/*
 * Copyright (C) 2022-2023 Colin Ian King.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 */
#include "stress-ng.h"
#include "core-put.h"

static const stress_help_t help[] = {
	{ NULL,	"mprotect N",	 "start N workers exercising mprotect on memory" },
	{ NULL,	"mprotect-ops N", "stop after N bogo mprotect operations" },
	{ NULL,	NULL,		 NULL }
};

#if defined(HAVE_MPROTECT)

typedef struct {
	const int	flag;
	const char 	*name;
} stress_mprotect_flags_t;

#define MPROTECT_MAX	(7)

static sigjmp_buf jmp_env;

static void NORETURN MLOCKED_TEXT stress_sig_handler(int signum)
{
	(void)signum;

	siglongjmp(jmp_env, 1);
}

static const stress_mprotect_flags_t mprotect_flags[] = {
#if defined(PROT_READ)
	{ PROT_READ,	"READ" },
#endif
#if defined(PROT_WRITE)
	{ PROT_WRITE,	"WRITE" },
#endif
#if defined(PROT_SEM)
	{ PROT_SEM,	"SEM" },
#endif
#if defined(PROT_SAO)
	{ PROT_SAO,	"SAO" },
#endif
#if defined(PROT_GROWSUP)
	{ PROT_GROWSUP,	"GROWSUP" },
#endif
#if defined(PROT_GROWSDOWN)
	{ PROT_GROWSDOWN, "GROWSDOWN" },
#endif
};

static void stress_mprotect_flags(
	const int flag,
	char *str,
	const size_t str_len)
{
	size_t i;

	if ((!str) || (str_len < 1))
		return;
	*str = '\0';

	for (i = 0; i < SIZEOF_ARRAY(mprotect_flags); i++) {
		if (flag & mprotect_flags[i].flag) {
			(void)shim_strlcat(str, " PROT_", str_len);
			(void)shim_strlcat(str, mprotect_flags[i].name, str_len);
		}
	}
}

static int stress_mprotect_mem(
	const stress_args_t *args,
	const size_t page_size,
	uint8_t *mem,
	const size_t mem_pages,
	const int *prot_flags,
	const size_t n_flags)
{
	const uint8_t *mem_end = mem + (page_size * mem_pages);

	if (stress_sighandler(args->name, SIGSEGV, stress_sig_handler, NULL) < 0)
		return EXIT_NO_RESOURCE;
	if (stress_sighandler(args->name, SIGBUS, stress_sig_handler, NULL) < 0)
		return EXIT_NO_RESOURCE;

	VOID_RET(int, sigsetjmp(jmp_env, 1));

	while (stress_continue(args)) {
		const uint32_t page = stress_mwc32modn(mem_pages);
		uint8_t *ptr = mem + (page_size * page);
		const size_t max_size = (size_t)(mem_end - ptr);
		const size_t size = stress_mwc32modn(max_size);
		int i;

		/* Don't set protection on data less than a page size */
		if ((max_size < page_size) || (size < page_size))
			continue;

		for (i = 0; (i < 10) && stress_continue(args); i++) {
			const int j = stress_mwc16modn(n_flags);

			if (mprotect((void *)ptr, size, prot_flags[j]) == 0) {
				stress_bogo_inc(args);

#if defined(PROT_READ) &&	\
    defined(PROT_WRITE)
				if ((prot_flags[j] & (PROT_READ | PROT_WRITE)) == 0) {
					char str[128];

					stress_uint8_put(*ptr);

					/* not readable, should not get here */
					stress_mprotect_flags(prot_flags[j], str, sizeof(str));
					pr_fail("%s: page %p was readable with PROT_READ unset, "
						"protection flags used:%s\n",
						args->name, ptr, str);
					return EXIT_FAILURE;
				}
#endif
#if defined(PROT_WRITE)
				/* not writeable, should not get here */
				if ((prot_flags[j] & PROT_WRITE) == 0) {
					char str[128];

					*ptr = 1;

					/* not writable, should not get here */
					stress_mprotect_flags(prot_flags[j], str, sizeof(str));
					pr_fail("%s: page %p was writable with PROT_WRITE unset, "
						"protection flags used:%s\n",
						args->name, ptr, str);
					return EXIT_FAILURE;
				}
#endif
				break;
			}
		}
	}
	return EXIT_SUCCESS;
}

/*
 *  stress_mprotect()
 *	stress mprotect
 */
static int stress_mprotect(const stress_args_t *args)
{
	const size_t page_size = args->page_size;
	const size_t mem_pages = (MPROTECT_MAX >> 1) + 1;
	const size_t mem_size = page_size * mem_pages;
	size_t i;
	uint8_t *mem;
	pid_t pids[MPROTECT_MAX];
	int prot_bits = 0, *prot_flags, rc = EXIT_SUCCESS;
	size_t n_flags;

#if defined(PROT_NONE)
	prot_bits |= PROT_NONE;
#endif
#if defined(PROT_READ)
	prot_bits |= PROT_READ;
#endif
#if defined(PROT_WRITE)
	prot_bits |= PROT_WRITE;
#endif
#if defined(PROT_SEM)
	prot_bits |= PROT_SEM;
#endif
#if defined(PROT_SAO)
	prot_bits |= PROT_SAO;
#endif
#if defined(PROT_GROWSUP)
	prot_bits |= PROT_GROWSUP;
#endif
#if defined(PROT_GROWSDOWN)
	prot_bits |= PROT_GROWSDOWN;
#endif

	n_flags = stress_flag_permutation(prot_bits, &prot_flags);
	if (!prot_flags) {
		pr_inf_skip("%s: cannot allocate protection masks, skipping stressor\n",
			args->name);
		return EXIT_NO_RESOURCE;
	}

	mem = (uint8_t *)mmap(NULL, mem_size, PROT_READ | PROT_WRITE,
				MAP_ANONYMOUS | MAP_SHARED, -1, 0);
	if (mem == MAP_FAILED) {
		pr_inf_skip("%s: cannot allocate %zd pages, skipping stressor\n",
			args->name, mem_pages);
		free(prot_flags);
		return EXIT_NO_RESOURCE;
	}

	/* Make sure this is killable by OOM killer */
	stress_set_oom_adjustment(args, true);

	stress_set_proc_state(args->name, STRESS_STATE_RUN);

	for (i = 0; i < MPROTECT_MAX; i++) {
		pids[i] = fork();
		if (pids[i] == 0) {
			int ret;

			ret = stress_mprotect_mem(args, page_size, mem, mem_pages, prot_flags, n_flags);
			_exit(ret);
		}
	}

	stress_mprotect_mem(args, page_size, mem, mem_pages, prot_flags, n_flags);
	if (stress_kill_and_wait_many(args, pids, MPROTECT_MAX, SIGALRM, true) == EXIT_FAILURE)
		rc = EXIT_FAILURE;

	stress_set_proc_state(args->name, STRESS_STATE_DEINIT);

	(void)munmap((void *)mem, mem_size);
	free(prot_flags);

	return rc;
}

stressor_info_t stress_mprotect_info = {
	.stressor = stress_mprotect,
	.class = CLASS_VM | CLASS_OS,
	.verify = VERIFY_ALWAYS,
	.help = help
};
#else
stressor_info_t stress_mprotect_info = {
	.stressor = stress_unimplemented,
	.class = CLASS_VM | CLASS_OS,
	.verify = VERIFY_ALWAYS,
	.help = help,
	.unimplemented_reason = "built without mprotect() system call"
};
#endif
