qtest: unlink QEMU pid file after startup

After starting the QEMU process and initializing the QMP connection, we
can read the pid file and unlink it.

Just stash away the pid instead of the pid filename.  This way we can
avoid pid file leaks since running tests may abort(3) without cleanup.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

diff --git a/tests/libqtest.c b/tests/libqtest.c
index 359d571..dd93be8 100644 (file)
--- a/tests/libqtest.c
+++ b/tests/libqtest.c
@@ -43,8 +43,8 @@ struct QTestState
     int qmp_fd;
     bool irq_level[MAX_IRQ];
     GString *rx;
-    gchar *pid_file; /* QEMU PID file */
     int child_pid;   /* Child process created to execute QEMU */
+    pid_t qemu_pid;  /* QEMU process spawned by our child */
     char *socket_path, *qmp_socket_path;
 };
 
@@ -90,13 +90,13 @@ static int socket_accept(int sock)
     return ret;
 }
 
-static pid_t qtest_qemu_pid(QTestState *s)
+static pid_t read_pid_file(const char *pid_file)
 {
     FILE *f;
     char buffer[1024];
     pid_t pid = -1;
 
-    f = fopen(s->pid_file, "r");
+    f = fopen(pid_file, "r");
     if (f) {
         if (fgets(buffer, sizeof(buffer), f)) {
             pid = atoi(buffer);
@@ -147,7 +147,6 @@ QTestState *qtest_init(const char *extra_args)
     s->qmp_fd = socket_accept(qmpsock);
 
     s->rx = g_string_new("");
-    s->pid_file = pid_file;
     s->child_pid = pid;
     for (i = 0; i < MAX_IRQ; i++) {
         s->irq_level[i] = false;
@@ -157,8 +156,12 @@ QTestState *qtest_init(const char *extra_args)
     qtest_qmp_discard_response(s, "");
     qtest_qmp_discard_response(s, "{ 'execute': 'qmp_capabilities' }");
 
+    s->qemu_pid = read_pid_file(pid_file);
+    unlink(pid_file);
+    g_free(pid_file);
+
     if (getenv("QTEST_STOP")) {
-        kill(qtest_qemu_pid(s), SIGSTOP);
+        kill(s->qemu_pid, SIGSTOP);
     }
 
     return s;
@@ -168,19 +171,16 @@ void qtest_quit(QTestState *s)
 {
     int status;
 
-    pid_t pid = qtest_qemu_pid(s);
-    if (pid != -1) {
-        kill(pid, SIGTERM);
-        waitpid(pid, &status, 0);
+    if (s->qemu_pid != -1) {
+        kill(s->qemu_pid, SIGTERM);
+        waitpid(s->qemu_pid, &status, 0);
     }
 
     close(s->fd);
     close(s->qmp_fd);
     g_string_free(s->rx, true);
-    unlink(s->pid_file);
     unlink(s->socket_path);
     unlink(s->qmp_socket_path);
-    g_free(s->pid_file);
     g_free(s->socket_path);
     g_free(s->qmp_socket_path);
     g_free(s);