// Copyright 2016 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.

// This file is shared between executor and csource package.

#include <stdint.h>
#include <string.h>
#if defined(SYZ_EXECUTOR) || defined(SYZ_THREADED) || defined(SYZ_COLLIDE)
#include <pthread.h>
#include <stdlib.h>
#endif
#if defined(SYZ_EXECUTOR) || defined(SYZ_USE_TMP_DIR)
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#endif
#if defined(SYZ_EXECUTOR) || defined(SYZ_HANDLE_SEGV)
#include <setjmp.h>
#include <signal.h>
#include <string.h>
#endif
#if defined(SYZ_EXECUTOR) || (defined(SYZ_REPEAT) && defined(SYZ_WAIT_REPEAT))
#include <errno.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <time.h>
#endif
#if defined(SYZ_EXECUTOR) || defined(SYZ_DEBUG)
#include <stdarg.h>
#include <stdio.h>
#endif

#if defined(SYZ_EXECUTOR)
typedef long (*syscall_t)(long, long, long, long, long, long, long, long, long);

struct call_t {
	const char* name;
	int sys_nr;
	syscall_t call;
};

// Defined in generated syscalls_OS.h files.
extern call_t syscalls[];
extern unsigned syscall_count;
#endif

#if defined(SYZ_EXECUTOR) || (defined(SYZ_REPEAT) && defined(SYZ_WAIT_REPEAT)) ||            \
    defined(SYZ_USE_TMP_DIR) || defined(SYZ_TUN_ENABLE) || defined(SYZ_SANDBOX_NAMESPACE) || \
    defined(SYZ_SANDBOX_SETUID) || defined(SYZ_FAULT_INJECTION) || defined(__NR_syz_kvm_setup_cpu)
const int kFailStatus = 67;
const int kRetryStatus = 69;
#endif

#if defined(SYZ_EXECUTOR)
const int kErrorStatus = 68;
#endif

#if defined(SYZ_EXECUTOR) || (defined(SYZ_REPEAT) && defined(SYZ_WAIT_REPEAT)) ||            \
    defined(SYZ_USE_TMP_DIR) || defined(SYZ_TUN_ENABLE) || defined(SYZ_SANDBOX_NAMESPACE) || \
    defined(SYZ_SANDBOX_SETUID) || defined(SYZ_FAULT_INJECTION) || defined(__NR_syz_kvm_setup_cpu)
// logical error (e.g. invalid input program), use as an assert() alernative
__attribute__((noreturn)) static void fail(const char* msg, ...)
{
	int e = errno;
	fflush(stdout);
	va_list args;
	va_start(args, msg);
	vfprintf(stderr, msg, args);
	va_end(args);
	fprintf(stderr, " (errno %d)\n", e);
	// ENOMEM/EAGAIN is frequent cause of failures in fuzzing context,
	// so handle it here as non-fatal error.
	doexit((e == ENOMEM || e == EAGAIN) ? kRetryStatus : kFailStatus);
}
#endif

#if defined(SYZ_EXECUTOR)
// kernel error (e.g. wrong syscall return value)
__attribute__((noreturn)) static void error(const char* msg, ...)
{
	fflush(stdout);
	va_list args;
	va_start(args, msg);
	vfprintf(stderr, msg, args);
	va_end(args);
	fprintf(stderr, "\n");
	doexit(kErrorStatus);
}
#endif

#if defined(SYZ_EXECUTOR) || (defined(SYZ_REPEAT) && defined(SYZ_WAIT_REPEAT))
// just exit (e.g. due to temporal ENOMEM error)
__attribute__((noreturn)) static void exitf(const char* msg, ...)
{
	int e = errno;
	fflush(stdout);
	va_list args;
	va_start(args, msg);
	vfprintf(stderr, msg, args);
	va_end(args);
	fprintf(stderr, " (errno %d)\n", e);
	doexit(kRetryStatus);
}
#endif

#if defined(SYZ_EXECUTOR) || defined(SYZ_DEBUG)
static int flag_debug;

static void debug(const char* msg, ...)
{
	if (!flag_debug)
		return;
	va_list args;
	va_start(args, msg);
	vfprintf(stdout, msg, args);
	va_end(args);
	fflush(stdout);
}
#endif

#if defined(SYZ_EXECUTOR) || defined(SYZ_USE_BITMASKS)
#define BITMASK_LEN(type, bf_len) (type)((1ull << (bf_len)) - 1)

#define BITMASK_LEN_OFF(type, bf_off, bf_len) (type)(BITMASK_LEN(type, (bf_len)) << (bf_off))

#define STORE_BY_BITMASK(type, addr, val, bf_off, bf_len)                         \
	if ((bf_off) == 0 && (bf_len) == 0) {                                     \
		*(type*)(addr) = (type)(val);                                     \
	} else {                                                                  \
		type new_val = *(type*)(addr);                                    \
		new_val &= ~BITMASK_LEN_OFF(type, (bf_off), (bf_len));            \
		new_val |= ((type)(val)&BITMASK_LEN(type, (bf_len))) << (bf_off); \
		*(type*)(addr) = new_val;                                         \
	}
#endif

#if defined(SYZ_EXECUTOR) || defined(SYZ_HANDLE_SEGV)
static __thread int skip_segv;
static __thread jmp_buf segv_env;

static void segv_handler(int sig, siginfo_t* info, void* uctx)
{
	// Generated programs can contain bad (unmapped/protected) addresses,
	// which cause SIGSEGVs during copyin/copyout.
	// This handler ignores such crashes to allow the program to proceed.
	// We additionally opportunistically check that the faulty address
	// is not within executable data region, because such accesses can corrupt
	// output region and then fuzzer will fail on corrupted data.
	uintptr_t addr = (uintptr_t)info->si_addr;
	const uintptr_t prog_start = 1 << 20;
	const uintptr_t prog_end = 100 << 20;
	if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED) && (addr < prog_start || addr > prog_end)) {
		debug("SIGSEGV on %p, skipping\n", addr);
		_longjmp(segv_env, 1);
	}
	debug("SIGSEGV on %p, exiting\n", addr);
	doexit(sig);
	for (;;) {
	}
}

#define NONFAILING(...)                                              \
	{                                                            \
		__atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST); \
		if (_setjmp(segv_env) == 0) {                        \
			__VA_ARGS__;                                 \
		}                                                    \
		__atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST); \
	}
#endif

#if defined(SYZ_EXECUTOR) || defined(SYZ_USE_CHECKSUMS)
struct csum_inet {
	uint32_t acc;
};

static void csum_inet_init(struct csum_inet* csum)
{
	csum->acc = 0;
}

static void csum_inet_update(struct csum_inet* csum, const uint8_t* data, size_t length)
{
	if (length == 0)
		return;

	size_t i;
	for (i = 0; i < length - 1; i += 2)
		csum->acc += *(uint16_t*)&data[i];

	if (length & 1)
		csum->acc += (uint16_t)data[length - 1];

	while (csum->acc > 0xffff)
		csum->acc = (csum->acc & 0xffff) + (csum->acc >> 16);
}

static uint16_t csum_inet_digest(struct csum_inet* csum)
{
	return ~csum->acc;
}
#endif

#if defined(SYZ_EXECUTOR) || (defined(SYZ_REPEAT) && defined(SYZ_WAIT_REPEAT))
static uint64_t current_time_ms()
{
	struct timespec ts;

	if (clock_gettime(CLOCK_MONOTONIC, &ts))
		fail("clock_gettime failed");
	return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}
#endif