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 #include <sstream> 22 23 #include <binder/Parcel.h> 24 #include <utils/String8.h> 25 26 namespace android { 27 namespace binder { 28 29 // An object similar in function to a status_t except that it understands 30 // how exceptions are encoded in the prefix of a Parcel. Used like: 31 // 32 // Parcel data; 33 // Parcel reply; 34 // status_t status; 35 // binder::Status remote_exception; 36 // if ((status = data.writeInterfaceToken(interface_descriptor)) != OK || 37 // (status = data.writeInt32(function_input)) != OK) { 38 // // We failed to write into the memory of our local parcel? 39 // } 40 // if ((status = remote()->transact(transaction, data, &reply)) != OK) { 41 // // Something has gone wrong in the binder driver or libbinder. 42 // } 43 // if ((status = remote_exception.readFromParcel(reply)) != OK) { 44 // // The remote didn't correctly write the exception header to the 45 // // reply. 46 // } 47 // if (!remote_exception.isOk()) { 48 // // The transaction went through correctly, but the remote reported an 49 // // exception during handling. 50 // } 51 // 52 class Status final { 53 public: 54 // Keep the exception codes in sync with android/os/Parcel.java. 55 enum Exception { 56 EX_NONE = 0, 57 EX_SECURITY = -1, 58 EX_BAD_PARCELABLE = -2, 59 EX_ILLEGAL_ARGUMENT = -3, 60 EX_NULL_POINTER = -4, 61 EX_ILLEGAL_STATE = -5, 62 EX_NETWORK_MAIN_THREAD = -6, 63 EX_UNSUPPORTED_OPERATION = -7, 64 EX_SERVICE_SPECIFIC = -8, 65 EX_PARCELABLE = -9, 66 67 // This is special and Java specific; see Parcel.java. 68 EX_HAS_REPLY_HEADER = -128, 69 // This is special, and indicates to C++ binder proxies that the 70 // transaction has failed at a low level. 71 EX_TRANSACTION_FAILED = -129, 72 }; 73 74 // A more readable alias for the default constructor. 75 static Status ok(); 76 77 // Authors should explicitly pick whether their integer is: 78 // - an exception code (EX_* above) 79 // - service specific error code 80 // - status_t 81 // 82 // Prefer a generic exception code when possible, then a service specific 83 // code, and finally a status_t for low level failures or legacy support. 84 // Exception codes and service specific errors map to nicer exceptions for 85 // Java clients. 86 static Status fromExceptionCode(int32_t exceptionCode); 87 static Status fromExceptionCode(int32_t exceptionCode, 88 const String8& message); 89 static Status fromExceptionCode(int32_t exceptionCode, 90 const char* message); 91 92 static Status fromServiceSpecificError(int32_t serviceSpecificErrorCode); 93 static Status fromServiceSpecificError(int32_t serviceSpecificErrorCode, 94 const String8& message); 95 static Status fromServiceSpecificError(int32_t serviceSpecificErrorCode, 96 const char* message); 97 98 static Status fromStatusT(status_t status); 99 100 Status() = default; 101 ~Status() = default; 102 103 // Status objects are copyable and contain just simple data. 104 Status(const Status& status) = default; 105 Status(Status&& status) = default; 106 Status& operator=(const Status& status) = default; 107 108 // Bear in mind that if the client or service is a Java endpoint, this 109 // is not the logic which will provide/interpret the data here. 110 status_t readFromParcel(const Parcel& parcel); 111 status_t writeToParcel(Parcel* parcel) const; 112 113 // Set one of the pre-defined exception types defined above. 114 void setException(int32_t ex, const String8& message); 115 // Set a service specific exception with error code. 116 void setServiceSpecificError(int32_t errorCode, const String8& message); 117 // Setting a |status| != OK causes generated code to return |status| 118 // from Binder transactions, rather than writing an exception into the 119 // reply Parcel. This is the least preferable way of reporting errors. 120 void setFromStatusT(status_t status); 121 122 // Get information about an exception. 123 int32_t exceptionCode() const { return mException; } 124 const String8& exceptionMessage() const { return mMessage; } 125 status_t transactionError() const { 126 return mException == EX_TRANSACTION_FAILED ? mErrorCode : OK; 127 } 128 int32_t serviceSpecificErrorCode() const { 129 return mException == EX_SERVICE_SPECIFIC ? mErrorCode : 0; 130 } 131 132 bool isOk() const { return mException == EX_NONE; } 133 134 // For logging. 135 String8 toString8() const; 136 137 private: 138 Status(int32_t exceptionCode, int32_t errorCode); 139 Status(int32_t exceptionCode, int32_t errorCode, const String8& message); 140 141 // If |mException| == EX_TRANSACTION_FAILED, generated code will return 142 // |mErrorCode| as the result of the transaction rather than write an 143 // exception to the reply parcel. 144 // 145 // Otherwise, we always write |mException| to the parcel. 146 // If |mException| != EX_NONE, we write |mMessage| as well. 147 // If |mException| == EX_SERVICE_SPECIFIC we write |mErrorCode| as well. 148 int32_t mException = EX_NONE; 149 int32_t mErrorCode = 0; 150 String8 mMessage; 151 }; // class Status 152 153 // For gtest output logging 154 std::stringstream& operator<< (std::stringstream& stream, const Status& s); 155 156 } // namespace binder 157 } // namespace android 158 159 #endif // ANDROID_BINDER_STATUS_H 160
