/* Copyright (c) 2014-2017, 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"

#ifdef __linux__
#include <sys/prctl.h>
#ifdef HAVE_PRCTL_SECCOMP
#include <linux/seccomp.h>
#endif
#endif

#include "alcove_prctl_constants.h"

typedef struct {
    u_char type;
    unsigned long arg;
    char data[MAXMSGLEN];
    size_t len;
} alcove_prctl_arg_t;

enum {
    ALCOVE_PRARG_UNSIGNED_LONG,
    ALCOVE_PRARG_CSTRUCT,
    ALCOVE_PRARG_BINARY
};

#define PRARG(x) (((x).type) ? (unsigned long)(x).data : (x).arg)

/*
 * prctl(2)
 *
 */
    ssize_t
alcove_sys_prctl(alcove_state_t *ap, const char *arg, size_t len,
        char *reply, size_t rlen)
{
#ifdef __linux__
    int index = 0;
    int rindex = 0;
    int type = 0;
    int arity = 0;

    int option = 0;
    alcove_alloc_t *elem[4] = {0};
    ssize_t nelem[4] = {0};
    int i = 0;

    alcove_prctl_arg_t prarg[4] = {0};

    int rv = 0;

    UNUSED(ap);

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

    /* arg2, arg3, arg4, arg5 */
    for (i = 0; i < 4; i++) {
        if (alcove_get_type(arg, len, &index, &type, &arity) < 0)
            return -1;

        switch (type) {
            case ERL_SMALL_INTEGER_EXT:
            case ERL_INTEGER_EXT:
                if (alcove_decode_ulong(arg, len, &index, &prarg[i].arg) < 0)
                    return -1;

                break;

            case ERL_ATOM_EXT: {
                char define[MAXATOMLEN] = {0};
                long long val = 0;
                unsigned long constant = 0;

                if (alcove_decode_atom(arg, len, &index, define) < 0)
                    return -1;

                if (alcove_lookup_constant(define, &val,
                            alcove_prctl_constants) < 0)
                    return alcove_mk_error(reply, rlen, "enotsup");

                if (val < 0 || val > INT32_MAX)
                    return -1;

                constant = val;

                prarg[i].arg = constant;
                }
                break;

            case ERL_LIST_EXT:
                prarg[i].type = ALCOVE_PRARG_CSTRUCT;
                prarg[i].len = sizeof(prarg[i].data);
                if (alcove_decode_cstruct(arg, len, &index, prarg[i].data,
                        &(prarg[i].len), &(elem[i]), &(nelem[i])) < 0)
                    return -1;

                break;

            case ERL_BINARY_EXT:
                prarg[i].type = ALCOVE_PRARG_BINARY;
                if (arity > sizeof(prarg[i].data))
                    return -1;
                if (alcove_decode_binary(arg, len, &index,
                            prarg[i].data, &(prarg[i].len)) < 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 = prctl(option, PRARG(prarg[0]), PRARG(prarg[1]),
            PRARG(prarg[2]), PRARG(prarg[3]));

    if (rv < 0)
        return alcove_mk_errno(reply, rlen, errno);

    ALCOVE_ERR(alcove_encode_version(reply, rlen, &rindex));
    ALCOVE_ERR(alcove_encode_tuple_header(reply, rlen, &rindex, 6));
    ALCOVE_ERR(alcove_encode_atom(reply, rlen, &rindex, "ok"));
    ALCOVE_ERR(alcove_encode_long(reply, rlen, &rindex, rv));

    for (i = 0; i < 4; i++) {
        switch (prarg[i].type) {
            case ALCOVE_PRARG_UNSIGNED_LONG:
                ALCOVE_ERR(alcove_encode_ulonglong(reply, rlen, &rindex, prarg[i].arg));
                break;
            case ALCOVE_PRARG_CSTRUCT:
                ALCOVE_ERR(alcove_encode_cstruct(reply, rlen, &rindex,
                            prarg[i].data, prarg[i].len,
                            elem[i], nelem[i]));
                break;
            case ALCOVE_PRARG_BINARY:
                ALCOVE_ERR(alcove_encode_binary(reply, rlen, &rindex, prarg[i].data,
                            prarg[i].len));
                break;
            default:
                return -1;
        }
    }

    return rindex;
#else
    UNUSED(ap);
    UNUSED(arg);
    UNUSED(len);

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