[Qemu-devel] [PATCH 3/3] qtest: kill QEMU process on g_assert() failure

[Stefan Hajnoczi <stefanha@redhat.com>]

The QEMU process stays running if the test case fails.  This patch fixes
the leak by installing a SIGABRT signal handler which invokes
qtest_end().

In order to make that work for assertion failures during qtest_init(),
we need to initialize QTestState fields including file descriptors and
pids carefully.  qtest_quit() is then safe to call even during
qtest_init().

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 tests/libqtest.c | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/tests/libqtest.c b/tests/libqtest.c
index 8b2b2d7..09a0481 100644
--- a/tests/libqtest.c
+++ b/tests/libqtest.c
@@ -44,6 +44,7 @@ struct QTestState
     bool irq_level[MAX_IRQ];
     GString *rx;
     pid_t qemu_pid;  /* our child QEMU process */
+    struct sigaction sigact_old; /* restored on exit */
 };
 
 #define g_assert_no_errno(ret) do { \
@@ -88,6 +89,11 @@ static int socket_accept(int sock)
     return ret;
 }
 
+static void sigabrt_handler(int signo)
+{
+    qtest_end();
+}
+
 QTestState *qtest_init(const char *extra_args)
 {
     QTestState *s;
@@ -96,11 +102,22 @@ QTestState *qtest_init(const char *extra_args)
     gchar *qmp_socket_path;
     gchar *command;
     const char *qemu_binary;
+    struct sigaction sigact;
 
     qemu_binary = getenv("QTEST_QEMU_BINARY");
     g_assert(qemu_binary != NULL);
 
-    s = g_malloc(sizeof(*s));
+    s = g_malloc0(sizeof(*s));
+    s->fd = -1;
+    s->qmp_fd = -1;
+    s->qemu_pid = -1;
+
+    /* Catch SIGABRT to clean up on g_assert() failure */
+    sigact = (struct sigaction){
+        .sa_handler = sigabrt_handler,
+        .sa_flags = SA_RESETHAND,
+    };
+    sigaction(SIGABRT, &sigact, &s->sigact_old);
 
     socket_path = g_strdup_printf("/tmp/qtest-%d.sock", getpid());
     qmp_socket_path = g_strdup_printf("/tmp/qtest-%d.qmp", getpid());
@@ -150,13 +167,19 @@ void qtest_quit(QTestState *s)
 {
     int status;
 
+    sigaction(SIGABRT, &s->sigact_old, NULL);
+
     if (s->qemu_pid != -1) {
         kill(s->qemu_pid, SIGTERM);
         waitpid(s->qemu_pid, &status, 0);
     }
 
-    close(s->fd);
-    close(s->qmp_fd);
+    if (s->fd != -1) {
+        close(s->fd);
+    }
+    if (s->qmp_fd != -1) {
+        close(s->qmp_fd);
+    }
     g_string_free(s->rx, true);
     g_free(s);
 }
-- 
1.8.5.3