.\" ************************************************************************** .\" * _ _ ____ _ .\" * Project ___| | | | _ \| | .\" * / __| | | | |_) | | .\" * | (__| |_| | _ <| |___ .\" * \___|\___/|_| \_\_____| .\" * .\" * Copyright (C) 1998 - 2017, 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 .\" * are also available at https://curl.haxx.se/docs/copyright.html. .\" * .\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell .\" * copies of the Software, and permit persons to whom the Software is .\" * furnished to do so, under the terms of the COPYING file. .\" * .\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY .\" * KIND, either express or implied. .\" * .\" ************************************************************************** .TH curl_global_init 3 "11 May 2004" "libcurl 7.12" "libcurl Manual" .SH NAME curl_global_init - Global libcurl initialisation .SH SYNOPSIS .B #include <curl/curl.h> .sp .BI "CURLcode curl_global_init(long " flags ");" .ad .SH DESCRIPTION This function sets up the program environment that libcurl needs. Think of it as an extension of the library loader. This function must be called at least once within a program (a program is all the code that shares a memory space) before the program calls any other function in libcurl. The environment it sets up is constant for the life of the program and is the same for every program, so multiple calls have the same effect as one call. The flags option is a bit pattern that tells libcurl exactly what features to init, as described below. Set the desired bits by ORing the values together. In normal operation, you must specify CURL_GLOBAL_ALL. Don't use any other value unless you are familiar with it and mean to control internal operations of libcurl. \fBThis function is not thread safe.\fP You must not call it when any other thread in the program (i.e. a thread sharing the same memory) is running. This doesn't just mean no other thread that is using libcurl. Because \fIcurl_global_init(3)\fP calls functions of other libraries that are similarly thread unsafe, it could conflict with any other thread that uses these other libraries. If you are initializing libcurl from a Windows DLL you should not initialize it from DllMain or a static initializer because Windows holds the loader lock during that time and it could cause a deadlock. See the description in \fIlibcurl(3)\fP of global environment requirements for details of how to use this function. .SH FLAGS .IP CURL_GLOBAL_ALL Initialize everything possible. This sets all known bits except \fBCURL_GLOBAL_ACK_EINTR\fP. .IP CURL_GLOBAL_SSL (This flag's presence or absence serves no meaning since 7.57.0. The description below is for older libcurl versions.) Initialize SSL. The implication here is that if this bit is not set, the initialization of the SSL layer needs to be done by the application or at least outside of libcurl. The exact procedure how to do SSL initialization depends on the TLS backend libcurl uses. Doing TLS based transfers without having the TLS layer initialized may lead to unexpected behaviors. .IP CURL_GLOBAL_WIN32 Initialize the Win32 socket libraries. The implication here is that if this bit is not set, the initialization of winsock has to be done by the application or you risk getting undefined behaviors. This option exists for when the initialization is handled outside of libcurl so there's no need for libcurl to do it again. .IP CURL_GLOBAL_NOTHING Initialise nothing extra. This sets no bit. .IP CURL_GLOBAL_DEFAULT A sensible default. It will init both SSL and Win32. Right now, this equals the functionality of the \fBCURL_GLOBAL_ALL\fP mask. .IP CURL_GLOBAL_ACK_EINTR When this flag is set, curl will acknowledge EINTR condition when connecting or when waiting for data. Otherwise, curl waits until full timeout elapses. (Added in 7.30.0) .SH RETURN VALUE If this function returns non-zero, something went wrong and you cannot use the other curl functions. .SH "SEE ALSO" .BR curl_global_init_mem "(3), " .BR curl_global_cleanup "(3), " .BR curl_global_sslset "(3), " .BR curl_easy_init "(3) " .BR libcurl "(3) "