[Xen-devel] [PATCH v5 02/15] libxl_qmp: Connect to QMP socket

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

This is a first patch to implement libxl__ev_qmp, it only connects to
the QMP socket of QEMU and registers a fd callback that does nothing.

Callback functions will be implemented in following patches.

Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---

Notes:
    v5:
        nits
        use a define instead of a static int for 
QMP_CAPABILITY_NEGOCIATION_MSGID
        use a switch in qmp_ev_callback_writable to check qmp_state
        Add a description of the different value of libxl__qmp_state enum.

 tools/libxl/libxl_internal.h | 16 +++++++
 tools/libxl/libxl_qmp.c      | 91 ++++++++++++++++++++++++++++++++++++
 2 files changed, 107 insertions(+)

diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 979a9947f0..9bcab39f00 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -414,6 +414,19 @@ _hidden int libxl__ev_qmp_send(libxl__gc *gc, 
libxl__ev_qmp *ev,
                                const char *cmd, libxl__json_object *args);
 _hidden void libxl__ev_qmp_dispose(libxl__gc *gc, libxl__ev_qmp *ev);
 
+typedef enum {
+    /* initial state */
+    qmp_state_disconnected = 1,
+    /* connected to QMP socket, waiting for greeting message */
+    qmp_state_connecting,
+    /* greeting message received */
+    qmp_state_greeting,
+    /* qmp_capabilities command sent, waiting for reply */
+    qmp_state_capability_negotiation,
+    /* ready to send commands */
+    qmp_state_connected,
+} libxl__qmp_state;
+
 struct libxl__ev_qmp {
     /* caller should include this in their own struct */
     /* caller must fill these in, and they must all remain valid */
@@ -423,6 +436,9 @@ struct libxl__ev_qmp {
 
     /* remaining fields are private to libxl_ev_qmp_* */
     int id;
+    libxl__carefd *qmp_cfd;
+    libxl__ev_fd qmp_efd;
+    libxl__qmp_state qmp_state;
 };
 
 
diff --git a/tools/libxl/libxl_qmp.c b/tools/libxl/libxl_qmp.c
index bdf1778cf1..167829a5ec 100644
--- a/tools/libxl/libxl_qmp.c
+++ b/tools/libxl/libxl_qmp.c
@@ -1280,6 +1280,97 @@ int libxl__qmp_initializations(libxl__gc *gc, uint32_t 
domid,
     return ret;
 }
 
+/* ------------ Implementation of libxl__ev_qmp ---------------- */
+
+static void qmp_ev_fd_callback(libxl__egc *egc, libxl__ev_fd *ev_fd,
+                               int fd, short events, short revents)
+{
+}
+
+static int qmp_ev_connect(libxl__gc *gc, libxl__ev_qmp *ev)
+{
+    int rc, r;
+    struct sockaddr_un un;
+    const char *qmp_socket_path;
+
+    if (ev->qmp_state != qmp_state_disconnected)
+        return 0;
+
+    qmp_socket_path = libxl__qemu_qmp_path(gc, ev->domid);
+
+    LOGD(DEBUG, ev->domid, "Connecting to %s", qmp_socket_path);
+
+    libxl__carefd_begin();
+    ev->qmp_cfd = libxl__carefd_opened(CTX, socket(AF_UNIX, SOCK_STREAM, 0));
+    if (!ev->qmp_cfd) {
+        LOGED(ERROR, ev->domid, "socket() failed");
+        rc = ERROR_FAIL;
+        goto out;
+    }
+    rc = libxl_fd_set_nonblock(CTX, libxl__carefd_fd(ev->qmp_cfd), 1);
+    if (rc)
+        goto out;
+
+    rc = libxl__prepare_sockaddr_un(gc, &un, qmp_socket_path, "QMP socket");
+    if (rc)
+        goto out;
+
+    r = connect(libxl__carefd_fd(ev->qmp_cfd),
+                (struct sockaddr *) &un, sizeof(un));
+    if (r) {
+        LOGED(ERROR, ev->domid, "Failed to connect to QMP socket %s",
+              qmp_socket_path);
+        rc = ERROR_FAIL;
+        goto out;
+    }
+
+    rc = libxl__ev_fd_register(gc, &ev->qmp_efd, qmp_ev_fd_callback,
+                               libxl__carefd_fd(ev->qmp_cfd), POLLIN);
+    if (rc)
+        goto out;
+
+    ev->qmp_state = qmp_state_connecting;
+    return 0;
+
+out:
+    libxl__carefd_close(ev->qmp_cfd);
+    ev->qmp_cfd = NULL;
+    return rc;
+}
+
+
+/*
+ * libxl__ev_qmp_*
+ */
+
+void libxl__ev_qmp_init(libxl__ev_qmp *ev)
+{
+    ev->id = -1;
+
+    ev->qmp_cfd = NULL;
+    libxl__ev_fd_init(&ev->qmp_efd);
+    ev->qmp_state = qmp_state_disconnected;
+}
+
+int libxl__ev_qmp_send(libxl__gc *gc, libxl__ev_qmp *ev,
+                       const char *cmd, libxl__json_object *args)
+{
+    LOGD(DEBUG, ev->domid, " ev %p, cmd '%s'", ev, cmd);
+
+    /* Connect to QEMU if not already connected */
+    return qmp_ev_connect(gc, ev);
+}
+
+void libxl__ev_qmp_dispose(libxl__gc *gc, libxl__ev_qmp *ev)
+{
+    LOGD(DEBUG, ev->domid, " ev %p", ev);
+
+    libxl__ev_fd_deregister(gc, &ev->qmp_efd);
+    libxl__carefd_close(ev->qmp_cfd);
+
+    libxl__ev_qmp_init(ev);
+}
+
 /*
  * Local variables:
  * mode: C
-- 
Anthony PERARD


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