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/* GNU Objective C Runtime initialization

   Copyright (C) 1993, 1995, 1996, 1997, 2002, 2009, 2010

   Free Software Foundation, Inc.

   Contributed by Kresten Krab Thorup

   +load support contributed by Ovidiu Predescu <ovidiu@net-community.com>

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under the

terms of the GNU General Public License as published by the Free Software

Foundation; either version 3, or (at your option) any later version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY

WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more

details.

Under Section 7 of GPL version 3, you are granted additional

permissions described in the GCC Runtime Library Exception, version

3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and

a copy of the GCC Runtime Library Exception along with this program;

see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see

<http://www.gnu.org/licenses/>.  */

/* Uncommented the following line to enable debug logging.  Use this

   only while debugging the runtime.  */

/* #define DEBUG 1 */

#include "objc-private/common.h"

#include "objc-private/error.h"

#include "objc/runtime.h"

#include "objc/thr.h"

#include "objc-private/hash.h"

#include "objc-private/objc-list.h" 

#include "objc-private/module-abi-8.h" 

#include "objc-private/runtime.h"   /* For __objc_resolve_class_links().  */

#include "objc-private/selector.h"  /* For __sel_register_typed_name().  */

#include "objc-private/objc-sync.h" /* For __objc_sync_init() */

#include "objc-private/protocols.h" /* For __objc_protocols_init(),

                                       __objc_protocols_add_protocol()

                                       __objc_protocols_register_selectors() */

#include "objc-private/accessors.h" /* For __objc_accessors_init() */

/* The version number of this runtime.  This must match the number

   defined in gcc (objc-act.c).  */

#define OBJC_VERSION 8

#define PROTOCOL_VERSION 2

/* This list contains modules currently loaded into the runtime and

   for which the +load method (and the load callback, if any) has not

   been called yet.  */

static struct objc_list *__objc_module_list = 0;         /* !T:MUTEX */

/* This list contains all proto_list's not yet assigned class

   links.  */

static struct objc_list *unclaimed_proto_list = 0;       /* !T:MUTEX */

/* List of unresolved static instances.  */

static struct objc_list *uninitialized_statics = 0;      /* !T:MUTEX */

/* List of duplicated classes found while loading modules.  If we find

   a class twice, we ignore it the second time.  On some platforms,

   where the order in which modules are loaded is well defined, this

   allows you to replace a class in a shared library by linking in a

   new implementation which is loaded in in the right order, and which

   overrides the existing one.

   Protected by __objc_runtime_mutex.  */

static cache_ptr duplicate_classes = NULL;

/* Global runtime "write" mutex.  Having a single mutex prevents

   deadlocks, but reduces concurrency.  To improve concurrency, some

   groups of functions in the runtime have their own separate mutex

   (eg, __class_table_lock in class.c); to avoid deadlocks, these

   routines must make sure that they never acquire any other lock

   while holding their own local lock.  Ie, they should lock, execute

   some C code that does not perform any calls to other runtime

   functions which may potentially lock different locks, then unlock.

   If they need to perform any calls to other runtime functions that

   may potentially lock other locks, then they should use the global

   __objc_runtime_mutex.  */

objc_mutex_t __objc_runtime_mutex = 0;

/* Number of threads that are alive.  */

int __objc_runtime_threads_alive = 1;                   /* !T:MUTEX */

/* Check compiler vs runtime version.  */

static void init_check_module_version (struct objc_module *);

/* Assign isa links to protos.  */

static void __objc_init_protocols (struct objc_protocol_list *protos);

/* Assign isa link to a protocol, and register it.  */

static void __objc_init_protocol (struct objc_protocol *protocol);

/* Add protocol to class.  */

static void __objc_class_add_protocols (Class, struct objc_protocol_list *);

/* Load callback hook.  */

void (*_objc_load_callback) (Class class, struct objc_category *category) = 0; /* !T:SAFE */

/* Are all categories/classes resolved ?  */

BOOL __objc_dangling_categories = NO;           /* !T:UNUSED */

/* Sends +load to all classes and categories in certain

   situations.  */

static void objc_send_load (void);

/* Inserts all the classes defined in module in a tree of classes that

   resembles the class hierarchy.  This tree is traversed in preorder

   and the classes in its nodes receive the +load message if these

   methods were not executed before.  The algorithm ensures that when

   the +load method of a class is executed all the superclasses have

   been already received the +load message.  */

static void __objc_create_classes_tree (struct objc_module *module);

/* Calls the _objc_load_callback for each class and category in the

   module (if _objc_load_callback is not NULL).  */

static void __objc_call_load_callback (struct objc_module *module);

/* A special version that works only before the classes are completely

   installed in the runtime.  */

static BOOL class_is_subclass_of_class (Class class, Class superclass);

/* This is a node in the class tree hierarchy used to send +load

   messages.  */

typedef struct objc_class_tree

{

  /* The class corresponding to the node.  */

  Class class;

  /* This is a linked list of all the direct subclasses of this class.

     'head' points to a subclass node; 'tail' points to the next

     objc_list node (whose 'head' points to another subclass node,

     etc).  */

  struct objc_list *subclasses;

} objc_class_tree;

/* This is a linked list of objc_class_tree trees.  The head of these

   trees are root classes (their super class is Nil).  These different

   trees represent different class hierarchies.  */

static struct objc_list *__objc_class_tree_list = NULL;

/* Keeps the +load methods who have been already executed. This hash

   should not be destroyed during the execution of the program.  */

static cache_ptr __objc_load_methods = NULL;

/* This function is used when building the class tree used to send

   ordinately the +load message to all classes needing it.  The tree

   is really needed so that superclasses will get the message before

   subclasses.

   This tree may contain classes which are being loaded (or have just

   being loaded), and whose super_class pointers have not yet been

   resolved.  This implies that their super_class pointers point to a

   string with the name of the superclass; when the first message is

   sent to the class (/an object of that class) the class links will

   be resolved, which will replace the super_class pointers with

   pointers to the actual superclasses.

   Unfortunately, the tree might also contain classes which had been

   loaded previously, and whose class links have already been

   resolved.

   This function returns the superclass of a class in both cases, and

   can be used to build the determine the class relationships while

   building the tree.  */

static Class  class_superclass_of_class (Class class)

{

  char *super_class_name;

  /* If the class links have been resolved, use the resolved

     links.  */

  if (CLS_ISRESOLV (class))

    return class->super_class;

  /* Else, 'class' has not yet been resolved.  This means that its

     super_class pointer is really the name of the super class (rather

     than a pointer to the actual superclass).  */

  super_class_name = (char *)class->super_class;

  /* Return Nil for a root class.  */

  if (super_class_name == NULL)

    return Nil;

  /* Lookup the superclass of non-root classes.  */

  return objc_getClass (super_class_name);

}

/* Creates a tree of classes whose topmost class is directly inherited

   from `upper' and the bottom class in this tree is `bottom_class'.

   If `upper' is Nil, creates a class hierarchy up to a root class.

   The classes in this tree are super classes of `bottom_class'.  The

   `subclasses' member of each tree node point to the list of

   subclasses for the node.  */

static objc_class_tree *

create_tree_of_subclasses_inherited_from (Class bottom_class, Class upper)

{

  Class superclass;

  objc_class_tree *tree, *prev;

  DEBUG_PRINTF ("create_tree_of_subclasses_inherited_from:");

  DEBUG_PRINTF (" bottom_class = %s, upper = %s\n",

                (bottom_class ? bottom_class->name : NULL),

                (upper ? upper->name : NULL));

  superclass = class_superclass_of_class (bottom_class);

  prev = objc_calloc (1, sizeof (objc_class_tree));

  prev->class = bottom_class;

  if (superclass == upper)

    return prev;

  while (superclass != upper)

    {

      tree = objc_calloc (1, sizeof (objc_class_tree));

      tree->class = superclass;

      tree->subclasses = list_cons (prev, tree->subclasses);

      superclass = class_superclass_of_class (superclass);

      prev = tree;

    }

  return tree;

}

/* Insert the `class' into the proper place in the `tree' class

   hierarchy.  This function returns a new tree if the class has been

   successfully inserted into the tree or NULL if the class is not

   part of the classes hierarchy described by `tree'.  This function

   is private to objc_tree_insert_class (), you should not call it

   directly.  */

static objc_class_tree *

__objc_tree_insert_class (objc_class_tree *tree, Class class)

{

  DEBUG_PRINTF ("__objc_tree_insert_class: tree = %p (root: %s), class = %s\n",

                tree, ((tree && tree->class) ? tree->class->name : "Nil"), class->name);

  if (tree == NULL)

    return create_tree_of_subclasses_inherited_from (class, NULL);

  else if (class == tree->class)

    {

      /* `class' has been already inserted.  */

      DEBUG_PRINTF (" 1. class %s was previously inserted\n", class->name);

      return tree;

    }

  else if (class_superclass_of_class (class) == tree->class)

    {

      /* If class is a direct subclass of tree->class then add class

         to the list of subclasses. First check to see if it wasn't

         already inserted.  */

      struct objc_list *list = tree->subclasses;

      objc_class_tree *node;

      while (list)

        {

          /* Class has been already inserted; do nothing just return

             the tree.  */

          if (((objc_class_tree *) list->head)->class == class)

            {

              DEBUG_PRINTF (" 2. class %s was previously inserted\n",

                            class->name);

              return tree;

            }

          list = list->tail;

        }

      /* Create a new node class and insert it into the list of

         subclasses.  */

      node = objc_calloc (1, sizeof (objc_class_tree));

      node->class = class;

      tree->subclasses = list_cons (node, tree->subclasses);

      DEBUG_PRINTF (" 3. class %s inserted\n", class->name);

      return tree;

    }

  else

    {

      /* The class is not a direct subclass of tree->class.  Search

         for class's superclasses in the list of subclasses.  */

      struct objc_list *subclasses = tree->subclasses;

      /* Precondition: the class must be a subclass of tree->class;

         otherwise return NULL to indicate our caller that it must

         take the next tree.  */

      if (! class_is_subclass_of_class (class, tree->class))

        return NULL;

      for (; subclasses != NULL; subclasses = subclasses->tail)

        {

          Class aClass = ((objc_class_tree *) (subclasses->head))->class;

          if (class_is_subclass_of_class (class, aClass))

            {

              /* If we found one of class's superclasses we insert the

                 class into its subtree and return the original tree

                 since nothing has been changed.  */

              subclasses->head

                  = __objc_tree_insert_class (subclasses->head, class);

              DEBUG_PRINTF (" 4. class %s inserted\n", class->name);

              return tree;

            }

        }

      /* We haven't found a subclass of `class' in the `subclasses'

         list.  Create a new tree of classes whose topmost class is a

         direct subclass of tree->class.  */

      {

        objc_class_tree *new_tree

          = create_tree_of_subclasses_inherited_from (class, tree->class);

        tree->subclasses = list_cons (new_tree, tree->subclasses);

        DEBUG_PRINTF (" 5. class %s inserted\n", class->name);

        return tree;

      }

    }

}

/* This function inserts `class' in the right tree hierarchy classes.  */

static void

objc_tree_insert_class (Class class)

{

  struct objc_list *list_node;

  objc_class_tree *tree;

  list_node = __objc_class_tree_list;

  while (list_node)

    {

      /* Try to insert the class in this class hierarchy.  */

      tree = __objc_tree_insert_class (list_node->head, class);

      if (tree)

        {

          list_node->head = tree;

          return;

        }

      else

        list_node = list_node->tail;

    }

  /* If the list was finished but the class hasn't been inserted, we

     don't have an existing class hierarchy that can accomodate it.

     Create a new one.  */

  __objc_class_tree_list = list_cons (NULL, __objc_class_tree_list);

  __objc_class_tree_list->head = __objc_tree_insert_class (NULL, class);

}

/* Traverse tree in preorder. Used to send +load.  */

static void

objc_preorder_traverse (objc_class_tree *tree,

                        int level,

                        void (*function) (objc_class_tree *, int))

{

  struct objc_list *node;

  (*function) (tree, level);

  for (node = tree->subclasses; node; node = node->tail)

    objc_preorder_traverse (node->head, level + 1, function);

}

/* Traverse tree in postorder. Used to destroy a tree.  */

static void

objc_postorder_traverse (objc_class_tree *tree,

                         int level,

                         void (*function) (objc_class_tree *, int))

{

  struct objc_list *node;

  for (node = tree->subclasses; node; node = node->tail)

    objc_postorder_traverse (node->head, level + 1, function);

  (*function) (tree, level);

}

/* Used to print a tree class hierarchy.  */

#ifdef DEBUG

static void

__objc_tree_print (objc_class_tree *tree, int level)

{

  int i;

  for (i = 0; i < level; i++)

    printf ("  ");

  printf ("%s\n", tree->class->name);

}

#endif

/* Walks on a linked list of methods in the reverse order and executes

   all the methods corresponding to the `+load' selector.  Walking in

   the reverse order assures the +load of class is executed first and

   then +load of categories because of the way in which categories are

   added to the class methods.  This function needs to be called with

   the objc_runtime_mutex locked.  */

static void

__objc_send_load_using_method_list (struct objc_method_list *method_list, Class class)

{

  static SEL load_selector = 0;

  int i;

  if (!method_list)

    return;

  /* This needs no lock protection because we are called with the

     objc_runtime_mutex locked.  */

  if (!load_selector)

    load_selector = sel_registerName ("load");

  /* method_list is a linked list of method lists; since we're

     executing in reverse order, we need to do the next list before we

     do this one.  */

  __objc_send_load_using_method_list (method_list->method_next, class);

  /* Search the method list.  */

  for (i = 0; i < method_list->method_count; i++)

    {

      struct objc_method *mth = &method_list->method_list[i];

      /* We are searching for +load methods that we haven't executed

         yet.  */

      if (mth->method_name && sel_eq (mth->method_name, load_selector)

          && ! objc_hash_is_key_in_hash (__objc_load_methods, mth->method_imp))

        {

          /* Add this method into the +load hash table, so we won't

             execute it again next time.  */

          objc_hash_add (&__objc_load_methods,

                         mth->method_imp,

                         mth->method_imp);

          /* Call +load.  */

          DEBUG_PRINTF (" begin of [%s +load]\n", class->name);

          (*mth->method_imp) ((id)class, mth->method_name);

          DEBUG_PRINTF (" end of [%s +load]\n", class->name);

          break;

        }

    }

}

/* This function needs to be called with the objc_runtime_mutex

   locked.  */

static void

__objc_send_load (objc_class_tree *tree,

                  int level __attribute__ ((__unused__)))

{

  Class class = tree->class;

  struct objc_method_list *method_list = class->class_pointer->methods;

  DEBUG_PRINTF ("+load: need to send load to class '%s'\n", class->name);

  __objc_send_load_using_method_list (method_list, class);

}

static void

__objc_destroy_class_tree_node (objc_class_tree *tree,

                                int level __attribute__ ((__unused__)))

{

  objc_free (tree);

}

/* This is used to check if the relationship between two classes

   before the runtime completely installs the classes.  */

static BOOL

class_is_subclass_of_class (Class class, Class superclass)

{

  for (; class != Nil;)

    {

      if (class == superclass)

        return YES;

      class = class_superclass_of_class (class);

    }

  return NO;

}

/* This list contains all the classes in the runtime system for whom

   their superclasses are not yet known to the runtime.  */

static struct objc_list *unresolved_classes = 0;

/* Extern function used to reference the Object class.  */

extern void __objc_force_linking (void);

void

__objc_force_linking (void)

{

  extern void __objc_linking (void);

  __objc_linking ();

}

/* Run through the statics list, removing modules as soon as all its

   statics have been initialized.  */

static void

objc_init_statics (void)

{

  struct objc_list **cell = &uninitialized_statics;

  struct objc_static_instances **statics_in_module;

  objc_mutex_lock (__objc_runtime_mutex);

  while (*cell)

    {

      int module_initialized = 1;

      for (statics_in_module = (*cell)->head;

           *statics_in_module; statics_in_module++)

        {

          struct objc_static_instances *statics = *statics_in_module;

          Class class = objc_getClass (statics->class_name);

          if (! class)

            {

              /* It is unfortunate that this will cause all the

                 statics initialization to be done again (eg, if we

                 already initialized constant strings, and are now

                 initializing protocols, setting module_initialized to

                 again).  It would be good to be able to track if we

                 have already initialized some of them.  */

              module_initialized = 0;

            }

          else

            {

              /* Note that if this is a list of Protocol objects, some

                 of them may have been initialized already (because

                 they were attached to classes or categories, and the

                 class/category loading code automatically fixes them

                 up), and some of them may not.  We really need to go

                 through the whole list to be sure!  Protocols are

                 also special because we want to register them and

                 register all their selectors.  */

              id *inst;

              if (strcmp (statics->class_name, "Protocol") == 0)

                {

                  /* Protocols are special, because not only we want

                     to fix up their class pointers, but we also want

                     to register them and their selectors with the

                     runtime.  */

                  for (inst = &statics->instances[0]; *inst; inst++)

                    __objc_init_protocol ((struct objc_protocol *)*inst);

                }

              else

                {

                  /* Other static instances (typically constant

                     strings) are easier as we just fix up their class

                     pointers.  */

                  for (inst = &statics->instances[0]; *inst; inst++)

                    (*inst)->class_pointer = class;

                }

            }

        }

      if (module_initialized)

        {

          /* Remove this module from the uninitialized list.  */

          struct objc_list *this = *cell;

          *cell = this->tail;

          objc_free (this);

        }

      else

        cell = &(*cell)->tail;

    }

  objc_mutex_unlock (__objc_runtime_mutex);

}

/* This function is called by constructor functions generated for each

   module compiled.  (_GLOBAL_$I$...) The purpose of this function is

   to gather the module pointers so that they may be processed by the

   initialization routines as soon as possible.  */

void

__objc_exec_class (struct objc_module *module)

{

  /* Have we processed any constructors previously?  This flag is used

     to indicate that some global data structures need to be

     built.  */

  static BOOL previous_constructors = 0;

  static struct objc_list *unclaimed_categories = 0;

  /* The symbol table (defined in objc-private/module-abi-8.h)

     generated by gcc.  */

  struct objc_symtab *symtab = module->symtab;

  /* The statics in this module.  */

  struct objc_static_instances **statics

    = symtab->defs[symtab->cls_def_cnt + symtab->cat_def_cnt];

  /* Entry used to traverse hash lists.  */

  struct objc_list **cell;

  /* The table of selector references for this module.  */

  struct objc_selector *selectors = symtab->refs;

  int i;

  DEBUG_PRINTF ("\n__objc_exec_class (%p) - start processing module...\n", module);

  /* Check gcc version.  */

  init_check_module_version (module);

  /* On the first call of this routine, initialize some data

     structures.  */

  if (! previous_constructors)

    {

        /* Initialize thread-safe system.  */

      __objc_init_thread_system ();

      __objc_runtime_threads_alive = 1;

      __objc_runtime_mutex = objc_mutex_allocate ();

      __objc_init_selector_tables ();

      __objc_init_class_tables ();

      __objc_init_dispatch_tables ();

      duplicate_classes = objc_hash_new (8,

                                         (hash_func_type)objc_hash_ptr,

                                         objc_compare_ptrs);

      __objc_load_methods = objc_hash_new (128,

                                           (hash_func_type)objc_hash_ptr,

                                           objc_compare_ptrs);

      __objc_protocols_init ();

      __objc_accessors_init ();

      __objc_sync_init ();

      previous_constructors = 1;

    }

  /* Save the module pointer so that later we remember to call +load

     on all classes and categories on it.  */

  objc_mutex_lock (__objc_runtime_mutex);

  __objc_module_list = list_cons (module, __objc_module_list);

  /* Replace referenced selectors from names to SELs.  */

  if (selectors)

    {

      DEBUG_PRINTF (" registering selectors\n");

      __objc_register_selectors_from_module (selectors);

    }

  /* Parse the classes in the load module and gather selector

     information.  */

  for (i = 0; i < symtab->cls_def_cnt; ++i)

    {

      Class class = (Class) symtab->defs[i];

      const char *superclass = (char *) class->super_class;

      /* Make sure we have what we think.  */

      assert (CLS_ISCLASS (class));

      assert (CLS_ISMETA (class->class_pointer));

      DEBUG_PRINTF (" installing class '%s'\n", class->name);

      /* Workaround for a bug in clang: Clang may set flags other than

         _CLS_CLASS and _CLS_META even when compiling for the

         traditional ABI (version 8), confusing our runtime.  Try to

         wipe these flags out.  */

      if (CLS_ISCLASS (class))

        __CLS_INFO (class) = _CLS_CLASS;

      else

        __CLS_INFO (class) = _CLS_META;

      /* Initialize the subclass list to be NULL.  In some cases it

         isn't and this crashes the program.  */

      class->subclass_list = NULL;

      if (__objc_init_class (class))

        {

          /* Check to see if the superclass is known in this point. If

             it's not add the class to the unresolved_classes list.  */

          if (superclass && ! objc_getClass (superclass))

            unresolved_classes = list_cons (class, unresolved_classes);

        }

    }

  /* Process category information from the module.  */

  for (i = 0; i < symtab->cat_def_cnt; ++i)

    {

      struct objc_category *category = symtab->defs[i + symtab->cls_def_cnt];

      Class class = objc_getClass (category->class_name);

      /* If the class for the category exists then append its

         methods.  */

      if (class)

        {

          DEBUG_PRINTF (" installing category '%s (%s)'\n", category->class_name, category->category_name);

          /* Do instance methods.  */

          if (category->instance_methods)

            class_add_method_list (class, category->instance_methods);

          /* Do class methods.  */

          if (category->class_methods)

            class_add_method_list ((Class) class->class_pointer,

                                   category->class_methods);

          if (category->protocols)

            {

              __objc_init_protocols (category->protocols);

              __objc_class_add_protocols (class, category->protocols);

            }

          /* Register the instance methods as class methods, this is

             only done for root classes.  */

          __objc_register_instance_methods_to_class (class);

        }

      else

        {

          DEBUG_PRINTF (" delaying installation of category '%s (%s)'\n", category->class_name, category->category_name);

          /* The object to which the category methods belong can't be

             found.  Save the information.  */

          unclaimed_categories = list_cons (category, unclaimed_categories);

        }

    }

  if (statics)

    uninitialized_statics = list_cons (statics, uninitialized_statics);

  if (uninitialized_statics)

    objc_init_statics ();

  /* Scan the unclaimed category hash.  Attempt to attach any

     unclaimed categories to objects.  */

  for (cell = &unclaimed_categories; *cell; )

    {

      struct objc_category *category = (*cell)->head;

      Class class = objc_getClass (category->class_name);

      if (class)

        {

          DEBUG_PRINTF (" installing (delayed) category '%s (%s)'\n", category->class_name, category->category_name);

          list_remove_head (cell);

          if (category->instance_methods)

            class_add_method_list (class, category->instance_methods);