static ngx_inline ngx_int_t⏎
    ngx_output_chain_as_is(ngx_output_chain_ctx_t *ctx, ngx_buf_t *buf);⏎
#if (NGX_HAVE_AIO_SENDFILE)⏎
static ngx_int_t ngx_output_chain_aio_setup(ngx_output_chain_ctx_t *ctx,⏎
    ngx_file_t *file);⏎
#endif⏎
static ngx_int_t ngx_output_chain_add_copy(ngx_pool_t *pool,⏎
    ngx_chain_t **chain, ngx_chain_t *in);⏎
static ngx_int_t ngx_output_chain_align_file_buf(ngx_output_chain_ctx_t *ctx,⏎
    off_t bsize);⏎
static ngx_int_t ngx_output_chain_get_buf(ngx_output_chain_ctx_t *ctx,⏎
    off_t bsize);⏎
static ngx_int_t ngx_output_chain_copy_buf(ngx_output_chain_ctx_t *ctx);⏎
⏎
⏎
ngx_int_t⏎
ngx_output_chain(ngx_output_chain_ctx_t *ctx, ngx_chain_t *in)⏎
{⏎
    off_t         bsize;⏎
    ngx_int_t     rc, last;⏎
    ngx_chain_t  *cl, *out, **last_out;⏎
⏎
    if (ctx->in == NULL && ctx->busy == NULL⏎
#if (NGX_HAVE_FILE_AIO || NGX_THREADS)⏎
        && !ctx->aio⏎
#endif⏎
       )⏎
    {⏎
        /*⏎
         * the short path for the case when the ctx->in and ctx->busy chains⏎
         * are empty, the incoming chain is empty too or has the single buf⏎
         * that does not require the copy⏎
         */⏎
⏎
        if (in == NULL) {⏎
            return ctx->output_filter(ctx->filter_ctx, in);⏎
        }⏎
⏎
        if (in->next == NULL⏎
#if (NGX_SENDFILE_LIMIT)⏎
            && !(in->buf->in_file && in->buf->file_last > NGX_SENDFILE_LIMIT)⏎
#endif⏎
            && ngx_output_chain_as_is(ctx, in->buf))⏎
        {⏎
            return ctx->output_filter(ctx->filter_ctx, in);⏎
        }⏎
    }⏎
⏎
    /* add the incoming buf to the chain ctx->in */⏎
⏎
    if (in) {⏎
        if (ngx_output_chain_add_copy(ctx->pool, &ctx->in, in) == NGX_ERROR) {⏎
            return NGX_ERROR;⏎
        }⏎
    }⏎