study_objc4/objc4-779.1/test/badCache.m

/*
TEST_CRASHES
TEST_RUN_OUTPUT
arm
OK: badCache.m
OR
crash now
objc\[\d+\]: Method cache corrupted.*
objc\[\d+\]: .*
objc\[\d+\]: .*
objc\[\d+\]: .*
objc\[\d+\]: .*
objc\[\d+\]: Method cache corrupted.*
objc\[\d+\]: HALTED
END
*/


#include "test.h"

// Test objc_msgSend's detection of infinite loops during cache scan.

#if __arm__

int main()
{
    testwarn("objc_msgSend on arm doesn't detect infinite loops");
    fprintf(stderr, "arm\n");
    succeed(__FILE__);
}

#else

#include "testroot.i"

#if __LP64__
typedef uint32_t mask_t;
#else
typedef uint16_t mask_t;
#endif

struct bucket_t {
    uintptr_t sel;
    uintptr_t imp;
};

struct cache_t {
    uintptr_t buckets;
    mask_t mask;
    mask_t occupied;
};

struct class_t {
    void *isa;
    void *supercls;
    struct cache_t cache;
};

@interface Subclass : TestRoot @end
@implementation Subclass @end

int main()
{
    Class cls = [TestRoot class];
    id obj = [cls new];
    [obj self];

    struct cache_t *cache = &((__bridge struct class_t *)cls)->cache;
    
    // Figure out which cache mask scheme is in use by examining the existing bits.
    int low4 = 0;
#if __LP64__
    int top16 = 0;
#endif
    int outlined = 0;
  
    if (cache->buckets & 0xf) {
        low4 = 1;
#if __LP64__
    } else if ((cache->buckets & (0xffffULL << 48))) {
        top16 = 1;
#endif
    } else {
        outlined = 1;
    }
    
#   define COUNT 4
#   define COUNTSHIFT 14
    struct bucket_t *buckets = (struct bucket_t *)calloc(sizeof(struct bucket_t), COUNT+1);
    for (int i = 0; i < COUNT; i++) {
        buckets[i].sel = ~0;
        buckets[i].imp = ~0;
    }
    buckets[COUNT].sel = 1;
    buckets[COUNT].imp = (uintptr_t)buckets;

    if (low4) {
        cache->buckets = (uintptr_t)buckets | COUNTSHIFT;
#if __LP64__
    } else if (top16) {
        cache->buckets = ((uintptr_t)(COUNT - 1) << 48) | (uintptr_t)buckets;
#endif
    } else if (outlined) {
        cache->mask = COUNT-1;
        cache->buckets = (uintptr_t)buckets;
    }

    cache->occupied = 0;
    
    fprintf(stderr, "crash now\n");
    [obj self];

    fail("should have crashed");
}

#endif