libobjc/protocols.c

   1 /* GNU Objective C Runtime protocol related functions.
   2    Copyright (C) 2010-2021 Free Software Foundation, Inc.
   3    Contributed by Nicola Pero
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under the
   8 terms of the GNU General Public License as published by the Free Software
   9 Foundation; either version 3, or (at your option) any later version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  13 FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  14 details.
  15
  16 Under Section 7 of GPL version 3, you are granted additional
  17 permissions described in the GCC Runtime Library Exception, version
  18 3.1, as published by the Free Software Foundation.
  19
  20 You should have received a copy of the GNU General Public License and
  21 a copy of the GCC Runtime Library Exception along with this program;
  22 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 <http://www.gnu.org/licenses/>.  */
  24
  25 #include "objc-private/common.h"
  26 #include "objc/runtime.h"
  27 #include "objc-private/module-abi-8.h" /* For runtime structures  */
  28 #include "objc/thr.h"
  29 #include "objc-private/runtime.h"      /* the kitchen sink */
  30 #include "objc-private/hash.h"         /* For the hash table of protocols.  */
  31 #include "objc-private/protocols.h"    /* For __objc_protocols_init() and
  32                                           __objc_protocols_add_protocol().  */
  33 #include <stdlib.h>                    /* For malloc.  */
  34
  35 /* This is a table that maps a name to a Protocol instance with that
  36    name.  Because there may be multiple Protocol instances with the
  37    same name (no harm in that) the table records only one
  38    instance.  */
  39 static cache_ptr __protocols_hashtable;
  40
  41 /* A mutex protecting the protocol_hashtable.  */
  42 static objc_mutex_t __protocols_hashtable_lock = NULL;
  43
  44 /* Called at startup by init.c.  */
  45 void
  46 __objc_protocols_init (void)
  47 {
  48   __protocols_hashtable_lock = objc_mutex_allocate ();
  49
  50   /* The keys in the table are strings, and the values are Protocol
  51      objects.  */
  52   __protocols_hashtable = objc_hash_new (64, (hash_func_type) objc_hash_string,
  53                                          (compare_func_type) objc_compare_strings);
  54 }
  55
  56 /* Add a protocol to the hashtable.  */
  57 void
  58 __objc_protocols_add_protocol (const char *name, struct objc_protocol *object)
  59 {
  60   objc_mutex_lock (__protocols_hashtable_lock);
  61
  62   /* If we find a protocol with the same name already in the
  63      hashtable, we do not need to add the new one, because it will be
  64      identical to it.  This in the reasonable assumption that two
  65      protocols with the same name are identical, which is expected in
  66      any sane program.  If we are really paranoid, we would compare
  67      the protocols and abort if they are not identical.
  68      Unfortunately, this would slow down the startup of all
  69      Objective-C programs while trying to catch a problem that has
  70      never been seen in practice, so we don't do it.  */
  71   if (! objc_hash_is_key_in_hash (__protocols_hashtable, name))
  72     objc_hash_add (&__protocols_hashtable, name, object);
  73
  74   objc_mutex_unlock (__protocols_hashtable_lock);
  75 }
  76
  77 Protocol *
  78 objc_getProtocol (const char *name)
  79 {
  80   Protocol *protocol;
  81
  82   if (name == NULL)
  83     return NULL;
  84
  85   objc_mutex_lock (__protocols_hashtable_lock);
  86   protocol = (Protocol *)(objc_hash_value_for_key (__protocols_hashtable, name));
  87   objc_mutex_unlock (__protocols_hashtable_lock);
  88
  89   return protocol;
  90 }
  91
  92 Protocol **
  93 objc_copyProtocolList (unsigned int *numberOfReturnedProtocols)
  94 {
  95   unsigned int count = 0;
  96   Protocol **returnValue = NULL;
  97   node_ptr node;
  98
  99   objc_mutex_lock (__protocols_hashtable_lock);
 100
 101   /* Count how many protocols we have.  */
 102   node = objc_hash_next (__protocols_hashtable, NULL);
 103   while (node)
 104     {
 105       count++;
 106       node = objc_hash_next (__protocols_hashtable, node);
 107     }
 108
 109   if (count != 0)
 110     {
 111       unsigned int i = 0;
 112
 113       /* Allocate enough memory to hold them.  */
 114       returnValue = (Protocol **)(malloc (sizeof (Protocol *) * (count + 1)));
 115
 116       /* Copy the protocols.  */
 117       node = objc_hash_next (__protocols_hashtable, NULL);
 118       while (node)
 119         {
 120           returnValue[i] = node->value;
 121           i++;
 122           node = objc_hash_next (__protocols_hashtable, node);
 123         }
 124
 125       returnValue[i] = NULL;
 126     }
 127   objc_mutex_unlock (__protocols_hashtable_lock);
 128
 129   if (numberOfReturnedProtocols)
 130     *numberOfReturnedProtocols = count;
 131
 132   return returnValue;
 133 }
 134
 135 BOOL
 136 class_addProtocol (Class class_, Protocol *protocol)
 137 {
 138   struct objc_protocol_list *protocols;
 139
 140   if (class_ == Nil  ||  protocol == NULL)
 141     return NO;
 142
 143   if (class_conformsToProtocol (class_, protocol))
 144     return NO;
 145
 146   /* Check that it is a Protocol object before casting it to (struct
 147      objc_protocol *).  */
 148   if (protocol->class_pointer != objc_lookUpClass ("Protocol"))
 149     return NO;
 150
 151   objc_mutex_lock (__objc_runtime_mutex);
 152
 153   /* Create the objc_protocol_list.  */
 154   protocols = malloc (sizeof (struct objc_protocol_list));
 155   protocols->count = 1;
 156   protocols->list[0] = (struct objc_protocol *)protocol;
 157
 158   /* Attach it to the list of class protocols.  */
 159   protocols->next = class_->protocols;
 160   class_->protocols = protocols;
 161
 162   objc_mutex_unlock (__objc_runtime_mutex);
 163
 164   return YES;
 165 }
 166
 167 BOOL
 168 class_conformsToProtocol (Class class_, Protocol *protocol)
 169 {
 170   struct objc_protocol_list* proto_list;
 171
 172   if (class_ == Nil  ||  protocol == NULL)
 173     return NO;
 174
 175   /* Check that it is a Protocol object before casting it to (struct
 176      objc_protocol *).  */
 177   if (protocol->class_pointer != objc_lookUpClass ("Protocol"))
 178     return NO;
 179
 180   /* Acquire the runtime lock because the list of protocols for a
 181      class may be modified concurrently, for example if another thread
 182      calls class_addProtocol(), or dynamically loads from a file a
 183      category of the class.  */
 184   objc_mutex_lock (__objc_runtime_mutex);
 185   proto_list = class_->protocols;
 186
 187   while (proto_list)
 188     {
 189       size_t i;
 190       for (i = 0; i < proto_list->count; i++)
 191         {
 192           if (proto_list->list[i] == (struct objc_protocol *)protocol
 193               || protocol_conformsToProtocol ((Protocol *)proto_list->list[i],
 194                                               protocol))
 195             {
 196               objc_mutex_unlock (__objc_runtime_mutex);
 197               return YES;
 198             }
 199         }
 200       proto_list = proto_list->next;
 201     }
 202
 203   objc_mutex_unlock (__objc_runtime_mutex);
 204   return NO;
 205 }
 206
 207 Protocol **
 208 class_copyProtocolList (Class class_, unsigned int *numberOfReturnedProtocols)
 209 {
 210   unsigned int count = 0;
 211   Protocol **returnValue = NULL;
 212   struct objc_protocol_list* proto_list;
 213
 214   if (class_ == Nil)
 215     {
 216       if (numberOfReturnedProtocols)
 217         *numberOfReturnedProtocols = 0;
 218       return NULL;
 219     }
 220
 221   /* Lock the runtime mutex because the class protocols may be
 222      concurrently modified.  */
 223   objc_mutex_lock (__objc_runtime_mutex);
 224
 225   /* Count how many protocols we have.  */
 226   proto_list = class_->protocols;
 227
 228   while (proto_list)
 229     {
 230       count = count + proto_list->count;
 231       proto_list = proto_list->next;
 232     }
 233
 234   if (count != 0)
 235     {
 236       unsigned int i = 0;
 237
 238       /* Allocate enough memory to hold them.  */
 239       returnValue = (Protocol **)(malloc (sizeof (Protocol *) * (count + 1)));
 240
 241       /* Copy the protocols.  */
 242       proto_list = class_->protocols;
 243
 244       while (proto_list)
 245         {
 246           size_t j;
 247           for (j = 0; j < proto_list->count; j++)
 248             {
 249               returnValue[i] = (Protocol *)proto_list->list[j];
 250               i++;
 251             }
 252           proto_list = proto_list->next;
 253         }
 254
 255       returnValue[i] = NULL;
 256     }
 257   objc_mutex_unlock (__objc_runtime_mutex);
 258
 259   if (numberOfReturnedProtocols)
 260     *numberOfReturnedProtocols = count;
 261
 262   return returnValue;
 263 }
 264
 265 BOOL
 266 protocol_conformsToProtocol (Protocol *protocol, Protocol *anotherProtocol)
 267 {
 268   struct objc_protocol_list* proto_list;
 269
 270   if (protocol == NULL  ||  anotherProtocol == NULL)
 271     return NO;
 272
 273   if (protocol == anotherProtocol)
 274     return YES;
 275
 276   /* Check that the objects are Protocol objects before casting them
 277      to (struct objc_protocol *).  */
 278   if (protocol->class_pointer != anotherProtocol->class_pointer)
 279     return NO;
 280
 281   if (protocol->class_pointer != objc_lookUpClass ("Protocol"))
 282     return NO;
 283
 284   if (strcmp (((struct objc_protocol *)protocol)->protocol_name,
 285               ((struct objc_protocol *)anotherProtocol)->protocol_name) == 0)
 286     return YES;
 287
 288   /* We do not acquire any lock because protocols are currently
 289      immutable.  We can freely iterate over a protocol structure.  */
 290   proto_list = ((struct objc_protocol *)protocol)->protocol_list;
 291   while (proto_list)
 292     {
 293       size_t i;
 294
 295       for (i = 0; i < proto_list->count; i++)
 296         {
 297           if (protocol_conformsToProtocol ((Protocol *)proto_list->list[i], anotherProtocol))
 298             return YES;
 299         }
 300       proto_list = proto_list->next;
 301     }
 302
 303   return NO;
 304 }
 305
 306 BOOL
 307 protocol_isEqual (Protocol *protocol, Protocol *anotherProtocol)
 308 {
 309   if (protocol == anotherProtocol)
 310     return YES;
 311
 312   if (protocol == NULL  ||  anotherProtocol == NULL)
 313     return NO;
 314
 315   /* Check that the objects are Protocol objects before casting them
 316      to (struct objc_protocol *).  */
 317   if (protocol->class_pointer != anotherProtocol->class_pointer)
 318     return NO;
 319
 320   if (protocol->class_pointer != objc_lookUpClass ("Protocol"))
 321     return NO;
 322
 323   /* Equality between formal protocols is only formal (nothing to do
 324      with actually checking the list of methods they have!).  Two
 325      formal Protocols are equal if and only if they have the same
 326      name.
 327
 328      Please note (for comparisons with other implementations) that
 329      checking the names is equivalent to checking that Protocol A
 330      conforms to Protocol B and Protocol B conforms to Protocol A,
 331      because this happens iff they have the same name.  If they have
 332      different names, A conforms to B if and only if A includes B, but
 333      the situation where A includes B and B includes A is a circular
 334      dependency between Protocols which is forbidden by the compiler,
 335      so A conforms to B and B conforms to A with A and B having
 336      different names is an impossible case.  */
 337   if (strcmp (((struct objc_protocol *)protocol)->protocol_name,
 338               ((struct objc_protocol *)anotherProtocol)->protocol_name) == 0)
 339     return YES;
 340
 341   return NO;
 342 }
 343
 344 const char *
 345 protocol_getName (Protocol *protocol)
 346 {
 347   /* Check that it is a Protocol object before casting it to (struct
 348      objc_protocol *).  */
 349   if (protocol->class_pointer != objc_lookUpClass ("Protocol"))
 350     return NULL;
 351
 352   return ((struct objc_protocol *)protocol)->protocol_name;
 353 }
 354
 355 struct objc_method_description protocol_getMethodDescription (Protocol *protocol,
 356                                                               SEL selector,
 357                                                               BOOL requiredMethod,
 358                                                               BOOL instanceMethod)
 359 {
 360   struct objc_method_description no_result = { NULL, NULL };
 361   struct objc_method_description_list *methods;
 362   int i;
 363
 364   /* TODO: New ABI.  */
 365   /* The current ABI does not have any information on optional protocol methods.  */
 366   if (! requiredMethod)
 367     return no_result;
 368
 369   /* Check that it is a Protocol object before casting it to (struct
 370      objc_protocol *).  */
 371   if (protocol->class_pointer != objc_lookUpClass ("Protocol"))
 372     return no_result;
 373
 374   if (instanceMethod)
 375     methods = ((struct objc_protocol *)protocol)->instance_methods;
 376   else
 377     methods = ((struct objc_protocol *)protocol)->class_methods;
 378
 379   if (methods)
 380     {
 381       for (i = 0; i < methods->count; i++)
 382         {
 383           if (sel_isEqual (methods->list[i].name, selector))
 384             return methods->list[i];
 385           /*
 386           if (strcmp (sel_getName (methods->list[i].name), selector_name) == 0)
 387             return methods->list[i];
 388           */
 389         }
 390     }
 391
 392   return no_result;
 393 }
 394
 395 struct objc_method_description *protocol_copyMethodDescriptionList (Protocol *protocol,
 396                                                                     BOOL requiredMethod,
 397                                                                     BOOL instanceMethod,
 398                                                                     unsigned int *numberOfReturnedMethods)
 399 {
 400   struct objc_method_description_list *methods;
 401   unsigned int count = 0;
 402   struct objc_method_description *returnValue = NULL;
 403
 404   /* TODO: New ABI */
 405   /* The current ABI does not have any information on optional protocol methods.  */
 406   if (! requiredMethod)
 407     {
 408       if (numberOfReturnedMethods)
 409         *numberOfReturnedMethods = 0;
 410
 411       return NULL;
 412     }
 413
 414   /* Check that it is a Protocol object before casting it to (struct
 415      objc_protocol *).  */
 416   if (protocol == NULL  ||  protocol->class_pointer != objc_lookUpClass ("Protocol"))
 417     {
 418       if (numberOfReturnedMethods)
 419         *numberOfReturnedMethods = 0;
 420
 421       return NULL;
 422     }
 423
 424   /* We do not acquire any lock because protocols are currently
 425      immutable.  We can freely iterate over a protocol structure.  */
 426
 427   if (instanceMethod)
 428     methods = ((struct objc_protocol *)protocol)->instance_methods;
 429   else
 430     methods = ((struct objc_protocol *)protocol)->class_methods;
 431
 432   if (methods)
 433     {
 434       unsigned int i;
 435       count = methods->count;
 436
 437       /* Allocate enough memory to hold them.  */
 438       returnValue = (struct objc_method_description *)(malloc (sizeof (struct objc_method_description) * (count + 1)));
 439
 440       /* Copy them.  */
 441       for (i = 0; i < count; i++)
 442         {
 443           returnValue[i].name = methods->list[i].name;
 444           returnValue[i].types = methods->list[i].types;
 445         }
 446       returnValue[i].name = NULL;
 447       returnValue[i].types = NULL;
 448     }
 449
 450   if (numberOfReturnedMethods)
 451     *numberOfReturnedMethods = count;
 452
 453   return returnValue;
 454 }
 455
 456 Property protocol_getProperty (Protocol *protocol, const char *propertyName,
 457                                BOOL requiredProperty, BOOL instanceProperty)
 458 {
 459   if (protocol == NULL  ||  propertyName == NULL)
 460     return NULL;
 461
 462   if (!requiredProperty  ||  !instanceProperty)
 463     return NULL;
 464
 465   /* Check that it is a Protocol object before casting it to (struct
 466      objc_protocol *).  */
 467   if (protocol->class_pointer != objc_lookUpClass ("Protocol"))
 468     return NULL;
 469
 470   /* TODO: New ABI.  */
 471   /* The current ABI does not have any information on protocol properties.  */
 472   return NULL;
 473 }
 474
 475 Property *protocol_copyPropertyList (Protocol *protocol, unsigned int *numberOfReturnedProperties)
 476 {
 477   unsigned int count = 0;
 478   Property *returnValue = NULL;
 479
 480   /* Check that it is a Protocol object before casting it to (struct
 481      objc_protocol *).  */
 482   if (protocol == NULL  ||  protocol->class_pointer != objc_lookUpClass ("Protocol"))
 483     {
 484       if (numberOfReturnedProperties)
 485         *numberOfReturnedProperties = 0;
 486
 487       return NULL;
 488     }
 489
 490   /* We do not acquire any lock because protocols are currently
 491      immutable.  We can freely iterate over a protocol structure.  */
 492
 493   /* TODO: New ABI.  */
 494   /* The current ABI does not have any information on protocol properties.  */
 495   if (numberOfReturnedProperties)
 496     *numberOfReturnedProperties = count;
 497
 498   return returnValue;
 499 }
 500
 501 Protocol **protocol_copyProtocolList (Protocol *protocol, unsigned int *numberOfReturnedProtocols)
 502 {
 503   unsigned int count = 0;
 504   Protocol **returnValue = NULL;
 505   struct objc_protocol_list* proto_list;
 506
 507   /* Check that it is a Protocol object before casting it to (struct
 508      objc_protocol *).  */
 509   if (protocol == NULL  ||  protocol->class_pointer != objc_lookUpClass ("Protocol"))
 510     {
 511       if (numberOfReturnedProtocols)
 512         *numberOfReturnedProtocols = 0;
 513
 514       return NULL;
 515     }
 516
 517   /* We do not acquire any lock because protocols are currently
 518      immutable.  We can freely iterate over a protocol structure.  */
 519
 520   /* Count how many protocols we have.  */
 521   proto_list = ((struct objc_protocol *)protocol)->protocol_list;
 522
 523   while (proto_list)
 524     {
 525       count = count + proto_list->count;
 526       proto_list = proto_list->next;
 527     }
 528
 529   if (count != 0)
 530     {
 531       unsigned int i = 0;
 532
 533       /* Allocate enough memory to hold them.  */
 534       returnValue = (Protocol **)(malloc (sizeof (Protocol *) * (count + 1)));
 535
 536       /* Copy the protocols.  */
 537       proto_list = ((struct objc_protocol *)protocol)->protocol_list;
 538
 539       while (proto_list)
 540         {
 541           size_t j;
 542           for (j = 0; j < proto_list->count; j++)
 543             {
 544               returnValue[i] = (Protocol *)proto_list->list[j];
 545               i++;
 546             }
 547           proto_list = proto_list->next;
 548         }
 549
 550       returnValue[i] = NULL;
 551     }
 552
 553   if (numberOfReturnedProtocols)
 554     *numberOfReturnedProtocols = count;
 555
 556   return returnValue;
 557 }