23fe1a52dc
Currently, we use `pipe` for `wakeup_create`, which requires ***two***
file descriptors. Furthermore, given its complexity inside, `pipe` is a
bit heavyweight for just a simple event wait/notify mechanism.
`eventfd` would be a more suitable solution for this kind of scenario,
kernel also advocates for developers to use `eventfd` instead of `pipe`
in some simple use cases:
Applications can use an eventfd file descriptor instead of a pipe
(see pipe(2) in all cases where a pipe is used simply to signal
events. The kernel overhead of an eventfd file descriptor is much
lower than that of a pipe, and only one file descriptor is required
(versus the two required for a pipe).
This change adds the new backend of `eventfd` for `wakeup_create` and
uses it where available, eliminating the overhead of `pipe`. Also, it
optimizes the `wakeup_create` to eliminate the system calls that make
file descriptors non-blocking by moving the logic of setting
non-blocking flags on file descriptors to `socketpair.c` and using
`SOCK_NONBLOCK` for `socketpair(2)`, `EFD_NONBLOCK` for `eventfd(2)`.
Ref:
https://man7.org/linux/man-pages/man7/pipe.7.html
https://man7.org/linux/man-pages/man2/eventfd.2.html
https://man7.org/linux/man-pages/man2/socketpair.2.html
https://www.gnu.org/software/gnulib/manual/html_node/eventfd.html
Closes #13874
263 lines
6.8 KiB
C
263 lines
6.8 KiB
C
/***************************************************************************
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* _ _ ____ _
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* Project ___| | | | _ \| |
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* / __| | | | |_) | |
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* | (__| |_| | _ <| |___
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* \___|\___/|_| \_\_____|
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*
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* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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*
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* This software is licensed as described in the file COPYING, which
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* you should have received as part of this distribution. The terms
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* are also available at https://curl.se/docs/copyright.html.
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*
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* You may opt to use, copy, modify, merge, publish, distribute and/or sell
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* copies of the Software, and permit persons to whom the Software is
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* furnished to do so, under the terms of the COPYING file.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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* SPDX-License-Identifier: curl
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*
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***************************************************************************/
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#include "curl_setup.h"
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#include "socketpair.h"
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#include "urldata.h"
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#include "rand.h"
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#if defined(USE_EVENTFD)
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#ifdef HAVE_SYS_EVENTFD_H
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#include <sys/eventfd.h>
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#endif
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int Curl_eventfd(curl_socket_t socks[2], bool nonblocking)
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{
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int efd = eventfd(0, nonblocking ? EFD_CLOEXEC | EFD_NONBLOCK : EFD_CLOEXEC);
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if(efd == -1) {
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socks[0] = socks[1] = CURL_SOCKET_BAD;
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return -1;
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}
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socks[0] = socks[1] = efd;
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return 0;
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}
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#elif defined(HAVE_PIPE)
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#ifdef HAVE_FCNTL
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#include <fcntl.h>
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#endif
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int Curl_pipe(curl_socket_t socks[2], bool nonblocking)
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{
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if(pipe(socks))
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return -1;
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#ifdef HAVE_FCNTL
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if(fcntl(socks[0], F_SETFD, FD_CLOEXEC) ||
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fcntl(socks[1], F_SETFD, FD_CLOEXEC) ) {
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close(socks[0]);
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close(socks[1]);
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socks[0] = socks[1] = CURL_SOCKET_BAD;
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return -1;
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}
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#endif
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if(nonblocking) {
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if(curlx_nonblock(socks[0], TRUE) < 0 ||
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curlx_nonblock(socks[1], TRUE) < 0) {
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close(socks[0]);
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close(socks[1]);
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socks[0] = socks[1] = CURL_SOCKET_BAD;
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return -1;
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}
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}
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return 0;
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}
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#endif
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#if !defined(HAVE_SOCKETPAIR) && !defined(CURL_DISABLE_SOCKETPAIR)
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#ifdef _WIN32
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/*
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* This is a socketpair() implementation for Windows.
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*/
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#include <string.h>
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#include <io.h>
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#else
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#ifdef HAVE_NETDB_H
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#include <netdb.h>
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#endif
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#ifdef HAVE_NETINET_IN_H
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#include <netinet/in.h> /* IPPROTO_TCP */
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#endif
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#ifdef HAVE_ARPA_INET_H
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#include <arpa/inet.h>
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#endif
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#ifndef INADDR_LOOPBACK
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#define INADDR_LOOPBACK 0x7f000001
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#endif /* !INADDR_LOOPBACK */
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#endif /* !_WIN32 */
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#include "nonblock.h" /* for curlx_nonblock */
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#include "timeval.h" /* needed before select.h */
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#include "select.h" /* for Curl_poll */
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/* The last 3 #include files should be in this order */
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#include "curl_printf.h"
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#include "curl_memory.h"
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#include "memdebug.h"
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int Curl_socketpair(int domain, int type, int protocol,
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curl_socket_t socks[2], bool nonblocking)
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{
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union {
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struct sockaddr_in inaddr;
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struct sockaddr addr;
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} a;
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curl_socket_t listener;
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curl_socklen_t addrlen = sizeof(a.inaddr);
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int reuse = 1;
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struct pollfd pfd[1];
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(void)domain;
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(void)type;
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(void)protocol;
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listener = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
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if(listener == CURL_SOCKET_BAD)
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return -1;
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memset(&a, 0, sizeof(a));
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a.inaddr.sin_family = AF_INET;
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a.inaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
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a.inaddr.sin_port = 0;
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socks[0] = socks[1] = CURL_SOCKET_BAD;
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#if defined(_WIN32) || defined(__CYGWIN__)
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/* don't set SO_REUSEADDR on Windows */
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(void)reuse;
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#ifdef SO_EXCLUSIVEADDRUSE
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{
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int exclusive = 1;
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if(setsockopt(listener, SOL_SOCKET, SO_EXCLUSIVEADDRUSE,
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(char *)&exclusive, (curl_socklen_t)sizeof(exclusive)) == -1)
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goto error;
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}
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#endif
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#else
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if(setsockopt(listener, SOL_SOCKET, SO_REUSEADDR,
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(char *)&reuse, (curl_socklen_t)sizeof(reuse)) == -1)
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goto error;
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#endif
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if(bind(listener, &a.addr, sizeof(a.inaddr)) == -1)
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goto error;
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if(getsockname(listener, &a.addr, &addrlen) == -1 ||
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addrlen < (int)sizeof(a.inaddr))
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goto error;
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if(listen(listener, 1) == -1)
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goto error;
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socks[0] = socket(AF_INET, SOCK_STREAM, 0);
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if(socks[0] == CURL_SOCKET_BAD)
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goto error;
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if(connect(socks[0], &a.addr, sizeof(a.inaddr)) == -1)
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goto error;
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/* use non-blocking accept to make sure we don't block forever */
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if(curlx_nonblock(listener, TRUE) < 0)
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goto error;
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pfd[0].fd = listener;
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pfd[0].events = POLLIN;
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pfd[0].revents = 0;
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(void)Curl_poll(pfd, 1, 1000); /* one second */
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socks[1] = accept(listener, NULL, NULL);
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if(socks[1] == CURL_SOCKET_BAD)
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goto error;
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else {
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struct curltime start = Curl_now();
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char rnd[9];
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char check[sizeof(rnd)];
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char *p = &check[0];
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size_t s = sizeof(check);
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if(Curl_rand(NULL, (unsigned char *)rnd, sizeof(rnd)))
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goto error;
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/* write data to the socket */
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swrite(socks[0], rnd, sizeof(rnd));
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/* verify that we read the correct data */
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do {
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ssize_t nread;
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pfd[0].fd = socks[1];
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pfd[0].events = POLLIN;
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pfd[0].revents = 0;
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(void)Curl_poll(pfd, 1, 1000); /* one second */
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nread = sread(socks[1], p, s);
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if(nread == -1) {
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int sockerr = SOCKERRNO;
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/* Don't block forever */
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if(Curl_timediff(Curl_now(), start) > (60 * 1000))
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goto error;
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if(
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#ifdef WSAEWOULDBLOCK
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/* This is how Windows does it */
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(WSAEWOULDBLOCK == sockerr)
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#else
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/* errno may be EWOULDBLOCK or on some systems EAGAIN when it
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returned due to its inability to send off data without
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blocking. We therefore treat both error codes the same here */
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(EWOULDBLOCK == sockerr) || (EAGAIN == sockerr) ||
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(EINTR == sockerr) || (EINPROGRESS == sockerr)
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#endif
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) {
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continue;
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}
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goto error;
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}
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s -= nread;
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if(s) {
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p += nread;
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continue;
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}
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if(memcmp(rnd, check, sizeof(check)))
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goto error;
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break;
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} while(1);
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}
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if(nonblocking)
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if(curlx_nonblock(socks[0], TRUE) < 0 ||
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curlx_nonblock(socks[1], TRUE) < 0)
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goto error;
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sclose(listener);
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return 0;
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error:
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sclose(listener);
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sclose(socks[0]);
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sclose(socks[1]);
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return -1;
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}
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#else
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int Curl_socketpair(int domain, int type, int protocol,
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curl_socket_t socks[2], bool nonblocking)
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{
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#ifdef SOCK_NONBLOCK
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type = nonblocking ? type | SOCK_NONBLOCK : type;
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#endif
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if(socketpair(domain, type, protocol, socks))
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return -1;
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#ifndef SOCK_NONBLOCK
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if(nonblocking) {
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if(curlx_nonblock(socks[0], TRUE) < 0 ||
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curlx_nonblock(socks[1], TRUE) < 0) {
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close(socks[0]);
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close(socks[1]);
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return -1;
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}
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}
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#endif
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return 0;
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}
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#endif /* ! HAVE_SOCKETPAIR */
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