libbinder: Handle transaction failures correctly
Java code expects status_t != OK to be caught at the JNI level in
android_util_Binder.cpp (see signalExceptionForError). We were
incorrectly mapping this kind of failure to a special exception type
and writing that exception type to parcels.
Instead, refuse to write EX_TRANSACTION_FAILED to a parcel and return
the status value instead.
While here, remove non-trivial constructors to push authors toward the
more explicit factory methods. Remove getException() and push authors
toward using the simpler getter methods. Fix minor camelCase issues.
Bug: 25615695
Test: system/tools/aidl integration tests still pass
Change-Id: I7cad3ac8ae8300b5ac0b466606f4934d01e503c5
diff --git a/include/binder/Status.h b/include/binder/Status.h
index 04738f8..d19824d 100644
--- a/include/binder/Status.h
+++ b/include/binder/Status.h
@@ -60,31 +60,31 @@
EX_ILLEGAL_STATE = -5,
EX_NETWORK_MAIN_THREAD = -6,
EX_UNSUPPORTED_OPERATION = -7,
- EX_TRANSACTION_FAILED = -8,
// This is special and Java specific; see Parcel.java.
EX_HAS_REPLY_HEADER = -128,
+ // This is special, and indicates to C++ binder proxies that the
+ // transaction has failed at a low level.
+ EX_TRANSACTION_FAILED = -129,
};
- // Allow authors to explicitly pick whether their integer is a status_t or
- // exception code.
- static Status fromExceptionCode(int32_t exception_code);
- static Status fromStatusT(status_t status);
// A more readable alias for the default constructor.
static Status ok();
+ // Allow authors to explicitly pick whether their integer is a status_t or
+ // exception code.
+ static Status fromExceptionCode(int32_t exceptionCode);
+ static Status fromExceptionCode(int32_t exceptionCode,
+ const String8& message);
+ static Status fromStatusT(status_t status);
Status() = default;
- Status(int32_t exception_code, const String8& message);
- Status(int32_t exception_code, const char* message);
-
+ ~Status() = default;
// Status objects are copyable and contain just simple data.
Status(const Status& status) = default;
Status(Status&& status) = default;
Status& operator=(const Status& status) = default;
- ~Status() = default;
-
// Bear in mind that if the client or service is a Java endpoint, this
// is not the logic which will provide/interpret the data here.
status_t readFromParcel(const Parcel& parcel);
@@ -92,16 +92,17 @@
// Set one of the pre-defined exception types defined above.
void setException(int32_t ex, const String8& message);
- // A few of the status_t values map to exception codes, but most of them
- // simply map to "transaction failed."
+ // Setting a |status| != OK causes generated code to return |status|
+ // from Binder transactions, rather than writing an exception into the
+ // reply Parcel.
void setFromStatusT(status_t status);
// Get information about an exception.
- // Any argument may be given as nullptr.
- void getException(int32_t* returned_exception,
- String8* returned_message) const;
int32_t exceptionCode() const { return mException; }
const String8& exceptionMessage() const { return mMessage; }
+ status_t transactionError() const {
+ return mException == EX_TRANSACTION_FAILED ? mErrorCode : OK;
+ }
bool isOk() const { return mException == EX_NONE; }
@@ -109,9 +110,17 @@
String8 toString8() const;
private:
- // We always write |mException| to the parcel.
- // If |mException| != EX_NONE, we write message as well.
+ Status(int32_t exception_code);
+ Status(int32_t exception_code, const String8& message);
+
+ // If |mException| == EX_TRANSACTION_FAILED, generated code will return
+ // |mErrorCode| as the result of the transaction rather than write an
+ // exception to the reply parcel.
+ //
+ // Otherwise, we always write |mException| to the parcel.
+ // If |mException| != EX_NONE, we write |mMessage| as well.
int32_t mException = EX_NONE;
+ int32_t mErrorCode = 0;
String8 mMessage;
}; // class Status