libs-base/Source/ObjectiveC2/runtime.c

#include "ObjectiveC2/objc/runtime.h"

/* Make glibc export strdup() */

#if defined __GLIBC__
#define __USE_BSD 1
#endif

#undef __objc_INCLUDE_GNU
#undef __thread_INCLUDE_GNU
#undef __objc_api_INCLUDE_GNU
#undef __encoding_INCLUDE_GNU

#define objc_object objc_object_gnu
#define id object_ptr_gnu
#define IMP objc_imp_gnu
#define Method objc_method_gnu

#define object_copy  gnu_object_copy
#define object_dispose  gnu_object_dispose
#define objc_super gnu_objc_super
#define objc_msg_lookup gnu_objc_msg_lookup
#define objc_msg_lookup_super gnu_objc_msg_lookup_super
#define BOOL GNU_BOOL
#define SEL GNU_SEL
#define Protocol GNU_Protocol
#define Class GNU_Class

#undef YES
#undef NO
#undef Nil
#undef nil

#include <objc/objc.h>
#include <objc/objc-api.h>
#undef GNU_BOOL
#include <objc/encoding.h>
#undef Class
#undef Protocol
#undef SEL
#undef objc_msg_lookup
#undef objc_msg_lookup_super
#undef objc_super
#undef Method
#undef IMP
#undef id
#undef objc_object

// Reinstall definitions.
#undef YES
#undef NO
#undef Nil
#undef nil
#define YES ((BOOL)1)
#define NO ((BOOL)0)
#define nil ((id)_OBJC_NULL_PTR)
#define Nil ((Class)_OBJC_NULL_PTR)

#include <string.h>
#include <stdlib.h>
#include <assert.h>

/**
 * Private runtime function for updating a dtable.
 */
void __objc_update_dispatch_table_for_class(Class);
/**
 * Private runtime function for determining whether a class responds to a
 * selector.
 */
BOOL __objc_responds_to(id, SEL);
/**
 *  Runtime library constant for uninitialized dispatch table.
 */
extern struct sarray *__objc_uninstalled_dtable;
/**
 * Mutex used to protect the ObjC runtime library data structures.
 */
extern objc_mutex_t __objc_runtime_mutex;

/* objc_skip_argspec() is often buggy as it calls the buggy objc_skip_offset()
 * so we use a local version.
 */
static inline const char *
skip_argspec(const char *types)
{
  if (types && *types)
    {
      types = objc_skip_typespec(types);
      if (*types == '+')
	types++;
      while (isdigit(*types))
	types++;
    }
  return types;
}

/**
 * Looks up the instance method in a specific class, without recursing into
 * superclasses.
 */
static Method
class_getInstanceMethodNonrecursive(Class aClass, SEL aSelector)
{
  if (Nil != aClass)
    {
      struct objc_method_list *methods;

      for (methods = aClass->methods;
        methods != NULL; methods = methods->method_next)
	{
	  int i;

	  for (i = 0; i < methods->method_count; i++)
	    {
	      Method_t method = &methods->method_list[i];

	      if (method->method_name->sel_id == aSelector->sel_id)
		{
		  return method;
		}
	    }
	}
    }
  return NULL;
}

static void
objc_updateDtableForClassContainingMethod(Method m)
{
  Class nextClass = Nil;
  void *state = NULL;
  SEL sel = method_getName(m);

  while (Nil != (nextClass = objc_next_class(&state)))
    {
      if (class_getInstanceMethodNonrecursive(nextClass, sel) == m)
	{
	  __objc_update_dispatch_table_for_class(nextClass);
	  return;
	}
    }
}


BOOL
class_addIvar(Class cls, const char *name,
  size_t size, uint8_t alignment, const char *types)
{
  struct objc_ivar_list *ivarlist;
  unsigned off;
  Ivar ivar;

  if (Nil == cls || CLS_ISRESOLV(cls) || CLS_ISMETA(cls))
    {
      return NO;
    }

  if (class_getInstanceVariable(cls, name) != NULL)
    {
      return NO;
    }

  ivarlist = cls->ivars;

  if (NULL == ivarlist)
    {
      cls->ivars = malloc(sizeof(struct objc_ivar_list));
      cls->ivars->ivar_count = 1;
    }
  else
    {
      ivarlist->ivar_count++;
      // objc_ivar_list contains one ivar.  Others follow it.
      cls->ivars = realloc(ivarlist, sizeof(struct objc_ivar_list)
	+ (ivarlist->ivar_count - 1) * sizeof(struct objc_ivar));
    }

  ivar = &cls->ivars->ivar_list[cls->ivars->ivar_count - 1];
  ivar->ivar_name = strdup(name);
  ivar->ivar_type = strdup(types);
  // Round up the offset of the ivar so it is correctly aligned.
  off = cls->instance_size >> alignment;
  if (off << alignment != cls->instance_size)
    {
      off++;
    }
  off = off << alignment; 
  ivar->ivar_offset = off;
  // Increase the instance size to make space for this.
  cls->instance_size = ivar->ivar_offset + size;
  return YES;
}

BOOL
class_addMethod(Class cls, SEL name, IMP imp, const char *types)
{
  const char *methodName = sel_get_name(name);
  struct objc_method_list *methods;

  for (methods = cls->methods; methods != NULL;
    methods = methods->method_next)
    {
      int i;

      for (i = 0; i < methods->method_count; i++)
	{
	  Method_t method = &methods->method_list[i];

	  if (strcmp(sel_get_name(method->method_name), methodName) == 0)
	    {
	      return NO;
	    }
	}
    }

  methods = malloc(sizeof(struct objc_method_list));
  methods->method_next = cls->methods;
  cls->methods = methods;

  methods->method_count = 1;
  methods->method_list[0].method_name
    = sel_register_typed_name(methodName, types);
  methods->method_list[0].method_types = strdup(types);
  methods->method_list[0].method_imp = (objc_imp_gnu) imp;

  if (CLS_ISRESOLV(cls))
    {
      __objc_update_dispatch_table_for_class(cls);
    }

  return YES;
}

BOOL
class_addProtocol(Class cls, Protocol * protocol)
{
  struct objc_protocol_list *protocols;

  if (class_conformsToProtocol(cls, protocol))
    {
      return NO;
    }
  protocols = cls->protocols;
  protocols = malloc(sizeof(struct objc_protocol_list));
  if (protocols == NULL)
    {
      return NO;
    }
  protocols->next = cls->protocols;
  protocols->count = 1;
  protocols->list[0] = protocol;
  cls->protocols = protocols;

  return YES;
}

Ivar *
class_copyIvarList(Class cls, unsigned int *outCount)
{
  struct objc_ivar_list *ivarlist = cls->ivars;
  unsigned int count = 0;
  unsigned int index;
  Ivar *list;

  if (ivarlist != NULL)
    {
      count = ivarlist->ivar_count;
    }
  if (outCount != NULL)
    {
      *outCount = count;
    }
  if (count == 0)
    {
      return NULL;
    }

  list = malloc((count + 1) * sizeof(struct objc_ivar *));
  list[count] = NULL;
  count = 0;
  for (index = 0; index < ivarlist->ivar_count; index++)
    {
      list[count++] = &ivarlist->ivar_list[index];
    }

  return list;
}

Method *
class_copyMethodList(Class cls, unsigned int *outCount)
{
  unsigned int count = 0;
  Method *list;
  struct objc_method_list *methods;

  for (methods = cls->methods; methods != NULL; methods = methods->method_next)
    {
      count += methods->method_count;
    }
  if (outCount != NULL)
    {
      *outCount = count;
    }
  if (count == 0)
    {
      return NULL;
    }

  list = malloc((count + 1) * sizeof(struct objc_method *));
  list[count] = NULL;
  count = 0;
  for (methods = cls->methods; methods != NULL; methods = methods->method_next)
    {
      unsigned int	index;

      for (index = 0; index < methods->method_count; index++)
	{
          list[count++] = &methods->method_list[index];
	}
    }

  return list;
}

Protocol **
class_copyProtocolList(Class cls, unsigned int *outCount)
{
  struct objc_protocol_list *protocolList = cls->protocols;
  struct objc_protocol_list *list;
  unsigned int count = 0;
  Protocol **protocols;

  for (list = protocolList; list != NULL; list = list->next)
    {
      count += list->count;
    }
  if (outCount != NULL)
    {
      *outCount = count;
    }
  if (count == 0)
    {
      return NULL;
    }

  protocols = malloc((count + 1) * sizeof(Protocol *));
  protocols[count] = NULL;
  count = 0;
  for (list = protocolList; list != NULL; list = list->next)
    {
      memcpy(&protocols[count], list->list, list->count * sizeof(Protocol *));
      count += list->count;
    }
  return protocols;
}

id
class_createInstance(Class cls, size_t extraBytes)
{
  extern id NSAllocateObject(Class, uintptr_t, void*);
  return NSAllocateObject(cls, extraBytes, 0);
}

Method
class_getInstanceMethod(Class aClass, SEL aSelector)
{
  Method method = class_getInstanceMethodNonrecursive(aClass, aSelector);

  if (method == NULL)
    {
      // TODO: Check if this should be NULL or aClass
      Class superclass = class_getSuperclass(aClass);

      if (superclass == NULL)
	{
	  return NULL;
	}
      return class_getInstanceMethod(superclass, aSelector);
    }
  return method;
}

Method
class_getClassMethod(Class aClass, SEL aSelector)
{
  if (Nil == aClass)
    {
      return NULL;
    }
  return class_getInstanceMethod(aClass->class_pointer, aSelector);
}

Ivar
class_getClassVariable(Class cls, const char *name)
{
  assert(0 && "Class variables not implemented");
  return NULL;
}

size_t
class_getInstanceSize(Class cls)
{
  if (Nil == cls)
    {
      return 0;
    }
  return cls->instance_size;
}

Ivar
class_getInstanceVariable(Class cls, const char *name)
{
  if (Nil != cls && NULL != name)
    {
      while (cls != Nil)
	{
	  struct objc_ivar_list *ivarlist = cls->ivars;

	  if (ivarlist != NULL)
	    {
	      int i;

	      for (i = 0; i < ivarlist->ivar_count; i++)
		{
		  Ivar ivar = &ivarlist->ivar_list[i];

		  if (strcmp(ivar->ivar_name, name) == 0)
		    {
		      return ivar;
		    }
		}
	    }
	  cls = class_getSuperclass(cls);
	}
    }
  return NULL;
}

void object_setIvar(id object, Ivar ivar, id value)
{
  char *addr = (char*)object;
  addr += ivar_getOffset(ivar);
  *(id*)addr = value;
}

Ivar object_setInstanceVariable(id obj, const char *name, void *value)
{
  Ivar ivar = class_getInstanceVariable(object_getClass(obj), name);
  object_setIvar(obj, ivar, value);
  return ivar;
}

id object_getIvar(id object, Ivar ivar)
{
  return *(id*)(((char*)object) + ivar_getOffset(ivar));
}

Ivar object_getInstanceVariable(id obj, const char *name, void **outValue)
{
  Ivar ivar = class_getInstanceVariable(object_getClass(obj), name);
  if (NULL != outValue)
    {
      *outValue = object_getIvar(obj, ivar);
    }
  return ivar;
}



// The format of the char* is undocumented.  This function is only ever used in
// conjunction with class_setIvarLayout().
const char *
class_getIvarLayout(Class cls)
{
  if (Nil == cls)
    {
      return 0;
    }
  return (char *) cls->ivars;
}

/* For the next two functions ...
 * It would be nice to use objc_msg_lookup(), but we can't because that
 * requires an instance rather than a class as its argument.  Trying to
 * pass the address of the class as if it was an instance won't work since 
 * the instance variables will be missing and any forwarding callback used
 * by a proxy may try to use the instance variables and crash/fail in
 * interesting ways.
 */ 
IMP
class_getMethodImplementation(Class cls, SEL name)
{
  if (Nil == cls || 0 == name)
    {
      return 0;
    }
  return (IMP) get_imp(cls, name);
}
IMP
class_getMethodImplementation_stret(Class cls, SEL name)
{
  if (Nil == cls || 0 == name)
    {
      return 0;
    }
  return (IMP) get_imp(cls, name);
}

const char *
class_getName(Class cls)
{
  if (Nil == cls)
    {
      return "nil";	// This is what OSX does.
    }
  if (CLS_ISCLASS(cls) || CLS_ISMETA(cls))
    {
      return cls->name;
    }
  return NULL;
}

void __objc_resolve_class_links(void);

Class
class_getSuperclass(Class cls)
{
  if (Nil == cls)
    {
      return 0;
    }
  if (!CLS_ISRESOLV(cls))
    {
      /* This class is not yet resolved ... so lookup superclass by name.
       * We need to allow for this case because we might doing a lookup in
       * a class which has not yet been registered with the runtime and
       * which might have ivars or methods added after this call (so we
       * mustn't resolve this class now).
       */
      return (Class)objc_getClass((const char*)cls->super_class);
    }
  return cls->super_class;
}

int
class_getVersion(Class cls)
{
  if (Nil == cls)
    {
      return 0;
    }
  return class_get_version(cls);
}

const char *
class_getWeakIvarLayout(Class cls)
{
  assert(0 && "Weak ivars not supported");
  return NULL;
}

BOOL
class_isMetaClass(Class cls)
{
  if (Nil == cls || !CLS_ISMETA(cls))
    {
      return NO;
    }
  return YES;
}

IMP
class_replaceMethod(Class cls, SEL name, IMP imp, const char *types)
{
  Method method = class_getInstanceMethodNonrecursive(cls, name);

  if (method == NULL)
    {
      class_addMethod(cls, name, imp, types);
      return NULL;
    }
  else
    {
      IMP old = (IMP) method->method_imp;
      method->method_imp = (objc_imp_gnu) imp;
      if (CLS_ISRESOLV(cls))
        {
          __objc_update_dispatch_table_for_class(cls);
        }
      return old;
    }
}


BOOL
class_respondsToSelector(Class cls, SEL sel)
{
  if (cls != 0 && sel != 0 && __objc_responds_to((id) & cls, sel) != 0)
    return YES;
  return NO;
}

void
class_setIvarLayout(Class cls, const char *layout)
{
  struct objc_ivar_list *list = (struct objc_ivar_list *) layout;
  size_t listsize = sizeof(struct objc_ivar_list) +
    sizeof(struct objc_ivar) * (list->ivar_count - 1);
  cls->ivars = malloc(listsize);
  memcpy(cls->ivars, list, listsize);
}

OBJC_DEPRECATED Class
class_setSuperclass(Class cls, Class newSuper)
{
  Class oldSuper = cls->super_class;
  cls->super_class = newSuper;
  return oldSuper;
}

void
class_setVersion(Class theClass, int version)
{
  class_set_version(theClass, version);
}

void
class_setWeakIvarLayout(Class cls, const char *layout)
{
  assert(0 && "Not implemented");
}

const char *
ivar_getName(Ivar ivar)
{
  return ivar->ivar_name;
}

ptrdiff_t
ivar_getOffset(Ivar ivar)
{
  return ivar->ivar_offset;
}

const char *
ivar_getTypeEncoding(Ivar ivar)
{
  return ivar->ivar_type;
}

static size_t
lengthOfTypeEncoding(const char *types)
{
  const char *end = skip_argspec(types);
  size_t length;

  end--;
  while (isdigit(*end))
    {
      end--;
    }
  length = end - types + 1;
  return length;
}

static char *
copyTypeEncoding(const char *types)
{
  size_t length = lengthOfTypeEncoding(types);
  char *copy = malloc(length + 1);

  memcpy(copy, types, length);
  copy[length] = '\0';
  return copy;
}

static const char *
findParameterStart(const char *types, unsigned int index)
{
  unsigned int i;

  for (i = 0; i < index; i++)
    {
      types = skip_argspec(types);
      if ('\0' == *types)
	{
	  return NULL;
	}
    }
  return types;
}

char *
method_copyArgumentType(Method method, unsigned int index)
{
  const char *types = findParameterStart(method->method_types, index);

  if (NULL == types)
    {
      return NULL;
    }
  return copyTypeEncoding(types);
}

char *
method_copyReturnType(Method method)
{
  return copyTypeEncoding(method->method_types);
}

void
method_exchangeImplementations(Method m1, Method m2)
{
  IMP tmp = (IMP) m1->method_imp;

  m1->method_imp = m2->method_imp;
  m2->method_imp = (objc_imp_gnu) tmp;
  objc_updateDtableForClassContainingMethod(m1);
  objc_updateDtableForClassContainingMethod(m2);
}

void
method_getArgumentType(Method method,
 unsigned int index, char *dst, size_t dst_len)
{
  const char *types;
  size_t length;

  types = findParameterStart(method->method_types, index);
  if (NULL == types)
    {
      strncpy(dst, "", dst_len);
      return;
    }
  length = lengthOfTypeEncoding(types);
  if (length < dst_len)
    {
      memcpy(dst, types, length);
      dst[length] = '\0';
    }
  else
    {
      memcpy(dst, types, dst_len);
    }
}

IMP
method_getImplementation(Method method)
{
  return method ? (IMP) method->method_imp : (IMP) 0;
}

SEL
method_getName(Method method)
{
  return method ? method->method_name : (SEL) 0;
}

unsigned
method_getNumberOfArguments(Method method)
{
  if (0 == method)
    {
      return 0;
    }
  else
    {
      unsigned int count = 0;
      const char *types = method->method_types;

      while ('\0' != *types)
	{
	  types = skip_argspec(types);
	  count++;
	}
      return count - 1;
    }
}

void
method_getReturnType(Method method, char *dst, size_t dst_len)
{
  if (0 == method)
    {
      if (dst_len > 0)
	{
          dst[0] = '\0';
	}
    }
  else
    {
      //TODO: Coped and pasted code.  Factor it out.
      const char *types = method->method_types;
      size_t length = lengthOfTypeEncoding(types);

      if (length < dst_len)
	{
	  memcpy(dst, types, length);
	  dst[length] = '\0';
	}
      else if (dst_len > 0)
	{
	  memcpy(dst, types, dst_len);
	}
    }
}

const char *
method_getTypeEncoding(Method method)
{
  if (0 == method)
    {
      return 0;
    }
  return method->method_types;
}

IMP
method_setImplementation(Method method, IMP imp)
{
  if (0 == method)
    {
      return (IMP)0;
    }
  else
    {
      IMP old = (IMP) method->method_imp;

      method->method_imp = (objc_imp_gnu) old;
      objc_updateDtableForClassContainingMethod(method);
      return old;
    }
}

id
objc_getClass(const char *name)
{
  return (id) objc_get_class(name);
}

int
objc_getClassList(Class * buffer, int bufferLen)
{
  int count = 0;

  if (buffer == NULL)
    {
      void *state = NULL;
      while (Nil != objc_next_class(&state))
	{
	  count++;
	}
    }
  else
    {
      Class nextClass;
      void *state = NULL;

      while (Nil != (nextClass = objc_next_class(&state)) && bufferLen > 0)
	{
	  count++;
	  bufferLen--;
	  *(buffer++) = nextClass;
	}
    }
  return count;
}

id
objc_getMetaClass(const char *name)
{
  Class cls = (Class) objc_getClass(name);
  return cls == Nil ? nil : (id) cls->class_pointer;
}

id
objc_getRequiredClass(const char *name)
{
  id cls = objc_getClass(name);

  if (nil == cls)
    {
      abort();
    }
  return cls;
}

id
objc_lookUpClass(const char *name)
{
  // TODO: Check these are the right way around.
  return (id) objc_lookup_class(name);
}

static void
freeMethodLists(Class aClass)
{
  struct objc_method_list *methods = aClass->methods;
  struct objc_method_list *current;

  while (methods != NULL)
    {
      int i;

      for (i = 0; i < methods->method_count; i++)
	{
	  free((void *) methods->method_list[i].method_types);
	}
      current = methods;
      methods = methods->method_next;
      free(current);
    }
}

static void
freeIvarLists(Class aClass)
{
  struct objc_ivar_list *ivarlist = aClass->ivars;
  int i;

  if (NULL == ivarlist)
    {
      return;
    }

  for (i = 0; i < ivarlist->ivar_count; i++)
    {
      Ivar ivar = &ivarlist->ivar_list[i];

      free((void *) ivar->ivar_type);
      free((void *) ivar->ivar_name);
    }
  free(ivarlist);
}

/*
 * Removes a class from the subclass list found on its super class.
 * Must be called with the objc runtime mutex locked.
 */
static inline void
safe_remove_from_subclass_list(Class cls)
{
  Class sub = cls->super_class->subclass_list;

  if (sub == cls)
    {
      cls->super_class->subclass_list = cls->sibling_class;
    }
  else
    {
      while (sub != NULL)
	{
	  if (sub->sibling_class == cls)
	    {
	      sub->sibling_class = cls->sibling_class;
	      break;
	    }
	  sub = sub->sibling_class;
	}
    }
}

void
objc_disposeClassPair(Class cls)
{
  Class meta;

  if (cls == 0)
    {
      return;
    }
  meta = ((id) cls)->isa;

  if (objc_lookUpClass (class_getName (cls)) == (id)cls)
    {
      fprintf(stderr, "*** ERROR *** function objc_disposeClassPair() called "
	"on registered class pair '%s'\n", class_getName(cls));
      return;
    /*
       The runtime provides no mechanism to remove a class.
       The following code essentially frees the memory used by a class without
       fully removing it ... which obviously tends to cause random crashes
       later on if anything tries to use the class or to traverse data
       structures containing the class.
       Indeed, it's hard to see how this function could ever be made to work
       (what if there are subclasses of the class being removed, or if
       there are instances of the class?) even with changes to the runtime.
      
      // Remove from the runtime system so nothing tries updating the dtable
      // while we are freeing the class.
      objc_mutex_lock(__objc_runtime_mutex);
      safe_remove_from_subclass_list(meta);
      safe_remove_from_subclass_list(cls);
      objc_mutex_unlock(__objc_runtime_mutex);
    */
    }

  // Free the method and ivar lists.
  freeMethodLists(cls);
  freeMethodLists(meta);
  freeIvarLists(cls);

  // Free the class and metaclass
  free(meta);
  free(cls);
}

Class
objc_allocateClassPair(Class superclass, const char *name, size_t extraBytes)
{
  Class newClass;
  Class metaClass;

  // Check the class doesn't already exist.
  if (nil != objc_lookUpClass(name))
    {
      return Nil;
    }

  newClass = calloc(1, sizeof(struct objc_class) + extraBytes);

  if (Nil == newClass)
    {
      return Nil;
    }

  // Create the metaclass
  metaClass = calloc(1, sizeof(struct objc_class));

  // Initialize the metaclass
  metaClass->class_pointer = superclass->class_pointer->class_pointer;
  metaClass->super_class = superclass->class_pointer;
  metaClass->name = strdup(name);
  metaClass->info = _CLS_META;
  metaClass->dtable = __objc_uninstalled_dtable;
  metaClass->instance_size = sizeof(struct objc_class);

  // Set up the new class
  newClass->class_pointer = metaClass;
  // Set the superclass pointer to the name.  The runtime will fix this when
  // the class links are resolved.
  newClass->super_class = (Class) superclass->name;
  newClass->name = strdup(name);
  newClass->info = _CLS_CLASS;
  newClass->dtable = __objc_uninstalled_dtable;
  newClass->instance_size = superclass->instance_size;

  return newClass;
}

Class
objc_allocateMetaClass(Class superclass, size_t extraBytes)
{
  Class metaClass = calloc(1, sizeof(struct objc_class) + extraBytes);

  // Initialize the metaclass
  metaClass->class_pointer = superclass->class_pointer->class_pointer;
  metaClass->super_class = superclass->class_pointer;
  metaClass->name = "hidden class"; //strdup(superclass->name);
  metaClass->info = _CLS_RESOLV | _CLS_INITIALIZED | _CLS_META;
  metaClass->dtable = __objc_uninstalled_dtable;
  metaClass->instance_size = sizeof(struct objc_class);

  return metaClass;
}

void *
object_getIndexedIvars(id obj)
{
  if (class_isMetaClass(obj->isa))
    {
      return ((char *) obj) + sizeof(struct objc_class);
    }
  return ((char *) obj) + obj->isa->instance_size;
}

Class
object_getClass(id obj)
{
  if (nil != obj)
    {
      return obj->isa;
    }
  return Nil;
}

Class
object_setClass(id obj, Class cls)
{
  if (nil != obj)
    {
      Class oldClass = obj->isa;

      obj->isa = cls;
      return oldClass;
    }
  return Nil;
}

const char *
object_getClassName(id obj)
{
  return class_getName(object_getClass(obj));
}

void __objc_add_class_to_hash(Class cls);
void __objc_resolve_class_links(void);

void
objc_registerClassPair(Class cls)
{
  Class metaClass;
  Class	existing;

  if (Nil == cls)
    {
      fprintf(stderr, "*** ERROR *** function objc_registerClassPair() called "
	"on Nil class pair '%s'\n", class_getName(cls));
    }
  existing = (Class)objc_lookUpClass (class_getName (cls));
  if (existing == cls)
    {
      return;	// Already registered
    }
  else if (Nil != existing)
    {
      fprintf(stderr, "*** ERROR *** function objc_registerClassPair() called "
	"for class pair with name ('%s') of existing class.\n",
	class_getName(cls));
      return;
    }

  // Initialize the dispatch table for the class and metaclass.
  metaClass = cls->class_pointer;
  __objc_update_dispatch_table_for_class(metaClass);
  __objc_update_dispatch_table_for_class(cls);
  __objc_add_class_to_hash(cls);
  // Add pointer from super class
  __objc_resolve_class_links();
}

/*
static id
objectNew(id cls)
{
  static SEL newSel = NULL;
  IMP newIMP;

  if (NULL == newSel)
    {
      newSel = sel_get_uid("new");
    }
  newIMP = (IMP) objc_msg_lookup((void *) cls, newSel);
  return newIMP((id) cls, newSel);
}
*/

Protocol *
objc_getProtocol(const char *name)
{
  Protocol *p = NULL;
  Class cls;
  void *iterator = NULL;

  /* Protocols are not centrally registered in the GNU runtime.
   * So we just find the first match we can.
   */

  while (p == NULL && (cls = objc_next_class(&iterator)))
    {
      struct objc_protocol_list *pcllist = cls->protocols;
      size_t i;

      while (p == NULL && pcllist != NULL)
	{
	  for (i = 0; i < pcllist->count; i++)
	    {
	      if (strcmp(pcllist->list[i]->protocol_name, name) == 0)
		{
		  p = (Protocol*)pcllist->list[i];
		  break;
		}
	    }
	  pcllist = pcllist->next;
	}
    }

  return p;
}

Protocol **
objc_copyProtocolList(unsigned int *count)
{
  *count = 0;
  return NULL;
}

BOOL
protocol_conformsToProtocol(Protocol *p1, Protocol *p2)
{
  struct objc_protocol_list *list = p1->protocol_list;

  // A protocol trivially conforms to itself
  if (strcmp(p1->protocol_name, p2->protocol_name) == 0)
    {
      return YES;
    }

  for (list = p1->protocol_list; list != NULL; list = list->next)
    {
      int i;

      for (i = 0; i < list->count; i++)
	{
	  if (strcmp(list->list[i]->protocol_name, p2->protocol_name) == 0)
	    {
	      return YES;
	    }
	  if (protocol_conformsToProtocol((Protocol*)list->list[i], p2))
	    {
	      return YES;
	    }
	}
    }
  return NO;
}

BOOL
class_conformsToProtocol(Class cls, Protocol *protocol)
{
  struct objc_protocol_list *protocols;

  while (cls)
    {
      for (protocols = cls->protocols;
	protocols != NULL; protocols = protocols->next)
	{
	  int i;

	  for (i = 0; i < protocols->count; i++)
	    {
	      Protocol *p1 = (Protocol*)protocols->list[i];

	      if (strcmp(p1->protocol_name, protocol->protocol_name) == 0)
		{
		  return YES;
		}
	      if (protocol_conformsToProtocol(p1, protocol))
		{
		  return YES;
		}
	    }
	}
      cls = cls->super_class;
    }
  return NO;
}

struct objc_method_description_list {
  int count;
  struct objc_method_description list[1];
};

struct objc_method_description *
protocol_copyMethodDescriptionList(Protocol *p,
  BOOL isRequiredMethod,
  BOOL isInstanceMethod, unsigned int *count)
{
  struct objc_method_description *output = NULL;
  unsigned int outputCount = 0;
  struct objc_method_description_list *methods;

  if (isInstanceMethod)
    {
      methods = p->instance_methods;
    }
  else
    {
      methods = p->class_methods;
    }

  if (methods != NULL)
    {
      int i;

      outputCount = methods->count;
      output = malloc(outputCount * sizeof(struct objc_method_description));

      for (i = 0; i < methods->count; i++)
	{
	  output[i] = methods->list[i];
	  // HACK: the name field of the objc_method_description struct 
	  // is supposed to be a selector, but testing reveals it is a string
	  output[i].name = sel_registerName((const char *) output[i].name);
	}
    }

  *count = outputCount;
  return output;
}

Protocol **
protocol_copyProtocolList(Protocol * p, unsigned int *count)
{
  Protocol **output = NULL;
  unsigned int outputCount = 0;
  struct objc_protocol_list *list;

  for (list = p->protocol_list; list != NULL; list = list->next)
    {
      int i;

      for (i = 0; i < list->count; i++)
	{
	  outputCount++;
	}
    }

  if (outputCount > 0)
    {
      output = malloc(outputCount * sizeof(Protocol *));
    }

  for (list = p->protocol_list; list != NULL; list = list->next)
    {
      int i;

      for (i = 0; i < list->count; i++)
	{
	  output[i] = (Protocol*)list->list[i];
	}
    }

  *count = outputCount;
  return output;
}

const char *
protocol_getName(Protocol * p)
{
  if (NULL != p)
    {
      return p->protocol_name;
    }
  return NULL;
}

struct objc_method_description protocol_getMethodDescription(Protocol *p,
  SEL aSel, BOOL isRequiredMethod, BOOL isInstanceMethod)
{
  struct objc_method_description output = {NULL, NULL};

  if (p != NULL)
    {
      struct objc_method_description_list *methods;
      const char *name = sel_getName(aSel);
      int i;

      if (isInstanceMethod)
	{
          methods = p->instance_methods;
	}
      else
	{
	  methods = p->class_methods;
	}

      if (methods != NULL)
	{
	  for (i = 0; i < methods->count; i++)
	    {
	      if (!strcmp((char*)methods->list[i].name, name))
		{
		  output = methods->list[i];
		  // HACK: the name field of the objc_method_description struct 
		  // is supposed to be a selector, but testing reveals it is a string
		  output.name = sel_registerName((const char *) output.name);
		  break;
		}
	    }
	}
    }
  return output;
}


BOOL
protocol_isEqual(Protocol * p, Protocol * other)
{
  if (NULL == p || NULL == other)
    {
      return NO;
    }
  if (p == other || 0 == strcmp(p->protocol_name, other->protocol_name))
    {
      return YES;
    }
  return NO;
}

const char *
sel_getName(SEL sel)
{
  if (sel == 0)
    return "<null selector>";
  return sel_get_name(sel);
}

SEL
sel_getUid(const char *selName)
{
  return sel_registerName(selName);
}

BOOL
sel_isEqual(SEL sel1, SEL sel2)
{
  return sel_eq(sel1, sel2) ? YES : NO;
}

SEL
sel_registerName(const char *selName)
{
  if (selName == 0)
    return 0;
  return sel_register_name(selName);
}