view src/os/unix/ngx_darwin_sendfile_chain.c @ 7784:8cc5b0365ee5

Improved maximum errno detection. Previously, systems without sys_nerr (or _sys_nerr) were handled with an assumption that errors start at 0 and continuous. This is, however, not something POSIX requires, and not true on some platforms. Notably, on Linux, where sys_nerr is no longer available for newly linked binaries starting with glibc 2.32, there are gaps in error list, which used to stop us from properly detecting maximum errno. Further, on GNU/Hurd errors start at 0x40000001. With this change, maximum errno detection is moved to the runtime code, now able to ignore gaps, and also detects the first error if needed. This fixes observed "Unknown error" messages as seen on Linux with glibc 2.32 and on GNU/Hurd.
author Maxim Dounin <mdounin@mdounin.ru>
date Mon, 01 Mar 2021 20:00:43 +0300
parents 7cc2d3a96ea3
children
line wrap: on
line source


/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


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


/*
 * It seems that Darwin 9.4 (Mac OS X 1.5) sendfile() has the same
 * old bug as early FreeBSD sendfile() syscall:
 * http://bugs.freebsd.org/33771
 *
 * Besides sendfile() has another bug: if one calls sendfile()
 * with both a header and a trailer, then sendfile() ignores a file part
 * at all and sends only the header and the trailer together.
 * For this reason we send a trailer only if there is no a header.
 *
 * Although sendfile() allows to pass a header or a trailer,
 * it may send the header or the trailer and a part of the file
 * in different packets.  And FreeBSD workaround (TCP_NOPUSH option)
 * does not help.
 */


ngx_chain_t *
ngx_darwin_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
{
    int              rc;
    off_t            send, prev_send, sent;
    off_t            file_size;
    ssize_t          n;
    ngx_uint_t       eintr;
    ngx_err_t        err;
    ngx_buf_t       *file;
    ngx_event_t     *wev;
    ngx_chain_t     *cl;
    ngx_iovec_t      header, trailer;
    struct sf_hdtr   hdtr;
    struct iovec     headers[NGX_IOVS_PREALLOCATE];
    struct iovec     trailers[NGX_IOVS_PREALLOCATE];

    wev = c->write;

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

#if (NGX_HAVE_KQUEUE)

    if ((ngx_event_flags & NGX_USE_KQUEUE_EVENT) && wev->pending_eof) {
        (void) ngx_connection_error(c, wev->kq_errno,
                               "kevent() reported about an closed connection");
        wev->error = 1;
        return NGX_CHAIN_ERROR;
    }

#endif

    /* the maximum limit size is the maximum size_t value - the page size */

    if (limit == 0 || limit > (off_t) (NGX_MAX_SIZE_T_VALUE - ngx_pagesize)) {
        limit = NGX_MAX_SIZE_T_VALUE - ngx_pagesize;
    }

    send = 0;

    header.iovs = headers;
    header.nalloc = NGX_IOVS_PREALLOCATE;

    trailer.iovs = trailers;
    trailer.nalloc = NGX_IOVS_PREALLOCATE;

    for ( ;; ) {
        eintr = 0;
        prev_send = send;

        /* create the header iovec and coalesce the neighbouring bufs */

        cl = ngx_output_chain_to_iovec(&header, in, limit - send, c->log);

        if (cl == NGX_CHAIN_ERROR) {
            return NGX_CHAIN_ERROR;
        }

        send += header.size;

        if (cl && cl->buf->in_file && send < limit) {
            file = cl->buf;

            /* coalesce the neighbouring file bufs */

            file_size = ngx_chain_coalesce_file(&cl, limit - send);

            send += file_size;

            if (header.count == 0 && send < limit) {

                /*
                 * create the trailer iovec and coalesce the neighbouring bufs
                 */

                cl = ngx_output_chain_to_iovec(&trailer, cl, limit - send,
                                               c->log);
                if (cl == NGX_CHAIN_ERROR) {
                    return NGX_CHAIN_ERROR;
                }

                send += trailer.size;

            } else {
                trailer.count = 0;
            }

            /*
             * sendfile() returns EINVAL if sf_hdtr's count is 0,
             * but corresponding pointer is not NULL
             */

            hdtr.headers = header.count ? header.iovs : NULL;
            hdtr.hdr_cnt = header.count;
            hdtr.trailers = trailer.count ? trailer.iovs : NULL;
            hdtr.trl_cnt = trailer.count;

            sent = header.size + file_size;

            ngx_log_debug3(NGX_LOG_DEBUG_EVENT, c->log, 0,
                           "sendfile: @%O %O h:%uz",
                           file->file_pos, sent, header.size);

            rc = sendfile(file->file->fd, c->fd, file->file_pos,
                          &sent, &hdtr, 0);

            if (rc == -1) {
                err = ngx_errno;

                switch (err) {
                case NGX_EAGAIN:
                    break;

                case NGX_EINTR:
                    eintr = 1;
                    break;

                default:
                    wev->error = 1;
                    (void) ngx_connection_error(c, err, "sendfile() failed");
                    return NGX_CHAIN_ERROR;
                }

                ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, err,
                               "sendfile() sent only %O bytes", sent);
            }

            if (rc == 0 && sent == 0) {

                /*
                 * if rc and sent equal to zero, then someone
                 * has truncated the file, so the offset became beyond
                 * the end of the file
                 */

                ngx_log_error(NGX_LOG_ALERT, c->log, 0,
                              "sendfile() reported that \"%s\" was truncated",
                              file->file->name.data);

                return NGX_CHAIN_ERROR;
            }

            ngx_log_debug4(NGX_LOG_DEBUG_EVENT, c->log, 0,
                           "sendfile: %d, @%O %O:%O",
                           rc, file->file_pos, sent, file_size + header.size);

        } else {
            n = ngx_writev(c, &header);

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

            sent = (n == NGX_AGAIN) ? 0 : n;
        }

        c->sent += sent;

        in = ngx_chain_update_sent(in, sent);

        if (eintr) {
            send = prev_send + sent;
            continue;
        }

        if (send - prev_send != sent) {
            wev->ready = 0;
            return in;
        }

        if (send >= limit || in == NULL) {
            return in;
        }
    }
}