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 * Available since API level 29. 394 * 395 * \return calling pid or the current process's PID if this thread isn't processing a transaction. 396 * If the transaction being processed is a oneway transaction, then this method will return 0. 397 */ 398 pid_t AIBinder_getCallingPid() __INTRODUCED_IN(29); 399 400 /** 401 * Determine whether the current thread is currently executing an incoming transaction. 402 * 403 * \return true if the current thread is currently executing an incoming transaction, and false 404 * otherwise. 405 */ 406 bool AIBinder_isHandlingTransaction() __INTRODUCED_IN(33); 407 408 /** 409 * This can only be called if a strong reference to this object already exists in process. 410 * 411 * Available since API level 29. 412 * 413 * \param binder the binder object to add a refcount to. 414 */ 415 void AIBinder_incStrong(AIBinder* binder) __INTRODUCED_IN(29); 416 417 /** 418 * This will delete the object and call onDestroy once the refcount reaches zero. 419 * 420 * Available since API level 29. 421 * 422 * \param binder the binder object to remove a refcount from. 423 */ 424 void AIBinder_decStrong(AIBinder* binder) __INTRODUCED_IN(29); 425 426 /** 427 * For debugging only! 428 * 429 * Available since API level 29. 430 * 431 * \param binder the binder object to retrieve the refcount of. 432 * 433 * \return the number of strong-refs on this binder in this process. If binder is null, this will be 434 * -1. 435 */ 436 int32_t AIBinder_debugGetRefCount(AIBinder* binder) __INTRODUCED_IN(29); 437 438 /** 439 * This sets the class of an AIBinder object. This checks to make sure the remote object is of 440 * the expected class. A class must be set in order to use transactions on an AIBinder object. 441 * However, if an object is just intended to be passed through to another process or used as a 442 * handle this need not be called. 443 * 444 * This returns true if the class association succeeds. If it fails, no change is made to the 445 * binder object. 446 * 447 * Warning: this may fail if the binder is dead. 448 * 449 * Available since API level 29. 450 * 451 * \param binder the object to attach the class to. 452 * \param clazz the clazz to attach to binder. 453 * 454 * \return true if the binder has the class clazz and if the association was successful. 455 */ 456 bool AIBinder_associateClass(AIBinder* binder, const AIBinder_Class* clazz) __INTRODUCED_IN(29); 457 458 /** 459 * Returns the class that this binder was constructed with or associated with. 460 * 461 * Available since API level 29. 462 * 463 * \param binder the object that is being queried. 464 * 465 * \return the class that this binder is associated with. If this binder wasn't created with 466 * AIBinder_new, and AIBinder_associateClass hasn't been called, then this will return null. 467 */ 468 const AIBinder_Class* AIBinder_getClass(AIBinder* binder) __INTRODUCED_IN(29); 469 470 /** 471 * Value returned by onCreate for a local binder. For stateless classes (if onCreate returns 472 * null), this also returns null. For a remote binder, this will always return null. 473 * 474 * Available since API level 29. 475 * 476 * \param binder the object that is being queried. 477 * 478 * \return the userdata returned from AIBinder_onCreate when this object was created. This may be 479 * null for stateless objects. For remote objects, this is always null. 480 */ 481 void* AIBinder_getUserData(AIBinder* binder) __INTRODUCED_IN(29); 482 483 /** 484 * A transaction is a series of calls to these functions which looks this 485 * - call AIBinder_prepareTransaction 486 * - fill out the in parcel with parameters (lifetime of the 'in' variable) 487 * - call AIBinder_transact 488 * - read results from the out parcel (lifetime of the 'out' variable) 489 */ 490 491 /** 492 * Creates a parcel to start filling out for a transaction. This will add a header to the 493 * transaction that corresponds to android.os.Parcel#writeInterfaceToken. This may add debugging 494 * or other information to the transaction for platform use or to enable other features to work. The 495 * contents of this header is a platform implementation detail, and it is required to use 496 * libbinder_ndk. This parcel is to be sent via AIBinder_transact and it represents the input data 497 * to the transaction. It is recommended to check if the object is local and call directly into its 498 * user data before calling this as the parceling and unparceling cost can be avoided. This AIBinder 499 * must be either built with a class or associated with a class before using this API. 500 * 501 * This does not affect the ownership of binder. When this function succeeds, the in parcel's 502 * ownership is passed to the caller. At this point, the parcel can be filled out and passed to 503 * AIBinder_transact. Alternatively, if there is an error while filling out the parcel, it can be 504 * deleted with AParcel_delete. 505 * 506 * Available since API level 29. 507 * 508 * \param binder the binder object to start a transaction on. 509 * \param in out parameter for input data to the transaction. 510 * 511 * \return STATUS_OK on success. This will return STATUS_INVALID_OPERATION if the binder has not yet 512 * been associated with a class (see AIBinder_new and AIBinder_associateClass). 513 */ 514 binder_status_t AIBinder_prepareTransaction(AIBinder* binder, AParcel** in) __INTRODUCED_IN(29); 515 516 /** 517 * Transact using a parcel created from AIBinder_prepareTransaction. This actually communicates with 518 * the object representing this binder object. This also passes out a parcel to be used for the 519 * return transaction. This takes ownership of the in parcel and automatically deletes it after it 520 * is sent to the remote process. The output parcel is the result of the transaction. If the 521 * transaction has FLAG_ONEWAY, the out parcel will be empty. Otherwise, this will block until the 522 * remote process has processed the transaction, and the out parcel will contain the output data 523 * from transaction. 524 * 525 * This does not affect the ownership of binder. The out parcel's ownership is passed to the caller 526 * and must be released with AParcel_delete when finished reading. 527 * 528 * Available since API level 29. 529 * 530 * \param binder the binder object to transact on. 531 * \param code the implementation-specific code representing which transaction should be taken. 532 * \param in the implementation-specific input data to this transaction. 533 * \param out the implementation-specific output data to this transaction. 534 * \param flags possible flags to alter the way in which the transaction is conducted or 0. 535 * 536 * \return the result from the kernel or from the remote process. Usually, implementation-specific 537 * error codes are written to the output parcel, and the transaction code is reserved for kernel 538 * errors or error codes that have been repeated from subsequent transactions. 539 */ 540 binder_status_t AIBinder_transact(AIBinder* binder, transaction_code_t code, AParcel** in, 541 AParcel** out, binder_flags_t flags) __INTRODUCED_IN(29); 542 543 /** 544 * This does not take any ownership of the input binder, but it can be used to retrieve it if 545 * something else in some process still holds a reference to it. 546 * 547 * Available since API level 29. 548 * 549 * \param binder object to create a weak pointer to. 550 * 551 * \return object representing a weak pointer to binder (or null if binder is null). 552 */ 553 __attribute__((warn_unused_result)) AIBinder_Weak* AIBinder_Weak_new(AIBinder* binder) 554 __INTRODUCED_IN(29); 555 556 /** 557 * Deletes the weak reference. This will have no impact on the lifetime of the binder. 558 * 559 * Available since API level 29. 560 * 561 * \param weakBinder object created with AIBinder_Weak_new. 562 */ 563 void AIBinder_Weak_delete(AIBinder_Weak* weakBinder) __INTRODUCED_IN(29); 564 565 /** 566 * If promotion succeeds, result will have one strong refcount added to it. Otherwise, this returns 567 * null. 568 * 569 * Available since API level 29. 570 * 571 * \param weakBinder weak pointer to attempt retrieving the original object from. 572 * 573 * \return an AIBinder object with one refcount given to the caller or null. 574 */ 575 __attribute__((warn_unused_result)) AIBinder* AIBinder_Weak_promote(AIBinder_Weak* weakBinder) 576 __INTRODUCED_IN(29); 577 578 /** 579 * This function is executed on death receipt. See AIBinder_linkToDeath/AIBinder_unlinkToDeath. 580 * 581 * Available since API level 29. 582 * 583 * \param cookie the cookie passed to AIBinder_linkToDeath. 584 */ 585 typedef void (*AIBinder_DeathRecipient_onBinderDied)(void* cookie) __INTRODUCED_IN(29); 586 587 /** 588 * This function is intended for cleaning up the data in the provided cookie, and it is executed 589 * when the DeathRecipient is unlinked. When the DeathRecipient is unlinked due to a death receipt, 590 * this method is called after the call to onBinderDied. 591 * 592 * This method is called once for each binder that is unlinked. Hence, if the same cookie is passed 593 * to multiple binders, then the caller is responsible for reference counting the cookie. 594 * 595 * See also AIBinder_linkToDeath/AIBinder_unlinkToDeath. 596 * 597 * WARNING: Make sure the lifetime of this cookie is long enough. If it is dynamically 598 * allocated, it should be deleted with AIBinder_DeathRecipient_setOnUnlinked. 599 * 600 * Available since API level 33. 601 * 602 * \param cookie the cookie passed to AIBinder_linkToDeath. 603 */ 604 typedef void (*AIBinder_DeathRecipient_onBinderUnlinked)(void* cookie) __INTRODUCED_IN(33); 605 606 /** 607 * Creates a new binder death recipient. This can be attached to multiple different binder objects. 608 * 609 * Available since API level 29. 610 * 611 * WARNING: Make sure the lifetime of this cookie is long enough. If it is dynamically 612 * allocated, it should be deleted with AIBinder_DeathRecipient_setOnUnlinked. 613 * 614 * \param onBinderDied the callback to call when this death recipient is invoked. 615 * 616 * \return the newly constructed object (or null if onBinderDied is null). 617 */ 618 __attribute__((warn_unused_result)) AIBinder_DeathRecipient* AIBinder_DeathRecipient_new( 619 AIBinder_DeathRecipient_onBinderDied onBinderDied) __INTRODUCED_IN(29); 620 621 /** 622 * Set the callback to be called when this DeathRecipient is unlinked from a binder. The callback is 623 * called in the following situations: 624 * 625 * 1. If the binder died, shortly after the call to onBinderDied. 626 * 2. If the binder is explicitly unlinked with AIBinder_unlinkToDeath or 627 * AIBinder_DeathRecipient_delete, after any pending onBinderDied calls 628 * finish. 629 * 3. During or shortly after the AIBinder_linkToDeath call if it returns an error. 630 * 631 * It is guaranteed that the callback is called exactly once for each call to linkToDeath unless the 632 * process is aborted before the binder is unlinked. 633 * 634 * Be aware that when the binder is explicitly unlinked, it is not guaranteed that onUnlinked has 635 * been called before the call to AIBinder_unlinkToDeath or AIBinder_DeathRecipient_delete returns. 636 * For example, if the binder dies concurrently with a call to AIBinder_unlinkToDeath, the binder is 637 * not unlinked until after the death notification is delivered, even if AIBinder_unlinkToDeath 638 * returns before that happens. 639 * 640 * This method should be called before linking the DeathRecipient to a binder because the function 641 * pointer is cached. If you change it after linking to a binder, it is unspecified whether the old 642 * binder will call the old or new onUnlinked callback. 643 * 644 * The onUnlinked argument may be null. In this case, no notification is given when the binder is 645 * unlinked. 646 * 647 * Available since API level 33. 648 * 649 * \param recipient the DeathRecipient to set the onUnlinked callback for. 650 * \param onUnlinked the callback to call when a binder is unlinked from recipient. 651 */ 652 void AIBinder_DeathRecipient_setOnUnlinked(AIBinder_DeathRecipient* recipient, 653 AIBinder_DeathRecipient_onBinderUnlinked onUnlinked) 654 __INTRODUCED_IN(33); 655 656 /** 657 * Deletes a binder death recipient. It is not necessary to call AIBinder_unlinkToDeath before 658 * calling this as these will all be automatically unlinked. 659 * 660 * Be aware that it is not safe to immediately deallocate the cookie when this call returns. If you 661 * need to clean up the cookie, you should do so in the onUnlinked callback, which can be set using 662 * AIBinder_DeathRecipient_setOnUnlinked. 663 * 664 * Available since API level 29. 665 * 666 * \param recipient the binder to delete (previously created with AIBinder_DeathRecipient_new). 667 */ 668 void AIBinder_DeathRecipient_delete(AIBinder_DeathRecipient* recipient) __INTRODUCED_IN(29); 669 670 /** 671 * Gets the extension registered with AIBinder_setExtension. 672 * 673 * See AIBinder_setExtension. 674 * 675 * Available since API level 30. 676 * 677 * \param binder the object to get the extension of. 678 * \param outExt the returned extension object. Will be null if there is no extension set or 679 * non-null with one strong ref count. 680 * 681 * \return error of getting the interface (may be a transaction error if this is 682 * remote binder). STATUS_UNEXPECTED_NULL if binder is null. 683 */ 684 binder_status_t AIBinder_getExtension(AIBinder* binder, AIBinder** outExt) __INTRODUCED_IN(30); 685 686 /** 687 * Gets the extension of a binder interface. This allows a downstream developer to add 688 * an extension to an interface without modifying its interface file. This should be 689 * called immediately when the object is created before it is passed to another thread. 690 * No thread safety is required. 691 * 692 * For instance, imagine if we have this interface: 693 * interface IFoo { void doFoo(); } 694 * 695 * A). Historical option that has proven to be BAD! Only the original 696 * author of an interface should change an interface. If someone 697 * downstream wants additional functionality, they should not ever 698 * change the interface or use this method. 699 * 700 * BAD TO DO: interface IFoo { BAD TO DO 701 * BAD TO DO: void doFoo(); BAD TO DO 702 * BAD TO DO: + void doBar(); // adding a method BAD TO DO 703 * BAD TO DO: } BAD TO DO 704 * 705 * B). Option that this method enables. 706 * Leave the original interface unchanged (do not change IFoo!). 707 * Instead, create a new interface in a downstream package: 708 * 709 * package com.<name>; // new functionality in a new package 710 * interface IBar { void doBar(); } 711 * 712 * When registering the interface, add: 713 * std::shared_ptr<MyFoo> foo = new MyFoo; // class in AOSP codebase 714 * std::shared_ptr<MyBar> bar = new MyBar; // custom extension class 715 * ... = AIBinder_setExtension(foo->asBinder().get(), bar->asBinder().get()); 716 * // handle error 717 * 718 * Then, clients of IFoo can get this extension: 719 * SpAIBinder binder = ...; 720 * std::shared_ptr<IFoo> foo = IFoo::fromBinder(binder); // handle if null 721 * SpAIBinder barBinder; 722 * ... = AIBinder_getExtension(barBinder.get()); 723 * // handle error 724 * std::shared_ptr<IBar> bar = IBar::fromBinder(barBinder); 725 * // type is checked with AIBinder_associateClass 726 * // if bar is null, then there is no extension or a different 727 * // type of extension 728 * 729 * Available since API level 30. 730 * 731 * \param binder the object to get the extension on. Must be local. 732 * \param ext the extension to set (binder will hold a strong reference to this) 733 * 734 * \return OK on success, STATUS_INVALID_OPERATION if binder is not local, STATUS_UNEXPECTED_NULL 735 * if either binder is null. 736 */ 737 binder_status_t AIBinder_setExtension(AIBinder* binder, AIBinder* ext) __INTRODUCED_IN(30); 738 739 /** 740 * Retrieve the class descriptor for the class. 741 * 742 * Available since API level 31. 743 * 744 * \param clazz the class to fetch the descriptor from 745 * 746 * \return the class descriptor string. This pointer will never be null; a 747 * descriptor is required to define a class. The pointer is owned by the class 748 * and will remain valid as long as the class does. For a local class, this will 749 * be the same value (not necessarily pointer equal) as is passed into 750 * AIBinder_Class_define. Format is utf-8. 751 */ 752 const char* AIBinder_Class_getDescriptor(const AIBinder_Class* clazz) __INTRODUCED_IN(31); 753 754 /** 755 * Whether AIBinder is less than another. 756 * 757 * This provides a per-process-unique total ordering of binders where a null 758 * AIBinder* object is considered to be before all other binder objects. 759 * For instance, two binders refer to the same object in a local or remote 760 * process when both AIBinder_lt(a, b) and AIBinder(b, a) are false. This API 761 * might be used to insert and lookup binders in binary search trees. 762 * 763 * AIBinder* pointers themselves actually also create a per-process-unique total 764 * ordering. However, this ordering is inconsistent with AIBinder_Weak_lt for 765 * remote binders. So, in general, this function should be preferred. 766 * 767 * Available since API level 31. 768 * 769 * \param lhs comparison object 770 * \param rhs comparison object 771 * 772 * \return whether "lhs < rhs" is true 773 */ 774 bool AIBinder_lt(const AIBinder* lhs, const AIBinder* rhs) __INTRODUCED_IN(31); 775 776 /** 777 * Clone an AIBinder_Weak. Useful because even if a weak binder promotes to a 778 * null value, after further binder transactions, it may no longer promote to a 779 * null value. 780 * 781 * Available since API level 31. 782 * 783 * \param weak Object to clone 784 * 785 * \return clone of the input parameter. This must be deleted with 786 * AIBinder_Weak_delete. Null if weak input parameter is also null. 787 */ 788 AIBinder_Weak* AIBinder_Weak_clone(const AIBinder_Weak* weak) __INTRODUCED_IN(31); 789 790 /** 791 * Whether AIBinder_Weak is less than another. 792 * 793 * This provides a per-process-unique total ordering of binders which is exactly 794 * the same as AIBinder_lt. Similarly, a null AIBinder_Weak* is considered to be 795 * ordered before all other weak references. 796 * 797 * This function correctly distinguishes binders even if one is deallocated. So, 798 * for instance, an AIBinder_Weak* entry representing a deleted binder will 799 * never compare as equal to an AIBinder_Weak* entry which represents a 800 * different allocation of a binder, even if the two binders were originally 801 * allocated at the same address. That is: 802 * 803 * AIBinder* a = ...; // imagine this has address 0x8 804 * AIBinder_Weak* bWeak = AIBinder_Weak_new(a); 805 * AIBinder_decStrong(a); // a may be deleted, if this is the last reference 806 * AIBinder* b = ...; // imagine this has address 0x8 (same address as b) 807 * AIBinder_Weak* bWeak = AIBinder_Weak_new(b); 808 * 809 * Then when a/b are compared with other binders, their order will be preserved, 810 * and it will either be the case that AIBinder_Weak_lt(aWeak, bWeak) OR 811 * AIBinder_Weak_lt(bWeak, aWeak), but not both. 812 * 813 * Unlike AIBinder*, the AIBinder_Weak* addresses themselves have nothing to do 814 * with the underlying binder. 815 * 816 * Available since API level 31. 817 * 818 * \param lhs comparison object 819 * \param rhs comparison object 820 * 821 * \return whether "lhs < rhs" is true 822 */ 823 bool AIBinder_Weak_lt(const AIBinder_Weak* lhs, const AIBinder_Weak* rhs) __INTRODUCED_IN(31); 824 825 __END_DECLS 826 827 /** @} */ 828