1 /* 2 * Copyright (C) 2015 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef ANDROID_BINDER_STATUS_H 18 #define ANDROID_BINDER_STATUS_H 19 20 #include <cstdint> 21 22 #include <binder/Parcel.h> 23 #include <utils/String8.h> 24 25 namespace android { 26 namespace binder { 27 28 // An object similar in function to a status_t except that it understands 29 // how exceptions are encoded in the prefix of a Parcel. Used like: 30 // 31 // Parcel data; 32 // Parcel reply; 33 // status_t status; 34 // binder::Status remote_exception; 35 // if ((status = data.writeInterfaceToken(interface_descriptor)) != OK || 36 // (status = data.writeInt32(function_input)) != OK) { 37 // // We failed to write into the memory of our local parcel? 38 // } 39 // if ((status = remote()->transact(transaction, data, &reply)) != OK) { 40 // // Something has gone wrong in the binder driver or libbinder. 41 // } 42 // if ((status = remote_exception.readFromParcel(reply)) != OK) { 43 // // The remote didn't correctly write the exception header to the 44 // // reply. 45 // } 46 // if (!remote_exception.isOk()) { 47 // // The transaction went through correctly, but the remote reported an 48 // // exception during handling. 49 // } 50 // 51 class Status final { 52 public: 53 // Keep the exception codes in sync with android/os/Parcel.java. 54 enum Exception { 55 EX_NONE = 0, 56 EX_SECURITY = -1, 57 EX_BAD_PARCELABLE = -2, 58 EX_ILLEGAL_ARGUMENT = -3, 59 EX_NULL_POINTER = -4, 60 EX_ILLEGAL_STATE = -5, 61 EX_NETWORK_MAIN_THREAD = -6, 62 EX_UNSUPPORTED_OPERATION = -7, 63 EX_SERVICE_SPECIFIC = -8, 64 65 // This is special and Java specific; see Parcel.java. 66 EX_HAS_REPLY_HEADER = -128, 67 // This is special, and indicates to C++ binder proxies that the 68 // transaction has failed at a low level. 69 EX_TRANSACTION_FAILED = -129, 70 }; 71 72 // A more readable alias for the default constructor. 73 static Status ok(); 74 // Authors should explicitly pick whether their integer is: 75 // - an exception code (EX_* above) 76 // - service specific error code 77 // - status_t 78 // 79 // Prefer a generic exception code when possible, then a service specific 80 // code, and finally a status_t for low level failures or legacy support. 81 // Exception codes and service specific errors map to nicer exceptions for 82 // Java clients. 83 static Status fromExceptionCode(int32_t exceptionCode); 84 static Status fromExceptionCode(int32_t exceptionCode, 85 const String8& message); 86 static Status fromServiceSpecificError(int32_t serviceSpecificErrorCode); 87 static Status fromServiceSpecificError(int32_t serviceSpecificErrorCode, 88 const String8& message); 89 static Status fromStatusT(status_t status); 90 91 Status() = default; 92 ~Status() = default; 93 94 // Status objects are copyable and contain just simple data. 95 Status(const Status& status) = default; 96 Status(Status&& status) = default; 97 Status& operator=(const Status& status) = default; 98 99 // Bear in mind that if the client or service is a Java endpoint, this 100 // is not the logic which will provide/interpret the data here. 101 status_t readFromParcel(const Parcel& parcel); 102 status_t writeToParcel(Parcel* parcel) const; 103 104 // Set one of the pre-defined exception types defined above. 105 void setException(int32_t ex, const String8& message); 106 // Set a service specific exception with error code. 107 void setServiceSpecificError(int32_t errorCode, const String8& message); 108 // Setting a |status| != OK causes generated code to return |status| 109 // from Binder transactions, rather than writing an exception into the 110 // reply Parcel. This is the least preferable way of reporting errors. 111 void setFromStatusT(status_t status); 112 113 // Get information about an exception. 114 int32_t exceptionCode() const { return mException; } 115 const String8& exceptionMessage() const { return mMessage; } 116 status_t transactionError() const { 117 return mException == EX_TRANSACTION_FAILED ? mErrorCode : OK; 118 } 119 int32_t serviceSpecificErrorCode() const { 120 return mException == EX_SERVICE_SPECIFIC ? mErrorCode : 0; 121 } 122 123 bool isOk() const { return mException == EX_NONE; } 124 125 // For logging. 126 String8 toString8() const; 127 128 private: 129 Status(int32_t exceptionCode, int32_t errorCode); 130 Status(int32_t exceptionCode, int32_t errorCode, const String8& message); 131 132 // If |mException| == EX_TRANSACTION_FAILED, generated code will return 133 // |mErrorCode| as the result of the transaction rather than write an 134 // exception to the reply parcel. 135 // 136 // Otherwise, we always write |mException| to the parcel. 137 // If |mException| != EX_NONE, we write |mMessage| as well. 138 // If |mException| == EX_SERVICE_SPECIFIC we write |mErrorCode| as well. 139 int32_t mException = EX_NONE; 140 int32_t mErrorCode = 0; 141 String8 mMessage; 142 }; // class Status 143 144 // For gtest output logging 145 template<typename T> 146 T& operator<< (T& stream, const Status& s) { 147 stream << s.toString8().string(); 148 return stream; 149 } 150 151 } // namespace binder 152 } // namespace android 153 154 #endif // ANDROID_BINDER_STATUS_H 155
