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| From | Ben Pfaff <blp@cs.stanford.edu> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Teaching C |
| Date | 2011-09-14 19:58 -0700 |
| Message-ID | <87y5xqy0iv.fsf@blp.benpfaff.org> (permalink) |
| References | (1 earlier) <pan.2011.09.14.12.31.49.174000@nowhere.com> <j4qa4f$4hh$1@speranza.aioe.org> <lnpqj2amz7.fsf@nuthaus.mib.org> <j4r4in$pv2$1@speranza.aioe.org> <lnd3f2a6kl.fsf@nuthaus.mib.org> |
Keith Thompson <kst-u@mib.org> writes: > That's interesting (and disappointing). I had guessed that, > since execv() can easily invoke any program with argv[0]==NULL, > most production-quality Unix programs would check argv[0] before > dereferencing it. Apparently I was mistaken. Under Unix, it's also easy to invoke a program without any file descriptors at all, so that stdin, stdout, and stderr are all invalid. The first fopen() successful call ends up functioning as stdin, the next as stdout, and the next as stderr. Few production-quality Unix programs defend against this, because it's a *really* unconventional way to invoke a program. No one (as far as I know) really expects it to be useful to do this. I think that invoking a program with a null argv[0] is similar, though perhaps less extreme. It's not a useful or conventional thing to do, and so there's not much value in checking carefully for it. (It could be a security issue for a setuid program. Fortunately there are few of those and they are usually both simple and carefully written.) -- Ben Pfaff http://benpfaff.org
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hexump.c jacob navia <jacob@spamsink.net> - 2011-09-09 22:53 +0200
Re: hexump.c tea strainer <nospam@nospam.com> - 2011-09-09 21:06 +0000
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-09 23:57 +0200
Re: hexump.c NicStevens <nic.stevens@gmail.com> - 2011-09-12 13:22 -0700
Re: hexump.c Ian Collins <ian-news@hotmail.com> - 2011-09-10 09:18 +1200
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-09 23:59 +0200
Re: hexump.c Ike Naar <ike@iceland.freeshell.org> - 2011-09-09 22:29 +0000
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-10 00:39 +0200
Re: hexump.c Ike Naar <ike@iceland.freeshell.org> - 2011-09-09 22:53 +0000
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-10 00:58 +0200
Re: hexump.c Seebs <usenet-nospam@seebs.net> - 2011-09-13 06:44 +0000
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-13 10:33 +0200
Re: hexump.c Fritz Wuehler <fritz@spamexpire-201109.rodent.frell.theremailer.net> - 2011-09-13 18:02 +0200
Teaching C (was Re: hexump.c) Kenneth Brody <kenbrody@spamcop.net> - 2011-09-13 16:36 -0400
Re: Teaching C (was Re: hexump.c) jacob navia <jacob@spamsink.net> - 2011-09-13 22:44 +0200
Re: Teaching C (was Re: hexump.c) Nobody <nobody@nowhere.com> - 2011-09-14 13:31 +0100
Re: Teaching C (was Re: hexump.c) jacob navia <jacob@spamsink.net> - 2011-09-14 15:27 +0200
Re: Teaching C (was Re: hexump.c) Richard Damon <news.x.richarddamon@xoxy.net> - 2011-09-14 11:49 -0400
Re: Teaching C (was Re: hexump.c) Keith Thompson <kst-u@mib.org> - 2011-09-14 13:27 -0700
Re: Teaching C (was Re: hexump.c) pacman@kosh.dhis.org (Alan Curry) - 2011-09-14 20:59 +0000
Re: Teaching C (was Re: hexump.c) Nobody <nobody@nowhere.com> - 2011-09-14 22:20 +0100
Re: Teaching C (was Re: hexump.c) James Kuyper <jameskuyper@verizon.net> - 2011-09-14 17:20 -0400
Re: Teaching C (was Re: hexump.c) pacman@kosh.dhis.org (Alan Curry) - 2011-09-15 01:51 +0000
Re: Teaching C (was Re: hexump.c) Keith Thompson <kst-u@mib.org> - 2011-09-14 19:29 -0700
Re: Teaching C (was Re: hexump.c) Keith Thompson <kst-u@mib.org> - 2011-09-14 19:21 -0700
Re: Teaching C Ben Pfaff <blp@cs.stanford.edu> - 2011-09-14 19:58 -0700
Re: Teaching C Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-09-14 21:55 -0600
Re: Teaching C James Kuyper <jameskuyper@verizon.net> - 2011-09-15 06:54 -0400
Re: Teaching C Keith Thompson <kst-u@mib.org> - 2011-09-15 11:58 -0700
Re: Teaching C Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 12:57 -0800
Re: Teaching C Nobody <nobody@nowhere.com> - 2011-09-15 14:25 +0100
Re: Teaching C Seebs <usenet-nospam@seebs.net> - 2011-09-16 22:00 +0000
Re: Teaching C (was Re: hexump.c) Kenneth Brody <kenbrody@spamcop.net> - 2011-09-14 12:54 -0400
Re: Teaching C (was Re: hexump.c) James Kuyper <jameskuyper@verizon.net> - 2011-09-14 13:26 -0400
Re: Teaching C (was Re: hexump.c) jacob navia <jacob@spamsink.net> - 2011-09-14 19:33 +0200
Re: Teaching C (was Re: hexump.c) jameskuyper <jameskuyper@verizon.net> - 2011-09-14 11:33 -0700
Re: Teaching C (was Re: hexump.c) jacob navia <jacob@spamsink.net> - 2011-09-14 21:17 +0200
Re: Teaching C (was Re: hexump.c) Kenneth Brody <kenbrody@spamcop.net> - 2011-09-16 11:47 -0400
Re: Teaching C (was Re: hexump.c) Seebs <usenet-nospam@seebs.net> - 2011-09-14 20:43 +0000
Re: Teaching C (was Re: hexump.c) Nobody <nobody@nowhere.com> - 2011-09-14 22:35 +0100
Re: Teaching C (was Re: hexump.c) gordonb.8a7i1@burditt.org (Gordon Burditt) - 2011-09-14 17:31 -0500
Re: Teaching C (was Re: hexump.c) jacob navia <jacob@spamsink.net> - 2011-09-14 19:32 +0200
Re: Teaching C (was Re: hexump.c) Kenneth Brody <kenbrody@spamcop.net> - 2011-09-16 11:27 -0400
Re: Teaching C (was Re: hexump.c) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-09-16 08:49 -0700
Re: Teaching C (was Re: hexump.c) James Kuyper <jameskuyper@verizon.net> - 2011-09-17 15:04 -0400
Re: hexump.c Keith Thompson <kst-u@mib.org> - 2011-09-13 20:31 -0700
Re: hexump.c Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-09-14 03:22 -0700
Re: hexump.c "BartC" <bc@freeuk.com> - 2011-09-14 11:40 +0100
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-14 13:54 +0200
Re: hexump.c Nobody <nobody@nowhere.com> - 2011-09-14 13:50 +0100
Re: hexump.c Keith Thompson <kst-u@mib.org> - 2011-09-14 11:35 -0700
Re: hexump.c Seebs <usenet-nospam@seebs.net> - 2011-09-14 19:12 +0000
Re: hexump.c John Bode <jfbode1029@gmail.com> - 2011-09-14 15:31 -0700
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-15 00:59 +0200
Re: hexump.c Kleuskes & Moos <kleuske@somewhere.else.net> - 2011-09-14 23:14 +0000
Re: hexump.c John Bode <jfbode1029@gmail.com> - 2011-09-15 08:52 -0700
Re: hexump.c Jens Gustedt <jens.gustedt@loria.fr> - 2011-09-14 21:22 +0200
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-14 21:26 +0200
Re: hexump.c Ian Collins <ian-news@hotmail.com> - 2011-09-15 07:32 +1200
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-14 21:44 +0200
Re: hexump.c Keith Thompson <kst-u@mib.org> - 2011-09-14 13:49 -0700
Re: hexump.c Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-09-16 00:50 +0300
Re: hexump.c Keith Thompson <kst-u@mib.org> - 2011-09-15 18:34 -0700
Re: hexump.c Keith Thompson <kst-u@mib.org> - 2011-09-14 12:16 -0700
Hypocrites jacob navia <jacob@spamsink.net> - 2011-09-14 21:40 +0200
Re: Hypocrites Keith Thompson <kst-u@mib.org> - 2011-09-14 19:11 -0700
Re: hexump.c Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-09-14 15:05 +0100
Re: hexump.c Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-09-14 07:56 -0700
Re: hexump.c "BartC" <bc@freeuk.com> - 2011-09-14 17:23 +0100
Re: hexump.c Seebs <usenet-nospam@seebs.net> - 2011-09-14 19:12 +0000
Re: hexump.c John Bode <jfbode1029@gmail.com> - 2011-09-14 15:24 -0700
Re: hexump.c gordonb.ik17p@burditt.org (Gordon Burditt) - 2011-09-09 18:16 -0500
Re: hexump.c Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-09-12 22:24 +0000
Re: hexump.c "Morris Keesan" <mkeesan@post.harvard.edu> - 2011-09-09 20:33 -0400
Re: hexump.c Ian Collins <ian-news@hotmail.com> - 2011-09-10 12:42 +1200
Re: hexump.c "Morris Keesan" <mkeesan@post.harvard.edu> - 2011-09-10 17:16 -0400
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-10 10:03 +0200
Re: hexump.c Nobody <nobody@nowhere.com> - 2011-09-10 10:04 +0100
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-10 11:41 +0200
Re: hexump.c pete <pfiland@mindspring.com> - 2011-09-10 05:51 -0400
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-10 12:38 +0200
Re: hexump.c Nobody <nobody@nowhere.com> - 2011-09-10 17:53 +0100
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-10 12:46 +0200
Re: hexump.c Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-09-10 13:03 +0100
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-10 15:34 +0200
Re: hexump.c "Morris Keesan" <mkeesan@post.harvard.edu> - 2011-09-10 17:37 -0400
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-11 00:10 +0200
Re: hexump.c Patrick Scheible <kkt@zipcon.net> - 2011-09-10 21:03 -0700
Re: hexump.c Barry Schwarz <schwarz45@yahoo.com> - 2011-09-11 00:37 -0700
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-11 13:56 +0200
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