#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>


ngx_chain_t *ngx_writev_chain(ngx_connection_t *c, ngx_chain_t *in)
{
    char            *prev;
    ssize_t          n, size;
    off_t            sent;
    struct iovec    *iov;
    ngx_err_t        err;
    ngx_array_t      io;
    ngx_chain_t     *cl;

    if (!c->write->ready) {
        return in;
    }

    ngx_init_array(io, c->pool, 10, sizeof(struct iovec), NGX_CHAIN_ERROR);

    prev = NULL;
    iov = NULL;

    /* create the iovec and coalesce the neighbouring hunks */

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

        if (prev == cl->hunk->pos) {
            iov->iov_len += cl->hunk->last - cl->hunk->pos;
            prev = cl->hunk->last;

        } else {
            ngx_test_null(iov, ngx_push_array(&io), NGX_CHAIN_ERROR);
            iov->iov_base = cl->hunk->pos;
            iov->iov_len = cl->hunk->last - cl->hunk->pos;
            prev = cl->hunk->last;
        }
    }

    n = writev(c->fd, io.elts, io.nelts);

    if (n == -1) {
        err = ngx_errno;
        if (err == NGX_EAGAIN) {
            ngx_log_error(NGX_LOG_INFO, c->log, err, "writev() EAGAIN");

        } else if (err == NGX_EINTR) {
            ngx_log_error(NGX_LOG_INFO, c->log, err, "writev() EINTR");

        } else {
            ngx_log_error(NGX_LOG_CRIT, c->log, err, "writev() failed");
            return NGX_CHAIN_ERROR;
        }
    }

    sent = n > 0 ? n : 0;

#if (NGX_DEBUG_WRITE_CHAIN)
    ngx_log_debug(c->log, "writev: " OFF_T_FMT  _ sent);
#endif

    c->sent += sent;

    for (cl = in; cl && sent > 0; cl = cl->next) {

        size = cl->hunk->last - cl->hunk->pos;

ngx_log_debug(c->log, "SIZE: %d" _ size);

        if (sent >= size) {
            sent -= size;

            if (cl->hunk->type & NGX_HUNK_IN_MEMORY) {
                cl->hunk->pos = cl->hunk->last;
            }

            continue;
        }

        if (cl->hunk->type & NGX_HUNK_IN_MEMORY) {
            cl->hunk->pos += sent;
        }

        break;
    }

    return cl;
}