Add some code to automatically exit the kernel test

I occasionally test libcap against a custom kernel using QEMU.
Now I have a simple exit binary for exiting with status.

From the top level, one can use:

  make ktest

However, for more control:

  cd kdebug
  make test

If you want to look around after the tests run:

  make shell

Exit the shell & QEMU with ctrl-D (or exit).

Signed-off-by: Andrew G. Morgan <morgan@kernel.org>

Makefile

@@ -8,7 +8,7 @@ include Make.Rules
 # flags
 #
 
-all install clean kdebug: %: %-here
+all install clean: %: %-here
 	$(MAKE) -C libcap $@
 ifneq ($(PAM_CAP),no)
 	$(MAKE) -C pam_cap $@
@@ -52,6 +52,9 @@ ifeq ($(GOLANG),yes)
 endif
 	$(MAKE) -C progs $@
 
+ktest: all
+	$(MAKE) -C kdebug test
+
 sudotest: all
 	$(MAKE) -C tests $@
 ifneq ($(PAM_CAP),no)

kdebug/Makefile

@@ -1,9 +1,17 @@
 topdir=$(shell pwd)/..
 include ../Make.Rules
 
-test:
+test: exit
+	rm -f interactive
 	./test-kernel.sh
 
+shell: exit
+	touch interactive
+	./test-kernel.sh
+
+exit: exit.c
+	$(CC) -O2 $< -o $@ --static
+
 all:
 	@echo cd to kdebug to test a kernel build
 
@@ -11,4 +19,4 @@ install:
 
 clean:
 	$(LOCALCLEAN)
-	rm -f fs.conf initramfs.img
+	rm -f fs.conf initramfs.img exit interactive

kdebug/exit.c

@@ -0,0 +1,36 @@
+/*
+ * See https://stackoverflow.com/questions/42208228/how-to-automatically-close-the-execution-of-the-qemu-after-end-of-process
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/io.h>
+#include <unistd.h>
+
+#define SHUTDOWN_PORT 0x604
+#define EXIT_PORT     0x501
+
+static void clean_exit(void) {
+    ioperm(SHUTDOWN_PORT, 16, 1);
+    outw(0x2000, SHUTDOWN_PORT);
+}
+
+int main(int argc, char **argv) {
+    int status;
+    if (argc != 2) {
+	clean_exit();
+    }
+    status = atoi(argv[1]);
+    printf("exiting with status %d (in three seconds)\n", status);
+    sleep(3);
+    if (!status) {
+	clean_exit();
+    }
+    ioperm(EXIT_PORT, 8, 1);
+    /*
+     * status returned is 1+(2*orig_status)
+     */
+    outb(status-1, EXIT_PORT);
+    printf("didn't exit.. did you include '-device isa-debug-exit'"
+	   " in qemu command?\n");
+    exit(1);
+}

kdebug/test-init.sh

@@ -10,5 +10,10 @@ echo done
 
 echo Hello, World
 cd /root
-./quicktest.sh
-sh -i
+if [ -f ./interactive ]; then
+    ./quicktest.sh
+    sh -i
+else
+    ./quicktest.sh || ./exit 1
+fi
+./exit

kdebug/test-kernel.sh

@@ -47,6 +47,7 @@ file /root/getcap $HERE/../progs/getcap 0755 0 0
 file /root/capsh $HERE/../progs/capsh 0755 0 0
 file /root/getpcaps $HERE/../progs/getpcaps 0755 0 0
 file /root/tcapsh-static $HERE/../progs/tcapsh-static 0755 0 0
+file /root/exit $HERE/exit 0755 0 0
 EOF
 
 # convenience for some local experiments
@@ -55,6 +56,10 @@ if [ -f "$HERE/extras.sh" ]; then
     . "$HERE/extras.sh"
 fi
 
+if [ -f "$HERE/interactive" ]; then
+    echo "file /root/interactive $HERE/interactive 0755 0 0" >> fs.conf
+fi
+
 COMMANDS="awk cat chmod cp dmesg fgrep id less ln ls mkdir mount pwd rm rmdir sh sort umount uniq vi"
 for f in $COMMANDS; do
     echo slink /bin/$f /sbin/busybox 0755 0 0 >> fs.conf
@@ -73,4 +78,5 @@ qemu-system-$(uname -m) -m 1024 \
 		   -kernel $KERNEL \
 		   -initrd initramfs.img \
 		   -append "$APPEND" \
-		   -smp sockets=2,dies=1,cores=4
+		   -smp sockets=2,dies=1,cores=4 \
+		   -device isa-debug-exit