alcove

/* Copyright (c) 2014, 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"

static int alcove_decode_iolist_internal(const char *buf, size_t len,
        int *index, char *res, size_t rlen, int *rindex, int depth);

    int
alcove_decode_iolist(const char *buf, size_t len, int *index,
        char *res, size_t *rlen)
{
    int type = 0;
    int arity = 0;
    int rindex = 0;

    if (alcove_get_type(buf, len, index, &type, &arity) < 0)
        return -1;

    switch (type) {
        case ERL_BINARY_EXT:
        case ERL_LIST_EXT:
        case ERL_NIL_EXT:
        case ERL_STRING_EXT:
            break;

        default:
            return -1;
    }

    if (alcove_decode_iolist_internal(buf, len, index,
                res, *rlen, &rindex, 0) < 0)
        return -1;

    *rlen = rindex;

    return 0;
}

    static int
alcove_decode_iolist_internal(const char *buf, size_t len, int *index,
        char *res, size_t rlen, int *rindex, int depth)
{
    int type = 0;
    int arity = 0;

    /* Arbitrary depth to avoid stack overflows */
    if (depth > 16)
        return -1;

    if (alcove_get_type(buf, len, index, &type, &arity) < 0)
        return -1;

    switch (type) {
        case ERL_STRING_EXT:
            if (*rindex + arity + 1 > rlen)
                return -1;

            if (ei_decode_string(buf, index, res + *rindex) < 0)
                return -1;

            /* Do not include trailing NULL */
            *rindex += arity;
            break;

        case ERL_BINARY_EXT: {
            long int length = 0;

            if (*rindex + arity > rlen)
                return -1;

            if (ei_decode_binary(buf, index, res + *rindex, &length) < 0)
                return -1;

            *rindex += length;
            }
            break;

        case ERL_SMALL_INTEGER_EXT: {
            unsigned long p = 0;

            if (*rindex + 1 > rlen)
                return -1;

            if (ei_decode_ulong(buf, index, &p) < 0)
                return -1;

            res[*rindex] = p;
            *rindex += 1;
            }
            break;

        case ERL_NIL_EXT:
            if (ei_decode_list_header(buf, index, &arity) < 0)
                return -1;
            break;

        case ERL_LIST_EXT: {
            int i = 0;
            int length = 0;

            if (ei_decode_list_header(buf, index, &length) < 0)
                return -1;

            for (i = 0; i < length; i++) {
                if (*rindex >= rlen)
                    return -1;
                if (alcove_decode_iolist_internal(buf, len, index,
                            res, rlen, rindex, depth + 1) < 0)
                    return -1;
            }

            /* [] */
            if (alcove_decode_list_header(buf, len, index, &length) < 0
                    || length != 0)
                return -1;

            }
            break;

        default:
            return -1;
    }

    return 0;
}