Merge "Revert "Revert "Ensure environment dependencies are correct"""

android/config.go

@@ -249,6 +249,20 @@ func (c *config) BlueprintToolLocation() string {
 	return filepath.Join(c.buildDir, "host", c.PrebuiltOS(), "bin")
 }
 
+// HostSystemTool looks for non-hermetic tools from the system we're running on.
+// Generally shouldn't be used, but useful to find the XCode SDK, etc.
+func (c *config) HostSystemTool(name string) string {
+	for _, dir := range filepath.SplitList(c.Getenv("PATH")) {
+		path := filepath.Join(dir, name)
+		if s, err := os.Stat(path); err != nil {
+			continue
+		} else if m := s.Mode(); !s.IsDir() && m&0111 != 0 {
+			return path
+		}
+	}
+	return name
+}
+
 // PrebuiltOS returns the name of the host OS used in prebuilts directories
 func (c *config) PrebuiltOS() string {
 	switch runtime.GOOS {
@@ -289,7 +303,7 @@ func (c *config) Getenv(key string) string {
 		if c.envFrozen {
 			panic("Cannot access new environment variables after envdeps are frozen")
 		}
-		val = os.Getenv(key)
+		val, _ = originalEnv[key]
 		c.envDeps[key] = val
 	}
 	return val

android/env.go

@@ -15,6 +15,9 @@
 package android
 
 import (
+	"os"
+	"strings"
+
 	"android/soong/env"
 
 	"github.com/google/blueprint"
@@ -27,6 +30,19 @@ import (
 // compare the contents of the environment variables, rewriting the file if necessary to cause
 // a manifest regeneration.
 
+var originalEnv map[string]string
+
+func init() {
+	originalEnv = make(map[string]string)
+	for _, env := range os.Environ() {
+		idx := strings.IndexRune(env, '=')
+		if idx != -1 {
+			originalEnv[env[:idx]] = env[idx+1:]
+		}
+	}
+	os.Clearenv()
+}
+
 func EnvSingleton() blueprint.Singleton {
 	return &envSingleton{}
 }