diff options
| -rw-r--r-- | regress/sys/kern/dup2_self/dup2_self.c | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/regress/sys/kern/dup2_self/dup2_self.c b/regress/sys/kern/dup2_self/dup2_self.c index 3b0a3936ae7..08a4cd4a94c 100644 --- a/regress/sys/kern/dup2_self/dup2_self.c +++ b/regress/sys/kern/dup2_self/dup2_self.c @@ -1,4 +1,4 @@ -/* $OpenBSD: dup2_self.c,v 1.1 2002/02/08 18:47:46 art Exp $ */ +/* $OpenBSD: dup2_self.c,v 1.2 2002/02/18 13:32:08 art Exp $ */ /* * Written by Artur Grabowski <art@openbsd.org> 2002 Public Domain. */ @@ -8,6 +8,26 @@ #include <err.h> #include <fcntl.h> +/* + * We're testing a small tweak in dup2 semantics. Normally dup and dup2 + * will clear the close-on-exec flag on the new fd (which appears to be + * an implementation mistake from start and not some planned behavior). + * In todays implementations of dup and dup2 we have to make an effort + * to really clear that flag. But all tested implementations of dup2 have + * another tweak. If we dup2(old, new) when old == new, the syscall + * short-circuits and returns early (because there is no need to do all + * the work (and there is a risk for serious mistakes)). So although the + * docs say that dup2 should "take 'old', close 'new' perform a dup(2) of + * 'old' into 'new'" the docs are not really followed because close-on-exec + * is not cleared on 'new'. + * + * Since everyone has this bug, we pretend that this is the way it is + * supposed to be and test here that it really works that way. + * + * This is a fine example on where two separate implementation fuckups + * take out each other and make the end-result the way it was meant to be. + */ + int main() { |