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                     22: .TH curl_global_init 3 "January 23, 2020" "libcurl 7.70.0" "libcurl Manual"
                     23: 
                     24: .SH NAME
                     25: curl_global_init - Global libcurl initialisation
                     26: .SH SYNOPSIS
                     27: .B #include <curl/curl.h>
                     28: .sp
                     29: .BI "CURLcode curl_global_init(long " flags ");"
                     30: .ad
                     31: .SH DESCRIPTION
                     32: This function sets up the program environment that libcurl needs.  Think of it
                     33: as an extension of the library loader.
                     34: 
                     35: This function must be called at least once within a program (a program is all
                     36: the code that shares a memory space) before the program calls any other
                     37: function in libcurl.  The environment it sets up is constant for the life of
                     38: the program and is the same for every program, so multiple calls have the same
                     39: effect as one call.
                     40: 
                     41: The flags option is a bit pattern that tells libcurl exactly what features to
                     42: init, as described below. Set the desired bits by ORing the values together.
                     43: In normal operation, you must specify CURL_GLOBAL_ALL.  Don't use any other
                     44: value unless you are familiar with it and mean to control internal operations of
                     45: libcurl.
                     46: 
                     47: \fBThis function is not thread safe.\fP You must not call it when any other
                     48: thread in the program (i.e. a thread sharing the same memory) is running.
                     49: This doesn't just mean no other thread that is using libcurl.  Because
                     50: \fIcurl_global_init(3)\fP calls functions of other libraries that are
                     51: similarly thread unsafe, it could conflict with any other thread that uses
                     52: these other libraries.
                     53: 
                     54: If you are initializing libcurl from a Windows DLL you should not initialize it
                     55: from DllMain or a static initializer because Windows holds the loader lock
                     56: during that time and it could cause a deadlock.
                     57: 
                     58: See the description in \fIlibcurl(3)\fP of global environment requirements for
                     59: details of how to use this function.
                     60: .SH FLAGS
                     61: .IP CURL_GLOBAL_ALL
                     62: Initialize everything possible. This sets all known bits except
                     63: \fBCURL_GLOBAL_ACK_EINTR\fP.
                     64: 
                     65: .IP CURL_GLOBAL_SSL
                     66: (This flag's presence or absence serves no meaning since 7.57.0. The
                     67: description below is for older libcurl versions.)
                     68: 
                     69: Initialize SSL.
                     70: 
                     71: The implication here is that if this bit is not set, the initialization of the
                     72: SSL layer needs to be done by the application or at least outside of
                     73: libcurl. The exact procedure how to do SSL initialization depends on the TLS
                     74: backend libcurl uses.
                     75: 
                     76: Doing TLS based transfers without having the TLS layer initialized may lead to
                     77: unexpected behaviors.
                     78: .IP CURL_GLOBAL_WIN32
                     79: Initialize the Win32 socket libraries.
                     80: 
                     81: The implication here is that if this bit is not set, the initialization of
                     82: winsock has to be done by the application or you risk getting undefined
                     83: behaviors. This option exists for when the initialization is handled outside
                     84: of libcurl so there's no need for libcurl to do it again.
                     85: .IP CURL_GLOBAL_NOTHING
                     86: Initialise nothing extra. This sets no bit.
                     87: .IP CURL_GLOBAL_DEFAULT
                     88: A sensible default. It will init both SSL and Win32. Right now, this equals
                     89: the functionality of the \fBCURL_GLOBAL_ALL\fP mask.
                     90: .IP CURL_GLOBAL_ACK_EINTR
                     91: This bit has no point since 7.69.0 but its behavior is instead the default.
                     92: 
                     93: Before 7.69.0: when this flag is set, curl will acknowledge EINTR condition
                     94: when connecting or when waiting for data.  Otherwise, curl waits until full
                     95: timeout elapses. (Added in 7.30.0)
                     96: .SH RETURN VALUE
                     97: If this function returns non-zero, something went wrong and you cannot use the
                     98: other curl functions.
                     99: .SH "SEE ALSO"
                    100: .BR curl_global_init_mem "(3), "
                    101: .BR curl_global_cleanup "(3), "
                    102: .BR curl_global_sslset "(3), "
                    103: .BR curl_easy_init "(3) "
                    104: .BR libcurl "(3) "