Support stdlib analyzers with nogo.

This immediately revealed an escape analysis violation (!), where
the sync.Map was being used in a context that escapes were not
allowed. This is a relatively minor fix and is included.

PiperOrigin-RevId: 328611237

2 files changed, 88 insertions, 0 deletions

diff --git a/tools/nogo/dump/BUILD b/tools/nogo/dump/BUILD
new file mode 100644
index 000000000..dfa29d651
--- /dev/null
+++ b/tools/nogo/dump/BUILD
@@ -0,0 +1,10 @@
+load("//tools:defs.bzl", "go_library")
+
+package(licenses = ["notice"])
+
+go_library(
+    name = "dump",
+    srcs = ["dump.go"],
+    nogo = False,
+    visibility = ["//tools:__subpackages__"],
+)
diff --git a/tools/nogo/dump/dump.go b/tools/nogo/dump/dump.go
new file mode 100644
index 000000000..f06567e0f
--- /dev/null
+++ b/tools/nogo/dump/dump.go
@@ -0,0 +1,78 @@
+// Copyright 2019 The gVisor Authors.
+//
+// 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.
+
+// Package dump contains data dump tools.
+//
+// The interface used by the package corresponds to the tool generated by the
+// nogo_dump_tool rule.
+//
+// This package is separate in order to avoid a dependency cycle.
+package dump
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+)
+
+var (
+	// Binary is the binary under analysis.
+	//
+	// See Reader, below.
+	binary = flag.String("binary", "", "binary under analysis")
+
+	// Reader is the input stream.
+	//
+	// This may be set instead of Binary.
+	Reader io.Reader
+
+	// Tool is the tool used to dump a binary.
+	tool = flag.String("dump_tool", "", "tool used to dump a binary")
+)
+
+// Command returns a command that will emit the dumped object on stdout.
+//
+// You must call Wait on the resulting command.
+func Command() (*exec.Cmd, io.Reader, error) {
+	var (
+		args  []string
+		stdin io.Reader
+	)
+	if *binary != "" {
+		args = append(args, *binary)
+		*binary = "" // Clear.
+	} else if Reader != nil {
+		stdin = Reader
+		Reader = nil // Clear.
+	} else {
+		// We have no input stream or binary.
+		return nil, nil, fmt.Errorf("no binary or reader provided!")
+	}
+
+	// Construct our command.
+	cmd := exec.Command(*tool, args...)
+	cmd.Stdin = stdin
+	cmd.Stderr = os.Stderr
+	out, err := cmd.StdoutPipe()
+	if err != nil {
+		return nil, nil, err
+	}
+	if err := cmd.Start(); err != nil {
+		return nil, nil, err
+	}
+
+	return cmd, out, err
+}