp.cox.net> ``` Hi, On Mon, 27 Nov 2006, Junio C Hamano wrote: > Martin Waitz writes: > > > All the lookup_{blob,tree,commit} functions check that the object > > really is of the requested type and return NULL otherwise. > > However this NULL pointer is not checked in the calling functions. > > > > Should we make lookup_* to just die when invoked on another object-type? > > Making lookup_{specific type} die when they see unexpected type > would not hurt that much, I think, aside from the possibility > that some callers may check NULL to see if object already > exists, but they should be using has_sha1_file() instead. And it would totally clobber the long term goal of libifying git. Ciao, Dscho ``` ## Junio C Hamano, 2006-11-28 00:13 Subject: Re: SEGV when lookup_* returns NULL Message-ID: <7v3b84e8cg.fsf@assigned-by-dhcp.cox.net> URL: https://gitlist.dev/e/7v3b84e8cg.fsf%40assigned-by-dhcp.cox.net In-Reply-To: ``` Johannes Schindelin writes: > And it would totally clobber the long term goal of libifying git. Why? You would certainly install your own die() handler by that time I presume? ``` ## Morten Welinder, 2006-11-28 02:23 Subject: Re: SEGV when lookup_* returns NULL Message-ID: <118833cc0611271823t3b1783cem38f031ac26ac0f94@mail.gmail.com> URL: https://gitlist.dev/e/118833cc0611271823t3b1783cem38f031ac26ac0f94%40mail.gmail.com In-Reply-To: <7v3b84e8cg.fsf@assigned-by-dhcp.cox.net> ``` > Why? You would certainly install your own die() handler by that > time I presume? Likely, but short of exiting or using longjmp/setjmp what can you do in such a "die"? Not much. And most GUI users will be unhappy with the exit approach. If there is any chance that the error is not the programmer's fault, a nice library ought to pass the error back somehow. ```