[Xen-devel] [PATCH RFC v3 1/8] golang/xenlight: Create stub package

[Ronald Rojas <ronladred@xxxxxxxxx>]

Create a basic Makefile to build and install libxenlight Golang
bindings. Also add a stub package which only opens libxl context.

Include a global xenlight.Ctx variable which can be used as the
default context by the entire program if desired.

For now, return simple errors. Proper error handling will be
added in next patch.

Signed-off-by: Ronald Rojas <ronladred@xxxxxxxxx>
Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxx>
---

Changes:

- Added global logger variable and destroyed the logger instance
when closing the context.

- Whitespace fixes

CC: xen-devel@xxxxxxxxxxxxx
CC: george.dunlap@xxxxxxxxxx
CC: ian.jackson@xxxxxxxxxxxxx
CC: wei.liu2@xxxxxxxxxx
---
---
 tools/Makefile                    |  1 +
 tools/Rules.mk                    |  7 ++++
 tools/golang/Makefile             | 27 ++++++++++++
 tools/golang/xenlight/Makefile    | 49 ++++++++++++++++++++++
 tools/golang/xenlight/xenlight.go | 88 +++++++++++++++++++++++++++++++++++++++
 5 files changed, 172 insertions(+)
 create mode 100644 tools/golang/Makefile
 create mode 100644 tools/golang/xenlight/Makefile
 create mode 100644 tools/golang/xenlight/xenlight.go

diff --git a/tools/Makefile b/tools/Makefile
index 77e0723..caa27f4 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -31,6 +31,7 @@ endif
 
 SUBDIRS-y += xenpmd
 SUBDIRS-y += libxl
+#SUBDIRS-$(CONFIG_GOLANG) += golang
 SUBDIRS-y += helpers
 SUBDIRS-$(CONFIG_X86) += xenpaging
 SUBDIRS-$(CONFIG_X86) += debugger/gdbsx
diff --git a/tools/Rules.mk b/tools/Rules.mk
index b35999b..b5b9ace 100644
--- a/tools/Rules.mk
+++ b/tools/Rules.mk
@@ -30,6 +30,13 @@ XENSTORE_XENSTORED ?= y
 debug ?= y
 debug_symbols ?= $(debug)
 
+# Uncomment to compile with Go
+CONFIG_GOLANG ?= y
+ifeq ($(CONFIG_GOLANG),y)
+XEN_GOPATH        = $(XEN_ROOT)/tools/golang
+XEN_GOCODE_URL    = golang.xenproject.org
+endif
+
 ifeq ($(debug_symbols),y)
 CFLAGS += -g3
 endif
diff --git a/tools/golang/Makefile b/tools/golang/Makefile
new file mode 100644
index 0000000..47a9235
--- /dev/null
+++ b/tools/golang/Makefile
@@ -0,0 +1,27 @@
+XEN_ROOT=$(CURDIR)/../..
+include $(XEN_ROOT)/tools/Rules.mk
+
+# In order to link against a package in Go, the package must live in a
+# directory tree in the way that Go expects.  To make this possible,
+# there must be a directory such that we can set GOPATH=${dir}, and
+# the package will be under $GOPATH/src/${full-package-path}.
+
+# So we set XEN_GOPATH to $XEN_ROOT/tools/golang.  The xenlight
+# "package build" directory ($PWD/xenlight) will create the "package
+# source" directory in the proper place.  Go programs can use this
+# package by setting GOPATH=$(XEN_GOPATH).
+
+SUBDIRS-y = xenlight
+
+.PHONY: build all
+all build: subdirs-all
+
+.PHONY: install
+install: subdirs-install
+
+.PHONY: clean
+clean: subdirs-clean
+       $(RM) -r src pkg
+
+.PHONY: distclean
+distclean: clean
diff --git a/tools/golang/xenlight/Makefile b/tools/golang/xenlight/Makefile
new file mode 100644
index 0000000..5db665d
--- /dev/null
+++ b/tools/golang/xenlight/Makefile
@@ -0,0 +1,49 @@
+XEN_ROOT=$(CURDIR)/../../..
+include $(XEN_ROOT)/tools/Rules.mk
+
+# Standing boldly against convention, we insist on installing the
+# package source under $(prefix)/share/gocode
+GOCODE_DIR ?= $(prefix)/share/gocode/
+GOXL_PKG_DIR = /src/$(XEN_GOCODE_URL)/xenlight/
+GOXL_INSTALL_DIR = $(GOCODE_DIR)$(GOXL_PKG_DIR)
+
+# PKGSOURCES: Files which comprise the distributed source package
+PKGSOURCES = xenlight.go
+
+GO ?= go
+
+.PHONY: all
+all: build
+
+.PHONY: package
+package: $(XEN_GOPATH)$(GOXL_PKG_DIR)$(PKGSOURCES)
+
+$(XEN_GOPATH)/src/$(XEN_GOCODE_URL)/xenlight/$(PKGSOURCES): $(PKGSOURCES)
+       $(INSTALL_DIR) $(XEN_GOPATH)$(GOXL_PKG_DIR)
+       $(INSTALL_DATA) $(PKGSOURCES) $(XEN_GOPATH)$(GOXL_PKG_DIR)
+
+# Go will do its own dependency checking, and not actuall go through
+# with the build if none of the input files have changed.
+#
+# NB that because the users of this library need to be able to
+# recompile the library from source, it needs to include '-lxenlight'
+# in the LDFLAGS; and thus we need to add -L$(XEN_XENLIGHT) here
+# so that it can find the actual library.
+.PHONY: build
+build: package
+       CGO_CFLAGS="$(CFLAGS_libxenlight) $(CFLAGS_libxentoollog)" 
CGO_LDFLAGS="$(LDLIBS_libxenlight) $(LDLIBS_libxentoollog)-L$(XEN_XENLIGHT) 
-L$(XEN_LIBXENTOOLLOG)" GOPATH=$(XEN_GOPATH) $(GO) install -x 
$(XEN_GOCODE_URL)/xenlight
+
+.PHONY: install
+install: build
+       $(INSTALL_DIR) $(DESTDIR)$(GOXL_INSTALL_DIR)
+       $(INSTALL_DATA) $(XEN_GOPATH)$(GOXL_PKG_DIR)$(PKGSOURCES) 
$(DESTDIR)$(GOXL_INSTALL_DIR)
+
+.PHONY: clean
+clean:
+       $(RM) -r $(XEN_GOPATH)$(GOXL_PKG_DIR)
+       $(RM) $(XEN_GOPATH)/pkg/*/$(XEN_GOCODE_URL)/xenlight.a
+
+.PHONY: distclean
+distclean: clean
+
+-include $(DEPS)
diff --git a/tools/golang/xenlight/xenlight.go 
b/tools/golang/xenlight/xenlight.go
new file mode 100644
index 0000000..b025961
--- /dev/null
+++ b/tools/golang/xenlight/xenlight.go
@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2016 George W. Dunlap, Citrix Systems UK Ltd
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; If not, see <http://www.gnu.org/licenses/>.
+ */
+package xenlight
+
+/*
+#cgo LDFLAGS: -lxenlight -lyajl -lxentoollog
+#include <stdlib.h>
+#include <libxl.h>
+*/
+import "C"
+
+/*
+ * Other flags that may be needed at some point:
+ *  -lnl-route-3 -lnl-3
+ *
+ * To get back to static linking:
+ * #cgo LDFLAGS: -lxenlight -lyajl_s -lxengnttab -lxenstore -lxenguest 
-lxentoollog -lxenevtchn -lxenctrl -lblktapctl -lxenforeignmemory -lxencall -lz 
-luuid -lutil
+ */
+
+import (
+       "fmt"
+       "unsafe"
+)
+
+/*
+ * Types: Builtins
+ */
+type Context struct {
+       ctx *C.libxl_ctx
+}
+
+/*
+ * Context
+ */
+var Ctx Context
+
+var logger *C.xentoollog_logger_stdiostream
+
+func (Ctx *Context) IsOpen() bool {
+       return Ctx.ctx != nil
+}
+
+func (Ctx *Context) Open() (err error) {
+       if Ctx.ctx != nil {
+               return
+       }
+
+       logger = C.xtl_createlogger_stdiostream(C.stderr, C.XTL_ERROR, 0)
+       ret := C.libxl_ctx_alloc(&Ctx.ctx, C.LIBXL_VERSION,
+               0, unsafe.Pointer(logger))
+
+       if ret != 0 {
+               err = fmt.Errorf("Error: %d", -ret)
+       }
+       return
+}
+
+func (Ctx *Context) Close() (err error) {
+       ret := C.libxl_ctx_free(Ctx.ctx)
+       Ctx.ctx = nil
+
+       if ret != 0 {
+               err = fmt.Errorf("Error: %d", -ret)
+       }
+       C.xtl_logger_destroy(unsafe.Pointer(logger))
+       return
+}
+
+func (Ctx *Context) CheckOpen() (err error) {
+       if Ctx.ctx == nil {
+               err = fmt.Errorf("Context not opened")
+       }
+       return
+}
-- 
2.7.3


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