libobjc/ivars.c

   1 /* GNU Objective C Runtime ivar 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 <string.h>                    /* For strcmp.  */
  31 #include <stdlib.h>                    /* For malloc.  */
  32
  33 struct objc_ivar *
  34 class_getInstanceVariable (Class class_, const char *name)
  35 {
  36   if (class_ != Nil  &&  name != NULL  &&  ! CLS_IS_IN_CONSTRUCTION (class_))
  37     {
  38       while (class_ != Nil)
  39         {
  40           struct objc_ivar_list *ivars = class_->ivars;
  41           if (ivars != NULL)
  42             {
  43               int i;
  44
  45               for (i = 0; i < ivars->ivar_count; i++)
  46                 {
  47                   struct objc_ivar *ivar = &(ivars->ivar_list[i]);
  48
  49                   if (!strcmp (ivar->ivar_name, name))
  50                     return ivar;
  51                 }
  52             }
  53           class_ = class_getSuperclass (class_);
  54         }
  55     }
  56   return NULL;
  57 }
  58
  59 struct objc_ivar *
  60 class_getClassVariable (Class class_, const char *name)
  61 {
  62   if (class_ == Nil)
  63     return NULL;
  64
  65   /* Logically, since a class is an instance of its meta-class, and
  66      since its class methods are the instance methods of the
  67      meta-class, class variables should be instance variables of the
  68      meta-class.  That is different from the normal use of having
  69      'static' variables in the class implementation file, because
  70      every class would have its own variables.
  71
  72      Anyway, it is all speculative at this stage, but if we get class
  73      variables in Objective-C, it is conceivable that this
  74      implementation should work.  */
  75   return class_getInstanceVariable (class_->class_pointer, name);
  76 }
  77
  78 void *
  79 object_getIndexedIvars (id object)
  80 {
  81   if (object == nil)
  82     return NULL;
  83   else
  84     return (void *)(((char *)object)
  85                     + object->class_pointer->instance_size);
  86 }
  87
  88 struct objc_ivar *
  89 object_getInstanceVariable (id object, const char *name, void **returnValue)
  90 {
  91   if (object == nil  ||  name == NULL)
  92     return NULL;
  93   else
  94     {
  95       struct objc_ivar * variable = class_getInstanceVariable (object->class_pointer, name);
  96
  97       if (variable != NULL  &&  returnValue != NULL)
  98         {
  99           char *location = (char *)object + variable->ivar_offset;
 100
 101           *returnValue = *((id *)location);
 102         }
 103
 104       return variable;
 105     }
 106 }
 107
 108 struct objc_ivar *
 109 object_setInstanceVariable (id object, const char *name, void *newValue)
 110 {
 111   if (object == nil  ||  name == NULL)
 112     return NULL;
 113   else
 114     {
 115       struct objc_ivar * variable = class_getInstanceVariable (object->class_pointer, name);
 116
 117       if (variable != NULL)
 118         {
 119           char *location = (char *)object + variable->ivar_offset;
 120
 121           *((id *)location) = (id)newValue;
 122         }
 123
 124       return variable;
 125     }
 126 }
 127
 128 id object_getIvar (id object, struct objc_ivar * variable)
 129 {
 130   if (object == nil  ||  variable == NULL)
 131     return nil;
 132   else
 133     {
 134       char *location = (char *)object + variable->ivar_offset;
 135
 136       return *((id *)location);
 137     }
 138 }
 139
 140 void object_setIvar (id object, struct objc_ivar * variable, id value)
 141 {
 142   if (object == nil  ||  variable == NULL)
 143     return;
 144   else
 145     {
 146       char *location = (char *)object + variable->ivar_offset;
 147
 148       *((id *)location) = value;
 149     }
 150 }
 151
 152 const char * ivar_getName (struct objc_ivar * variable)
 153 {
 154   if (variable == NULL)
 155     return NULL;
 156
 157   return variable->ivar_name;
 158 }
 159
 160 ptrdiff_t ivar_getOffset (struct objc_ivar * variable)
 161 {
 162   if (variable == NULL)
 163     return 0;
 164
 165   return (ptrdiff_t)(variable->ivar_offset);
 166 }
 167
 168 const char * ivar_getTypeEncoding (struct objc_ivar * variable)
 169 {
 170   if (variable == NULL)
 171     return NULL;
 172
 173   return variable->ivar_type;
 174 }
 175
 176 struct objc_ivar ** class_copyIvarList (Class class_, unsigned int *numberOfReturnedIvars)
 177 {
 178   unsigned int count = 0;
 179   struct objc_ivar **returnValue = NULL;
 180   struct objc_ivar_list* ivar_list;
 181
 182   if (class_ == Nil  ||  CLS_IS_IN_CONSTRUCTION (class_) || !class_->ivars)
 183     {
 184       if (numberOfReturnedIvars)
 185         *numberOfReturnedIvars = 0;
 186       return NULL;
 187     }
 188
 189   /* Count how many ivars we have.  */
 190   ivar_list = class_->ivars;
 191   count = ivar_list->ivar_count;
 192
 193   if (count != 0)
 194     {
 195       unsigned int i = 0;
 196
 197       /* Allocate enough memory to hold them.  */
 198       returnValue = (struct objc_ivar **)(malloc (sizeof (struct objc_ivar *) * (count + 1)));
 199
 200       /* Copy the ivars.  */
 201       for (i = 0; i < count; i++)
 202         returnValue[i] = &(ivar_list->ivar_list[i]);
 203
 204       returnValue[i] = NULL;
 205     }
 206
 207   if (numberOfReturnedIvars)
 208     *numberOfReturnedIvars = count;
 209
 210   return returnValue;
 211 }
 212
 213 BOOL
 214 class_addIvar (Class class_, const char * ivar_name, size_t size,
 215                unsigned char log_2_of_alignment, const char *type)
 216 {
 217   struct objc_ivar_list *ivars;
 218
 219   if (class_ == Nil
 220       || (! CLS_IS_IN_CONSTRUCTION (class_))
 221       || ivar_name == NULL
 222       || (strcmp (ivar_name, "") == 0)
 223       || size == 0
 224       || type == NULL)
 225     return NO;
 226
 227   /* Check if the class has an instance variable with that name
 228      already.  */
 229   ivars = class_->ivars;
 230
 231   if (ivars != NULL)
 232     {
 233       int i;
 234
 235       for (i = 0; i < ivars->ivar_count; i++)
 236         {
 237           struct objc_ivar *ivar = &(ivars->ivar_list[i]);
 238
 239           if (strcmp (ivar->ivar_name, ivar_name) == 0)
 240             return NO;
 241         }
 242     }
 243
 244   /* Ok, no direct ivars.  Check superclasses.  */
 245   if (class_getInstanceVariable (objc_getClass ((char *)(class_->super_class)),
 246                                  ivar_name))
 247     return NO;
 248
 249   /* Good.  Create space for the new instance variable.  */
 250   if (ivars)
 251     {
 252       int ivar_count = ivars->ivar_count + 1;
 253       int new_size = sizeof (struct objc_ivar_list)
 254         + (ivar_count - 1) * sizeof (struct objc_ivar);
 255
 256       ivars = (struct objc_ivar_list*) objc_realloc (ivars, new_size);
 257       ivars->ivar_count = ivar_count;
 258       class_->ivars = ivars;
 259     }
 260   else
 261     {
 262       int new_size = sizeof (struct objc_ivar_list);
 263
 264       ivars = (struct objc_ivar_list*) objc_malloc (new_size);
 265       ivars->ivar_count = 1;
 266       class_->ivars = ivars;
 267     }
 268
 269   /* Now ivars is set to a list of instance variables of the right
 270      size. */
 271   {
 272     struct objc_ivar *ivar = &(ivars->ivar_list[ivars->ivar_count - 1]);
 273     unsigned int alignment = 1 << log_2_of_alignment;
 274     int misalignment;
 275
 276     ivar->ivar_name = objc_malloc (strlen (ivar_name) + 1);
 277     strcpy ((char *)ivar->ivar_name, ivar_name);
 278
 279     ivar->ivar_type = objc_malloc (strlen (type) + 1);
 280     strcpy ((char *)ivar->ivar_type, type);
 281
 282     /* The new instance variable is placed at the end of the existing
 283        instance_size, at the first byte that is aligned with
 284        alignment.  */
 285     misalignment = class_->instance_size % alignment;
 286
 287     if (misalignment == 0)
 288       ivar->ivar_offset = class_->instance_size;
 289     else
 290       ivar->ivar_offset = class_->instance_size - misalignment + alignment;
 291
 292     class_->instance_size = ivar->ivar_offset + size;
 293   }
 294
 295   return YES;
 296 }
 297
 298
 299 const char *
 300 property_getName (struct objc_property * property __attribute__ ((__unused__)))
 301 {
 302   if (property == NULL)
 303     return NULL;
 304
 305   /* TODO: New ABI.  */
 306   /* The current ABI does not have any information on properties.  */
 307   return NULL;
 308 }
 309
 310 const char *
 311 property_getAttributes (struct objc_property * property __attribute__ ((__unused__)))
 312 {
 313   if (property == NULL)
 314     return NULL;
 315
 316   /* TODO: New ABI.  */
 317   /* The current ABI does not have any information on properties.  */
 318   return NULL;
 319 }
 320
 321 struct objc_property *
 322 class_getProperty (Class class_ __attribute__ ((__unused__)),
 323                    const char *propertyName __attribute__ ((__unused__)))
 324 {
 325   if (class_ == NULL  ||  propertyName == NULL)
 326     return NULL;
 327
 328   /* TODO: New ABI.  */
 329   /* The current ABI does not have any information on class properties.  */
 330   return NULL;
 331 }
 332
 333 struct objc_property **
 334 class_copyPropertyList (Class class_ __attribute__ ((__unused__)),
 335                         unsigned int *numberOfReturnedProperties __attribute__ ((__unused__)))
 336 {
 337   if (class_ == Nil)
 338     {
 339       if (numberOfReturnedProperties)
 340         *numberOfReturnedProperties = 0;
 341       return NULL;
 342     }
 343
 344   /* TODO: New ABI.  */
 345   /* The current ABI does not have any information on class properties.  */
 346   if (numberOfReturnedProperties)
 347     *numberOfReturnedProperties = 0;
 348
 349   return NULL;
 350 }
 351
 352 const char *
 353 class_getIvarLayout (Class class_ __attribute__ ((__unused__)))
 354 {
 355   return NULL;
 356 }
 357
 358 const char *
 359 class_getWeakIvarLayout (Class class_ __attribute__ ((__unused__)))
 360 {
 361   return NULL;
 362 }
 363
 364 void
 365 class_setIvarLayout (Class class_ __attribute__ ((__unused__)),
 366                      const char *layout __attribute__ ((__unused__)))
 367 {
 368   return;
 369 }
 370
 371 void
 372 class_setWeakIvarLayout (Class class_ __attribute__ ((__unused__)),
 373                          const char *layout __attribute__ ((__unused__)))
 374 {
 375   return;
 376 }