Date: Wed, 23 Apr 2008 10:30:39 +0200 From: Bernard van Gastel <bvgastel@bitpowder.com> To: Mike Meyer <mwm-keyword-freebsdhackers2.e313df@mired.org> Cc: Garrett Cooper <yanefbsd@gmail.com>, hackers@freebsd.org Subject: Re: strdup(NULL) supposed to create SIGSEGV? Message-ID: <5F412E73-29FC-4876-A6F0-9BC269876192@bitpowder.com> In-Reply-To: <20080423025048.6b51a580@bhuda.mired.org> References: <7d6fde3d0804222240j6b42b77yd86d8accb5a959fa@mail.gmail.com> <20080423025048.6b51a580@bhuda.mired.org>
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Op 23 apr 2008, om 08:50 heeft Mike Meyer het volgende geschreven: > On Tue, 22 Apr 2008 22:40:21 -0700 > "Garrett Cooper" <yanefbsd@gmail.com> wrote: > >> Hi all, >> I made an oops in a program, which uncovered "feature" in >> strdup(2) >> that I wasn't aware of before. So I was wondering, is >> strdup(pointer = NULL) >> supposed to segfault should this just return NULL and set errno? > > Yes, it's supposed to segfault. Check out what, say, strcpy does if > you ask it to copy a NULL pointer. And this is an improvement from the > bad old days, when they would happily walk through memory starting at > 0..... I don't like it this way. I would like: strdup(NULL) = NULL strdup(string) = copy of string strcpy(NULL, NULL) = NULL strcpy(s1, NULL) = ERROR strcpy(NULL, s2) = NULL (with s2 unchanged) strcpy(s1, s2) = normal But I am not sure of the implications. Maybe in some situation it is bad... Anyone? > > Besides, errno is used to signal errors from system calls. strdup > isn't a system call, it's a library function (says so at the top of > the man page). But strdup uses malloc, which is a system call (from the strdup manual: If insufficient memory is available, NULL is returned and errno is set to ENOMEM.) Regards, Bernard
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