From f91c9fe814916c2865ea76fda3714f39760183cc Mon Sep 17 00:00:00 2001
From: "Dmitry V. Levin" <ldv@altlinux.org>
Date: Tue, 6 Dec 2016 00:32:06 +0000
Subject: [PATCH] tests: robustify attach-p-cmd.test against race conditions

Introduce a synchronization mechanism between attach-p-cmd-p
and attach-p-cmd-cmd processes.

* tests/attach-p-cmd-cmd.c: Include <errno.h> and <sys/stat.h>.
(main): Wait for the lock directory creation by attach-p-cmd-p.
* tests/attach-p-cmd-p.c: Include <errno.h> and <sys/stat.h>.
(main): Create a lock directory and wait for its removal
by attach-p-cmd-cmd.
* tests/attach-p-cmd.test: Assume that test programs work.
---
 tests/attach-p-cmd-cmd.c | 13 +++++++++++--
 tests/attach-p-cmd-p.c   | 21 +++++++++++++++++++--
 tests/attach-p-cmd.test  |  5 ++---
 3 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/tests/attach-p-cmd-cmd.c b/tests/attach-p-cmd-cmd.c
index edfff206..d0f824e9 100644
--- a/tests/attach-p-cmd-cmd.c
+++ b/tests/attach-p-cmd-cmd.c
@@ -28,19 +28,28 @@
  */
 
 #include "tests.h"
+#include <errno.h>
 #include <stdio.h>
+#include <sys/stat.h>
 #include <unistd.h>
 
 int
 main(void)
 {
+	static const char lockdir[] = "attach-p-cmd.test-lock";
+	/* wait for the lock directory to be created by peer */
+	while (rmdir(lockdir)) {
+		if (ENOENT != errno)
+			perror_msg_and_fail("rmdir: %s", lockdir);
+	}
+
 	static const char dir[] = "attach-p-cmd.test cmd";
 	pid_t pid = getpid();
 	int rc = chdir(dir);
 
-	printf("%-5d chdir(\"%s\") = %d %s (%m)\n"
+	printf("%-5d chdir(\"%s\") = %s\n"
 	       "%-5d +++ exited with 0 +++\n",
-	       pid, dir, rc, errno2name(), pid);
+	       pid, dir, sprintrc(rc), pid);
 
 	return 0;
 }
diff --git a/tests/attach-p-cmd-p.c b/tests/attach-p-cmd-p.c
index d63371d4..254d19ae 100644
--- a/tests/attach-p-cmd-p.c
+++ b/tests/attach-p-cmd-p.c
@@ -28,9 +28,11 @@
  */
 
 #include "tests.h"
+#include <errno.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <sys/stat.h>
 #include <unistd.h>
 
 static void
@@ -43,12 +45,27 @@ main(void)
 {
 	const struct sigaction act = { .sa_handler = handler };
 	if (sigaction(SIGALRM, &act, NULL))
-		perror_msg_and_skip("sigaction");
+		perror_msg_and_fail("sigaction");
 
 	sigset_t mask = {};
 	sigaddset(&mask, SIGALRM);
 	if (sigprocmask(SIG_UNBLOCK, &mask, NULL))
-		perror_msg_and_skip("sigprocmask");
+		perror_msg_and_fail("sigprocmask");
+
+	static const char lockdir[] = "attach-p-cmd.test-lock";
+	/* create a lock directory */
+	if (mkdir(lockdir, 0700))
+		perror_msg_and_fail("mkdir: %s", lockdir);
+
+	/* wait for the lock directory to be removed by peer */
+	while (mkdir(lockdir, 0700)) {
+		if (EEXIST != errno)
+			perror_msg_and_fail("mkdir: %s", lockdir);
+	}
+
+	/* remove the lock directory */
+	if (rmdir(lockdir))
+		perror_msg_and_fail("rmdir: %s", lockdir);
 
 	alarm(1);
 	pause();
diff --git a/tests/attach-p-cmd.test b/tests/attach-p-cmd.test
index 27797196..2068cf1d 100755
--- a/tests/attach-p-cmd.test
+++ b/tests/attach-p-cmd.test
@@ -31,16 +31,15 @@
 
 run_prog_skip_if_failed \
 	kill -0 $$
-run_prog ./attach-p-cmd-cmd > /dev/null
-run_prog ./attach-p-cmd-p > /dev/null
 
+rm -rf attach-p-cmd.test-lock
 rm -f "$OUT"
 ./set_ptracer_any ./attach-p-cmd-p >> "$OUT" &
 tracee_pid=$!
 
 while ! [ -s "$OUT" ]; do
 	kill -0 $tracee_pid 2> /dev/null ||
-		fail_ 'set_ptracer_any sleep failed'
+		fail_ 'set_ptracer_any ./attach-p-cmd-p failed'
 done
 
 run_strace -a30 -echdir -p $tracee_pid ./attach-p-cmd-cmd > "$OUT"
-- 
2.40.0