Mercurial > hg > nginx
view src/os/unix/ngx_darwin_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 | 7cc2d3a96ea3 |
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> /* * 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; } } }