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 #include <string> 26 27 namespace android { 28 namespace binder { 29 30 // An object similar in function to a status_t except that it understands 31 // how exceptions are encoded in the prefix of a Parcel. Used like: 32 // 33 // Parcel data; 34 // Parcel reply; 35 // status_t status; 36 // binder::Status remote_exception; 37 // if ((status = data.writeInterfaceToken(interface_descriptor)) != OK || 38 // (status = data.writeInt32(function_input)) != OK) { 39 // // We failed to write into the memory of our local parcel? 40 // } 41 // if ((status = remote()->transact(transaction, data, &reply)) != OK) { 42 // // Something has gone wrong in the binder driver or libbinder. 43 // } 44 // if ((status = remote_exception.readFromParcel(reply)) != OK) { 45 // // The remote didn't correctly write the exception header to the 46 // // reply. 47 // } 48 // if (!remote_exception.isOk()) { 49 // // The transaction went through correctly, but the remote reported an 50 // // exception during handling. 51 // } 52 // 53 class Status final { 54 public: 55 // Keep the exception codes in sync with android/os/Parcel.java. 56 enum Exception { 57 EX_NONE = 0, 58 EX_SECURITY = -1, 59 EX_BAD_PARCELABLE = -2, 60 EX_ILLEGAL_ARGUMENT = -3, 61 EX_NULL_POINTER = -4, 62 EX_ILLEGAL_STATE = -5, 63 EX_NETWORK_MAIN_THREAD = -6, 64 EX_UNSUPPORTED_OPERATION = -7, 65 EX_SERVICE_SPECIFIC = -8, 66 EX_PARCELABLE = -9, 67 68 // This is special and Java specific; see Parcel.java. 69 EX_HAS_REPLY_HEADER = -128, 70 // This is special, and indicates to C++ binder proxies that the 71 // transaction has failed at a low level. 72 EX_TRANSACTION_FAILED = -129, 73 }; 74 75 // A more readable alias for the default constructor. 76 static Status ok(); 77 78 // Authors should explicitly pick whether their integer is: 79 // - an exception code (EX_* above) 80 // - service specific error code 81 // - status_t 82 // 83 // Prefer a generic exception code when possible, then a service specific 84 // code, and finally a status_t for low level failures or legacy support. 85 // Exception codes and service specific errors map to nicer exceptions for 86 // Java clients. 87 static Status fromExceptionCode(int32_t exceptionCode); 88 static Status fromExceptionCode(int32_t exceptionCode, 89 const String8& message); 90 static Status fromExceptionCode(int32_t exceptionCode, 91 const char* message); 92 93 static Status fromServiceSpecificError(int32_t serviceSpecificErrorCode); 94 static Status fromServiceSpecificError(int32_t serviceSpecificErrorCode, 95 const String8& message); 96 static Status fromServiceSpecificError(int32_t serviceSpecificErrorCode, 97 const char* message); 98 99 static Status fromStatusT(status_t status); 100 101 static std::string exceptionToString(status_t exceptionCode); 102 103 Status() = default; 104 ~Status() = default; 105 106 // Status objects are copyable and contain just simple data. 107 Status(const Status& status) = default; 108 Status(Status&& status) = default; 109 Status& operator=(const Status& status) = default; 110 111 // Bear in mind that if the client or service is a Java endpoint, this 112 // is not the logic which will provide/interpret the data here. 113 status_t readFromParcel(const Parcel& parcel); 114 status_t writeToParcel(Parcel* parcel) const; 115 116 // Set one of the pre-defined exception types defined above. 117 void setException(int32_t ex, const String8& message); 118 // Set a service specific exception with error code. 119 void setServiceSpecificError(int32_t errorCode, const String8& message); 120 // Setting a |status| != OK causes generated code to return |status| 121 // from Binder transactions, rather than writing an exception into the 122 // reply Parcel. This is the least preferable way of reporting errors. 123 void setFromStatusT(status_t status); 124 125 // Get information about an exception. exceptionCode()126 int32_t exceptionCode() const { return mException; } exceptionMessage()127 const String8& exceptionMessage() const { return mMessage; } transactionError()128 status_t transactionError() const { 129 return mException == EX_TRANSACTION_FAILED ? mErrorCode : OK; 130 } serviceSpecificErrorCode()131 int32_t serviceSpecificErrorCode() const { 132 return mException == EX_SERVICE_SPECIFIC ? mErrorCode : 0; 133 } 134 isOk()135 bool isOk() const { return mException == EX_NONE; } 136 137 // For logging. 138 String8 toString8() const; 139 140 private: 141 Status(int32_t exceptionCode, int32_t errorCode); 142 Status(int32_t exceptionCode, int32_t errorCode, const String8& message); 143 144 // If |mException| == EX_TRANSACTION_FAILED, generated code will return 145 // |mErrorCode| as the result of the transaction rather than write an 146 // exception to the reply parcel. 147 // 148 // Otherwise, we always write |mException| to the parcel. 149 // If |mException| != EX_NONE, we write |mMessage| as well. 150 // If |mException| == EX_SERVICE_SPECIFIC we write |mErrorCode| as well. 151 int32_t mException = EX_NONE; 152 int32_t mErrorCode = 0; 153 String8 mMessage; 154 }; // class Status 155 156 // For gtest output logging 157 std::stringstream& operator<< (std::stringstream& stream, const Status& s); 158 159 } // namespace binder 160 } // namespace android 161 162 #endif // ANDROID_BINDER_STATUS_H 163