Module Name: src
Committed By: kamil
Date: Sat Nov 5 01:49:53 UTC 2016
Modified Files:
src/tests/kernel: t_ptrace.c
Log Message:
Add new test attach1 in t_ptrace
This test asserts that tracer sees process termination before the parent
Currently this is not true for NetBSD.
The problem has been reported in gnats as kern/51600.
Originally an early version of this test triggered kernel panic, that
was fixed by Christos Zoulas -- thanks! Appropriate fixes are as follows:
http://mail-index.netbsd.org/source-changes/2016/11/04/msg078868.html
http://mail-index.netbsd.org/source-changes/2016/11/04/msg078869.html
Mark this test as expected failure and linked with proper PR.
As an interesting note, this test uses pipe(2) to perform IPC. Use for
messages uint8_t message to be sure that it will never by transmitted
partially from a caller to a callee, this assumption simplifies the code.
Add local function await_zombie() that takes process identifier (pid).
This function uses the sysctl(7) interface to probe p_stat of a requested
process and compares it with LSZOMB.
Try to keep closing all unneeded file descriptors for pipes in order to not
run out of fds later.
Sponsored by <The NetBSD Foundation>.
To generate a diff of this commit:
cvs rdiff -u -r1.8 -r1.9 src/tests/kernel/t_ptrace.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/tests/kernel/t_ptrace.c
diff -u src/tests/kernel/t_ptrace.c:1.8 src/tests/kernel/t_ptrace.c:1.9
--- src/tests/kernel/t_ptrace.c:1.8 Fri Nov 4 09:08:11 2016
+++ src/tests/kernel/t_ptrace.c Sat Nov 5 01:49:53 2016
@@ -1,4 +1,4 @@
-/* $NetBSD: t_ptrace.c,v 1.8 2016/11/04 09:08:11 kamil Exp $ */
+/* $NetBSD: t_ptrace.c,v 1.9 2016/11/05 01:49:53 kamil Exp $ */
/*-
* Copyright (c) 2016 The NetBSD Foundation, Inc.
@@ -27,15 +27,17 @@
*/
#include <sys/cdefs.h>
-__RCSID("$NetBSD: t_ptrace.c,v 1.8 2016/11/04 09:08:11 kamil Exp $");
+__RCSID("$NetBSD: t_ptrace.c,v 1.9 2016/11/05 01:49:53 kamil Exp $");
#include <sys/param.h>
#include <sys/types.h>
#include <sys/ptrace.h>
+#include <sys/sysctl.h>
#include <sys/wait.h>
#include <err.h>
#include <errno.h>
#include <signal.h>
+#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
@@ -68,6 +70,34 @@ do { \
__FILE__, __LINE__, __func__, #x); \
} while (0)
+/* This function is currently designed to be run in the main/parent process */
+static void
+await_zombie(pid_t process)
+{
+ struct kinfo_proc2 p;
+ size_t len = sizeof(p);
+
+ const int name[] = {
+ [0] = CTL_KERN,
+ [1] = KERN_PROC2,
+ [2] = KERN_PROC_PID,
+ [3] = process,
+ [4] = sizeof(p),
+ [5] = 1
+ };
+
+ const size_t namelen = __arraycount(name);
+
+ /* Await the process becoming a zombie */
+ while(1) {
+ ATF_REQUIRE(sysctl(name, namelen, &p, &len, NULL, 0) == 0);
+
+ if (p.p_stat == LSZOMB)
+ break;
+
+ ATF_REQUIRE(usleep(1000) == 0);
+ }
+}
ATF_TC(traceme1);
ATF_TC_HEAD(traceme1, tc)
@@ -467,12 +497,144 @@ ATF_TC_BODY(traceme4, tc)
ATF_REQUIRE(errno == ECHILD);
}
+ATF_TC(attach1);
+ATF_TC_HEAD(attach1, tc)
+{
+ atf_tc_set_md_var(tc, "descr",
+ "Assert that tracer sees process termination before the parent");
+}
+
+ATF_TC_BODY(attach1, tc)
+{
+ int fds_totracee[2], fds_totracer[2], fds_fromtracer[2];
+ int status, rv;
+ const int exitval_tracee = 5;
+ const int exitval_tracer = 10;
+ pid_t tracee, tracer, wpid;
+ uint8_t msg = 0xde; /* dummy message for IPC based on pipe(2) */
+
+ /* XXX: Linux&FreeBSD and NetBSD have different behavior here.
+ * Tracer on NetBSD isn't promoted to observe - before child's parent -
+ * that tracee exited (and became zombie).
+ */
+ atf_tc_expect_fail("PR kern/51600");
+
+ printf("Spawn tracee\n");
+ ATF_REQUIRE(pipe(fds_totracee) == 0);
+ ATF_REQUIRE((tracee = fork()) != -1);
+ if (tracee == 0) {
+ FORKEE_ASSERT(close(fds_totracee[1]) == 0);
+
+ /* Wait for message from the parent */
+ rv = read(fds_totracee[0], &msg, sizeof(msg));
+ FORKEE_ASSERT(rv == sizeof(msg));
+
+ _exit(exitval_tracee);
+ }
+ ATF_REQUIRE(close(fds_totracee[0]) == 0);
+
+ printf("Spawn debugger\n");
+ ATF_REQUIRE(pipe(fds_totracer) == 0);
+ ATF_REQUIRE(pipe(fds_fromtracer) == 0);
+ ATF_REQUIRE((tracer = fork()) != -1);
+ if (tracer == 0) {
+ /* No IPC to communicate with the child */
+ FORKEE_ASSERT(close(fds_totracee[1]) == 0);
+
+ FORKEE_ASSERT(close(fds_totracer[1]) == 0);
+ FORKEE_ASSERT(close(fds_fromtracer[0]) == 0);
+
+ FORKEE_ASSERT(ptrace(PT_ATTACH, tracee, NULL, 0) != -1);
+
+ /* Wait for tracee and assert that it was stopped w/ SIGSTOP */
+ wpid = waitpid(tracee, &status, 0);
+ FORKEE_ASSERTX(wpid == tracee);
+ FORKEE_ASSERTX(!WIFEXITED(status));
+ FORKEE_ASSERTX(!WIFCONTINUED(status));
+ FORKEE_ASSERTX(!WIFSIGNALED(status));
+ FORKEE_ASSERTX(WIFSTOPPED(status));
+ FORKEE_ASSERTX(WSTOPSIG(status) == SIGSTOP);
+
+ /* Resume tracee with PT_CONTINUE */
+ FORKEE_ASSERT(ptrace(PT_CONTINUE, tracee, (void *)1, 0) != -1);
+
+ /* Inform parent that tracer has attached to tracee */
+ rv = write(fds_fromtracer[1], &msg, sizeof(msg));
+ FORKEE_ASSERT(rv == sizeof(msg));
+
+ /* Wait for parent */
+ rv = read(fds_totracer[0], &msg, sizeof(msg));
+ FORKEE_ASSERT(rv == sizeof(msg));
+
+ /* Wait for tracee and assert that it exited */
+ wpid = waitpid(tracee, &status, 0);
+ FORKEE_ASSERTX(wpid == tracee);
+ FORKEE_ASSERTX(WIFEXITED(status));
+ FORKEE_ASSERTX(!WIFCONTINUED(status));
+ FORKEE_ASSERTX(!WIFSIGNALED(status));
+ FORKEE_ASSERTX(!WIFSTOPPED(status));
+ FORKEE_ASSERTX(WEXITSTATUS(status) == exitval_tracee);
+
+ _exit(exitval_tracer);
+ }
+ ATF_REQUIRE(close(fds_totracer[0]) == 0);
+ ATF_REQUIRE(close(fds_fromtracer[1]) == 0);
+
+ printf("Wait for the tracer to attach to the tracee\n");
+ rv = read(fds_fromtracer[0], &msg, sizeof(msg));
+ ATF_REQUIRE(rv == sizeof(msg));
+
+ printf("Resume the tracee and let it exit\n");
+ rv = write(fds_totracee[1], &msg, sizeof(msg));
+ ATF_REQUIRE(rv == sizeof(msg));
+
+ printf("fds_totracee is no longer needed - close it\n");
+ ATF_REQUIRE(close(fds_totracee[1]) == 0);
+
+ printf("Detect that tracee is zombie\n");
+ await_zombie(tracee);
+
+ printf("Assert that there is no status about tracee - "
+ "Tracer must detect zombie first\n");
+ wpid = waitpid(tracee, &status, WNOHANG);
+ ATF_REQUIRE(wpid == 0);
+
+ printf("Resume the tracer and let it detect exited tracee\n");
+ rv = write(fds_totracer[1], &msg, sizeof(msg));
+ ATF_REQUIRE(rv == sizeof(msg));
+
+ printf("Wait for tracer to finish its job and exit\n");
+ wpid = waitpid(tracer, &status, 0);
+ ATF_REQUIRE(wpid == tracer);
+ ATF_REQUIRE(WIFEXITED(status));
+ ATF_REQUIRE(!WIFCONTINUED(status));
+ ATF_REQUIRE(!WIFSIGNALED(status));
+ ATF_REQUIRE(!WIFSTOPPED(status));
+ ATF_REQUIRE(WEXITSTATUS(status) == exitval_tracer);
+
+ printf("Wait for tracer to finish its job and exit\n");
+ wpid = waitpid(tracee, &status, WNOHANG);
+ ATF_REQUIRE(wpid == tracee);
+ ATF_REQUIRE(WIFEXITED(status));
+ ATF_REQUIRE(!WIFCONTINUED(status));
+ ATF_REQUIRE(!WIFSIGNALED(status));
+ ATF_REQUIRE(!WIFSTOPPED(status));
+ ATF_REQUIRE(WEXITSTATUS(status) == exitval_tracee);
+
+ printf("fds_fromtracer is no longer needed - close it\n");
+ ATF_REQUIRE(close(fds_fromtracer[0]) == 0);
+
+ printf("fds_totracer is no longer needed - close it\n");
+ ATF_REQUIRE(close(fds_totracer[1]) == 0);
+}
+
ATF_TP_ADD_TCS(tp)
{
ATF_TP_ADD_TC(tp, traceme1);
ATF_TP_ADD_TC(tp, traceme2);
ATF_TP_ADD_TC(tp, traceme3);
ATF_TP_ADD_TC(tp, traceme4);
+ ATF_TP_ADD_TC(tp, attach1);
return atf_no_error();
}
