/* Copyright (c) 2017, Michael Santos <michael.santos@gmail.com>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#include "alcove.h"
#include "alcove_call.h"

#ifndef HAVE_SECCOMP
#ifdef __linux__
#include <syscall.h>
#endif
#endif

#ifdef __linux__
#ifdef HAVE_PRCTL_SECCOMP
#include <linux/seccomp.h>
#include <linux/filter.h>
#include <linux/audit.h>
#include <sys/ptrace.h>
#endif
#endif

#include "alcove_seccomp_constants.h"

typedef struct {
    char data[MAXMSGLEN];
    size_t len;
} alcove_seccomp_arg_t;

#ifdef __linux__
#ifndef HAVE_SECCOMP
static int seccomp(unsigned int operation, unsigned int flags, void *args);
#endif
#endif

/*
 * seccomp(2)
 *
 */
#ifdef __linux__
#ifndef HAVE_SECCOMP
  static int
seccomp(unsigned int operation, unsigned int flags, void *args)
{
#ifdef __NR_seccomp
    return syscall(__NR_seccomp, operation, flags, args);
#else
#pragma message "No support for seccomp(2)"
    errno = ENOSYS;
    return -1;
#endif
}
#endif
#endif

    ssize_t
alcove_sys_seccomp(alcove_state_t *ap, const char *arg, size_t len,
        char *reply, size_t rlen)
{
#ifdef __linux__
    int index = 0;
    int type = 0;
    int arity = 0;

    unsigned int operation = 0;
    unsigned int flags = 0;
    alcove_alloc_t *elem = NULL;
    ssize_t nelem = 0;

    alcove_seccomp_arg_t args = {0};

    int rv = 0;

    UNUSED(ap);

    /* operation */
    switch (alcove_decode_constant(arg, len, &index, (int *)&operation,
                alcove_seccomp_constants)) {
        case 0:
            break;
        case 1:
            return alcove_mk_error(reply, rlen, "enotsup");
        default:
            return -1;
    }

    /* flags */
    switch (alcove_decode_constant(arg, len, &index, (int *)&flags,
                alcove_seccomp_constants)) {
        case 0:
            break;
        case 1:
            return alcove_mk_error(reply, rlen, "enotsup");
        default:
            return -1;
    }

    /* args */
    if (alcove_get_type(arg, len, &index, &type, &arity) < 0)
        return -1;

    switch (type) {
        case ERL_LIST_EXT:
            args.len = sizeof(args.data);
            if (alcove_decode_cstruct(arg, len, &index, args.data,
                    &(args.len), &elem, &nelem) < 0)
                return -1;

            break;

        case ERL_NIL_EXT:
            if (alcove_decode_list_header(arg, len, &index, &arity) < 0 ||
                    arity != 0)
                return -1;

            break;

        default:
            return -1;
    }

    rv = seccomp(operation, flags, args.len == 0 ? NULL : args.data);

    return (rv < 0)
        ? alcove_mk_errno(reply, rlen, errno)
        : alcove_mk_atom(reply, rlen, "ok");
#else
    UNUSED(ap);
    UNUSED(arg);
    UNUSED(len);

    return alcove_mk_atom(reply, rlen, "undef");
#endif
}