Set umask of system server to 0077

This matches the previous behavior of java.io.File file and directory creation.

BUG: 2898660

Change-Id: Ie8978a3fc44abfd22f8046e66742e715354220a8
Signed-off-by: Mike Lockwood <lockwood@android.com>

core/java/android/os/FileUtils.java

@@ -85,6 +85,8 @@ public class FileUtils
 
     public static native int getPermissions(String file, int[] outPermissions);
 
+    public static native int setUMask(int mask);
+
     /** returns the FAT file system volume ID for the volume mounted 
      * at the given mount point, or -1 for failure
      * @param mount point for FAT volume

core/java/com/android/internal/os/ZygoteInit.java

@@ -22,6 +22,7 @@ import android.content.res.TypedArray;
 import android.graphics.drawable.Drawable;
 import android.net.LocalServerSocket;
 import android.os.Debug;
+import android.os.FileUtils;
 import android.os.SystemClock;
 import android.os.SystemProperties;
 import android.util.Config;
@@ -506,6 +507,9 @@ public class ZygoteInit {
 
         closeServerSocket();
 
+        // set umask to 0077 so new files and directories will default to owner-only permissions.
+        FileUtils.setUMask(FileUtils.S_IRWXG | FileUtils.S_IRWXO);
+
         /*
          * Pass the remaining arguments to SystemServer.
          * "--nice-name=system_server com.android.server.SystemServer"

core/jni/android_os_FileUtils.cpp

@@ -113,6 +113,11 @@ jint android_os_FileUtils_getPermissions(JNIEnv* env, jobject clazz,
     #endif
 }
 
+jint android_os_FileUtils_setUMask(JNIEnv* env, jobject clazz, jint mask)
+{
+    return umask(mask);
+}
+
 jint android_os_FileUtils_getFatVolumeId(JNIEnv* env, jobject clazz, jstring path)
 {
     #if HAVE_ANDROID_OS
@@ -170,6 +175,7 @@ jboolean android_os_FileUtils_getFileStatus(JNIEnv* env, jobject clazz, jstring
 static const JNINativeMethod methods[] = {
     {"setPermissions",  "(Ljava/lang/String;III)I", (void*)android_os_FileUtils_setPermissions},
     {"getPermissions",  "(Ljava/lang/String;[I)I", (void*)android_os_FileUtils_getPermissions},
+    {"setUMask",        "(I)I",                    (void*)android_os_FileUtils_setUMask},
     {"getFatVolumeId",  "(Ljava/lang/String;)I", (void*)android_os_FileUtils_getFatVolumeId},
     {"getFileStatus",  "(Ljava/lang/String;Landroid/os/FileUtils$FileStatus;)Z", (void*)android_os_FileUtils_getFileStatus},
 };