go_marshal: Implement automatic generation of ABI marshalling code.

This CL implements go_marshal, a code generation utility for
automatically serializing and deserializing ABI structs.

The go_marshal tool automatically generates implementations of the new
marshal interface. Unlike binary.Marshal/Unmarshal, the generated
interface implementations use no runtime reflection, and translates to
a single memcpy for most structs. See go_marshal/README.md for
details.

PiperOrigin-RevId: 268065475

1 files changed, 73 insertions, 0 deletions

diff --git a/tools/go_marshal/main.go b/tools/go_marshal/main.go
new file mode 100644
index 000000000..3d12eb93c
--- /dev/null
+++ b/tools/go_marshal/main.go
@@ -0,0 +1,73 @@
+// Copyright 2019 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// go_marshal is a code generation utility for automatically generating code to
+// marshal go data structures to memory.
+//
+// This binary is typically run as part of the build process, and is invoked by
+// the go_marshal bazel rule defined in defs.bzl.
+//
+// See README.md.
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"strings"
+
+	"gvisor.dev/gvisor/tools/go_marshal/gomarshal"
+)
+
+var (
+	pkg            = flag.String("pkg", "", "output package")
+	output         = flag.String("output", "", "output file")
+	outputTest     = flag.String("output_test", "", "output file for tests")
+	imports        = flag.String("imports", "", "comma-separated list of extra packages to import in generated code")
+	declarationPkg = flag.String("declarationPkg", "", "import path of target declaring the types we're generating on")
+)
+
+func main() {
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, "Usage: %s <input go src files>\n", os.Args[0])
+		flag.PrintDefaults()
+	}
+	flag.Parse()
+	if len(flag.Args()) == 0 {
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	if *pkg == "" {
+		flag.Usage()
+		fmt.Fprint(os.Stderr, "Flag -pkg must be provided.\n")
+		os.Exit(1)
+	}
+
+	var extraImports []string
+	if len(*imports) > 0 {
+		// Note: strings.Split(s, sep) returns s if sep doesn't exist in s. Thus
+		// we check for an empty imports list to avoid emitting an empty string
+		// as an import.
+		extraImports = strings.Split(*imports, ",")
+	}
+	g, err := gomarshal.NewGenerator(flag.Args(), *output, *outputTest, *pkg, *declarationPkg, extraImports)
+	if err != nil {
+		panic(err)
+	}
+
+	if err := g.Run(); err != nil {
+		panic(err)
+	}
+}