Revert "Revert "Revert "Add path interposer"""

This reverts commit c59a92cb1a.

Reason for revert: tests are broken with long OUT_DIRs
They're directly calling net.Listen, and not using the fallback
for long socket names.

Change-Id: Id14cbd499fd9b36c6926b7552d3554340cb0916c

ui/build/path.go

@@ -1,149 +0,0 @@
-// Copyright 2018 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 build
-
-import (
-	"fmt"
-	"io/ioutil"
-	"os"
-	"path/filepath"
-	"strings"
-
-	"github.com/google/blueprint/microfactory"
-
-	"android/soong/ui/build/paths"
-)
-
-func parsePathDir(dir string) []string {
-	f, err := os.Open(dir)
-	if err != nil {
-		return nil
-	}
-	defer f.Close()
-
-	if s, err := f.Stat(); err != nil || !s.IsDir() {
-		return nil
-	}
-
-	infos, err := f.Readdir(-1)
-	if err != nil {
-		return nil
-	}
-
-	ret := make([]string, 0, len(infos))
-	for _, info := range infos {
-		if m := info.Mode(); !m.IsDir() && m&0111 != 0 {
-			ret = append(ret, info.Name())
-		}
-	}
-	return ret
-}
-
-func SetupPath(ctx Context, config Config) {
-	if config.pathReplaced {
-		return
-	}
-
-	ctx.BeginTrace("path")
-	defer ctx.EndTrace()
-
-	origPath, _ := config.Environment().Get("PATH")
-	myPath := filepath.Join(config.OutDir(), ".path")
-	interposer := myPath + "_interposer"
-
-	var cfg microfactory.Config
-	cfg.Map("android/soong", "build/soong")
-	cfg.TrimPath, _ = filepath.Abs(".")
-	if _, err := microfactory.Build(&cfg, interposer, "android/soong/cmd/path_interposer"); err != nil {
-		ctx.Fatalln("Failed to build path interposer:", err)
-	}
-
-	if err := ioutil.WriteFile(interposer+"_origpath", []byte(origPath), 0777); err != nil {
-		ctx.Fatalln("Failed to write original path:", err)
-	}
-
-	entries, err := paths.LogListener(ctx.Context, interposer+"_log")
-	if err != nil {
-		ctx.Fatalln("Failed to listen for path logs:", err)
-	}
-
-	go func() {
-		for log := range entries {
-			curPid := os.Getpid()
-			for i, proc := range log.Parents {
-				if proc.Pid == curPid {
-					log.Parents = log.Parents[i:]
-					break
-				}
-			}
-			procPrints := []string{
-				"See https://android.googlesource.com/platform/build/+/master/Changes.md#PATH_Tools for more information.",
-			}
-			if len(log.Parents) > 0 {
-				procPrints = append(procPrints, "Process tree:")
-				for i, proc := range log.Parents {
-					procPrints = append(procPrints, fmt.Sprintf("%s→ %s", strings.Repeat(" ", i), proc.Command))
-				}
-			}
-
-			config := paths.GetConfig(log.Basename)
-			if config.Error {
-				ctx.Printf("Disallowed PATH tool %q used: %#v", log.Basename, log.Args)
-				for _, line := range procPrints {
-					ctx.Println(line)
-				}
-			} else {
-				ctx.Verbosef("Unknown PATH tool %q used: %#v", log.Basename, log.Args)
-				for _, line := range procPrints {
-					ctx.Verboseln(line)
-				}
-			}
-		}
-	}()
-
-	ensureEmptyDirectoriesExist(ctx, myPath)
-
-	var execs []string
-	for _, pathEntry := range filepath.SplitList(origPath) {
-		if pathEntry == "" {
-			// Ignore the current directory
-			continue
-		}
-		// TODO(dwillemsen): remove path entries under TOP? or anything
-		// that looks like an android source dir? They won't exist on
-		// the build servers, since they're added by envsetup.sh.
-		// (Except for the JDK, which is configured in ui/build/config.go)
-
-		execs = append(execs, parsePathDir(pathEntry)...)
-	}
-
-	allowAllSymlinks := config.Environment().IsEnvTrue("TEMPORARY_DISABLE_PATH_RESTRICTIONS")
-	for _, name := range execs {
-		if !paths.GetConfig(name).Symlink && !allowAllSymlinks {
-			continue
-		}
-
-		err := os.Symlink("../.path_interposer", filepath.Join(myPath, name))
-		// Intentionally ignore existing files -- that means that we
-		// just created it, and the first one should win.
-		if err != nil && !os.IsExist(err) {
-			ctx.Fatalln("Failed to create symlink:", err)
-		}
-	}
-
-	myPath, _ = filepath.Abs(myPath)
-	config.Environment().Set("PATH", myPath)
-	config.pathReplaced = true
-}