// SPDX-License-Identifier: GPL-2.0-only
/*
 * vdso_restorer.c - tests vDSO-based signal restore
 * Copyright (c) 2015 Andrew Lutomirski
 *
 * This makes sure that sa_restorer == NULL keeps working on 32-bit
 * configurations.  Modern glibc doesn't use it under any circumstances,
 * so it's easy to overlook breakage.
 *
 * 64-bit userspace has never supported sa_restorer == NULL, so this is
 * 32-bit only.
 */

#define _GNU_SOURCE

#include <err.h>
#include <stdio.h>
#include <dlfcn.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <syscall.h>
#include <sys/syscall.h>

/* Open-code this -- the headers are too messy to easily use them. */
struct real_sigaction {
        void *handler;
        unsigned long flags;
        void *restorer;
        unsigned int mask[2];
};

static volatile sig_atomic_t handler_called;

static void handler_with_siginfo(int sig, siginfo_t *info, void *ctx_void)
{
        handler_called = 1;
}

static void handler_without_siginfo(int sig)
{
        handler_called = 1;
}

int main()
{
        int nerrs = 0;
        struct real_sigaction sa;

        void *vdso = dlopen("linux-vdso.so.1",
                            RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
        if (!vdso)
                vdso = dlopen("linux-gate.so.1",
                              RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
        if (!vdso) {
                printf("[SKIP]\tFailed to find vDSO.  Tests are not expected to work.\n");
                return 0;
        }

        memset(&sa, 0, sizeof(sa));
        sa.handler = handler_with_siginfo;
        sa.flags = SA_SIGINFO;
        sa.restorer = NULL;     /* request kernel-provided restorer */

        printf("[RUN]\tRaise a signal, SA_SIGINFO, sa.restorer == NULL\n");

        if (syscall(SYS_rt_sigaction, SIGUSR1, &sa, NULL, 8) != 0)
                err(1, "raw rt_sigaction syscall");

        raise(SIGUSR1);

        if (handler_called) {
                printf("[OK]\tSA_SIGINFO handler returned successfully\n");
        } else {
                printf("[FAIL]\tSA_SIGINFO handler was not called\n");
                nerrs++;
        }

        printf("[RUN]\tRaise a signal, !SA_SIGINFO, sa.restorer == NULL\n");

        sa.flags = 0;
        sa.handler = handler_without_siginfo;
        if (syscall(SYS_sigaction, SIGUSR1, &sa, 0) != 0)
                err(1, "raw sigaction syscall");
        handler_called = 0;

        raise(SIGUSR1);

        if (handler_called) {
                printf("[OK]\t!SA_SIGINFO handler returned successfully\n");
        } else {
                printf("[FAIL]\t!SA_SIGINFO handler was not called\n");
                nerrs++;
        }

        return nerrs;
}