libbinder: Add binder::Status type

This object implements equivalent functionality to the Java logic which
serializes and re-throws exceptions from services.

Bug: 25615695
Test: Integration test for generated AIDL code reveals this to work
      correctly.

Change-Id: Ic80c9def0dd232582ea9c49717ec50894af6bfc2
diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index c808948..c1e6f0e 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -23,6 +23,7 @@
 #include <binder/Binder.h>
 #include <binder/BpBinder.h>
 #include <binder/ProcessState.h>
+#include <binder/Status.h>
 #include <binder/TextOutput.h>
 
 #include <errno.h>
@@ -69,9 +70,6 @@
 // Note: must be kept in sync with android/os/StrictMode.java's PENALTY_GATHER
 #define STRICT_MODE_PENALTY_GATHER (0x40 << 16)
 
-// Note: must be kept in sync with android/os/Parcel.java's EX_HAS_REPLY_HEADER
-#define EX_HAS_REPLY_HEADER -128
-
 // XXX This can be made public if we want to provide
 // support for typed data.
 struct small_flat_data
@@ -1206,7 +1204,8 @@
 
 status_t Parcel::writeNoException()
 {
-    return writeInt32(0);
+    binder::Status status;
+    return status.writeToParcel(this);
 }
 
 void Parcel::remove(size_t /*start*/, size_t /*amt*/)
@@ -1619,18 +1618,9 @@
 
 int32_t Parcel::readExceptionCode() const
 {
-  int32_t exception_code = readAligned<int32_t>();
-  if (exception_code == EX_HAS_REPLY_HEADER) {
-    int32_t header_start = dataPosition();
-    int32_t header_size = readAligned<int32_t>();
-    // Skip over fat responses headers.  Not used (or propagated) in
-    // native code
-    setDataPosition(header_start + header_size);
-    // And fat response headers are currently only used when there are no
-    // exceptions, so return no error:
-    return 0;
-  }
-  return exception_code;
+    binder::Status status;
+    status.readFromParcel(*this);
+    return status.exceptionCode();
 }
 
 native_handle* Parcel::readNativeHandle() const