Update test/* directory, it seem to be a bit bit-rotted

Added README; modified sigkill_rain.c to be more understandable,
made clone.c compile; added wait_must_be_interruptible.c test;
updated Makefile and .gitignore.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>

test/.gitignore

@@ -1,7 +1,9 @@
+vfork
 fork
 sig
 skodic
-vfork
 clone
 leaderkill
 childthread
+sigkill_rain
+wait_must_be_interruptible

test/Makefile

@@ -2,11 +2,15 @@
 # $Id$
 #
 
-all: vfork fork sig skodic clone leaderkill childthread
+all: \
+    vfork fork sig skodic clone leaderkill childthread \
+    sigkill_rain wait_must_be_interruptible
 
 leaderkill: LDFLAGS += -pthread
 
 childthread: LDFLAGS += -pthread
 
 clean distclean:
-	rm -f clone vfork fork sig leaderkill *.o core
+	rm -f *.o core \
+    vfork fork sig skodic clone leaderkill childthread \
+    sigkill_rain wait_must_be_interruptible

test/README

@@ -0,0 +1,17 @@
+To run a test:
+* Run make
+* Run resulting executable(s) under strace
+* Check strace output and/or program's output and exitcode
+
+To add a new test:
+* Add its .c source to this dir
+* Add it to "all" and "clean" targets in Makefile
+* Add it to .gitignore file
+
+Please spend some time making your testcase understandable.
+For example, it may print an explanation how it should be used
+(which strace options to use, and what to look for in strace output).
+
+If possible, make it so that your testcase detects error/bug
+it is intended to test for, and prints error message and exits with 1
+if the bug is detected, instead of relying on user to peruse strace output.

test/clone.c

@@ -1,3 +1,6 @@
+/* for CLONE_foo: */
+#define _GNU_SOURCE 1
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <sched.h>

test/sigkill_rain.c

@@ -1,12 +1,10 @@
-/* This test is not yet added to Makefile */
-
 #include <stdlib.h>
 #include <stddef.h>
 #include <unistd.h>
 #include <signal.h>
-
 #include <sys/types.h>
 #include <sys/socket.h>
+#include <stdio.h>
 
 static const struct sockaddr sa;
 
@@ -16,6 +14,12 @@ int main(int argc, char *argv[])
 	int pid;
 	sigset_t set;
 
+	printf(
+"Please run me under 'strace -f -oLOG', and examine LOG file for incorrect\n"
+"decoding of interrupted syscalls: grep for 'sendto', '??" /* anti-trigraph gap */ "?', 'unavailable'.\n"
+"Pass number of iterations in argv[1] (default: 999).\n"
+	);
+
 	sigemptyset(&set);
 	sigaddset(&set, SIGCHLD);
 	sigprocmask(SIG_BLOCK, &set, NULL);
@@ -57,7 +61,7 @@ int main(int argc, char *argv[])
 				 */
 				switch (loops & 1) {
 				case 0:
-					break; /* intentional empty */
+					break; /* intentionally empty */
 				case 1:
 					sendto(-1, "Hello cruel world", 17, 0, &sa, sizeof(sa));
 					break;

test/wait_must_be_interruptible.c

@@ -0,0 +1,83 @@
+#include <unistd.h>
+#include <sys/types.h>
+#include <signal.h>
+#include <sys/wait.h>
+#include <stdio.h>
+
+/* Expected order is:
+ * Child signals parent
+ * Parent got signal
+ * Child will exit now
+ *
+ * The bug we test for: under strace -f, last two lines are swapped
+ * because wait syscall is suspended by strace and thus can't be interrupted.
+ */
+
+static const char msg1[] = "Child signals parent\n";
+static const char msg2[] = "Parent got signal\n";
+static const char msg3[] = "Child will exit now\n";
+
+static void handler(int s)
+{
+	write(1, msg2, sizeof(msg2)-1);
+}
+
+static void test()
+{
+	/* Note: in Linux, signal() installs handler with SA_RESTART flag,
+	 * therefore wait will be restarted.
+	 */
+	signal(SIGALRM, handler);
+
+	if (fork() == 0) {
+		/* child */
+		sleep(1);
+		write(1, msg1, sizeof(msg1)-1);
+		kill(getppid(), SIGALRM);
+		sleep(1);
+		write(1, msg3, sizeof(msg3)-1);
+		_exit(0);
+	}
+
+	/* parent */
+	wait(NULL);
+	_exit(0);
+}
+
+int main()
+{
+	char buf1[80];
+	char buf2[80];
+	char buf3[80];
+	int pipefd[2];
+
+	printf("Please run me under 'strace -f'\n");
+
+	pipe(pipefd);
+
+	if (fork() == 0) {
+		if (pipefd[1] != 1) {
+			dup2(pipefd[1], 1);
+			close(pipefd[1]);
+		}
+		test();
+	}
+
+	if (pipefd[0] != 0) {
+		dup2(pipefd[0], 0);
+		close(pipefd[0]);
+	}
+	fgets(buf1, 80, stdin);	printf("%s", buf1);
+	fgets(buf2, 80, stdin);	printf("%s", buf2);
+	fgets(buf3, 80, stdin);	printf("%s", buf3);
+
+	if (strcmp(buf1, msg1) != 0
+	 || strcmp(buf2, msg2) != 0
+	 || strcmp(buf3, msg3) != 0
+	) {
+		printf("ERROR! Expected order:\n%s%s%s", msg1, msg2, msg3);
+		return 1;
+	}
+	printf("Good: wait seems to be correctly interrupted by signals\n");
+	return 0;
+}