swtpm: Implement ctrlchannel_set_client_fd()

Implement ctrlchannel_set_client_fd() to set a new client
fd and return its current value.

Use this new function to set the file descriptor to -1 upon
closing its associate file descriptor in the main loop.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>

src/swtpm/ctrlchannel.c

@@ -101,6 +101,15 @@ int ctrlchannel_get_client_fd(struct ctrlchannel *cc)
     return cc->clientfd;
 }
 
+int ctrlchannel_set_client_fd(struct ctrlchannel *cc, int fd)
+{
+    int clientfd = cc->clientfd;
+
+    cc->clientfd = fd;
+
+    return clientfd;
+}
+
 static int ctrlchannel_return_state(ptm_getstate *pgs, int fd)
 {
     uint32_t blobtype = be32toh(pgs->u.req.type);

src/swtpm/ctrlchannel.h

@@ -47,6 +47,7 @@ struct mainLoopParams;
 struct ctrlchannel *ctrlchannel_new(int fd, bool isclient);
 int ctrlchannel_get_fd(struct ctrlchannel *cc);
 int ctrlchannel_get_client_fd(struct ctrlchannel *cc);
+int ctrlchannel_set_client_fd(struct ctrlchannel *cc, int fd);
 int ctrlchannel_process_fd(int fd,
                            struct libtpms_callbacks *cbs,
                            bool *terminate,

src/swtpm/mainloop.c

@@ -262,6 +262,7 @@ skip_process:
 
     if (ctrlclntfd >= 0)
         close(ctrlclntfd);
+    ctrlchannel_set_client_fd(mlp->cc, -1);
 
     if (mlp->fd >= 0) {
         close(mlp->fd);