libobjc/objc-private/module-abi-8.h

   1 /* Definitions of Module Structures used by ABI version 8
   2    Copyright (C) 1993-2021 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under the
   7 terms of the GNU General Public License as published by the Free Software
   8 Foundation; either version 3, or (at your option) any later version.
   9
  10 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  11 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  12 FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  13 details.
  14
  15 Under Section 7 of GPL version 3, you are granted additional
  16 permissions described in the GCC Runtime Library Exception, version
  17 3.1, as published by the Free Software Foundation.
  18
  19 You should have received a copy of the GNU General Public License and
  20 a copy of the GCC Runtime Library Exception along with this program;
  21 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  22 <http://www.gnu.org/licenses/>.  */
  23
  24 #ifndef __objc_private_module_abi_8_INCLUDE_GNU
  25 #define __objc_private_module_abi_8_INCLUDE_GNU
  26
  27 /* For every class which happens to have statically allocated instances in
  28    this module, one OBJC_STATIC_INSTANCES is allocated by the compiler.
  29    INSTANCES is NULL terminated and points to all statically allocated
  30    instances of this class.  */
  31 struct objc_static_instances
  32 {
  33   char *class_name;
  34 #ifdef __cplusplus
  35   id instances[1];
  36 #else
  37   id instances[0];
  38 #endif
  39 };
  40
  41 /* Whereas a Module (defined further down) is the root (typically) of a file,
  42    a Symtab is the root of the class and category definitions within the
  43    module.
  44
  45    A Symtab contains a variable length array of pointers to classes and
  46    categories  defined in the module.   */
  47 struct objc_symtab
  48 {
  49   unsigned long sel_ref_cnt;  /* Unused (always set to 0). */
  50   struct objc_selector *refs; /* The table of selectors referenced in
  51                                  this module.  This is terminated by a
  52                                  selector with NULL sel_id and NULL
  53                                  sel_types.  Note that we use the type
  54                                  'struct objc_selector *' and not
  55                                  'SEL' (which is 'const struct
  56                                  objc_selector *') because the sel_id
  57                                  of these selectors is patched up by
  58                                  the runtime when the module is
  59                                  loaded.  */
  60   unsigned short cls_def_cnt; /* Number of classes compiled (defined)
  61                                  in the module. */
  62   unsigned short cat_def_cnt; /* Number of categories compiled
  63                                  (defined) in the module. */
  64   void      *defs[1];         /* Variable array of pointers.
  65                                  cls_def_cnt of type Class followed by
  66                                  cat_def_cnt of type Category_t,
  67                                  followed by a NULL terminated array
  68                                  of objc_static_instances. */
  69 };
  70
  71 /* The compiler generates one of these structures for each module that
  72    composes the executable (eg main.m).
  73
  74    This data structure is the root of the definition tree for the
  75    module.
  76
  77    A collect program runs between ld stages and creates a ObjC ctor
  78    array.  That array holds a pointer to each module structure of the
  79    executable.  */
  80 struct objc_module
  81 {
  82   unsigned long version;      /* Version of the Module data
  83                                  structure.  */
  84   unsigned long size;         /* sizeof(Module) according to the
  85                                  compiler - only used to sanity check
  86                                  that it matches sizeof(Module)
  87                                  according to the runtime.  */
  88   const char* name;           /* Name of the file used to compile the
  89                                  module - not set by modern compilers
  90                                  for security reasons.  */
  91   struct objc_symtab *symtab; /* Pointer to the Symtab of the module.
  92                                  The Symtab holds an array of pointers
  93                                  to the classes and categories defined
  94                                  in the module. */
  95 };
  96
  97 /* The compiler generates one of these structures for a class that has
  98    instance variables defined in its specification.  */
  99 struct objc_ivar
 100 {
 101   const char* ivar_name;  /* Name of the instance variable as entered
 102                              in the class definition. */
 103   const char* ivar_type;  /* Description of the Ivar's type.  Useful
 104                              for debuggers. */
 105   int        ivar_offset; /* Byte offset from the base address of the
 106                              instance structure to the variable. */
 107 };
 108
 109 struct objc_ivar_list
 110 {
 111   int   ivar_count;              /* Number of structures (Ivar)
 112                                     contained in the list.  One
 113                                     structure per instance variable
 114                                     defined in the class. */
 115   struct objc_ivar ivar_list[1]; /* Variable length structure. */
 116 };
 117
 118 /* The compiler generates one (or more) of these structures for a
 119    class that has methods defined in its specification.
 120
 121    The implementation of a class can be broken into separate pieces in
 122    a file and categories can break them across modules. To handle this
 123    problem is a singly linked list of methods.  */
 124 struct objc_method
 125 {
 126   SEL         method_name;  /* This variable is the method's name.
 127                                The compiler puts a char* here, and
 128                                it's replaced by a real SEL at runtime
 129                                when the method is registered.  */
 130   const char* method_types; /* Description of the method's parameter
 131                                list.  Used when registering the
 132                                selector with the runtime.  When that
 133                                happens, method_name will contain the
 134                                method's parameter list.  */
 135   IMP         method_imp;   /* Address of the method in the
 136                                executable. */
 137 };
 138
 139 struct objc_method_list
 140 {
 141   struct objc_method_list*  method_next; /* This variable is used to
 142                                             link a method list to
 143                                             another.  It is a singly
 144                                             linked list. */
 145   int            method_count;            /* Number of methods defined
 146                                              in this structure. */
 147   struct objc_method method_list[1];      /* Variable length
 148                                              structure. */
 149 };
 150
 151 /* Note that a 'struct objc_method_description' as embedded inside a
 152    Protocol uses the same trick as a 'struct objc_method': the
 153    method_name is a 'char *' according to the compiler, who puts the
 154    method name as a string in there.  At runtime, the selectors need
 155    to be registered, and the method_name then becomes a SEL.  */
 156 struct objc_method_description_list
 157 {
 158   int count;
 159   struct objc_method_description list[1];
 160 };
 161
 162 struct objc_protocol {
 163   struct objc_class* class_pointer;
 164   char *protocol_name;
 165   struct objc_protocol_list *protocol_list;
 166   struct objc_method_description_list *instance_methods, *class_methods;
 167 };
 168
 169
 170 struct objc_protocol_list
 171 {
 172   struct objc_protocol_list *next;
 173   size_t count;
 174   struct objc_protocol *list[1];
 175 };
 176
 177 /*
 178   The compiler generates one of these structures for each class.
 179
 180   This structure is the definition for classes.
 181
 182   This structure is generated by the compiler in the executable and
 183   used by the run-time during normal messaging operations.  Therefore
 184   some members change type. The compiler generates "char* const" and
 185   places a string in the following member variables: super_class.
 186 */
 187 struct objc_class {
 188   struct objc_class*  class_pointer;    /* Pointer to the class's meta
 189                                            class. */
 190   struct objc_class*  super_class;      /* Pointer to the super
 191                                            class. NULL for class
 192                                            Object. */
 193   const char*         name;             /* Name of the class. */
 194   long                version;          /* Unknown. */
 195   unsigned long       info;             /* Bit mask.  See class masks
 196                                            defined below. */
 197   long                instance_size;    /* Size in bytes of the class.
 198                                            The sum of the class
 199                                            definition and all super
 200                                            class definitions. */
 201 #ifdef _WIN64
 202   /* We pad the structure manually to prevent warning when -Wpadded is
 203      used.  The compiler automatically pads the structures that it
 204      generates, so this manually padded structure still matches the
 205      one generated by the compiler, but if we don't pad manually,
 206      -Wpadded detects that padding is being added and generates
 207      annoying warnings.  This hack is necessary as on LLP64 targets
 208      sizeof (long) isn't equal to sizeof (void *).  */
 209   long pad;
 210 #endif
 211   struct objc_ivar_list* ivars;         /* Pointer to a structure that
 212                                            describes the instance
 213                                            variables in the class
 214                                            definition.  NULL indicates
 215                                            no instance variables.
 216                                            Does not include super
 217                                            class variables. */
 218   struct objc_method_list*  methods;    /* Linked list of instance
 219                                            methods defined for the
 220                                            class. */
 221   struct sarray *    dtable;            /* Pointer to instance method
 222                                            dispatch table. */
 223   struct objc_class* subclass_list;     /* Subclasses */
 224   struct objc_class* sibling_class;
 225
 226   struct objc_protocol_list *protocols; /* Protocols conformed to */
 227   void* gc_object_type;
 228 };
 229
 230 /* This is used to assure consistent access to the info field of
 231    classes.  */
 232 #ifndef HOST_BITS_PER_LONG
 233 # define HOST_BITS_PER_LONG  (sizeof(long)*8)
 234 #endif
 235
 236 #define __CLS_INFO(cls) ((cls)->info)
 237 #define __CLS_ISINFO(cls, mask) ((__CLS_INFO(cls)&mask)==mask)
 238 #define __CLS_SETINFO(cls, mask) (__CLS_INFO(cls) |= mask)
 239 #define __CLS_SETNOTINFO(cls, mask) (__CLS_INFO(cls) &= ~mask)
 240
 241 /* The structure is of type MetaClass */
 242 #define _CLS_META 0x2L
 243 #define CLS_ISMETA(cls) ((cls)&&__CLS_ISINFO(cls, _CLS_META))
 244
 245 /* The structure is of type Class */
 246 #define _CLS_CLASS 0x1L
 247 #define CLS_ISCLASS(cls) ((cls)&&__CLS_ISINFO(cls, _CLS_CLASS))
 248
 249 /* The class is initialized within the runtime.  This means that it
 250    has had correct super and sublinks assigned.  */
 251 #define _CLS_RESOLV 0x8L
 252 #define CLS_ISRESOLV(cls) __CLS_ISINFO(cls, _CLS_RESOLV)
 253 #define CLS_SETRESOLV(cls) __CLS_SETINFO(cls, _CLS_RESOLV)
 254
 255 /* The class has been send a +initialize message or a such is not
 256    defined for this class.  */
 257 #define _CLS_INITIALIZED 0x04L
 258 #define CLS_ISINITIALIZED(cls) __CLS_ISINFO(cls, _CLS_INITIALIZED)
 259 #define CLS_SETINITIALIZED(cls) __CLS_SETINFO(cls, _CLS_INITIALIZED)
 260
 261 /* The class is being constructed; it has been allocated using
 262    objc_allocateClassPair(), but has not been registered yet by using
 263    objc_registerClassPair().  This means it is possible to freely add
 264    instance variables to the class, but it can't be used for anything
 265    yet.  */
 266 #define _CLS_IN_CONSTRUCTION 0x10L
 267 #define CLS_IS_IN_CONSTRUCTION(cls) __CLS_ISINFO(cls, _CLS_IN_CONSTRUCTION)
 268 #define CLS_SET_IN_CONSTRUCTION(cls) __CLS_SETINFO(cls, _CLS_IN_CONSTRUCTION)
 269 #define CLS_SET_NOT_IN_CONSTRUCTION(cls) __CLS_SETNOTINFO(cls, _CLS_IN_CONSTRUCTION)
 270
 271 /* The class number of this class.  This must be the same for both the
 272    class and its meta class object.  */
 273 #define CLS_GETNUMBER(cls) (__CLS_INFO(cls) >> (HOST_BITS_PER_LONG/2))
 274 #define CLS_SETNUMBER(cls, num) \
 275   ({ (cls)->info <<= (HOST_BITS_PER_LONG/2); \
 276      (cls)->info >>= (HOST_BITS_PER_LONG/2); \
 277      __CLS_SETINFO(cls, (((unsigned long)num) << (HOST_BITS_PER_LONG/2))); })
 278
 279 /* The compiler generates one of these structures for each category.
 280    A class may have many categories and contain both instance and
 281    factory methods.  */
 282 struct objc_category
 283 {
 284   const char*   category_name;                /* Name of the category.
 285                                                  Name contained in the
 286                                                  () of the category
 287                                                  definition.  */
 288   const char*   class_name;                   /* Name of the class to
 289                                                  which the category
 290                                                  belongs.  */
 291   struct objc_method_list  *instance_methods; /* Linked list of
 292                                                  instance methods
 293                                                  defined in the
 294                                                  category. NULL
 295                                                  indicates no instance
 296                                                  methods defined.  */
 297   struct objc_method_list *class_methods;     /* Linked list of
 298                                                  factory methods
 299                                                  defined in the
 300                                                  category.  NULL
 301                                                  indicates no class
 302                                                  methods defined.  */
 303   struct objc_protocol_list *protocols;       /* List of Protocols
 304                                                  conformed to.  */
 305 };
 306
 307 #endif /* __objc_private_module_abi_8_INCLUDE_GNU */