Add a Go replacement for our top-level Make wrapper

Right now this mostly just copies what Make is doing in
build/core/ninja.mk and build/core/soong.mk. The only major feature it
adds is a rotating log file with some verbose logging.

There is one major functional difference -- you cannot override random
Make variables during the Make phase anymore. The environment variable
is set, and if Make uses ?= or the equivalent, it can still use those
variables. We already made this change for Kati, which also loads all of
the same code and actually does the build, so it has been half-removed
for a while.

The only "UI" this implements is what I'll call "Make Emulation" mode --
it's expected that current command lines will continue working, and
we'll explore alternate user interfaces later.

We're still using Make as a wrapper, but all it does is call into this
single Go program, it won't even load the product configuration. Once
this is default, we can start moving individual users over to using this
directly (still in Make emulation mode), skipping the Make wrapper.

Ideas for the future:
* Generating trace files showing time spent in Make/Kati/Soong/Ninja
  (also importing ninja traces into the same stream). I had this working
  in a previous version of this patch, but removed it to keep the size
  down and focus on the current features.
* More intelligent SIGALRM handling, once we fully remove the Make
  wrapper (which hides the SIGALRM)
* Reading the experimental binary output stream from Ninja, so that we
  can always save the verbose log even if we're not printing it out to
  the console

Test: USE_SOONG_UI=true m -j blueprint_tools
Change-Id: I884327b9a8ae24499eb6c56f6e1ad26df1cfa4e4

2 files changed, 111 insertions, 0 deletions

diff --git a/cmd/soong_ui/Android.bp b/cmd/soong_ui/Android.bp
new file mode 100644
index 00000000..6d6ef339
--- /dev/null
+++ b/cmd/soong_ui/Android.bp
@@ -0,0 +1,24 @@
+// Copyright 2017 Google Inc. All rights reserved.
+//
+// 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.
+
+blueprint_go_binary {
+    name: "soong_ui",
+    deps: [
+        "soong-ui-build",
+        "soong-ui-logger",
+    ],
+    srcs: [
+        "main.go",
+    ],
+}
diff --git a/cmd/soong_ui/main.go b/cmd/soong_ui/main.go
new file mode 100644
index 00000000..994c54dc
--- /dev/null
+++ b/cmd/soong_ui/main.go
@@ -0,0 +1,87 @@
+// Copyright 2017 Google Inc. All rights reserved.
+//
+// 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 main
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"android/soong/ui/build"
+	"android/soong/ui/logger"
+)
+
+func indexList(s string, list []string) int {
+	for i, l := range list {
+		if l == s {
+			return i
+		}
+	}
+
+	return -1
+}
+
+func inList(s string, list []string) bool {
+	return indexList(s, list) != -1
+}
+
+func main() {
+	log := logger.New(os.Stderr)
+	defer log.Cleanup()
+
+	if len(os.Args) < 2 || !inList("--make-mode", os.Args) {
+		log.Fatalln("The `soong` native UI is not yet available.")
+	}
+
+	// Precondition: the current directory is the top of the source tree
+	if _, err := os.Stat("build/soong/root.bp"); err != nil {
+		if os.IsNotExist(err) {
+			log.Fatalln("soong_ui should run from the root of the source directory: build/soong/root.bp not found")
+		}
+		log.Fatalln("Error verifying tree state:", err)
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	build.SetupSignals(log, cancel, log.Cleanup)
+
+	buildCtx := &build.ContextImpl{
+		Context:        ctx,
+		Logger:         log,
+		StdioInterface: build.StdioImpl{},
+	}
+	config := build.NewConfig(buildCtx, os.Args[1:]...)
+
+	log.SetVerbose(config.IsVerbose())
+	if err := os.MkdirAll(config.OutDir(), 0777); err != nil {
+		log.Fatalf("Error creating out directory: %v", err)
+	}
+	log.SetOutput(filepath.Join(config.OutDir(), "build.log"))
+
+	if start, ok := os.LookupEnv("TRACE_BEGIN_SOONG"); ok {
+		if !strings.HasSuffix(start, "N") {
+			if start_time, err := strconv.ParseUint(start, 10, 64); err == nil {
+				log.Verbosef("Took %dms to start up.",
+					time.Since(time.Unix(0, int64(start_time))).Nanoseconds()/time.Millisecond.Nanoseconds())
+			}
+		}
+	}
+
+	build.Build(buildCtx, config, build.BuildAll)
+}