Unverified Commit 1b8ed4ad authored by Daniel Stenberg's avatar Daniel Stenberg
Browse files

libcurl-thread.3: expand somewhat on the NO_SIGNAL motivation 

Multi-threaded applictions basically MUST set CURLOPT_NO_SIGNAL to 1L to
avoid the risk of getting a SIGPIPE.

Either way, a multi-threaded application that uses libcurl/openssl needs
to have a signhandler for or ignore SIGPIPE on its own.

Based on discussions in #2800
Closes #2904
parent 3c7511b9

docs/libcurl/libcurl-thread.3

+9 −3
Original line number Diff line number Diff line
@@ -5,7 +5,7 @@ 
.\" *                            | (__| |_| |  _ <| |___

.\" *                             \___|\___/|_| \_\_____|

.\" *

.\" * Copyright (C) 2015 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.

.\" * Copyright (C) 2015 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.

.\" *

.\" * This software is licensed as described in the file COPYING, which

.\" * you should have received as part of this distribution. The terms
@@ -79,8 +79,14 @@ all handles. Everything will or might work fine except that timeouts are not 
honored during the DNS lookup - which you can work around by building libcurl

with c-ares or threaded-resolver support. c-ares is a library that provides

asynchronous name resolves. On some platforms, libcurl simply will not

function properly multi-threaded unless the \fICURLOPT_NOSIGNAL(3)\fP option is

set.

function properly multi-threaded unless the \fICURLOPT_NOSIGNAL(3)\fP option

is set.



When \fICURLOPT_NOSIGNAL(3)\fP is set to 1L, your application needs to deal

with the risk of a SIGPIPE (that at least the OpenSSL backend can

trigger). Note that setting \fICURLOPT_NOSIGNAL(3)\fP to 0L will not work in a

threaded situation as there will be race where libcurl risks restoring the

former signal handler while another thread should still ignore it.

.IP "Name resolving"

\fBgethostby* functions and other system calls.\fP These functions, provided

by your operating system, must be thread safe. It is very important that