Add new 'update_engine_log' GID

Add a new GID for controlling access to the update
engine logs.

This is an enabler for a new permission to grant
access update engine logs only:
  android.permission.READ_UPDATE_ENGINE_LOGS

Note: holders of android.permission.READ_LOGS will
still have access to update engine logs.

Bug: 397893018
Test: Flash software, check permissions of directory
    Flash software without this patch. Flash software with this
    CL on top. Confirm permission. Confirm log files included in
    bugreport.
Change-Id: I9632cf1b894a6deafd33a769f736b0736e8ca82e
diff --git a/libcutils/include/private/android_filesystem_config.h b/libcutils/include/private/android_filesystem_config.h
index 2aaafbe..b6aded0 100644
--- a/libcutils/include/private/android_filesystem_config.h
+++ b/libcutils/include/private/android_filesystem_config.h
@@ -144,6 +144,7 @@
 #define AID_UPROBESTATS 1093         /* uid for uprobestats */
 #define AID_CROS_EC 1094             /* uid for accessing ChromeOS EC (cros_ec) */
 #define AID_MMD 1095                 /* uid for memory management daemon */
+#define AID_UPDATE_ENGINE_LOG 1096   /* GID for accessing update_engine logs */
 // Additions to this file must be made in AOSP, *not* in internal branches.
 // You will also need to update expect_ids() in bionic/tests/grp_pwd_test.cpp.
 
diff --git a/rootdir/init.rc b/rootdir/init.rc
index 1545d09..404029b 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -790,7 +790,8 @@
     mkdir /data/misc/vold 0700 root root
     mkdir /data/misc/boottrace 0771 system shell
     mkdir /data/misc/update_engine 0700 root root
-    mkdir /data/misc/update_engine_log 02750 root log
+    mkdir /data/misc/update_engine_log 02750 root update_engine_log
+    chown root update_engine_log /data/misc/update_engine_log
     mkdir /data/misc/trace 0700 root root
     # create location to store surface and window trace files
     mkdir /data/misc/wmtrace 0700 system system