Re: t5570 trap use in start/stop_git_daemon
On Fri, Feb 13, 2015 at 02:44:03AM -0500, Jeff King wrote:
On Thu, Feb 12, 2015 at 03:31:12PM -0500, Randall S. Becker wrote:
On the NonStop port, we found that trap was causing an issue with test
success for t5570. When start_git_daemon completes, the shell (ksh,bash) on
this platform is sending a signal 0 that is being caught and acted on by the
trap command within the start_git_daemon and stop_git_daemon functions. I am
taking this up with the operating system group,
Yeah, that seems wrong. If it were a subshell, even, I could see some
argument for it, but it seems odd to trap 0 when a function returns
(bash does have a RETURN trap, which AFAIK is bash-specific, but it
should not trigger a 0-trap).
Hmm, today I learned something new about ksh. Apparently when you use
the function keyword to define a function like:
function foo {
trap 'echo trapped' EXIT
}
echo before
foo
echo after
then the trap runs when the function exits! If you declare the same
function as:
foo() {
trap 'echo trapped' EXIT
}
it behaves differently. POSIX shell does not have the function keyword,
of course, and we are not using it here. Bash _does_ have the function
keyword, but seems to behave POSIX-y even when it is present. I.e.,
running the first script:
$ ksh foo.sh
before
trapped
after
$ bash foo.sh
before
after
trapped
$ dash foo.sh
foo.sh: 3: foo.sh: function: not found
foo.sh: 5: foo.sh: Syntax error: } unexpected
Switching to the second form, all three produce:
before
after
trapped
I don't know if that is all helpful to your bug-tracking or analysis,
but for whatever reason it looks like your ksh is using localized traps
for both forms of function. But as far as I know, bash has never behaved
that way (I just grepped its CHANGES file for mentions of trap and found
nothing likely).
-Peff
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Re: t5570 trap use in start/stop_git_daemon
Jeff King peff at peff.net writes:
On Fri, Feb 13, 2015 at 02:44:03AM -0500, Jeff King wrote:
On Thu, Feb 12, 2015 at 03:31:12PM -0500, Randall S. Becker wrote:
snip
Hmm, today I learned something new about ksh. Apparently when you use
the function keyword to define a function like:
function foo {
trap 'echo trapped' EXIT
}
echo before
foo
echo after
then the trap runs when the function exits! If you declare the same
function as:
foo() {
trap 'echo trapped' EXIT
}
it behaves differently. POSIX shell does not have the function keyword,
of course, and we are not using it here. Bash _does_ have the function
keyword, but seems to behave POSIX-y even when it is present. I.e.,
running the first script:
$ ksh foo.sh
before
trapped
after
$ bash foo.sh
before
after
trapped
$ dash foo.sh
foo.sh: 3: foo.sh: function: not found
foo.sh: 5: foo.sh: Syntax error: } unexpected
Switching to the second form, all three produce:
before
after
trapped
I don't know if that is all helpful to your bug-tracking or analysis,
but for whatever reason it looks like your ksh is using localized traps
for both forms of function. But as far as I know, bash has never behaved
that way (I just grepped its CHANGES file for mentions of trap and found
nothing likely).
-Peff
Both versions produce your first output on our platform
$ ksh foo1.sh
before
trapped
after
$ bash foo1.sh
before
after
trapped
$ ksh foo2.sh
before
trapped
after
$ bash foo2.sh
before
after
trapped
$
This might have been one (or even _the_) reason why we picked bash as our
SHELL_PATH in config.mak.uname (I don't remember, it's more than 2 years
ago), not sure which shell Randall's test used?
bye, Jojo
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RE: t5570 trap use in start/stop_git_daemon
On 2015/02/13 3:58AM Joachim Schmitz wrote:
Jeff King peff at peff.net writes:
On Fri, Feb 13, 2015 at 02:44:03AM -0500, Jeff King wrote:
On Thu, Feb 12, 2015 at 03:31:12PM -0500, Randall S. Becker wrote:
snip
Hmm, today I learned something new about ksh. Apparently when you use
the function keyword to define a function like:
function foo {
trap 'echo trapped' EXIT
}
echo before
foo
echo after
then the trap runs when the function exits! If you declare the same
function as:
foo() {
trap 'echo trapped' EXIT
}
it behaves differently. POSIX shell does not have the function keyword,
of course, and we are not using it here. Bash _does_ have the function
keyword, but seems to behave POSIX-y even when it is present. I.e.,
running the first script:
$ ksh foo.sh
before
trapped
after
$ bash foo.sh
before
after
trapped
snip
Both versions produce your first output on our platform
$ ksh foo1.sh
before
trapped
after
$ bash foo1.sh
before
after
trapped
$ ksh foo2.sh
before
trapped
after
$ bash foo2.sh
before
after
trapped
$
This might have been one (or even _the_) reason why we picked bash as our
SHELL_PATH in config.mak.uname (I don't remember, it's more than 2 years
ago), not sure which shell Randall's test used?
I tested both for trying to get t5570 to work. No matter which, without
resetting the trap, function return would kill the git-daemon and the test
would fail.
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Re: t5570 trap use in start/stop_git_daemon
On Thu, Feb 12, 2015 at 03:31:12PM -0500, Randall S. Becker wrote:
On the NonStop port, we found that trap was causing an issue with test
success for t5570. When start_git_daemon completes, the shell (ksh,bash) on
this platform is sending a signal 0 that is being caught and acted on by the
trap command within the start_git_daemon and stop_git_daemon functions. I am
taking this up with the operating system group,
Yeah, that seems wrong. If it were a subshell, even, I could see some
argument for it, but it seems odd to trap 0 when a function returns
(bash does have a RETURN trap, which AFAIK is bash-specific, but it
should not trigger a 0-trap).
but in any case, it may be
appropriate to include a trap reset at the end of both functions, as below.
I verified this change on SUSE Linux.
diff --git a/t/lib-git-daemon.sh b/t/lib-git-daemon.sh
index bc4b341..543e98a 100644
--- a/t/lib-git-daemon.sh
+++ b/t/lib-git-daemon.sh
@@ -62,6 +62,7 @@ start_git_daemon() {
test_skip_or_die $GIT_TEST_GIT_DAEMON \
git daemon failed to start
fi
+ trap '' EXIT
}
I don't think this is the right thing to do. That trap is meant to live
beyond the function's return. Without it, there is nothing to clean up
the running git-daemon if we exit the test script prematurely (e.g., by
a test failing in immediate-mode). We pollute the environment with a
running process which would cause subsequent test runs to fail.
stop_git_daemon() {
@@ -84,4 +85,6 @@ stop_git_daemon() {
fi
GIT_DAEMON_PID=
rm -f git_daemon_output
+
+ trap '' EXIT
}
This one is slightly less bad, in that we are dropping our
daemon-specific cleanup here anyway. But the appropriate trap is still:
trap 'die' EXIT
which we set earlier in the function. Without it, the test harness's
ability to detect a premature failure is lost.
So I do not know quite what is going on with your shell, but turning off
the traps in these functions is definitely not an acceptable (general)
workaround; it makes things much worse on working platforms.
-Peff
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