static ngx_int_t
ngx_event_pipe_write_chain_to_temp_file(ngx_event_pipe_t *p)
{
    ssize_t       size, bsize, n;
    ngx_buf_t    *b;
    ngx_uint_t    prev_last_shadow;
    ngx_chain_t  *cl, *tl, *next, *out, **ll, **last_out, **last_free, fl;

    if (p->buf_to_file) {
        fl.buf = p->buf_to_file;
        fl.next = p->in;
        out = &fl;

    } else {
        out = p->in;
    }

    if (!p->cacheable) {

        size = 0;
        cl = out;
        ll = NULL;
        prev_last_shadow = 1;

        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, p->log, 0,
                       "pipe offset: %O", p->temp_file->offset);

        do {
            bsize = cl->buf->last - cl->buf->pos;

            ngx_log_debug4(NGX_LOG_DEBUG_EVENT, p->log, 0,
                           "pipe buf ls:%d %p, pos %p, size: %z",
                           cl->buf->last_shadow, cl->buf->start,
                           cl->buf->pos, bsize);

            if (prev_last_shadow
                && ((size + bsize > p->temp_file_write_size)
                    || (p->temp_file->offset + size + bsize
                        > p->max_temp_file_size)))
            {
                break;
            }

            prev_last_shadow = cl->buf->last_shadow;

            size += bsize;
            ll = &cl->next;
            cl = cl->next;

        } while (cl);

        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, p->log, 0, "size: %z", size);

        if (ll == NULL) {
            return NGX_BUSY;
        }

        if (cl) {
           p->in = cl;
           *ll = NULL;

        } else {
           p->in = NULL;
           p->last_in = &p->in;
        }

    } else {
        p->in = NULL;
        p->last_in = &p->in;
    }

    n = ngx_write_chain_to_temp_file(p->temp_file, out);

    if (n == NGX_ERROR) {
        return NGX_ABORT;
    }

    if (p->buf_to_file) {
        p->temp_file->offset = p->buf_to_file->last - p->buf_to_file->pos;
        n -= p->buf_to_file->last - p->buf_to_file->pos;
        p->buf_to_file = NULL;
        out = out->next;
    }

    if (n > 0) {
        /* update previous buffer or add new buffer */

        if (p->out) {
            for (cl = p->out; cl->next; cl = cl->next) { /* void */ }

            b = cl->buf;

            if (b->file_last == p->temp_file->offset) {
                p->temp_file->offset += n;
                b->file_last = p->temp_file->offset;
                goto free;
            }

            last_out = &cl->next;

        } else {
            last_out = &p->out;
        }

        cl = ngx_chain_get_free_buf(p->pool, &p->free);
        if (cl == NULL) {
            return NGX_ABORT;
        }

        b = cl->buf;

        ngx_memzero(b, sizeof(ngx_buf_t));

        b->tag = p->tag;

        b->file = &p->temp_file->file;
        b->file_pos = p->temp_file->offset;
        p->temp_file->offset += n;
        b->file_last = p->temp_file->offset;

        b->in_file = 1;
        b->temp_file = 1;

        *last_out = cl;
    }

free:

    for (last_free = &p->free_raw_bufs;
         *last_free != NULL;
         last_free = &(*last_free)->next)
    {
        /* void */
    }

    for (cl = out; cl; cl = next) {
        next = cl->next;

        cl->next = p->free;
        p->free = cl;

        b = cl->buf;

        if (b->last_shadow) {

            tl = ngx_alloc_chain_link(p->pool);
            if (tl == NULL) {
                return NGX_ABORT;
            }

            tl->buf = b->shadow;
            tl->next = NULL;

            *last_free = tl;
            last_free = &tl->next;

            b->shadow->pos = b->shadow->start;
            b->shadow->last = b->shadow->start;

            ngx_event_pipe_remove_shadow_links(b->shadow);
        }
    }

    return NGX_OK;
}