/*
 * interpose_profile.c — Profiling interposer for heap layout analysis
 *
 * Logs all malloc/free calls from AppleJPEGXL with sizes and caller info.
 * Output: one line per operation, parseable by the mutation test harness.
 *
 * Build:
 *   clang -shared -o interpose_profile.dylib interpose_profile.c
 *
 * Use:
 *   DYLD_INSERT_LIBRARIES=./interpose_profile.dylib ./wkwebview_poc poc.jxl 2>/tmp/profile.log
 */
#include <stdio.h>
#include <stdlib.h>
#include <dlfcn.h>
#include <string.h>
#include <stdint.h>
#include <unistd.h>
#include <malloc/malloc.h>

typedef struct {
    const void *replacement;
    const void *replacee;
} interpose_t;

static int initialized = 0;
static int in_hook = 0;
static int op_count = 0;

static inline void real_free(void *ptr) {
    malloc_zone_t *zone = malloc_default_zone();
    if (zone && ptr) zone->free(zone, ptr);
}

__attribute__((constructor))
static void init(void) { initialized = 1; }

static void hooked_free(void *ptr) {
    if (!ptr) { return; }
    if (in_hook || !initialized) { real_free(ptr); return; }
    in_hook = 1;

    Dl_info info;
    void *ra = __builtin_return_address(0);
    if (dladdr(ra, &info) && info.dli_fname && strstr(info.dli_fname, "AppleJPEGXL")) {
        op_count++;
        size_t sz = malloc_size(ptr);
        const char *sym = info.dli_sname ? info.dli_sname : "?";
        unsigned long off = (unsigned long)((char *)ra - (char *)info.dli_saddr);
        char buf[256];
        int n = snprintf(buf, sizeof(buf),
            "FREE %d %p %zu %s+0x%lx\n",
            op_count, ptr, sz, sym, off);
        write(STDERR_FILENO, buf, n);
    }

    in_hook = 0;
    real_free(ptr);
}

static void *hooked_malloc(size_t size) {
    void *ptr = malloc_zone_malloc(malloc_default_zone(), size);
    if (!ptr || in_hook || !initialized) return ptr;
    in_hook = 1;

    Dl_info info;
    void *ra = __builtin_return_address(0);
    if (dladdr(ra, &info) && info.dli_fname && strstr(info.dli_fname, "AppleJPEGXL")) {
        op_count++;
        char buf[256];
        const char *sym = info.dli_sname ? info.dli_sname : "?";
        unsigned long off = (unsigned long)((char *)ra - (char *)info.dli_saddr);
        int n = snprintf(buf, sizeof(buf),
            "MALLOC %d %p %zu %s+0x%lx\n",
            op_count, ptr, size, sym, off);
        write(STDERR_FILENO, buf, n);
    }

    in_hook = 0;
    return ptr;
}

__attribute__((used))
static const interpose_t interposers[] __attribute__((section("__DATA,__interpose"))) = {
    { (const void *)hooked_free, (const void *)free },
    { (const void *)hooked_malloc, (const void *)malloc },
};