vtest: add support for sending caps v2 (v1.1)

I've come up with a workaround on the mesa side that should be
backwards compatible with old vtests and vice-versa.

It involves sending both caps 2 and 1 queries back to back,
and taking the first response an indication of what to expect,

v1.1: Check max_size is > 0 before mallocing

Reviewed-by: Jakob Bornecrantz <jakob@collabora.com>

vtest/vtest.h

@@ -28,7 +28,7 @@
 int vtest_create_renderer(int in_fd, int out_fd, uint32_t length);
 
 int vtest_send_caps(void);
-
+int vtest_send_caps2(void);
 int vtest_create_resource(void);
 int vtest_resource_unref(void);
 int vtest_submit_cmd(uint32_t length_dw);

vtest/vtest_protocol.h

@@ -48,6 +48,8 @@
 
 /* pass the process cmd line for debugging */
 #define VCMD_CREATE_RENDERER 8
+
+#define VCMD_GET_CAPS2 9
 /* get caps */
 /* 0 length cmd */
 /* resp VCMD_GET_CAPS + caps */

vtest/vtest_renderer.c

@@ -154,6 +154,37 @@ void vtest_destroy_renderer(void)
   renderer.out_fd = -1;
 }
 
+int vtest_send_caps2(void)
+{
+    uint32_t hdr_buf[2];
+    void *caps_buf;
+    int ret;
+    uint32_t max_ver, max_size;
+
+    virgl_renderer_get_cap_set(2, &max_ver, &max_size);
+
+    if (max_size == 0)
+	return -1;
+    caps_buf = malloc(max_size);
+    if (!caps_buf)
+	return -1;
+
+    virgl_renderer_fill_caps(2, 1, caps_buf);
+
+    hdr_buf[0] = max_size + 1;
+    hdr_buf[1] = 2;
+    ret = vtest_block_write(renderer.out_fd, hdr_buf, 8);
+    if (ret < 0)
+	goto end;
+    vtest_block_write(renderer.out_fd, caps_buf, max_size);
+    if (ret < 0)
+	goto end;
+
+end:
+    free(caps_buf);
+    return 0;
+}
+
 int vtest_send_caps(void)
 {
     uint32_t  max_ver, max_size;

vtest/vtest_server.c

@@ -129,6 +129,9 @@ again:
         vtest_renderer_create_fence();
 	ret = vtest_resource_busy_wait();
 	break;
+      case VCMD_GET_CAPS2:
+	ret = vtest_send_caps2();
+	break;
       default:
 	break;
       }