1 /* 2 * Copyright (C) 2018 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 /** 18 * @addtogroup NdkBinder 19 * @{ 20 */ 21 22 /** 23 * @file binder_ibinder.h 24 * @brief Object which can receive transactions and be sent across processes. 25 */ 26 27 #pragma once 28 29 #include <stdbool.h> 30 #include <stdint.h> 31 #include <sys/cdefs.h> 32 #include <sys/types.h> 33 34 #include <android/binder_parcel.h> 35 #include <android/binder_status.h> 36 37 __BEGIN_DECLS 38 39 /** 40 * Flags for AIBinder_transact. 41 */ 42 typedef uint32_t binder_flags_t; 43 enum { 44 /** 45 * The transaction will be dispatched and then returned to the caller. The outgoing process 46 * cannot block a call made by this, and execution of the call will not be waited on. An error 47 * can still be returned if the call is unable to be processed by the binder driver. All oneway 48 * calls are guaranteed to be ordered if they are sent on the same AIBinder object. 49 */ 50 FLAG_ONEWAY = 0x01, 51 }; 52 53 /** 54 * Codes for AIBinder_transact. This defines the range of codes available for 55 * usage. Other codes are used or reserved by the Android system. 56 */ 57 typedef uint32_t transaction_code_t; 58 enum { 59 /** 60 * The first transaction code available for user commands (inclusive). 61 */ 62 FIRST_CALL_TRANSACTION = 0x00000001, 63 /** 64 * The last transaction code available for user commands (inclusive). 65 */ 66 LAST_CALL_TRANSACTION = 0x00ffffff, 67 }; 68 69 /** 70 * Represents a type of AIBinder object which can be sent out. 71 */ 72 struct AIBinder_Class; 73 typedef struct AIBinder_Class AIBinder_Class; 74 75 /** 76 * Represents a local or remote object which can be used for IPC or which can itself be sent. 77 * 78 * This object has a refcount associated with it and will be deleted when its refcount reaches zero. 79 * How methods interactive with this refcount is described below. When using this API, it is 80 * intended for a client of a service to hold a strong reference to that service. This also means 81 * that user data typically should hold a strong reference to a local AIBinder object. A remote 82 * AIBinder object automatically holds a strong reference to the AIBinder object in the server's 83 * process. A typically memory layout looks like this: 84 * 85 * Key: 86 * ---> Ownership/a strong reference 87 * ...> A weak reference 88 * 89 * (process boundary) 90 * | 91 * MyInterface ---> AIBinder_Weak | ProxyForMyInterface 92 * ^ . | | 93 * | . | | 94 * | v | v 95 * UserData <--- AIBinder <-|- AIBinder 96 * | 97 * 98 * In this way, you'll notice that a proxy for the interface holds a strong reference to the 99 * implementation and that in the server process, the AIBinder object which was sent can be resent 100 * so that the same AIBinder object always represents the same object. This allows, for instance, an 101 * implementation (usually a callback) to transfer all ownership to a remote process and 102 * automatically be deleted when the remote process is done with it or dies. Other memory models are 103 * possible, but this is the standard one. 104 * 105 * If the process containing an AIBinder dies, it is possible to be holding a strong reference to 106 * an object which does not exist. In this case, transactions to this binder will return 107 * STATUS_DEAD_OBJECT. See also AIBinder_linkToDeath, AIBinder_unlinkToDeath, and AIBinder_isAlive. 108 * 109 * Once an AIBinder is created, anywhere it is passed (remotely or locally), there is a 1-1 110 * correspondence between the address of an AIBinder and the object it represents. This means that 111 * when two AIBinder pointers point to the same address, they represent the same object (whether 112 * that object is local or remote). This correspondance can be broken accidentally if AIBinder_new 113 * is erronesouly called to create the same object multiple times. 114 */ 115 struct AIBinder; 116 typedef struct AIBinder AIBinder; 117 118 /** 119 * The AIBinder object associated with this can be retrieved if it is still alive so that it can be 120 * re-used. The intention of this is to enable the same AIBinder object to always represent the same 121 * object. 122 */ 123 struct AIBinder_Weak; 124 typedef struct AIBinder_Weak AIBinder_Weak; 125 126 /** 127 * Represents a handle on a death notification. See AIBinder_linkToDeath/AIBinder_unlinkToDeath. 128 */ 129 struct AIBinder_DeathRecipient; 130 typedef struct AIBinder_DeathRecipient AIBinder_DeathRecipient; 131 132 /** 133 * This is called whenever a new AIBinder object is needed of a specific class. 134 * 135 * \param args these can be used to construct a new class. These are passed from AIBinder_new. 136 * \return this is the userdata representing the class. It can be retrieved using 137 * AIBinder_getUserData. 138 */ 139 typedef void* (*AIBinder_Class_onCreate)(void* args); 140 141 /** 142 * This is called whenever an AIBinder object is no longer referenced and needs destroyed. 143 * 144 * Typically, this just deletes whatever the implementation is. 145 * 146 * \param userData this is the same object returned by AIBinder_Class_onCreate 147 */ 148 typedef void (*AIBinder_Class_onDestroy)(void* userData); 149 150 /** 151 * This is called whenever a transaction needs to be processed by a local implementation. 152 * 153 * This method will be called after the equivalent of 154 * android.os.Parcel#enforceInterface is called. That is, the interface 155 * descriptor associated with the AIBinder_Class descriptor will already be 156 * checked. 157 * 158 * \param binder the object being transacted on. 159 * \param code implementation-specific code representing which transaction should be taken. 160 * \param in the implementation-specific input data to this transaction. 161 * \param out the implementation-specific output data to this transaction. 162 * 163 * \return the implementation-specific output code. This may be forwarded from another service, the 164 * result of a parcel read or write, or another error as is applicable to the specific 165 * implementation. Usually, implementation-specific error codes are written to the output parcel, 166 * and the transaction code is reserved for kernel errors or error codes that have been repeated 167 * from subsequent transactions. 168 */ 169 typedef binder_status_t (*AIBinder_Class_onTransact)(AIBinder* binder, transaction_code_t code, 170 const AParcel* in, AParcel* out); 171 172 /** 173 * This creates a new instance of a class of binders which can be instantiated. This is called one 174 * time during library initialization and cleaned up when the process exits or execs. 175 * 176 * None of these parameters can be null. 177 * 178 * Available since API level 29. 179 * 180 * \param interfaceDescriptor this is a unique identifier for the class. This is used internally for 181 * validity checks on transactions. This should be utf-8. 182 * \param onCreate see AIBinder_Class_onCreate. 183 * \param onDestroy see AIBinder_Class_onDestroy. 184 * \param onTransact see AIBinder_Class_onTransact. 185 * 186 * \return the class object representing these parameters or null on error. 187 */ 188 __attribute__((warn_unused_result)) AIBinder_Class* AIBinder_Class_define( 189 const char* interfaceDescriptor, AIBinder_Class_onCreate onCreate, 190 AIBinder_Class_onDestroy onDestroy, AIBinder_Class_onTransact onTransact) 191 __INTRODUCED_IN(29); 192 193 /** 194 * Dump information about an AIBinder (usually for debugging). 195 * 196 * When no arguments are provided, a brief overview of the interview should be given. 197 * 198 * \param binder interface being dumped 199 * \param fd file descriptor to be dumped to, should be flushed, ownership is not passed. 200 * \param args array of null-terminated strings for dump (may be null if numArgs is 0) 201 * \param numArgs number of args to be sent 202 * 203 * \return binder_status_t result of transaction (if remote, for instance) 204 */ 205 typedef binder_status_t (*AIBinder_onDump)(AIBinder* binder, int fd, const char** args, 206 uint32_t numArgs); 207 208 /** 209 * This sets the implementation of the dump method for a class. 210 * 211 * If this isn't set, nothing will be dumped when dump is called (for instance with 212 * android.os.Binder#dump). Must be called before any instance of the class is created. 213 * 214 * Available since API level 29. 215 * 216 * \param clazz class which should use this dump function 217 * \param onDump function to call when an instance of this binder class is being dumped. 218 */ 219 void AIBinder_Class_setOnDump(AIBinder_Class* clazz, AIBinder_onDump onDump) __INTRODUCED_IN(29); 220 221 /** 222 * Creates a new binder object of the appropriate class. 223 * 224 * Ownership of args is passed to this object. The lifecycle is implemented with AIBinder_incStrong 225 * and AIBinder_decStrong. When the reference count reaches zero, onDestroy is called. 226 * 227 * When this is called, the refcount is implicitly 1. So, calling decStrong exactly one time is 228 * required to delete this object. 229 * 230 * Once an AIBinder object is created using this API, re-creating that AIBinder for the same 231 * instance of the same class will break pointer equality for that specific AIBinder object. For 232 * instance, if someone erroneously created two AIBinder instances representing the same callback 233 * object and passed one to a hypothetical addCallback function and then later another one to a 234 * hypothetical removeCallback function, the remote process would have no way to determine that 235 * these two objects are actually equal using the AIBinder pointer alone (which they should be able 236 * to do). Also see the suggested memory ownership model suggested above. 237 * 238 * Available since API level 29. 239 * 240 * \param clazz the type of the object to be created. 241 * \param args the args to pass to AIBinder_onCreate for that class. 242 * 243 * \return a binder object representing the newly instantiated object. 244 */ 245 __attribute__((warn_unused_result)) AIBinder* AIBinder_new(const AIBinder_Class* clazz, void* args) 246 __INTRODUCED_IN(29); 247 248 /** 249 * If this is hosted in a process other than the current one. 250 * 251 * Available since API level 29. 252 * 253 * \param binder the binder being queried. 254 * 255 * \return true if the AIBinder represents an object in another process. 256 */ 257 bool AIBinder_isRemote(const AIBinder* binder) __INTRODUCED_IN(29); 258 259 /** 260 * If this binder is known to be alive. This will not send a transaction to a remote process and 261 * returns a result based on the last known information. That is, whenever a transaction is made, 262 * this is automatically updated to reflect the current alive status of this binder. This will be 263 * updated as the result of a transaction made using AIBinder_transact, but it will also be updated 264 * based on the results of bookkeeping or other transactions made internally. 265 * 266 * Available since API level 29. 267 * 268 * \param binder the binder being queried. 269 * 270 * \return true if the binder is alive. 271 */ 272 bool AIBinder_isAlive(const AIBinder* binder) __INTRODUCED_IN(29); 273 274 /** 275 * Built-in transaction for all binder objects. This sends a transaction that will immediately 276 * return. Usually this is used to make sure that a binder is alive, as a placeholder call, or as a 277 * sanity check. 278 * 279 * Available since API level 29. 280 * 281 * \param binder the binder being queried. 282 * 283 * \return STATUS_OK if the ping succeeds. 284 */ 285 binder_status_t AIBinder_ping(AIBinder* binder) __INTRODUCED_IN(29); 286 287 /** 288 * Built-in transaction for all binder objects. This dumps information about a given binder. 289 * 290 * See also AIBinder_Class_setOnDump, AIBinder_onDump. 291 * 292 * Available since API level 29. 293 * 294 * \param binder the binder to dump information about 295 * \param fd where information should be dumped to 296 * \param args null-terminated arguments to pass (may be null if numArgs is 0) 297 * \param numArgs number of args to send 298 * 299 * \return STATUS_OK if dump succeeds (or if there is nothing to dump) 300 */ 301 binder_status_t AIBinder_dump(AIBinder* binder, int fd, const char** args, uint32_t numArgs) 302 __INTRODUCED_IN(29); 303 304 /** 305 * Registers for notifications that the associated binder is dead. The same death recipient may be 306 * associated with multiple different binders. If the binder is local, then no death recipient will 307 * be given (since if the local process dies, then no recipient will exist to recieve a 308 * transaction). The cookie is passed to recipient in the case that this binder dies and can be 309 * null. The exact cookie must also be used to unlink this transaction (see AIBinder_linkToDeath). 310 * This function may return a binder transaction failure. The cookie can be used both for 311 * identification and holding user data. 312 * 313 * If binder is local, this will return STATUS_INVALID_OPERATION. 314 * 315 * Available since API level 29. 316 * 317 * \param binder the binder object you want to receive death notifications from. 318 * \param recipient the callback that will receive notifications when/if the binder dies. 319 * \param cookie the value that will be passed to the death recipient on death. 320 * 321 * \return STATUS_OK on success. 322 */ 323 binder_status_t AIBinder_linkToDeath(AIBinder* binder, AIBinder_DeathRecipient* recipient, 324 void* cookie) __INTRODUCED_IN(29); 325 326 /** 327 * Stops registration for the associated binder dying. Does not delete the recipient. This function 328 * may return a binder transaction failure and in case the death recipient cannot be found, it 329 * returns STATUS_NAME_NOT_FOUND. 330 * 331 * This only ever needs to be called when the AIBinder_DeathRecipient remains for use with other 332 * AIBinder objects. If the death recipient is deleted, all binders will automatically be unlinked. 333 * If the binder dies, it will automatically unlink. If the binder is deleted, it will be 334 * automatically unlinked. 335 * 336 * Available since API level 29. 337 * 338 * \param binder the binder object to remove a previously linked death recipient from. 339 * \param recipient the callback to remove. 340 * \param cookie the cookie used to link to death. 341 * 342 * \return STATUS_OK on success. STATUS_NAME_NOT_FOUND if the binder cannot be found to be unlinked. 343 */ 344 binder_status_t AIBinder_unlinkToDeath(AIBinder* binder, AIBinder_DeathRecipient* recipient, 345 void* cookie) __INTRODUCED_IN(29); 346 347 /** 348 * This returns the calling UID assuming that this thread is called from a thread that is processing 349 * a binder transaction (for instance, in the implementation of AIBinder_Class_onTransact). 350 * 351 * This can be used with higher-level system services to determine the caller's identity and check 352 * permissions. 353 * 354 * Available since API level 29. 355 * 356 * \return calling uid or the current process's UID if this thread isn't processing a transaction. 357 */ 358 uid_t AIBinder_getCallingUid() __INTRODUCED_IN(29); 359 360 /** 361 * This returns the calling PID assuming that this thread is called from a thread that is processing 362 * a binder transaction (for instance, in the implementation of AIBinder_Class_onTransact). 363 * 364 * This can be used with higher-level system services to determine the caller's identity and check 365 * permissions. However, when doing this, one should be aware of possible TOCTOU problems when the 366 * calling process dies and is replaced with another process with elevated permissions and the same 367 * PID. 368 * 369 * Available since API level 29. 370 * 371 * \return calling pid or the current process's PID if this thread isn't processing a transaction. 372 * If the transaction being processed is a oneway transaction, then this method will return 0. 373 */ 374 pid_t AIBinder_getCallingPid() __INTRODUCED_IN(29); 375 376 /** 377 * This can only be called if a strong reference to this object already exists in process. 378 * 379 * Available since API level 29. 380 * 381 * \param binder the binder object to add a refcount to. 382 */ 383 void AIBinder_incStrong(AIBinder* binder) __INTRODUCED_IN(29); 384 385 /** 386 * This will delete the object and call onDestroy once the refcount reaches zero. 387 * 388 * Available since API level 29. 389 * 390 * \param binder the binder object to remove a refcount from. 391 */ 392 void AIBinder_decStrong(AIBinder* binder) __INTRODUCED_IN(29); 393 394 /** 395 * For debugging only! 396 * 397 * Available since API level 29. 398 * 399 * \param binder the binder object to retrieve the refcount of. 400 * 401 * \return the number of strong-refs on this binder in this process. If binder is null, this will be 402 * -1. 403 */ 404 int32_t AIBinder_debugGetRefCount(AIBinder* binder) __INTRODUCED_IN(29); 405 406 /** 407 * This sets the class of an AIBinder object. This checks to make sure the remote object is of 408 * the expected class. A class must be set in order to use transactions on an AIBinder object. 409 * However, if an object is just intended to be passed through to another process or used as a 410 * handle this need not be called. 411 * 412 * This returns true if the class association succeeds. If it fails, no change is made to the 413 * binder object. 414 * 415 * Warning: this may fail if the binder is dead. 416 * 417 * Available since API level 29. 418 * 419 * \param binder the object to attach the class to. 420 * \param clazz the clazz to attach to binder. 421 * 422 * \return true if the binder has the class clazz and if the association was successful. 423 */ 424 bool AIBinder_associateClass(AIBinder* binder, const AIBinder_Class* clazz) __INTRODUCED_IN(29); 425 426 /** 427 * Returns the class that this binder was constructed with or associated with. 428 * 429 * Available since API level 29. 430 * 431 * \param binder the object that is being queried. 432 * 433 * \return the class that this binder is associated with. If this binder wasn't created with 434 * AIBinder_new, and AIBinder_associateClass hasn't been called, then this will return null. 435 */ 436 const AIBinder_Class* AIBinder_getClass(AIBinder* binder) __INTRODUCED_IN(29); 437 438 /** 439 * Value returned by onCreate for a local binder. For stateless classes (if onCreate returns 440 * null), this also returns null. For a remote binder, this will always return null. 441 * 442 * Available since API level 29. 443 * 444 * \param binder the object that is being queried. 445 * 446 * \return the userdata returned from AIBinder_onCreate when this object was created. This may be 447 * null for stateless objects. For remote objects, this is always null. 448 */ 449 void* AIBinder_getUserData(AIBinder* binder) __INTRODUCED_IN(29); 450 451 /** 452 * A transaction is a series of calls to these functions which looks this 453 * - call AIBinder_prepareTransaction 454 * - fill out the in parcel with parameters (lifetime of the 'in' variable) 455 * - call AIBinder_transact 456 * - read results from the out parcel (lifetime of the 'out' variable) 457 */ 458 459 /** 460 * Creates a parcel to start filling out for a transaction. This will add a header to the 461 * transaction that corresponds to android.os.Parcel#writeInterfaceToken. This may add debugging 462 * or other information to the transaction for platform use or to enable other features to work. The 463 * contents of this header is a platform implementation detail, and it is required to use 464 * libbinder_ndk. This parcel is to be sent via AIBinder_transact and it represents the input data 465 * to the transaction. It is recommended to check if the object is local and call directly into its 466 * user data before calling this as the parceling and unparceling cost can be avoided. This AIBinder 467 * must be either built with a class or associated with a class before using this API. 468 * 469 * This does not affect the ownership of binder. When this function succeeds, the in parcel's 470 * ownership is passed to the caller. At this point, the parcel can be filled out and passed to 471 * AIBinder_transact. Alternatively, if there is an error while filling out the parcel, it can be 472 * deleted with AParcel_delete. 473 * 474 * Available since API level 29. 475 * 476 * \param binder the binder object to start a transaction on. 477 * \param in out parameter for input data to the transaction. 478 * 479 * \return STATUS_OK on success. This will return STATUS_INVALID_OPERATION if the binder has not yet 480 * been associated with a class (see AIBinder_new and AIBinder_associateClass). 481 */ 482 binder_status_t AIBinder_prepareTransaction(AIBinder* binder, AParcel** in) __INTRODUCED_IN(29); 483 484 /** 485 * Transact using a parcel created from AIBinder_prepareTransaction. This actually communicates with 486 * the object representing this binder object. This also passes out a parcel to be used for the 487 * return transaction. This takes ownership of the in parcel and automatically deletes it after it 488 * is sent to the remote process. The output parcel is the result of the transaction. If the 489 * transaction has FLAG_ONEWAY, the out parcel will be empty. Otherwise, this will block until the 490 * remote process has processed the transaction, and the out parcel will contain the output data 491 * from transaction. 492 * 493 * This does not affect the ownership of binder. The out parcel's ownership is passed to the caller 494 * and must be released with AParcel_delete when finished reading. 495 * 496 * Available since API level 29. 497 * 498 * \param binder the binder object to transact on. 499 * \param code the implementation-specific code representing which transaction should be taken. 500 * \param in the implementation-specific input data to this transaction. 501 * \param out the implementation-specific output data to this transaction. 502 * \param flags possible flags to alter the way in which the transaction is conducted or 0. 503 * 504 * \return the result from the kernel or from the remote process. Usually, implementation-specific 505 * error codes are written to the output parcel, and the transaction code is reserved for kernel 506 * errors or error codes that have been repeated from subsequent transactions. 507 */ 508 binder_status_t AIBinder_transact(AIBinder* binder, transaction_code_t code, AParcel** in, 509 AParcel** out, binder_flags_t flags) __INTRODUCED_IN(29); 510 511 /** 512 * This does not take any ownership of the input binder, but it can be used to retrieve it if 513 * something else in some process still holds a reference to it. 514 * 515 * Available since API level 29. 516 * 517 * \param binder object to create a weak pointer to. 518 * 519 * \return object representing a weak pointer to binder (or null if binder is null). 520 */ 521 __attribute__((warn_unused_result)) AIBinder_Weak* AIBinder_Weak_new(AIBinder* binder) 522 __INTRODUCED_IN(29); 523 524 /** 525 * Deletes the weak reference. This will have no impact on the lifetime of the binder. 526 * 527 * Available since API level 29. 528 * 529 * \param weakBinder object created with AIBinder_Weak_new. 530 */ 531 void AIBinder_Weak_delete(AIBinder_Weak* weakBinder) __INTRODUCED_IN(29); 532 533 /** 534 * If promotion succeeds, result will have one strong refcount added to it. Otherwise, this returns 535 * null. 536 * 537 * Available since API level 29. 538 * 539 * \param weakBinder weak pointer to attempt retrieving the original object from. 540 * 541 * \return an AIBinder object with one refcount given to the caller or null. 542 */ 543 __attribute__((warn_unused_result)) AIBinder* AIBinder_Weak_promote(AIBinder_Weak* weakBinder) 544 __INTRODUCED_IN(29); 545 546 /** 547 * This function is executed on death receipt. See AIBinder_linkToDeath/AIBinder_unlinkToDeath. 548 * 549 * Available since API level 29. 550 * 551 * \param cookie the cookie passed to AIBinder_linkToDeath. 552 */ 553 typedef void (*AIBinder_DeathRecipient_onBinderDied)(void* cookie) __INTRODUCED_IN(29); 554 555 /** 556 * Creates a new binder death recipient. This can be attached to multiple different binder objects. 557 * 558 * Available since API level 29. 559 * 560 * \param onBinderDied the callback to call when this death recipient is invoked. 561 * 562 * \return the newly constructed object (or null if onBinderDied is null). 563 */ 564 __attribute__((warn_unused_result)) AIBinder_DeathRecipient* AIBinder_DeathRecipient_new( 565 AIBinder_DeathRecipient_onBinderDied onBinderDied) __INTRODUCED_IN(29); 566 567 /** 568 * Deletes a binder death recipient. It is not necessary to call AIBinder_unlinkToDeath before 569 * calling this as these will all be automatically unlinked. 570 * 571 * Available since API level 29. 572 * 573 * \param recipient the binder to delete (previously created with AIBinder_DeathRecipient_new). 574 */ 575 void AIBinder_DeathRecipient_delete(AIBinder_DeathRecipient* recipient) __INTRODUCED_IN(29); 576 577 /** 578 * Gets the extension registered with AIBinder_setExtension. 579 * 580 * See AIBinder_setExtension. 581 * 582 * Available since API level 30. 583 * 584 * \param binder the object to get the extension of. 585 * \param outExt the returned extension object. Will be null if there is no extension set or 586 * non-null with one strong ref count. 587 * 588 * \return error of getting the interface (may be a transaction error if this is 589 * remote binder). STATUS_UNEXPECTED_NULL if binder is null. 590 */ 591 binder_status_t AIBinder_getExtension(AIBinder* binder, AIBinder** outExt) __INTRODUCED_IN(30); 592 593 /** 594 * Gets the extension of a binder interface. This allows a downstream developer to add 595 * an extension to an interface without modifying its interface file. This should be 596 * called immediately when the object is created before it is passed to another thread. 597 * No thread safety is required. 598 * 599 * For instance, imagine if we have this interface: 600 * interface IFoo { void doFoo(); } 601 * 602 * A). Historical option that has proven to be BAD! Only the original 603 * author of an interface should change an interface. If someone 604 * downstream wants additional functionality, they should not ever 605 * change the interface or use this method. 606 * 607 * BAD TO DO: interface IFoo { BAD TO DO 608 * BAD TO DO: void doFoo(); BAD TO DO 609 * BAD TO DO: + void doBar(); // adding a method BAD TO DO 610 * BAD TO DO: } BAD TO DO 611 * 612 * B). Option that this method enables. 613 * Leave the original interface unchanged (do not change IFoo!). 614 * Instead, create a new interface in a downstream package: 615 * 616 * package com.<name>; // new functionality in a new package 617 * interface IBar { void doBar(); } 618 * 619 * When registering the interface, add: 620 * std::shared_ptr<MyFoo> foo = new MyFoo; // class in AOSP codebase 621 * std::shared_ptr<MyBar> bar = new MyBar; // custom extension class 622 * ... = AIBinder_setExtension(foo->asBinder().get(), bar->asBinder().get()); 623 * // handle error 624 * 625 * Then, clients of IFoo can get this extension: 626 * SpAIBinder binder = ...; 627 * std::shared_ptr<IFoo> foo = IFoo::fromBinder(binder); // handle if null 628 * SpAIBinder barBinder; 629 * ... = AIBinder_getExtension(barBinder.get()); 630 * // handle error 631 * std::shared_ptr<IBar> bar = IBar::fromBinder(barBinder); 632 * // type is checked with AIBinder_associateClass 633 * // if bar is null, then there is no extension or a different 634 * // type of extension 635 * 636 * Available since API level 30. 637 * 638 * \param binder the object to get the extension on. Must be local. 639 * \param ext the extension to set (binder will hold a strong reference to this) 640 * 641 * \return OK on success, STATUS_INVALID_OPERATION if binder is not local, STATUS_UNEXPECTED_NULL 642 * if either binder is null. 643 */ 644 binder_status_t AIBinder_setExtension(AIBinder* binder, AIBinder* ext) __INTRODUCED_IN(30); 645 646 /** 647 * Retrieve the class descriptor for the class. 648 * 649 * Available since API level 31. 650 * 651 * \param clazz the class to fetch the descriptor from 652 * 653 * \return the class descriptor string. This pointer will never be null; a 654 * descriptor is required to define a class. The pointer is owned by the class 655 * and will remain valid as long as the class does. For a local class, this will 656 * be the same value (not necessarily pointer equal) as is passed into 657 * AIBinder_Class_define. Format is utf-8. 658 */ 659 const char* AIBinder_Class_getDescriptor(const AIBinder_Class* clazz) __INTRODUCED_IN(31); 660 661 /** 662 * Whether AIBinder is less than another. 663 * 664 * This provides a per-process-unique total ordering of binders where a null 665 * AIBinder* object is considered to be before all other binder objects. 666 * For instance, two binders refer to the same object in a local or remote 667 * process when both AIBinder_lt(a, b) and AIBinder(b, a) are false. This API 668 * might be used to insert and lookup binders in binary search trees. 669 * 670 * AIBinder* pointers themselves actually also create a per-process-unique total 671 * ordering. However, this ordering is inconsistent with AIBinder_Weak_lt for 672 * remote binders. So, in general, this function should be preferred. 673 * 674 * Available since API level 31. 675 * 676 * \param lhs comparison object 677 * \param rhs comparison object 678 * 679 * \return whether "lhs < rhs" is true 680 */ 681 bool AIBinder_lt(const AIBinder* lhs, const AIBinder* rhs) __INTRODUCED_IN(31); 682 683 /** 684 * Clone an AIBinder_Weak. Useful because even if a weak binder promotes to a 685 * null value, after further binder transactions, it may no longer promote to a 686 * null value. 687 * 688 * Available since API level 31. 689 * 690 * \param weak Object to clone 691 * 692 * \return clone of the input parameter. This must be deleted with 693 * AIBinder_Weak_delete. Null if weak input parameter is also null. 694 */ 695 AIBinder_Weak* AIBinder_Weak_clone(const AIBinder_Weak* weak) __INTRODUCED_IN(31); 696 697 /** 698 * Whether AIBinder_Weak is less than another. 699 * 700 * This provides a per-process-unique total ordering of binders which is exactly 701 * the same as AIBinder_lt. Similarly, a null AIBinder_Weak* is considered to be 702 * ordered before all other weak references. 703 * 704 * This function correctly distinguishes binders even if one is deallocated. So, 705 * for instance, an AIBinder_Weak* entry representing a deleted binder will 706 * never compare as equal to an AIBinder_Weak* entry which represents a 707 * different allocation of a binder, even if the two binders were originally 708 * allocated at the same address. That is: 709 * 710 * AIBinder* a = ...; // imagine this has address 0x8 711 * AIBinder_Weak* bWeak = AIBinder_Weak_new(a); 712 * AIBinder_decStrong(a); // a may be deleted, if this is the last reference 713 * AIBinder* b = ...; // imagine this has address 0x8 (same address as b) 714 * AIBinder_Weak* bWeak = AIBinder_Weak_new(b); 715 * 716 * Then when a/b are compared with other binders, their order will be preserved, 717 * and it will either be the case that AIBinder_Weak_lt(aWeak, bWeak) OR 718 * AIBinder_Weak_lt(bWeak, aWeak), but not both. 719 * 720 * Unlike AIBinder*, the AIBinder_Weak* addresses themselves have nothing to do 721 * with the underlying binder. 722 * 723 * Available since API level 31. 724 * 725 * \param lhs comparison object 726 * \param rhs comparison object 727 * 728 * \return whether "lhs < rhs" is true 729 */ 730 bool AIBinder_Weak_lt(const AIBinder_Weak* lhs, const AIBinder_Weak* rhs) __INTRODUCED_IN(31); 731 732 __END_DECLS 733 734 /** @} */ 735