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#include "std_safe.h"
#include "dt_proxy.h"
#include "osfmk/unit_test_utils.h"

#include <mach/arm/vm_types.h>  // for vm_map_offset_t
#include <mach/mach_types.h>
#include <kern/assert.h>
#include <kern/trap_telemetry.h>
#include <kern/debug.h>

// This file is linked to the same .dylib as the XNU code static library
// to provide some utilities that XNU code relies on when building for unit-test

// This symbol normally comes from lastkernelconstructor.o but this object is not linked to libkernel since it is
// a zero length symbol, which fails to prelink with ld -r
// It is defined here again to resolve the external.
// It is used for debugging and in kext related functions which are not needed by the tester
void* last_kernel_symbol = NULL;

// In normal XNU build this is a global of type mach_header_64 that the linker adds. The user-space linker
// doesn't add it so it's added here to resolve the external. It's not needed by the tester. see <mach-o/ldsyms.h>
struct mach_header_64 _mh_execute_header;

// called from fake_init, setup proxies for darwintest asserts
struct dt_proxy_callbacks *dt_proxy = NULL;
void
set_dt_proxy_attached(struct dt_proxy_callbacks *p)
{
	dt_proxy = p;
}
struct dt_proxy_callbacks *
get_dt_proxy_attached(void)
{
	return dt_proxy;
}

// backtrace printing/collecting
// This calls libc backtrace(). XNU also has a backtrace() function but it's hidden using xnu_lib.unexport
// before this code is linked in
extern int backtrace(void **array, int size); // from execinfo.h
extern char **backtrace_symbols(void *const *array, int size);

#ifdef __BUILDING_WITH_SANITIZER__
extern void __sanitizer_symbolize_pc(void *pc, const char *fmt, char *out_buf, size_t out_buf_size);
#endif

void
print_collected_backtrace(struct backtrace_array *bt)
{
#ifdef __BUILDING_WITH_SANITIZER__
	// If compiled with any sanitizer, use __sanitizer_symbolize_pc as it gives much more info compared to backtrace_symbols
	char description[1024];
	for (int idx = 0; idx < bt->nptrs; idx++) {
		__sanitizer_symbolize_pc(bt->buffer[idx], "%p %F %L", description, sizeof(description));
		raw_printf("%d\t%s\n", idx, description);
	}
#else
	char** strings = backtrace_symbols(bt->buffer, bt->nptrs);
	PT_QUIET; PT_ASSERT_NOTNULL(strings, "backtrace_symbols");
	for (int idx = 0; idx < bt->nptrs; idx++) {
		raw_printf("%s\n", strings[idx]);
	}
	free(strings);
#endif
	raw_printf("\n");
}

void
print_current_backtrace(void)
{
	struct backtrace_array bt;
	bt.nptrs = backtrace(bt.buffer, 100);
	print_collected_backtrace(&bt);
}

struct backtrace_array *
collect_current_backtrace(void)
{
	struct backtrace_array *bt = malloc(sizeof(struct backtrace_array));
	bt->nptrs = backtrace(bt->buffer, 100);
	return bt;
}


// check if panic/assert were expected by the test using T_ASSERT_PANIC
struct ut_expected_panic_s ut_expected_panic;

void
ut_check_expected_panic(const char* panic_str)
{
	if (!ut_expected_panic.expect_panic) {
		return;
	}
	ut_expected_panic.expect_panic = false;
	if (ut_expected_panic.str_contains != NULL) {
		if (strstr(panic_str, ut_expected_panic.str_contains) == NULL) {
			PT_LOG_FMTSTR("Panic with unexpected panic-string, expected: `%s`", ut_expected_panic.str_contains);
			return;
		}
	}
	PT_LOG("Panic was expected");
	longjmp(ut_expected_panic.jb, 1);
}

// This function is called on an assert instead of invoking a brk instruction which would trap the kernel
__attribute__((noreturn)) void
ut_assert_trap(int code, long a, long b, long c)
{
	struct kernel_panic_reason pr = {};

	switch (code) {
	case XNU_HARD_TRAP_ASSERT_FAILURE:
		panic_assert_format(pr.buf, sizeof(pr.buf), (struct mach_assert_hdr *)a, b, c);
		PT_LOG_OR_RAW_FMTSTR("%s", pr.buf);
		break;

	case XNU_HARD_TRAP_SAFE_UNLINK:
		snprintf(pr.buf, sizeof(pr.buf),
		    "panic: corrupt list around element %p", (void *)a);
		PT_LOG_OR_RAW_FMTSTR("%s", pr.buf);
		break;

	default:
		snprintf(pr.buf, sizeof(pr.buf), "%x", code);
		PT_LOG_OR_RAW_FMTSTR("Unknown assert code %s", pr.buf);
		break;
	}

	ut_check_expected_panic(pr.buf); // may not return
	PT_FAIL("🧘 Unexpected assert fail, exiting");
	print_current_backtrace();
	abort();
}

// This function can be called from the tested code to force a context switch when using fibers
// See the mock implementation
void
ut_fibers_ctxswitch(void)
{
}

// This function can be called from the tested code to force a context switch to a specific fiber
// See the mock implementation
void
ut_fibers_ctxswitch_to(int fiber_id)
{
}

// This function can be called from the tested code to get the current fiber id when using fibers, -1 otherwise
// See the mock implementation
int
ut_fibers_current_id(void)
{
	return -1;
}

static void
fail_not_mocked()
{
	PT_FAIL("This function should never be called since it is mocked by the mocks dylib");
}

// This function is changed from being a macro. It needs to have an implementation
// in the code attached to XNU so that it can be mocked
__mockable void
lock_disable_preemption_for_thread(thread_t t)
{
	fail_not_mocked();
}

__mockable __attribute__((const)) thread_t
current_thread_fast(void)
{
	fail_not_mocked();
	return NULL;
}

// Mocks runtime registration facilities.
// These need to be here since both libmocks.dylib and *.pmocks.dylib depend on it
static struct {
	struct mock_entry* mel_head;
	struct mock_entry** mel_tail;
} g_mock_entries_list = {
	.mel_tail = &g_mock_entries_list.mel_head,
};

void
_mock_entry_register(struct mock_entry *entry)
{
	*g_mock_entries_list.mel_tail = entry;
	g_mock_entries_list.mel_tail = &entry->me_next;
}

struct mock_entry*
_mock_entry_first(void)
{
	return g_mock_entries_list.mel_head;
}

// Note: For private-mocks (pmocks), this shows the mock in both the test-executable and the *.pmock.dylib
// The version in the test-executable however never gets called since interposing doesn't consider
// executables.
void
ut_print_all_mocks(void)
{
	for (struct mock_entry* me = _mock_entry_first(); me != NULL; me = me->me_next) {
		raw_printf("name: %s  original:%p  mock:%p  from: %s\n", me->me_name, me->me_original_func, me->me_mock_func, me->me_location);
	}
}