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> // historical 22 #include <ostream> 23 24 #include <binder/Common.h> 25 #include <binder/Parcel.h> 26 #include <utils/String8.h> 27 #include <string> 28 29 namespace android { 30 namespace binder { 31 32 // An object similar in function to a status_t except that it understands 33 // how exceptions are encoded in the prefix of a Parcel. Used like: 34 // 35 // Parcel data; 36 // Parcel reply; 37 // status_t status; 38 // binder::Status remote_exception; 39 // if ((status = data.writeInterfaceToken(interface_descriptor)) != OK || 40 // (status = data.writeInt32(function_input)) != OK) { 41 // // We failed to write into the memory of our local parcel? 42 // } 43 // if ((status = remote()->transact(transaction, data, &reply)) != OK) { 44 // // Something has gone wrong in the binder driver or libbinder. 45 // } 46 // if ((status = remote_exception.readFromParcel(reply)) != OK) { 47 // // The remote didn't correctly write the exception header to the 48 // // reply. 49 // } 50 // if (!remote_exception.isOk()) { 51 // // The transaction went through correctly, but the remote reported an 52 // // exception during handling. 53 // } 54 // 55 class LIBBINDER_EXPORTED Status final { 56 public: 57 // Keep the exception codes in sync with android/os/Parcel.java. 58 enum Exception { 59 EX_NONE = 0, 60 EX_SECURITY = -1, 61 EX_BAD_PARCELABLE = -2, 62 EX_ILLEGAL_ARGUMENT = -3, 63 EX_NULL_POINTER = -4, 64 EX_ILLEGAL_STATE = -5, 65 EX_NETWORK_MAIN_THREAD = -6, 66 EX_UNSUPPORTED_OPERATION = -7, 67 EX_SERVICE_SPECIFIC = -8, 68 EX_PARCELABLE = -9, 69 70 // This is special and Java specific; see Parcel.java. 71 EX_HAS_REPLY_HEADER = -128, 72 // This is special, and indicates to C++ binder proxies that the 73 // transaction has failed at a low level. 74 EX_TRANSACTION_FAILED = -129, 75 }; 76 77 // A more readable alias for the default constructor. 78 static Status ok(); 79 80 // Authors should explicitly pick whether their integer is: 81 // - an exception code (EX_* above) 82 // - service specific error code 83 // - status_t 84 // 85 // Prefer a generic exception code when possible, then a service specific 86 // code, and finally a status_t for low level failures or legacy support. 87 // Exception codes and service specific errors map to nicer exceptions for 88 // Java clients. 89 static Status fromExceptionCode(int32_t exceptionCode); 90 static Status fromExceptionCode(int32_t exceptionCode, 91 const String8& message); 92 static Status fromExceptionCode(int32_t exceptionCode, 93 const char* message); 94 95 // warning: this is still considered an error if it is constructed with a 96 // zero value error code. Please use Status::ok() instead and avoid zero 97 // error codes 98 static Status fromServiceSpecificError(int32_t serviceSpecificErrorCode); 99 static Status fromServiceSpecificError(int32_t serviceSpecificErrorCode, 100 const String8& message); 101 static Status fromServiceSpecificError(int32_t serviceSpecificErrorCode, 102 const char* message); 103 104 static Status fromStatusT(status_t status); 105 106 static std::string exceptionToString(status_t exceptionCode); 107 108 Status() = default; 109 ~Status() = default; 110 111 // Status objects are copyable and contain just simple data. 112 Status(const Status& status) = default; 113 Status(Status&& status) = default; 114 Status& operator=(const Status& status) = default; 115 116 // Bear in mind that if the client or service is a Java endpoint, this 117 // is not the logic which will provide/interpret the data here. 118 status_t readFromParcel(const Parcel& parcel); 119 status_t writeToParcel(Parcel* parcel) const; 120 121 // Convenience API to replace a Parcel with a status value, w/o requiring 122 // calling multiple APIs (makes generated code smaller). 123 status_t writeOverParcel(Parcel* parcel) const; 124 125 // Set one of the pre-defined exception types defined above. 126 void setException(int32_t ex, const String8& message); 127 // Set a service specific exception with error code. 128 void setServiceSpecificError(int32_t errorCode, const String8& message); 129 // Setting a |status| != OK causes generated code to return |status| 130 // from Binder transactions, rather than writing an exception into the 131 // reply Parcel. This is the least preferable way of reporting errors. 132 void setFromStatusT(status_t status); 133 134 // Get information about an exception. exceptionCode()135 int32_t exceptionCode() const { return mException; } exceptionMessage()136 const String8& exceptionMessage() const { return mMessage; } transactionError()137 status_t transactionError() const { 138 return mException == EX_TRANSACTION_FAILED ? mErrorCode : OK; 139 } serviceSpecificErrorCode()140 int32_t serviceSpecificErrorCode() const { 141 return mException == EX_SERVICE_SPECIFIC ? mErrorCode : 0; 142 } 143 isOk()144 bool isOk() const { return mException == EX_NONE; } 145 146 // For logging. 147 String8 toString8() const; 148 149 private: 150 Status(int32_t exceptionCode, int32_t errorCode); 151 Status(int32_t exceptionCode, int32_t errorCode, const String8& message); 152 153 // If |mException| == EX_TRANSACTION_FAILED, generated code will return 154 // |mErrorCode| as the result of the transaction rather than write an 155 // exception to the reply parcel. 156 // 157 // Otherwise, we always write |mException| to the parcel. 158 // If |mException| != EX_NONE, we write |mMessage| as well. 159 // If |mException| == EX_SERVICE_SPECIFIC we write |mErrorCode| as well. 160 int32_t mException = EX_NONE; 161 int32_t mErrorCode = 0; 162 String8 mMessage; 163 }; // class Status 164 165 static inline std::ostream& operator<< (std::ostream& o, const Status& s) { 166 return o << s.toString8(); 167 } 168 169 } // namespace binder 170 } // namespace android 171 172 #endif // ANDROID_BINDER_STATUS_H 173