/*      $NetBSD: h_segv.c,v 1.15 2024/05/14 15:54:16 riastradh Exp $    */

/*-
 * Copyright (c) 2017 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Christos Zoulas.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
#include <sys/cdefs.h>
__RCSID("$NetBSD: h_segv.c,v 1.15 2024/05/14 15:54:16 riastradh Exp $");

#define __TEST_FENV

#include <sys/types.h>
#include <sys/mman.h>
#include <sys/ptrace.h>

#include <err.h>
#include <fenv.h>
#if (__arm__ && !__SOFTFP__) || __aarch64__
#include <ieeefp.h> /* only need for ARM Cortex/Neon hack */
#endif
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static int flags;
#define F_RECURSE       1
#define F_HANDLE        2
#define F_MASK          4
#define F_IGNORE        8
#define F_CHECK         16

static struct {
        const char *n;
        int v;
} nv[] = {
        { "recurse",    F_RECURSE },
        { "handle",     F_HANDLE },
        { "mask",       F_MASK },
        { "ignore",     F_IGNORE },
        { "check",      F_CHECK }
};

static int sig;
static struct {
        const char *n;
        int v;
} sn[] = {
        { "segv",       SIGSEGV },
        { "trap",       SIGTRAP },
        { "ill",        SIGILL },
        { "fpe",        SIGFPE },
        { "bus",        SIGBUS }
};

static void
trigger_segv(void)
{
        volatile int *p = (int *)(intptr_t)atoi("0");

        *p = 1;
}

static void
trigger_trap(void)
{

#ifdef PTRACE_BREAKPOINT_ASM
        PTRACE_BREAKPOINT_ASM;
#else
        /* port me */
#endif  
}

static void
trigger_ill(void)
{

#ifdef PTRACE_ILLEGAL_ASM
        PTRACE_ILLEGAL_ASM;
#else
        /* port me */
#endif  
}

static void
check_fpe(void)
{
#if (__arm__ && !__SOFTFP__) || __aarch64__
        /*
         * Some NEON fpus do not trap on IEEE 754 FP exceptions.
         * Skip these tests if running on them and compiled for
         * hard float.
         */
        if (0 == fpsetmask(fpsetmask(FP_X_INV))) {
                printf("FPU does not implement traps on FP exceptions\n");
                exit(EXIT_FAILURE);
        }
#elif defined __riscv__
        printf("RISC-V does not support floating-point exception traps\n");
        exit(EXIT_FAILURE);
#endif
        exit(EXIT_SUCCESS);
}

volatile int ignore_result;

static void
trigger_fpe(void)
{
        volatile double a = getpid();
        volatile double b = strtol("0", NULL, 0);

#ifdef __HAVE_FENV
        feenableexcept(FE_ALL_EXCEPT);
#endif

        /*
         * Try to trigger SIGFPE either by dividing by zero (which is
         * defined to raise FE_DIVBYZERO, but may just return infinity
         * without trapping the exception) or by converting infinity to
         * integer.
         */
        ignore_result = (int)(a/b);
}

static void
trigger_bus(void)
{
        FILE *fp;
        char *p;

        /* Open an empty file for writing. */
        fp = tmpfile();
        if (fp == NULL)
                err(EXIT_FAILURE, "tmpfile");

        /*
         * Map an empty file with mmap(2) to a pointer.
         *
         * PROT_READ handles read-modify-write sequences emitted for
         * certain combinations of CPUs and compilers (e.g. Alpha AXP).
         */
        p = mmap(0, 1, PROT_READ|PROT_WRITE, MAP_PRIVATE, fileno(fp), 0);
        if (p == MAP_FAILED)
                err(EXIT_FAILURE, "mmap");

        /* Invalid memory access causes CPU trap, translated to SIGBUS */
        *p = 'a';
}

static void
trigger(void)
{

        switch (sig) {
        case SIGSEGV:
                trigger_segv();
                break;
        case SIGTRAP:
                trigger_trap();
                break;
        case SIGILL:
                trigger_ill();
                break;
        case SIGFPE:
                trigger_fpe();
                break;
        case SIGBUS:
                trigger_bus();
                break;
        default:
                break;
        }
}

static void
foo(int s)
{
        char buf[64];
        int i = snprintf(buf, sizeof(buf), "got %d\n", s);
        write(2, buf, i);

        if (flags & F_RECURSE)
                trigger();

        exit(EXIT_SUCCESS);
}

static __dead void
usage(void)
{
        const char *pname = getprogname();

        fprintf(stderr, "Usage: %s segv|trap|ill|fpe|bus "
                        "[recurse|mask|handle|ignore|check] ...\n", pname);

        exit(EXIT_FAILURE);
}

int
main(int argc, char *argv[])
{

        if (argc == 1)
            usage();

        for (int i = 1; i < argc; i++) {
                size_t j;
                for (j = 0; j < __arraycount(nv); j++) {
                        if (strcmp(nv[j].n, argv[i]) == 0) {
                                flags |= nv[j].v;
                                goto consumed;
                        }
                }
                for (j = 0; j < __arraycount(sn); j++) {
                        if (strcmp(sn[j].n, argv[i]) == 0) {
                                sig = sn[j].v;
                                goto consumed;
                        }
                }

                usage();

        consumed:
                continue;
        }

        if (flags == 0 || sig == 0)
                usage();

        if (flags & F_CHECK && sig != SIGFPE) {
                fprintf(stderr, "can only check for fpe support\n");
                return 1;
        }
        if (flags & F_CHECK)
                check_fpe();

        if (flags & F_HANDLE) {
                struct sigaction sa;

                sa.sa_flags = SA_RESTART;
                sa.sa_handler = foo;
                sigemptyset(&sa.sa_mask);
                if (sigaction(sig, &sa, NULL) == -1)
                        err(EXIT_FAILURE, "sigaction");
        }

        if (flags & F_MASK) {
                sigset_t set;

                sigemptyset(&set);
                sigaddset(&set, sig);
                if (sigprocmask(SIG_BLOCK, &set, NULL) == -1)
                        err(EXIT_FAILURE, "sigprocmask");
        }

        if (flags & F_IGNORE) {
                struct sigaction sa;

                memset(&sa, 0, sizeof(sa));
                sa.sa_handler = SIG_IGN;
                sigemptyset(&sa.sa_mask);
                if (sigaction(sig, &sa, NULL) == -1)
                        err(EXIT_FAILURE, "sigaction");
        }

        trigger();

        return EXIT_SUCCESS;
}