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 * This tells users of this class not to use a transaction header. By default, libbinder_ndk users 223 * read/write transaction headers implicitly (in the SDK, this must be manually written by 224 * android.os.Parcel#writeInterfaceToken, and it is read/checked with 225 * android.os.Parcel#enforceInterface). This method is provided in order to talk to legacy code 226 * which does not write an interface token. When this is disabled, type safety is reduced, so you 227 * must have a separate way of determining the binder you are talking to is the right type. Must 228 * be called before any instance of the class is created. 229 * 230 * Available since API level 33. 231 * 232 * WARNING: this API interacts badly with linkernamespaces. For correct behavior, you must 233 * use it on all instances of a class in the same process which share the same interface 234 * descriptor. In general, it is recommended you do not use this API, because it is disabling 235 * type safety. 236 * 237 * \param clazz class to disable interface header on. 238 */ 239 void AIBinder_Class_disableInterfaceTokenHeader(AIBinder_Class* clazz) __INTRODUCED_IN(33); 240 241 /** 242 * Creates a new binder object of the appropriate class. 243 * 244 * Ownership of args is passed to this object. The lifecycle is implemented with AIBinder_incStrong 245 * and AIBinder_decStrong. When the reference count reaches zero, onDestroy is called. 246 * 247 * When this is called, the refcount is implicitly 1. So, calling decStrong exactly one time is 248 * required to delete this object. 249 * 250 * Once an AIBinder object is created using this API, re-creating that AIBinder for the same 251 * instance of the same class will break pointer equality for that specific AIBinder object. For 252 * instance, if someone erroneously created two AIBinder instances representing the same callback 253 * object and passed one to a hypothetical addCallback function and then later another one to a 254 * hypothetical removeCallback function, the remote process would have no way to determine that 255 * these two objects are actually equal using the AIBinder pointer alone (which they should be able 256 * to do). Also see the suggested memory ownership model suggested above. 257 * 258 * Available since API level 29. 259 * 260 * \param clazz the type of the object to be created. 261 * \param args the args to pass to AIBinder_onCreate for that class. 262 * 263 * \return a binder object representing the newly instantiated object. 264 */ 265 __attribute__((warn_unused_result)) AIBinder* AIBinder_new(const AIBinder_Class* clazz, void* args) 266 __INTRODUCED_IN(29); 267 268 /** 269 * If this is hosted in a process other than the current one. 270 * 271 * Available since API level 29. 272 * 273 * \param binder the binder being queried. 274 * 275 * \return true if the AIBinder represents an object in another process. 276 */ 277 bool AIBinder_isRemote(const AIBinder* binder) __INTRODUCED_IN(29); 278 279 /** 280 * If this binder is known to be alive. This will not send a transaction to a remote process and 281 * returns a result based on the last known information. That is, whenever a transaction is made, 282 * this is automatically updated to reflect the current alive status of this binder. This will be 283 * updated as the result of a transaction made using AIBinder_transact, but it will also be updated 284 * based on the results of bookkeeping or other transactions made internally. 285 * 286 * Available since API level 29. 287 * 288 * \param binder the binder being queried. 289 * 290 * \return true if the binder is alive. 291 */ 292 bool AIBinder_isAlive(const AIBinder* binder) __INTRODUCED_IN(29); 293 294 /** 295 * Built-in transaction for all binder objects. This sends a transaction that will immediately 296 * return. Usually this is used to make sure that a binder is alive, as a placeholder call, or as a 297 * consistency check. 298 * 299 * Available since API level 29. 300 * 301 * \param binder the binder being queried. 302 * 303 * \return STATUS_OK if the ping succeeds. 304 */ 305 binder_status_t AIBinder_ping(AIBinder* binder) __INTRODUCED_IN(29); 306 307 /** 308 * Built-in transaction for all binder objects. This dumps information about a given binder. 309 * 310 * See also AIBinder_Class_setOnDump, AIBinder_onDump. 311 * 312 * Available since API level 29. 313 * 314 * \param binder the binder to dump information about 315 * \param fd where information should be dumped to 316 * \param args null-terminated arguments to pass (may be null if numArgs is 0) 317 * \param numArgs number of args to send 318 * 319 * \return STATUS_OK if dump succeeds (or if there is nothing to dump) 320 */ 321 binder_status_t AIBinder_dump(AIBinder* binder, int fd, const char** args, uint32_t numArgs) 322 __INTRODUCED_IN(29); 323 324 /** 325 * Registers for notifications that the associated binder is dead. The same death recipient may be 326 * associated with multiple different binders. If the binder is local, then no death recipient will 327 * be given (since if the local process dies, then no recipient will exist to receive a 328 * transaction). The cookie is passed to recipient in the case that this binder dies and can be 329 * null. The exact cookie must also be used to unlink this transaction (see AIBinder_unlinkToDeath). 330 * This function may return a binder transaction failure. The cookie can be used both for 331 * identification and holding user data. 332 * 333 * If binder is local, this will return STATUS_INVALID_OPERATION. 334 * 335 * Available since API level 29. 336 * 337 * \param binder the binder object you want to receive death notifications from. 338 * \param recipient the callback that will receive notifications when/if the binder dies. 339 * \param cookie the value that will be passed to the death recipient on death. 340 * 341 * \return STATUS_OK on success. 342 */ 343 binder_status_t AIBinder_linkToDeath(AIBinder* binder, AIBinder_DeathRecipient* recipient, 344 void* cookie) __INTRODUCED_IN(29); 345 346 /** 347 * Stops registration for the associated binder dying. Does not delete the recipient. This function 348 * may return a binder transaction failure and in case the death recipient cannot be found, it 349 * returns STATUS_NAME_NOT_FOUND. 350 * 351 * This only ever needs to be called when the AIBinder_DeathRecipient remains for use with other 352 * AIBinder objects. If the death recipient is deleted, all binders will automatically be unlinked. 353 * If the binder dies, it will automatically unlink. If the binder is deleted, it will be 354 * automatically unlinked. 355 * 356 * Be aware that it is not safe to immediately deallocate the cookie when this call returns. If you 357 * need to clean up the cookie, you should do so in the onUnlinked callback, which can be set using 358 * AIBinder_DeathRecipient_setOnUnlinked. 359 * 360 * Available since API level 29. 361 * 362 * \param binder the binder object to remove a previously linked death recipient from. 363 * \param recipient the callback to remove. 364 * \param cookie the cookie used to link to death. 365 * 366 * \return STATUS_OK on success. STATUS_NAME_NOT_FOUND if the binder cannot be found to be unlinked. 367 */ 368 binder_status_t AIBinder_unlinkToDeath(AIBinder* binder, AIBinder_DeathRecipient* recipient, 369 void* cookie) __INTRODUCED_IN(29); 370 371 /** 372 * This returns the calling UID assuming that this thread is called from a thread that is processing 373 * a binder transaction (for instance, in the implementation of AIBinder_Class_onTransact). 374 * 375 * This can be used with higher-level system services to determine the caller's identity and check 376 * permissions. 377 * 378 * Available since API level 29. 379 * 380 * \return calling uid or the current process's UID if this thread isn't processing a transaction. 381 */ 382 uid_t AIBinder_getCallingUid() __INTRODUCED_IN(29); 383 384 /** 385 * This returns the calling PID assuming that this thread is called from a thread that is processing 386 * a binder transaction (for instance, in the implementation of AIBinder_Class_onTransact). 387 * 388 * This can be used with higher-level system services to determine the caller's identity and check 389 * permissions. However, when doing this, one should be aware of possible TOCTOU problems when the 390 * calling process dies and is replaced with another process with elevated permissions and the same 391 * PID. 392 * 393 * Warning: oneway transactions do not receive PID. Even if you expect 394 * a transaction to be synchronous, a misbehaving client could send it 395 * as a synchronous call and result in a 0 PID here. Additionally, if 396 * there is a race and the calling process dies, the PID may still be 397 * 0 for a synchronous call. 398 * 399 * Available since API level 29. 400 * 401 * \return calling pid or the current process's PID if this thread isn't processing a transaction. 402 * If the transaction being processed is a oneway transaction, then this method will return 0. 403 */ 404 pid_t AIBinder_getCallingPid() __INTRODUCED_IN(29); 405 406 /** 407 * Determine whether the current thread is currently executing an incoming transaction. 408 * 409 * \return true if the current thread is currently executing an incoming transaction, and false 410 * otherwise. 411 */ 412 bool AIBinder_isHandlingTransaction() __INTRODUCED_IN(33); 413 414 /** 415 * This can only be called if a strong reference to this object already exists in process. 416 * 417 * Available since API level 29. 418 * 419 * \param binder the binder object to add a refcount to. 420 */ 421 void AIBinder_incStrong(AIBinder* binder) __INTRODUCED_IN(29); 422 423 /** 424 * This will delete the object and call onDestroy once the refcount reaches zero. 425 * 426 * Available since API level 29. 427 * 428 * \param binder the binder object to remove a refcount from. 429 */ 430 void AIBinder_decStrong(AIBinder* binder) __INTRODUCED_IN(29); 431 432 /** 433 * For debugging only! 434 * 435 * Available since API level 29. 436 * 437 * \param binder the binder object to retrieve the refcount of. 438 * 439 * \return the number of strong-refs on this binder in this process. If binder is null, this will be 440 * -1. 441 */ 442 int32_t AIBinder_debugGetRefCount(AIBinder* binder) __INTRODUCED_IN(29); 443 444 /** 445 * This sets the class of an AIBinder object. This checks to make sure the remote object is of 446 * the expected class. A class must be set in order to use transactions on an AIBinder object. 447 * However, if an object is just intended to be passed through to another process or used as a 448 * handle this need not be called. 449 * 450 * This returns true if the class association succeeds. If it fails, no change is made to the 451 * binder object. 452 * 453 * Warning: this may fail if the binder is dead. 454 * 455 * Available since API level 29. 456 * 457 * \param binder the object to attach the class to. 458 * \param clazz the clazz to attach to binder. 459 * 460 * \return true if the binder has the class clazz and if the association was successful. 461 */ 462 bool AIBinder_associateClass(AIBinder* binder, const AIBinder_Class* clazz) __INTRODUCED_IN(29); 463 464 /** 465 * Returns the class that this binder was constructed with or associated with. 466 * 467 * Available since API level 29. 468 * 469 * \param binder the object that is being queried. 470 * 471 * \return the class that this binder is associated with. If this binder wasn't created with 472 * AIBinder_new, and AIBinder_associateClass hasn't been called, then this will return null. 473 */ 474 const AIBinder_Class* AIBinder_getClass(AIBinder* binder) __INTRODUCED_IN(29); 475 476 /** 477 * Value returned by onCreate for a local binder. For stateless classes (if onCreate returns 478 * null), this also returns null. For a remote binder, this will always return null. 479 * 480 * Available since API level 29. 481 * 482 * \param binder the object that is being queried. 483 * 484 * \return the userdata returned from AIBinder_onCreate when this object was created. This may be 485 * null for stateless objects. For remote objects, this is always null. 486 */ 487 void* AIBinder_getUserData(AIBinder* binder) __INTRODUCED_IN(29); 488 489 /** 490 * A transaction is a series of calls to these functions which looks this 491 * - call AIBinder_prepareTransaction 492 * - fill out the in parcel with parameters (lifetime of the 'in' variable) 493 * - call AIBinder_transact 494 * - read results from the out parcel (lifetime of the 'out' variable) 495 */ 496 497 /** 498 * Creates a parcel to start filling out for a transaction. This will add a header to the 499 * transaction that corresponds to android.os.Parcel#writeInterfaceToken. This may add debugging 500 * or other information to the transaction for platform use or to enable other features to work. The 501 * contents of this header is a platform implementation detail, and it is required to use 502 * libbinder_ndk. This parcel is to be sent via AIBinder_transact and it represents the input data 503 * to the transaction. It is recommended to check if the object is local and call directly into its 504 * user data before calling this as the parceling and unparceling cost can be avoided. This AIBinder 505 * must be either built with a class or associated with a class before using this API. 506 * 507 * This does not affect the ownership of binder. When this function succeeds, the in parcel's 508 * ownership is passed to the caller. At this point, the parcel can be filled out and passed to 509 * AIBinder_transact. Alternatively, if there is an error while filling out the parcel, it can be 510 * deleted with AParcel_delete. 511 * 512 * Available since API level 29. 513 * 514 * \param binder the binder object to start a transaction on. 515 * \param in out parameter for input data to the transaction. 516 * 517 * \return STATUS_OK on success. This will return STATUS_INVALID_OPERATION if the binder has not yet 518 * been associated with a class (see AIBinder_new and AIBinder_associateClass). 519 */ 520 binder_status_t AIBinder_prepareTransaction(AIBinder* binder, AParcel** in) __INTRODUCED_IN(29); 521 522 /** 523 * Transact using a parcel created from AIBinder_prepareTransaction. This actually communicates with 524 * the object representing this binder object. This also passes out a parcel to be used for the 525 * return transaction. This takes ownership of the in parcel and automatically deletes it after it 526 * is sent to the remote process. The output parcel is the result of the transaction. If the 527 * transaction has FLAG_ONEWAY, the out parcel will be empty. Otherwise, this will block until the 528 * remote process has processed the transaction, and the out parcel will contain the output data 529 * from transaction. 530 * 531 * This does not affect the ownership of binder. The out parcel's ownership is passed to the caller 532 * and must be released with AParcel_delete when finished reading. 533 * 534 * Available since API level 29. 535 * 536 * \param binder the binder object to transact on. 537 * \param code the implementation-specific code representing which transaction should be taken. 538 * \param in the implementation-specific input data to this transaction. 539 * \param out the implementation-specific output data to this transaction. 540 * \param flags possible flags to alter the way in which the transaction is conducted or 0. 541 * 542 * \return the result from the kernel or from the remote process. Usually, implementation-specific 543 * error codes are written to the output parcel, and the transaction code is reserved for kernel 544 * errors or error codes that have been repeated from subsequent transactions. 545 */ 546 binder_status_t AIBinder_transact(AIBinder* binder, transaction_code_t code, AParcel** in, 547 AParcel** out, binder_flags_t flags) __INTRODUCED_IN(29); 548 549 /** 550 * This does not take any ownership of the input binder, but it can be used to retrieve it if 551 * something else in some process still holds a reference to it. 552 * 553 * Available since API level 29. 554 * 555 * \param binder object to create a weak pointer to. 556 * 557 * \return object representing a weak pointer to binder (or null if binder is null). 558 */ 559 __attribute__((warn_unused_result)) AIBinder_Weak* AIBinder_Weak_new(AIBinder* binder) 560 __INTRODUCED_IN(29); 561 562 /** 563 * Deletes the weak reference. This will have no impact on the lifetime of the binder. 564 * 565 * Available since API level 29. 566 * 567 * \param weakBinder object created with AIBinder_Weak_new. 568 */ 569 void AIBinder_Weak_delete(AIBinder_Weak* weakBinder) __INTRODUCED_IN(29); 570 571 /** 572 * If promotion succeeds, result will have one strong refcount added to it. Otherwise, this returns 573 * null. 574 * 575 * Available since API level 29. 576 * 577 * \param weakBinder weak pointer to attempt retrieving the original object from. 578 * 579 * \return an AIBinder object with one refcount given to the caller or null. 580 */ 581 __attribute__((warn_unused_result)) AIBinder* AIBinder_Weak_promote(AIBinder_Weak* weakBinder) 582 __INTRODUCED_IN(29); 583 584 /** 585 * This function is executed on death receipt. See AIBinder_linkToDeath/AIBinder_unlinkToDeath. 586 * 587 * Available since API level 29. 588 * 589 * \param cookie the cookie passed to AIBinder_linkToDeath. 590 */ 591 typedef void (*AIBinder_DeathRecipient_onBinderDied)(void* cookie) __INTRODUCED_IN(29); 592 593 /** 594 * This function is intended for cleaning up the data in the provided cookie, and it is executed 595 * when the DeathRecipient is unlinked. When the DeathRecipient is unlinked due to a death receipt, 596 * this method is called after the call to onBinderDied. 597 * 598 * This method is called once for each binder that is unlinked. Hence, if the same cookie is passed 599 * to multiple binders, then the caller is responsible for reference counting the cookie. 600 * 601 * See also AIBinder_linkToDeath/AIBinder_unlinkToDeath. 602 * 603 * WARNING: Make sure the lifetime of this cookie is long enough. If it is dynamically 604 * allocated, it should be deleted with AIBinder_DeathRecipient_setOnUnlinked. 605 * 606 * Available since API level 33. 607 * 608 * \param cookie the cookie passed to AIBinder_linkToDeath. 609 */ 610 typedef void (*AIBinder_DeathRecipient_onBinderUnlinked)(void* cookie) __INTRODUCED_IN(33); 611 612 /** 613 * Creates a new binder death recipient. This can be attached to multiple different binder objects. 614 * 615 * Available since API level 29. 616 * 617 * WARNING: Make sure the lifetime of this cookie is long enough. If it is dynamically 618 * allocated, it should be deleted with AIBinder_DeathRecipient_setOnUnlinked. 619 * 620 * \param onBinderDied the callback to call when this death recipient is invoked. 621 * 622 * \return the newly constructed object (or null if onBinderDied is null). 623 */ 624 __attribute__((warn_unused_result)) AIBinder_DeathRecipient* AIBinder_DeathRecipient_new( 625 AIBinder_DeathRecipient_onBinderDied onBinderDied) __INTRODUCED_IN(29); 626 627 /** 628 * Set the callback to be called when this DeathRecipient is unlinked from a binder. The callback is 629 * called in the following situations: 630 * 631 * 1. If the binder died, shortly after the call to onBinderDied. 632 * 2. If the binder is explicitly unlinked with AIBinder_unlinkToDeath or 633 * AIBinder_DeathRecipient_delete, after any pending onBinderDied calls 634 * finish. 635 * 3. During or shortly after the AIBinder_linkToDeath call if it returns an error. 636 * 637 * It is guaranteed that the callback is called exactly once for each call to linkToDeath unless the 638 * process is aborted before the binder is unlinked. 639 * 640 * Be aware that when the binder is explicitly unlinked, it is not guaranteed that onUnlinked has 641 * been called before the call to AIBinder_unlinkToDeath or AIBinder_DeathRecipient_delete returns. 642 * For example, if the binder dies concurrently with a call to AIBinder_unlinkToDeath, the binder is 643 * not unlinked until after the death notification is delivered, even if AIBinder_unlinkToDeath 644 * returns before that happens. 645 * 646 * This method should be called before linking the DeathRecipient to a binder because the function 647 * pointer is cached. If you change it after linking to a binder, it is unspecified whether the old 648 * binder will call the old or new onUnlinked callback. 649 * 650 * The onUnlinked argument may be null. In this case, no notification is given when the binder is 651 * unlinked. 652 * 653 * Available since API level 33. 654 * 655 * \param recipient the DeathRecipient to set the onUnlinked callback for. 656 * \param onUnlinked the callback to call when a binder is unlinked from recipient. 657 */ 658 void AIBinder_DeathRecipient_setOnUnlinked(AIBinder_DeathRecipient* recipient, 659 AIBinder_DeathRecipient_onBinderUnlinked onUnlinked) 660 __INTRODUCED_IN(33); 661 662 /** 663 * Deletes a binder death recipient. It is not necessary to call AIBinder_unlinkToDeath before 664 * calling this as these will all be automatically unlinked. 665 * 666 * Be aware that it is not safe to immediately deallocate the cookie when this call returns. If you 667 * need to clean up the cookie, you should do so in the onUnlinked callback, which can be set using 668 * AIBinder_DeathRecipient_setOnUnlinked. 669 * 670 * Available since API level 29. 671 * 672 * \param recipient the binder to delete (previously created with AIBinder_DeathRecipient_new). 673 */ 674 void AIBinder_DeathRecipient_delete(AIBinder_DeathRecipient* recipient) __INTRODUCED_IN(29); 675 676 /** 677 * Gets the extension registered with AIBinder_setExtension. 678 * 679 * See AIBinder_setExtension. 680 * 681 * Available since API level 30. 682 * 683 * \param binder the object to get the extension of. 684 * \param outExt the returned extension object. Will be null if there is no extension set or 685 * non-null with one strong ref count. 686 * 687 * \return error of getting the interface (may be a transaction error if this is 688 * remote binder). STATUS_UNEXPECTED_NULL if binder is null. 689 */ 690 binder_status_t AIBinder_getExtension(AIBinder* binder, AIBinder** outExt) __INTRODUCED_IN(30); 691 692 /** 693 * Gets the extension of a binder interface. This allows a downstream developer to add 694 * an extension to an interface without modifying its interface file. This should be 695 * called immediately when the object is created before it is passed to another thread. 696 * No thread safety is required. 697 * 698 * For instance, imagine if we have this interface: 699 * interface IFoo { void doFoo(); } 700 * 701 * A). Historical option that has proven to be BAD! Only the original 702 * author of an interface should change an interface. If someone 703 * downstream wants additional functionality, they should not ever 704 * change the interface or use this method. 705 * 706 * BAD TO DO: interface IFoo { BAD TO DO 707 * BAD TO DO: void doFoo(); BAD TO DO 708 * BAD TO DO: + void doBar(); // adding a method BAD TO DO 709 * BAD TO DO: } BAD TO DO 710 * 711 * B). Option that this method enables. 712 * Leave the original interface unchanged (do not change IFoo!). 713 * Instead, create a new interface in a downstream package: 714 * 715 * package com.<name>; // new functionality in a new package 716 * interface IBar { void doBar(); } 717 * 718 * When registering the interface, add: 719 * std::shared_ptr<MyFoo> foo = new MyFoo; // class in AOSP codebase 720 * std::shared_ptr<MyBar> bar = new MyBar; // custom extension class 721 * SpAIBinder binder = foo->asBinder(); // target binder to extend 722 * ... = AIBinder_setExtension(binder.get(), bar->asBinder().get()); 723 * ... = AServiceManager_addService(binder.get(), instanceName); 724 * // handle error 725 * 726 * Do not use foo->asBinder().get() as the target binder argument to 727 * AIBinder_setExtensions because asBinder it creates a new binder 728 * object that will be destroyed after the function is called. The same 729 * binder object must be used for AIBinder_setExtension and 730 * AServiceManager_addService to register the service with an extension. 731 * 732 * Then, clients of IFoo can get this extension: 733 * SpAIBinder binder = ...; 734 * std::shared_ptr<IFoo> foo = IFoo::fromBinder(binder); // handle if null 735 * SpAIBinder barBinder; 736 * ... = AIBinder_getExtension(barBinder.get()); 737 * // handle error 738 * std::shared_ptr<IBar> bar = IBar::fromBinder(barBinder); 739 * // type is checked with AIBinder_associateClass 740 * // if bar is null, then there is no extension or a different 741 * // type of extension 742 * 743 * Available since API level 30. 744 * 745 * \param binder the object to get the extension on. Must be local. 746 * \param ext the extension to set (binder will hold a strong reference to this) 747 * 748 * \return OK on success, STATUS_INVALID_OPERATION if binder is not local, STATUS_UNEXPECTED_NULL 749 * if either binder is null. 750 */ 751 binder_status_t AIBinder_setExtension(AIBinder* binder, AIBinder* ext) __INTRODUCED_IN(30); 752 753 /** 754 * Retrieve the class descriptor for the class. 755 * 756 * Available since API level 31. 757 * 758 * \param clazz the class to fetch the descriptor from 759 * 760 * \return the class descriptor string. This pointer will never be null; a 761 * descriptor is required to define a class. The pointer is owned by the class 762 * and will remain valid as long as the class does. For a local class, this will 763 * be the same value (not necessarily pointer equal) as is passed into 764 * AIBinder_Class_define. Format is utf-8. 765 */ 766 const char* AIBinder_Class_getDescriptor(const AIBinder_Class* clazz) __INTRODUCED_IN(31); 767 768 /** 769 * Whether AIBinder is less than another. 770 * 771 * This provides a per-process-unique total ordering of binders where a null 772 * AIBinder* object is considered to be before all other binder objects. 773 * For instance, two binders refer to the same object in a local or remote 774 * process when both AIBinder_lt(a, b) and AIBinder(b, a) are false. This API 775 * might be used to insert and lookup binders in binary search trees. 776 * 777 * AIBinder* pointers themselves actually also create a per-process-unique total 778 * ordering. However, this ordering is inconsistent with AIBinder_Weak_lt for 779 * remote binders. So, in general, this function should be preferred. 780 * 781 * Available since API level 31. 782 * 783 * \param lhs comparison object 784 * \param rhs comparison object 785 * 786 * \return whether "lhs < rhs" is true 787 */ 788 bool AIBinder_lt(const AIBinder* lhs, const AIBinder* rhs) __INTRODUCED_IN(31); 789 790 /** 791 * Clone an AIBinder_Weak. Useful because even if a weak binder promotes to a 792 * null value, after further binder transactions, it may no longer promote to a 793 * null value. 794 * 795 * Available since API level 31. 796 * 797 * \param weak Object to clone 798 * 799 * \return clone of the input parameter. This must be deleted with 800 * AIBinder_Weak_delete. Null if weak input parameter is also null. 801 */ 802 AIBinder_Weak* AIBinder_Weak_clone(const AIBinder_Weak* weak) __INTRODUCED_IN(31); 803 804 /** 805 * Whether AIBinder_Weak is less than another. 806 * 807 * This provides a per-process-unique total ordering of binders which is exactly 808 * the same as AIBinder_lt. Similarly, a null AIBinder_Weak* is considered to be 809 * ordered before all other weak references. 810 * 811 * This function correctly distinguishes binders even if one is deallocated. So, 812 * for instance, an AIBinder_Weak* entry representing a deleted binder will 813 * never compare as equal to an AIBinder_Weak* entry which represents a 814 * different allocation of a binder, even if the two binders were originally 815 * allocated at the same address. That is: 816 * 817 * AIBinder* a = ...; // imagine this has address 0x8 818 * AIBinder_Weak* bWeak = AIBinder_Weak_new(a); 819 * AIBinder_decStrong(a); // a may be deleted, if this is the last reference 820 * AIBinder* b = ...; // imagine this has address 0x8 (same address as b) 821 * AIBinder_Weak* bWeak = AIBinder_Weak_new(b); 822 * 823 * Then when a/b are compared with other binders, their order will be preserved, 824 * and it will either be the case that AIBinder_Weak_lt(aWeak, bWeak) OR 825 * AIBinder_Weak_lt(bWeak, aWeak), but not both. 826 * 827 * Unlike AIBinder*, the AIBinder_Weak* addresses themselves have nothing to do 828 * with the underlying binder. 829 * 830 * Available since API level 31. 831 * 832 * \param lhs comparison object 833 * \param rhs comparison object 834 * 835 * \return whether "lhs < rhs" is true 836 */ 837 bool AIBinder_Weak_lt(const AIBinder_Weak* lhs, const AIBinder_Weak* rhs) __INTRODUCED_IN(31); 838 839 __END_DECLS 840 841 /** @} */ 842