block-struct-return.c [plain text]
#include <stdio.h>
#include <stdlib.h>
typedef struct bigbig {
int array[512];
char more[32];
} BigStruct_t;
BigStruct_t (^global)(void) = ^{ return *(BigStruct_t *)malloc(sizeof(struct bigbig)); };
const char * getBlockSignature(void *);
BigStruct_t foo(int param) {
BigStruct_t x;
BigStruct_t (^f)(int) = ^(int param) {
BigStruct_t *result = malloc(sizeof(BigStruct_t));
result->array[23] = param;
return *result;
};
getBlockSignature(f);
return x;
}
enum {
BLOCK_HAS_COPY_DISPOSE = (1 << 25),
BLOCK_HAS_CXX_OBJ = (1 << 26),
BLOCK_IS_GLOBAL = (1 << 28),
BLOCK_USE_STRET = (1 << 29),
BLOCK_HAS_OBJC_TYPE = (1 << 30)
};
struct block_descriptor_big {
unsigned long int reserved;
unsigned long int size;
void (*copy)(void *dst, void *src); void (*dispose)(void *); const char *signature; const char *layout; };
struct block_descriptor_small {
unsigned long int reserved;
unsigned long int size;
const char *signature; const char *layout; };
struct block_layout_abi { void *isa;
int flags;
int reserved;
void (*invoke)(void *, ...);
struct block_descriptor_big *descriptor;
};
const char *getBlockSignature(void *block) {
struct block_layout_abi *layout = (struct block_layout_abi *)block;
if (layout->flags & BLOCK_HAS_COPY_DISPOSE)
return layout->descriptor->signature;
else
return ((struct block_descriptor_small *)layout->descriptor)->signature;
}
int usesStruct(void *block) {
struct block_layout_abi *layout = (struct block_layout_abi *)block;
int want = BLOCK_USE_STRET;
return (layout->flags & want) == want;
}
int main(int argc, char *argv[]) {
printf("desired global flags: %d\n", BLOCK_USE_STRET | BLOCK_IS_GLOBAL );
printf("desired stack flags: %d\n", BLOCK_USE_STRET );
if (!usesStruct(global))
return 1;
BigStruct_t x;
BigStruct_t (^local)(int) = ^(int param) {
BigStruct_t *result = (BigStruct_t *)malloc(sizeof(BigStruct_t));
result->array[23] = argc;
return *result;
};
if (!usesStruct(global))
return 1;
if (usesStruct(^void(int x){ }))
return 1;
return 0;
}