darling-libobjc2/blocks_runtime.m

248 lines
8.0 KiB
Objective-C

/*
* Copyright (c) 2009 Remy Demarest
* Portions Copyright (c) 2009 David Chisnall
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#import "objc/blocks_runtime.h"
#import "objc/runtime.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
/* Makes the compiler happy even without Foundation */
@interface Dummy
- (id)retain;
- (void)release;
@end
// Descriptor attributes
enum {
BLOCK_HAS_COPY_DISPOSE = (1 << 25),
BLOCK_HAS_CTOR = (1 << 26), // helpers have C++ code
BLOCK_IS_GLOBAL = (1 << 28),
BLOCK_HAS_DESCRIPTOR = (1 << 29), // interim until complete world build is accomplished
};
// _Block_object_assign() and _Block_object_dispose() flag helpers.
enum {
BLOCK_FIELD_IS_OBJECT = 3, // id, NSObject, __attribute__((NSObject)), block, ...
BLOCK_FIELD_IS_BLOCK = 7, // a block variable
BLOCK_FIELD_IS_BYREF = 8, // the on stack structure holding the __block variable
BLOCK_FIELD_IS_WEAK = 16, // declared __weak
BLOCK_BYREF_CALLER = 128, // called from byref copy/dispose helpers
};
// Helper structure
struct psy_block_literal {
void *isa; // initialized to &_NSConcreteStackBlock or &_NSConcreteGlobalBlock
int flags;
int reserved;
void (*invoke)(void *, ...);
struct {
unsigned long int reserved; // NULL
unsigned long int size; // sizeof(struct Block_literal_1)
// optional helper functions
void (*copy_helper)(void *dst, void *src);
void (*dispose_helper)(void *src);
} *descriptor;
const char *types;
};
// Helper structure
struct psy_block_byref_obj {
void *isa; // uninitialized
struct psy_block_byref_obj *forwarding;
int flags; //refcount;
int size;
void (*byref_keep)(struct psy_block_byref_obj *dst, struct psy_block_byref_obj *src);
void (*byref_dispose)(struct psy_block_byref_obj *);
};
/* Certain field types require runtime assistance when being copied to the
* heap. The following function is used to copy fields of types: blocks,
* pointers to byref structures, and objects (including
* __attribute__((NSObject)) pointers. BLOCK_FIELD_IS_WEAK is orthogonal to
* the other choices which are mutually exclusive. Only in a Block copy helper
* will one see BLOCK_FIELD_IS_BYREF.
*/
void _Block_object_assign(void *destAddr, void *object, const int flags)
{
//printf("Copying %x to %x with flags %x\n", object, destAddr, flags);
// FIXME: Needs to be implemented
if(flags & BLOCK_FIELD_IS_WEAK)
{
}
else
{
if(flags & BLOCK_FIELD_IS_BYREF)
{
struct psy_block_byref_obj *src = object;
struct psy_block_byref_obj **dst = destAddr;
/* I followed Apple's specs saying byref's "flags" field should
* represent the refcount but it still contains real flag, so this
* is a little hack...
*/
if((src->flags & ~BLOCK_HAS_COPY_DISPOSE) == 0)
{
*dst = malloc(src->size);
memcpy(*dst, src, src->size);
if (src->forwarding == src)
{
(*dst)->forwarding = *dst;
}
if(src->size >= sizeof(struct psy_block_byref_obj))
{
src->byref_keep(*dst, src);
}
}
else *dst = src;
(*dst)->flags++;
}
else if((flags & BLOCK_FIELD_IS_BLOCK) == BLOCK_FIELD_IS_BLOCK)
{
struct psy_block_literal *src = object;
struct psy_block_literal **dst = destAddr;
*dst = Block_copy(src);
}
else if((flags & BLOCK_FIELD_IS_OBJECT) == BLOCK_FIELD_IS_OBJECT)
{
id src = object;
id *dst = destAddr;
*dst = [src retain];
}
}
}
/* Similarly a compiler generated dispose helper needs to call back for each
* field of the byref data structure. (Currently the implementation only packs
* one field into the byref structure but in principle there could be more).
* The same flags used in the copy helper should be used for each call
* generated to this function:
*/
void _Block_object_dispose(void *object, const int flags)
{
// FIXME: Needs to be implemented
if(flags & BLOCK_FIELD_IS_WEAK)
{
}
else
{
if(flags & BLOCK_FIELD_IS_BYREF)
{
struct psy_block_byref_obj *src = object;
src->flags--;
if((src->flags & ~BLOCK_HAS_COPY_DISPOSE) == 0)
{
if(src->size >= sizeof(struct psy_block_byref_obj))
src->byref_dispose(src);
free(src);
}
}
else if((flags & ~BLOCK_BYREF_CALLER) == BLOCK_FIELD_IS_BLOCK)
{
struct psy_block_literal *src = object;
Block_release(src);
}
else if((flags & ~BLOCK_BYREF_CALLER) == BLOCK_FIELD_IS_OBJECT)
{
id src = object;
[src release];
}
}
}
struct StackBlockClass {
void *isa; // initialized to &_NSConcreteStackBlock or &_NSConcreteGlobalBlock
int flags;
int reserved;
void (*invoke)(void *, ...);
struct {
unsigned long int reserved; // NULL
unsigned long int size; // sizeof(struct Block_literal_1)
// optional helper functions
void (*copy_helper)(void *dst, void *src);
void (*dispose_helper)(void *src);
} *descriptor;
const char *types;
};
// Copy a block to the heap if it's still on the stack or increments its retain count.
void *_Block_copy(void *src)
{
struct StackBlockClass *self = src;
struct StackBlockClass *ret = self;
extern void _NSConcreteStackBlock __attribute__((weak));
// If the block is Global, there's no need to copy it on the heap.
if(self->isa == &_NSConcreteStackBlock && self->flags & BLOCK_HAS_DESCRIPTOR)
{
if(self->reserved == 0)
{
ret = malloc(self->descriptor->size);
memcpy(ret, self, self->descriptor->size);
if(self->flags & BLOCK_HAS_COPY_DISPOSE)
self->descriptor->copy_helper(ret, self);
memcpy(self, ret, self->descriptor->size);
}
ret->reserved++;
}
return ret;
}
// Release a block and frees the memory when the retain count hits zero.
void _Block_release(void *src)
{
struct StackBlockClass *self = src;
extern void _NSConcreteStackBlock __attribute__((weak));
if(self->isa == &_NSConcreteStackBlock && // A Global block doesn't need to be released
self->flags & BLOCK_HAS_DESCRIPTOR && // Should always be true...
self->reserved > 0) // If false, then it's not allocated on the heap, we won't release auto memory !
{
self->reserved--;
if(self->reserved == 0)
{
if(self->flags & BLOCK_HAS_COPY_DISPOSE)
self->descriptor->dispose_helper(self);
free(self);
}
}
}
const char *_Block_get_types(void *blk)
{
struct psy_block_literal *block = blk;
return block->types;
}