[PATCH v2 24/24] contrib/plugins: Add cc plugin

[Akihiko Odaki]

This demonstrates how to write a plugin in C++.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 docs/devel/tcg-plugins.rst |  8 ++++++++
 configure                  | 15 ++++++++++++---
 contrib/plugins/Makefile   |  5 +++++
 contrib/plugins/cc.cc      | 17 +++++++++++++++++
 tests/tcg/Makefile.target  |  3 +++
 5 files changed, 45 insertions(+), 3 deletions(-)
 create mode 100644 contrib/plugins/cc.cc

diff --git a/docs/devel/tcg-plugins.rst b/docs/devel/tcg-plugins.rst
index c9f8b27590..0a11f8036c 100644
--- a/docs/devel/tcg-plugins.rst
+++ b/docs/devel/tcg-plugins.rst
@@ -584,6 +584,14 @@ The plugin has a number of arguments, all of them are 
optional:
   configuration arguments implies ``l2=on``.
   (default: N = 2097152 (2MB), B = 64, A = 16)
 
+- contrib/plugins/cc.cc
+
+cc plugin demonstrates how to write a plugin in C++. It simply outputs
+"hello, world" to the plugin log::
+
+  $ qemu-system-arm $(QEMU_ARGS) \
+    -plugin ./contrib/plugins/libcc.so -d plugin
+
 API
 ---
 
diff --git a/configure b/configure
index 26ec5e4f54..0065b0dfe0 100755
--- a/configure
+++ b/configure
@@ -293,10 +293,18 @@ else
   cc="${CC-${cross_prefix}gcc}"
 fi
 
-if test -z "${CXX}${cross_prefix}"; then
-  cxx="c++"
+if test -n "${CXX+x}"; then
+  cxx="$CXX"
 else
-  cxx="${CXX-${cross_prefix}g++}"
+  if test -n "${cross_prefix}"; then
+    cxx="${cross_prefix}g++"
+  else
+    cxx="c++"
+  fi
+
+  if ! has "$cxx"; then
+    cxx=
+  fi
 fi
 
 # Preferred ObjC compiler:
@@ -1702,6 +1710,7 @@ echo "MESON=$meson" >> $config_host_mak
 echo "NINJA=$ninja" >> $config_host_mak
 echo "PKG_CONFIG=${pkg_config}" >> $config_host_mak
 echo "CC=$cc" >> $config_host_mak
+echo "CXX=$cxx" >> $config_host_mak
 echo "EXESUF=$EXESUF" >> $config_host_mak
 
 # use included Linux headers
diff --git a/contrib/plugins/Makefile b/contrib/plugins/Makefile
index b2b9db9f51..93d86b3d07 100644
--- a/contrib/plugins/Makefile
+++ b/contrib/plugins/Makefile
@@ -21,6 +21,9 @@ NAMES += lockstep
 NAMES += hwprofile
 NAMES += cache
 NAMES += drcov
+ifneq ($(CXX),)
+NAMES += cc
+endif
 
 SONAMES := $(addsuffix .so,$(addprefix lib,$(NAMES)))
 
@@ -31,6 +34,8 @@ CFLAGS += -fPIC -Wall
 CFLAGS += $(if $(CONFIG_DEBUG_TCG), -ggdb -O0)
 CFLAGS += -I$(SRC_PATH)/include/qemu
 
+CXXFLAGS := $(CFLAGS)
+
 all: $(SONAMES)
 
 %.o: %.c
diff --git a/contrib/plugins/cc.cc b/contrib/plugins/cc.cc
new file mode 100644
index 0000000000..83a5528db0
--- /dev/null
+++ b/contrib/plugins/cc.cc
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <qemu-plugin.h>
+
+extern "C" {
+
+QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
+
+QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
+                                           const qemu_info_t *info, int argc,
+                                           char **argv)
+{
+    qemu_plugin_outs("hello, world\n");
+    return 0;
+}
+
+};
diff --git a/tests/tcg/Makefile.target b/tests/tcg/Makefile.target
index 462289f47c..3d7837d3b8 100644
--- a/tests/tcg/Makefile.target
+++ b/tests/tcg/Makefile.target
@@ -149,6 +149,9 @@ PLUGIN_SRC=$(SRC_PATH)/tests/plugin
 PLUGIN_LIB=../../plugin
 VPATH+=$(PLUGIN_LIB)
 PLUGINS=$(patsubst %.c, lib%.so, $(notdir $(wildcard $(PLUGIN_SRC)/*.c)))
+ifneq ($(CXX),)
+PLUGINS+=$(patsubst %.cc, lib%.so, $(notdir $(wildcard $(PLUGIN_SRC)/*.cc)))
+endif
 
 # We need to ensure expand the run-plugin-TEST-with-PLUGIN
 # pre-requistes manually here as we can't use stems to handle it. We
-- 
2.41.0