[Xen-devel] [PATCH v3 13/31] libxl_qmp: Separate QMP message generation from qmp_send_prepare

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

This new function qmp_prepare_qmp_cmd() can be reuse later when
introducing a different way to communicate with a QMP server,
libxl__ev_qmp.

Also, add the QMP end of command '\r\n' into the generated string.

Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
 tools/libxl/libxl_qmp.c | 60 +++++++++++++++++++++++++++++------------
 1 file changed, 43 insertions(+), 17 deletions(-)

diff --git a/tools/libxl/libxl_qmp.c b/tools/libxl/libxl_qmp.c
index 1184ca823f..9f4c3f5c20 100644
--- a/tools/libxl/libxl_qmp.c
+++ b/tools/libxl/libxl_qmp.c
@@ -578,17 +578,17 @@ static int qmp_next(libxl__gc *gc, libxl__qmp_handler 
*qmp)
     return rc;
 }
 
-static char *qmp_send_prepare(libxl__gc *gc, libxl__qmp_handler *qmp,
-                              const char *cmd, libxl__json_object *args,
-                              qmp_callback_t callback, void *opaque,
-                              qmp_request_context *context)
+static char *qmp_prepare_qmp_cmd(libxl__gc *gc,
+                                 const char *cmd,
+                                 const libxl__json_object *args,
+                                 int id,
+                                 size_t *len_r)
 {
-    const unsigned char *buf = NULL;
-    char *ret = NULL;
-    libxl_yajl_length len = 0;
+    const unsigned char *buf;
+    libxl_yajl_length len;
     yajl_gen_status s;
     yajl_gen hand;
-    callback_id_pair *elm = NULL;
+    char *ret = NULL;
 
     hand = libxl_yajl_gen_alloc(NULL);
 
@@ -600,7 +600,7 @@ static char *qmp_send_prepare(libxl__gc *gc, 
libxl__qmp_handler *qmp,
     libxl__yajl_gen_asciiz(hand, "execute");
     libxl__yajl_gen_asciiz(hand, cmd);
     libxl__yajl_gen_asciiz(hand, "id");
-    yajl_gen_integer(hand, ++qmp->last_id_used);
+    yajl_gen_integer(hand, id);
     if (args) {
         libxl__yajl_gen_asciiz(hand, "arguments");
         libxl__json_object_to_yajl_gen(gc, hand, args);
@@ -610,6 +610,36 @@ static char *qmp_send_prepare(libxl__gc *gc, 
libxl__qmp_handler *qmp,
     s = yajl_gen_get_buf(hand, &buf, &len);
 
     if (s) {
+        goto out;
+    }
+
+    ret = libxl__malloc(NOGC, len + 3);
+    strncpy(ret, (const char *)buf, len + 3);
+    strncpy(ret + len, "\r\n", 3);
+    len += 2;
+
+    if (len_r)
+        *len_r = len;
+
+out:
+    yajl_gen_free(hand);
+    return ret;
+}
+
+static char *qmp_send_prepare(libxl__gc *gc, libxl__qmp_handler *qmp,
+                              const char *cmd, libxl__json_object *args,
+                              qmp_callback_t callback, void *opaque,
+                              qmp_request_context *context,
+                              size_t *len_r)
+{
+    char *buf;
+    callback_id_pair *elm;
+
+    buf = qmp_prepare_qmp_cmd(gc,
+                              cmd, args, ++qmp->last_id_used,
+                              NULL);
+
+    if (!buf) {
         LOGD(ERROR, qmp->domid, "Failed to generate a qmp command");
         goto out;
     }
@@ -625,13 +655,10 @@ static char *qmp_send_prepare(libxl__gc *gc, 
libxl__qmp_handler *qmp,
     elm->context = context;
     LIBXL_STAILQ_INSERT_TAIL(&qmp->callback_list, elm, next);
 
-    ret = libxl__strndup(gc, (const char*)buf, len);
-
     LOGD(DEBUG, qmp->domid, "next qmp command: '%s'", buf);
 
 out:
-    yajl_gen_free(hand);
-    return ret;
+    return buf;
 }
 
 static int qmp_send(libxl__qmp_handler *qmp,
@@ -643,7 +670,8 @@ static int qmp_send(libxl__qmp_handler *qmp,
     int rc = -1;
     GC_INIT(qmp->ctx);
 
-    buf = qmp_send_prepare(gc, qmp, cmd, args, callback, opaque, context);
+    buf = qmp_send_prepare(gc, qmp, cmd, args, callback, opaque, context,
+                           NULL);
 
     if (buf == NULL) {
         goto out;
@@ -659,12 +687,10 @@ static int qmp_send(libxl__qmp_handler *qmp,
                                 "QMP command", "QMP socket"))
             goto out;
     }
-    if (libxl_write_exactly(qmp->ctx, qmp->qmp_fd, "\r\n", 2,
-                            "CRLF", "QMP socket"))
-        goto out;
 
     rc = qmp->last_id_used;
 out:
+    free(buf);
     GC_FREE;
     return rc;
 }
-- 
Anthony PERARD


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