[DTrace-devel] [PATCH 19/19] test: Add another USDT open/close test

[Kris Van Hees]

On Thu, Aug 29, 2024 at 01:25:58AM -0400, eugene.loh at oracle.com wrote:
> From: Eugene Loh <eugene.loh at oracle.com>
> 
> There is already a test to check that "dtrace -l" sees USDT
> probes come and go as an executable loads and unloads a shared
> library with USDT probes.  (See dlclose1.sh.)  But it could
> also fail if DTrace does not immediately notice USDT probes
> coming or going.
> 
> Introduce a test that allows a grace period before DTrace
> notices a USDT probe come or go.
> 
> There is a deadlib.so here.  It is not needed for the test.
> It simply mimics other, similar tests.  The real thing to do
> might be to put these shared libraries, common to multiple
> tests, in test/triggers.

Perhaps a shared copy might be useful, but then again, these are generated
on-the-fly by the tests.

But keeping deadlib in this test makes no sense, since it is not used.

> Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
> ---
>  test/unittest/usdt/tst.dlclose4.r  |   5 +
>  test/unittest/usdt/tst.dlclose4.sh | 225 +++++++++++++++++++++++++++++
>  2 files changed, 230 insertions(+)
>  create mode 100644 test/unittest/usdt/tst.dlclose4.r
>  create mode 100755 test/unittest/usdt/tst.dlclose4.sh
> 
> diff --git a/test/unittest/usdt/tst.dlclose4.r b/test/unittest/usdt/tst.dlclose4.r
> new file mode 100644
> index 00000000..07927a4a
> --- /dev/null
> +++ b/test/unittest/usdt/tst.dlclose4.r
> @@ -0,0 +1,5 @@
> +as expected: USDT probe appeared
> +as expected: USDT probe disappeared
> +as expected: USDT probe appeared
> +as expected: USDT probe disappeared
> +success
> diff --git a/test/unittest/usdt/tst.dlclose4.sh b/test/unittest/usdt/tst.dlclose4.sh
> new file mode 100755
> index 00000000..015bc52c
> --- /dev/null
> +++ b/test/unittest/usdt/tst.dlclose4.sh
> @@ -0,0 +1,225 @@
> +#!/bin/bash
> +#
> +# Oracle Linux DTrace.
> +# Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
> +# Licensed under the Universal Permissive License v 1.0 as shown at
> +# http://oss.oracle.com/licenses/upl.
> +#
> +PATH=/usr/bin:/usr/sbin:$PATH
> +
> +#
> +# In this test, we send alternating USR1 and USR2 signals to an executable
> +# that responds by opening and closing, respectively, a shared library with
> +# USDT probes.  After each signal, we check "dtrace -l" to confirm that the
> +# USDT probes are and are not listed, as expected.
> +#
> +
> +dtrace=$1
> +CC=/usr/bin/gcc
> +CFLAGS=
> +
> +DIRNAME="$tmpdir/usdt-dlclose4.$$.$RANDOM"
> +mkdir -p $DIRNAME
> +cd $DIRNAME
> +
> +#
> +# Set up the source files.
> +#
> +
> +cat > Makefile <<EOF
> +all: main livelib.so deadlib.so
> +
> +main: main.o prov.o
> +	\$(CC) -o main main.o -ldl
> +
> +main.o: main.c
> +	\$(CC) -c main.c
> +
> +
> +livelib.so: livelib.o prov.o
> +	\$(CC) -shared -o livelib.so livelib.o prov.o -lc
> +
> +livelib.o: livelib.c prov.h
> +	\$(CC) -c livelib.c
> +
> +prov.o: livelib.o prov.d
> +	$dtrace -G -s prov.d livelib.o
> +
> +prov.h: prov.d
> +	$dtrace -h -s prov.d
> +
> +
> +deadlib.so: deadlib.o
> +	\$(CC) -shared -o deadlib.so deadlib.o -lc
> +
> +deadlib.o: deadlib.c
> +	\$(CC) -c deadlib.c
> +
> +clean:
> +	rm -f main.o livelib.o prov.o prov.h deadlib.o
> +
> +clobber: clean
> +	rm -f main livelib.so deadlib.so
> +EOF
> +
> +cat > prov.d <<EOF
> +provider test_prov {
> +	probe go();
> +};
> +EOF
> +
> +cat > livelib.c <<EOF
> +#include "prov.h"
> +
> +void
> +go(void)
> +{
> +	TEST_PROV_GO();
> +}
> +EOF
> +
> +cat > deadlib.c <<EOF
> +void
> +go(void)
> +{
> +}
> +EOF
> +
> +cat > main.c <<EOF
> +#include <dlfcn.h>
> +#include <unistd.h>
> +#include <signal.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +
> +void *live;
> +
> +/*
> + * Open and close livelib.so, thereby adding or removing USDT probes.
> + */
> +
> +static void my_open(int sig) {
> +	live = dlopen("./livelib.so", RTLD_LAZY | RTLD_LOCAL);
> +	if (live == NULL) {
> +		printf("dlopen of livelib.so failed: %s\n", dlerror());
> +		exit(1);
> +	}
> +}
> +
> +static void my_close(int sig) {
> +	dlclose(live);
> +}
> +
> +int
> +main(int argc, char **argv)
> +{
> +	struct sigaction act;
> +
> +	/*
> +	 * Set USR1 (USR2) to open (close) the livelib.so.
> +	 */
> +	act.sa_flags = 0;
> +	act.sa_handler = my_open;
> +	if (sigaction(SIGUSR1, &act, NULL)) {
> +		printf("set handler failed\n");
> +		return 1;
> +	}
> +	act.sa_handler = my_close;
> +	if (sigaction(SIGUSR2, &act, NULL)) {
> +		printf("set handler failed\n");
> +		return 1;
> +	}
> +
> +	/*
> +	 * Listen for signals.
> +	 */
> +	while (pause() == -1)
> +		;
> +
> +	return 0;
> +}
> +EOF
> +
> +#
> +# Build.
> +#
> +
> +make > /dev/null
> +if [ $? -ne 0 ]; then
> +	echo "failed to build" >& 2
> +	exit 1
> +fi
> +
> +# Define a function that looks for the USDT probe with "dtrace -l".
> +# For debugging, one could also check:
> +#     ls /run/dtrace/probes/$pid/test_prov$pid/livelib.so/go/go 
> +#     ls /run/dtrace/stash/dof-pid/$pid/*/parsed/test_prov:livelib.so:go:go 
> +
> +function check_USDT_probes() {
> +	$dtrace -lP test_prov$pid |& awk '
> +	    /ID *PROVIDER *MODULE *FUNCTION *NAME/ { next }
> +	    /test_prov'$pid' *livelib\.so *go *go/ { exit(0) }
> +	    /No probe matches description/ { exit(1) }'
> +	return $?
> +}
> +
> +# Define a function that checks loading the library:
> +# send USR1 and wait up to 6 seconds for the USDT probe to appear.
> +
> +function load_lib() {
> +	kill -s USR1 $pid
> +	for iter in `seq 6`; do
> +		sleep 1
> +		if check_USDT_probes; then
> +			iter=0
> +			break
> +		fi
> +	done
> +	if [[ $iter -ne 0 ]]; then
> +		echo did not see USDT probe
> +		kill -s KILL $pid
> +		exit 1
> +	fi
> +	echo as expected: USDT probe appeared
> +}
> +
> +# Define a function that checks unloading the library:
> +# send USR2 and wait up to 6 seconds for the USDT probe to disappear.
> +
> +function unload_lib() {
> +	kill -s USR2 $pid  # send USR2 to unload library and USDT probe
> +	for iter in `seq 6`; do
> +		sleep 1
> +		if ! check_USDT_probes; then
> +			iter=0
> +			break
> +		fi
> +	done
> +	if [[ $iter -ne 0 ]]; then
> +		echo still see USDT probe after timeout
> +		kill -s KILL $pid
> +		exit 1
> +	fi
> +	echo as expected: USDT probe disappeared
> +}
> +
> +# Start the process.
> +
> +./main &
> +pid=$!
> +sleep 2
> +
> +# Check.
> +
> +load_lib
> +unload_lib
> +load_lib
> +unload_lib
> +
> +# Clean up.
> +
> +kill -s KILL $pid
> +wait $pid >& /dev/null
> +
> +echo success
> +exit 0
> -- 
> 2.43.5
>