site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com On May 5, 2006, at 2:44 AM, Quinn wrote: Alternately, the fork()/exec()/wait() is encapsulated for you as well, if you use the system() library routine. Although I'm always leery of using "system" from a privileged program, like a daemon. This is mostly relevant when the program is setuid (where a potentially malicious caller can set up a specific environment to cause problems), but I take the overly cautious route and avoid it in any privileged program. I'm with Quinn here. System(3) belongs with gets(3) in that pile of tools that you never, ever use. Just my $0.01999999999. David _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.a... On May 5, 2006, at 12:02 PM, Michael Smith wrote: At 13:33 -0700 4/5/06, Terry Lambert wrote: I disagree. If you use full paths and properly vet the arguments for shell escapes (or if the paths and arguments are not extracted from user input in such a way that embedded shell escapes would be possible), the system(3) call is not substantially less safe than fork and exec. For that matter, the security difference between system(3) and popen (3) is zero, and the alternative to that involves some really, really ugly code (dup2 over top of STDERR_FILENO or whatever). That's just not something that most people will want to do if they can help it. :-) Thus, I don't think it makes sense to suggest avoiding these at all costs. You should, however, be careful when using them. Always use absolute paths. (This is important for some variants of exec(3) as well.) Avoid passing user input in as part of the argument list. If it is necessary to pass user input in as an argument, make sure it doesn't contain anything but letters, numbers, and spaces unless you -know- how to properly quote shell commands. And so on. This email sent to site_archiver@lists.apple.com