Mercurial > hg > nginx
view src/os/unix/ngx_freebsd_sendfile_chain.c @ 8018:5119c8150478
Fixed runtime handling of systems without EPOLLRDHUP support.
In 7583:efd71d49bde0 (nginx 1.17.5) along with introduction of the
ioctl(FIONREAD) support proper handling of systems without EPOLLRDHUP
support in the kernel (but with EPOLLRDHUP in headers) was broken.
Before the change, rev->available was never set to 0 unless
ngx_use_epoll_rdhup was also set (that is, runtime test for EPOLLRDHUP
introduced in 6536:f7849bfb6d21 succeeded). After the change,
rev->available might reach 0 on systems without runtime EPOLLRDHUP
support, stopping further reading in ngx_readv_chain() and ngx_unix_recv().
And, if EOF happened to be already reported along with the last event,
it is not reported again by epoll_wait(), leading to connection hangs
and timeouts on such systems.
This affects Linux kernels before 2.6.17 if nginx was compiled
with newer headers, and, more importantly, emulation layers, such as
DigitalOcean's App Platform's / gVisor's epoll emulation layer.
Fix is to explicitly check ngx_use_epoll_rdhup before the corresponding
rev->pending_eof tests in ngx_readv_chain() and ngx_unix_recv().
author | Marcus Ball <marcus.ball@live.com> |
---|---|
date | Mon, 30 May 2022 02:38:07 +0300 |
parents | b002ad258f1d |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_event.h> /* * Although FreeBSD sendfile() allows to pass a header and a trailer, * it cannot send a header with a part of the file in one packet until * FreeBSD 5.3. Besides, over the fast ethernet connection sendfile() * may send the partially filled packets, i.e. the 8 file pages may be sent * as the 11 full 1460-bytes packets, then one incomplete 324-bytes packet, * and then again the 11 full 1460-bytes packets. * * Therefore we use the TCP_NOPUSH option (similar to Linux's TCP_CORK) * to postpone the sending - it not only sends a header and the first part of * the file in one packet, but also sends the file pages in the full packets. * * But until FreeBSD 4.5 turning TCP_NOPUSH off does not flush a pending * data that less than MSS, so that data may be sent with 5 second delay. * So we do not use TCP_NOPUSH on FreeBSD prior to 4.5, although it can be used * for non-keepalive HTTP connections. */ ngx_chain_t * ngx_freebsd_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit) { int rc, flags; off_t send, prev_send, sent; size_t file_size; ssize_t n; ngx_err_t err; ngx_buf_t *file; ngx_uint_t eintr, eagain; #if (NGX_HAVE_SENDFILE_NODISKIO) ngx_uint_t ebusy; #endif 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; eagain = 0; flags = 0; header.iovs = headers; header.nalloc = NGX_IOVS_PREALLOCATE; trailer.iovs = trailers; trailer.nalloc = NGX_IOVS_PREALLOCATE; for ( ;; ) { eintr = 0; #if (NGX_HAVE_SENDFILE_NODISKIO) ebusy = 0; #endif 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 = (size_t) ngx_chain_coalesce_file(&cl, limit - send); send += file_size; if (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; } if (ngx_freebsd_use_tcp_nopush && c->tcp_nopush == NGX_TCP_NOPUSH_UNSET) { if (ngx_tcp_nopush(c->fd) == -1) { err = ngx_socket_errno; /* * there is a tiny chance to be interrupted, however, * we continue a processing without the TCP_NOPUSH */ if (err != NGX_EINTR) { wev->error = 1; (void) ngx_connection_error(c, err, ngx_tcp_nopush_n " failed"); return NGX_CHAIN_ERROR; } } else { c->tcp_nopush = NGX_TCP_NOPUSH_SET; ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, 0, "tcp_nopush"); } } /* * sendfile() does unneeded work 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; /* * the "nbytes bug" of the old sendfile() syscall: * http://bugs.freebsd.org/33771 */ if (!ngx_freebsd_sendfile_nbytes_bug) { header.size = 0; } sent = 0; #if (NGX_HAVE_SENDFILE_NODISKIO) flags = (c->busy_count <= 2) ? SF_NODISKIO : 0; if (file->file->directio) { flags |= SF_NOCACHE; } #endif rc = sendfile(file->file->fd, c->fd, file->file_pos, file_size + header.size, &hdtr, &sent, flags); if (rc == -1) { err = ngx_errno; switch (err) { case NGX_EAGAIN: eagain = 1; break; case NGX_EINTR: eintr = 1; break; #if (NGX_HAVE_SENDFILE_NODISKIO) case NGX_EBUSY: ebusy = 1; break; #endif 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); /* * sendfile() in FreeBSD 3.x-4.x may return value >= 0 * on success, although only 0 is documented */ } else if (rc >= 0 && sent == 0) { /* * if rc is OK 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 at %O", file->file->name.data, file->file_pos); return NGX_CHAIN_ERROR; } ngx_log_debug4(NGX_LOG_DEBUG_EVENT, c->log, 0, "sendfile: %d, @%O %O:%uz", 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 (NGX_HAVE_SENDFILE_NODISKIO) if (ebusy) { if (sent == 0) { c->busy_count++; ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "sendfile() busy, count:%d", c->busy_count); } else { c->busy_count = 0; } if (wev->posted) { ngx_delete_posted_event(wev); } ngx_post_event(wev, &ngx_posted_next_events); wev->ready = 0; return in; } c->busy_count = 0; #endif if (eagain) { /* * sendfile() may return EAGAIN, even if it has sent a whole file * part, it indicates that the successive sendfile() call would * return EAGAIN right away and would not send anything. * We use it as a hint. */ wev->ready = 0; return in; } if (eintr) { send = prev_send + sent; continue; } if (send - prev_send != sent) { wev->ready = 0; return in; } if (send >= limit || in == NULL) { return in; } } }